dom/canvas/WebGLContextGL.cpp
author Sylvestre Ledru <sledru@mozilla.com>
Thu, 17 Aug 2017 11:13:01 +0200
changeset 648192 c236dfe7dc98c387219d7cb45d0693560db708fd
parent 611280 aef0921e8682aef490ffb00fab256f0b4b0a0954
permissions -rw-r--r--
indent all (with js specific coding style) MozReview-Commit-ID: LU1md2wyB8

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "WebGLContext.h"
#include "WebGL2Context.h"

#include "WebGLActiveInfo.h"
#include "WebGLContextUtils.h"
#include "WebGLBuffer.h"
#include "WebGLVertexAttribData.h"
#include "WebGLShader.h"
#include "WebGLProgram.h"
#include "WebGLUniformLocation.h"
#include "WebGLFormats.h"
#include "WebGLFramebuffer.h"
#include "WebGLRenderbuffer.h"
#include "WebGLShaderPrecisionFormat.h"
#include "WebGLTexture.h"
#include "WebGLExtensions.h"
#include "WebGLVertexArray.h"

#include "nsDebug.h"
#include "nsReadableUtils.h"
#include "nsString.h"

#include "gfxContext.h"
#include "gfxPlatform.h"
#include "GLContext.h"

#include "nsContentUtils.h"
#include "nsError.h"
#include "nsLayoutUtils.h"

#include "CanvasUtils.h"
#include "gfxUtils.h"

#include "jsfriendapi.h"

#include "WebGLTexelConversions.h"
#include "WebGLValidateStrings.h"
#include <algorithm>

// needed to check if current OS is lower than 10.7
#if defined(MOZ_WIDGET_COCOA)
#include "nsCocoaFeatures.h"
#endif

#include "mozilla/DebugOnly.h"
#include "mozilla/dom/BindingUtils.h"
#include "mozilla/dom/ImageData.h"
#include "mozilla/dom/ToJSValue.h"
#include "mozilla/EndianUtils.h"
#include "mozilla/RefPtr.h"
#include "mozilla/UniquePtrExtensions.h"

namespace mozilla {

bool
WebGLContext::ValidateObject(const char* funcName, const WebGLProgram& object)
{
  return ValidateObject(funcName, object, true);
}

bool
WebGLContext::ValidateObject(const char* funcName, const WebGLShader& object)
{
  return ValidateObject(funcName, object, true);
}

using namespace mozilla::dom;
using namespace mozilla::gfx;
using namespace mozilla::gl;

//
//  WebGL API
//

void
WebGLContext::ActiveTexture(GLenum texture)
{
  if (IsContextLost())
    return;

  if (texture < LOCAL_GL_TEXTURE0 ||
      texture >= LOCAL_GL_TEXTURE0 + uint32_t(mGLMaxTextureUnits)) {
    return ErrorInvalidEnum(
      "ActiveTexture: texture unit %d out of range. "
      "Accepted values range from TEXTURE0 to TEXTURE0 + %d. "
      "Notice that TEXTURE0 != 0.",
      texture,
      mGLMaxTextureUnits);
  }

  MakeContextCurrent();
  mActiveTexture = texture - LOCAL_GL_TEXTURE0;
  gl->fActiveTexture(texture);
}

void
WebGLContext::AttachShader(WebGLProgram& program, WebGLShader& shader)
{
  if (IsContextLost())
    return;

  if (!ValidateObject("attachShader: program", program) ||
      !ValidateObject("attachShader: shader", shader)) {
    return;
  }

  program.AttachShader(&shader);
}

void
WebGLContext::BindAttribLocation(WebGLProgram& prog,
                                 GLuint location,
                                 const nsAString& name)
{
  if (IsContextLost())
    return;

  if (!ValidateObject("bindAttribLocation: program", prog))
    return;

  prog.BindAttribLocation(location, name);
}

void
WebGLContext::BindFramebuffer(GLenum target, WebGLFramebuffer* wfb)
{
  if (IsContextLost())
    return;

  if (!ValidateFramebufferTarget(target, "bindFramebuffer"))
    return;

  if (wfb && !ValidateObject("bindFramebuffer", *wfb))
    return;

  MakeContextCurrent();

  if (!wfb) {
    gl->fBindFramebuffer(target, 0);
  } else {
    GLuint framebuffername = wfb->mGLName;
    gl->fBindFramebuffer(target, framebuffername);
#ifdef ANDROID
    wfb->mIsFB = true;
#endif
  }

  switch (target) {
    case LOCAL_GL_FRAMEBUFFER:
      mBoundDrawFramebuffer = wfb;
      mBoundReadFramebuffer = wfb;
      break;
    case LOCAL_GL_DRAW_FRAMEBUFFER:
      mBoundDrawFramebuffer = wfb;
      break;
    case LOCAL_GL_READ_FRAMEBUFFER:
      mBoundReadFramebuffer = wfb;
      break;
    default:
      break;
  }
}

void
WebGLContext::BindRenderbuffer(GLenum target, WebGLRenderbuffer* wrb)
{
  if (IsContextLost())
    return;

  if (target != LOCAL_GL_RENDERBUFFER)
    return ErrorInvalidEnumInfo("bindRenderbuffer: target", target);

  if (wrb && !ValidateObject("bindRenderbuffer", *wrb))
    return;

  // Usually, we would now call into glBindRenderbuffer. However, since we have to
  // potentially emulate packed-depth-stencil, there's not a specific renderbuffer that
  // we know we should bind here.
  // Instead, we do all renderbuffer binding lazily.

  if (wrb) {
    wrb->mHasBeenBound = true;
  }

  mBoundRenderbuffer = wrb;
}

void
WebGLContext::BlendEquation(GLenum mode)
{
  if (IsContextLost())
    return;

  if (!ValidateBlendEquationEnum(mode, "blendEquation: mode"))
    return;

  MakeContextCurrent();
  gl->fBlendEquation(mode);
}

void
WebGLContext::BlendEquationSeparate(GLenum modeRGB, GLenum modeAlpha)
{
  if (IsContextLost())
    return;

  if (!ValidateBlendEquationEnum(modeRGB, "blendEquationSeparate: modeRGB") ||
      !ValidateBlendEquationEnum(modeAlpha, "blendEquationSeparate: modeAlpha"))
    return;

  MakeContextCurrent();
  gl->fBlendEquationSeparate(modeRGB, modeAlpha);
}

static bool
ValidateBlendFuncEnum(WebGLContext* webgl,
                      GLenum factor,
                      const char* funcName,
                      const char* varName)
{
  switch (factor) {
    case LOCAL_GL_ZERO:
    case LOCAL_GL_ONE:
    case LOCAL_GL_SRC_COLOR:
    case LOCAL_GL_ONE_MINUS_SRC_COLOR:
    case LOCAL_GL_DST_COLOR:
    case LOCAL_GL_ONE_MINUS_DST_COLOR:
    case LOCAL_GL_SRC_ALPHA:
    case LOCAL_GL_ONE_MINUS_SRC_ALPHA:
    case LOCAL_GL_DST_ALPHA:
    case LOCAL_GL_ONE_MINUS_DST_ALPHA:
    case LOCAL_GL_CONSTANT_COLOR:
    case LOCAL_GL_ONE_MINUS_CONSTANT_COLOR:
    case LOCAL_GL_CONSTANT_ALPHA:
    case LOCAL_GL_ONE_MINUS_CONSTANT_ALPHA:
    case LOCAL_GL_SRC_ALPHA_SATURATE:
      return true;

    default:
      const nsPrintfCString err("%s: %s", funcName, varName);
      webgl->ErrorInvalidEnumInfo(err.get(), factor);
      return false;
  }
}

static bool
ValidateBlendFuncEnums(WebGLContext* webgl,
                       GLenum srcRGB,
                       GLenum srcAlpha,
                       GLenum dstRGB,
                       GLenum dstAlpha,
                       const char* funcName)
{
  if (!webgl->IsWebGL2()) {
    if (dstRGB == LOCAL_GL_SRC_ALPHA_SATURATE ||
        dstAlpha == LOCAL_GL_SRC_ALPHA_SATURATE) {
      const nsPrintfCString err(
        "%s: LOCAL_GL_SRC_ALPHA_SATURATE as a destination"
        " blend function is disallowed in WebGL 1 (dstRGB ="
        " 0x%04x, dstAlpha = 0x%04x).",
        funcName,
        dstRGB,
        dstAlpha);
      webgl->ErrorInvalidEnum("%s", err.get());
      return false;
    }
  }

  if (!ValidateBlendFuncEnum(webgl, srcRGB, funcName, "srcRGB") ||
      !ValidateBlendFuncEnum(webgl, srcAlpha, funcName, "srcAlpha") ||
      !ValidateBlendFuncEnum(webgl, dstRGB, funcName, "dstRGB") ||
      !ValidateBlendFuncEnum(webgl, dstAlpha, funcName, "dstAlpha")) {
    return false;
  }

  return true;
}

void
WebGLContext::BlendFunc(GLenum sfactor, GLenum dfactor)
{
  if (IsContextLost())
    return;

  if (!ValidateBlendFuncEnums(
        this, sfactor, sfactor, dfactor, dfactor, "blendFunc"))
    return;

  if (!ValidateBlendFuncEnumsCompatibility(
        sfactor, dfactor, "blendFuncSeparate: srcRGB and dstRGB"))
    return;

  MakeContextCurrent();
  gl->fBlendFunc(sfactor, dfactor);
}

void
WebGLContext::BlendFuncSeparate(GLenum srcRGB,
                                GLenum dstRGB,
                                GLenum srcAlpha,
                                GLenum dstAlpha)
{
  if (IsContextLost())
    return;

  if (!ValidateBlendFuncEnums(
        this, srcRGB, srcAlpha, dstRGB, dstAlpha, "blendFuncSeparate"))
    return;

  // note that we only check compatibity for the RGB enums, no need to for the Alpha enums, see
  // "Section 6.8 forgetting to mention alpha factors?" thread on the public_webgl mailing list
  if (!ValidateBlendFuncEnumsCompatibility(
        srcRGB, dstRGB, "blendFuncSeparate: srcRGB and dstRGB"))
    return;

  MakeContextCurrent();
  gl->fBlendFuncSeparate(srcRGB, dstRGB, srcAlpha, dstAlpha);
}

GLenum
WebGLContext::CheckFramebufferStatus(GLenum target)
{
  const char funcName[] = "checkFramebufferStatus";
  if (IsContextLost())
    return LOCAL_GL_FRAMEBUFFER_UNSUPPORTED;

  if (!ValidateFramebufferTarget(target, funcName))
    return 0;

  WebGLFramebuffer* fb;
  switch (target) {
    case LOCAL_GL_FRAMEBUFFER:
    case LOCAL_GL_DRAW_FRAMEBUFFER:
      fb = mBoundDrawFramebuffer;
      break;

    case LOCAL_GL_READ_FRAMEBUFFER:
      fb = mBoundReadFramebuffer;
      break;

    default:
      MOZ_CRASH("GFX: Bad target.");
  }

  if (!fb)
    return LOCAL_GL_FRAMEBUFFER_COMPLETE;

  return fb->CheckFramebufferStatus(funcName).get();
}

already_AddRefed<WebGLProgram>
WebGLContext::CreateProgram()
{
  if (IsContextLost())
    return nullptr;
  RefPtr<WebGLProgram> globj = new WebGLProgram(this);
  return globj.forget();
}

already_AddRefed<WebGLShader>
WebGLContext::CreateShader(GLenum type)
{
  if (IsContextLost())
    return nullptr;

  if (type != LOCAL_GL_VERTEX_SHADER && type != LOCAL_GL_FRAGMENT_SHADER) {
    ErrorInvalidEnumInfo("createShader: type", type);
    return nullptr;
  }

  RefPtr<WebGLShader> shader = new WebGLShader(this, type);
  return shader.forget();
}

void
WebGLContext::CullFace(GLenum face)
{
  if (IsContextLost())
    return;

  if (!ValidateFaceEnum(face, "cullFace"))
    return;

  MakeContextCurrent();
  gl->fCullFace(face);
}

void
WebGLContext::DeleteFramebuffer(WebGLFramebuffer* fbuf)
{
  if (!ValidateDeleteObject("deleteFramebuffer", fbuf))
    return;

  fbuf->RequestDelete();

  if (mBoundReadFramebuffer == mBoundDrawFramebuffer) {
    if (mBoundDrawFramebuffer == fbuf) {
      BindFramebuffer(LOCAL_GL_FRAMEBUFFER,
                      static_cast<WebGLFramebuffer*>(nullptr));
    }
  } else if (mBoundDrawFramebuffer == fbuf) {
    BindFramebuffer(LOCAL_GL_DRAW_FRAMEBUFFER,
                    static_cast<WebGLFramebuffer*>(nullptr));
  } else if (mBoundReadFramebuffer == fbuf) {
    BindFramebuffer(LOCAL_GL_READ_FRAMEBUFFER,
                    static_cast<WebGLFramebuffer*>(nullptr));
  }
}

void
WebGLContext::DeleteRenderbuffer(WebGLRenderbuffer* rbuf)
{
  const char funcName[] = "deleteRenderbuffer";
  if (!ValidateDeleteObject(funcName, rbuf))
    return;

  if (mBoundDrawFramebuffer)
    mBoundDrawFramebuffer->DetachRenderbuffer(funcName, rbuf);

  if (mBoundReadFramebuffer)
    mBoundReadFramebuffer->DetachRenderbuffer(funcName, rbuf);

  rbuf->InvalidateStatusOfAttachedFBs(funcName);

  if (mBoundRenderbuffer == rbuf)
    BindRenderbuffer(LOCAL_GL_RENDERBUFFER, nullptr);

  rbuf->RequestDelete();
}

void
WebGLContext::DeleteTexture(WebGLTexture* tex)
{
  const char funcName[] = "deleteTexture";
  if (!ValidateDeleteObject(funcName, tex))
    return;

  if (mBoundDrawFramebuffer)
    mBoundDrawFramebuffer->DetachTexture(funcName, tex);

  if (mBoundReadFramebuffer)
    mBoundReadFramebuffer->DetachTexture(funcName, tex);

  GLuint activeTexture = mActiveTexture;
  for (int32_t i = 0; i < mGLMaxTextureUnits; i++) {
    if (mBound2DTextures[i] == tex || mBoundCubeMapTextures[i] == tex ||
        mBound3DTextures[i] == tex || mBound2DArrayTextures[i] == tex) {
      ActiveTexture(LOCAL_GL_TEXTURE0 + i);
      BindTexture(tex->Target().get(), nullptr);
    }
  }
  ActiveTexture(LOCAL_GL_TEXTURE0 + activeTexture);

  tex->RequestDelete();
}

void
WebGLContext::DeleteProgram(WebGLProgram* prog)
{
  if (!ValidateDeleteObject("deleteProgram", prog))
    return;

  prog->RequestDelete();
}

void
WebGLContext::DeleteShader(WebGLShader* shader)
{
  if (!ValidateDeleteObject("deleteShader", shader))
    return;

  shader->RequestDelete();
}

void
WebGLContext::DetachShader(WebGLProgram& program, const WebGLShader& shader)
{
  if (IsContextLost())
    return;

  // It's valid to attempt to detach a deleted shader, since it's still a
  // shader.
  if (!ValidateObject("detachShader: program", program) ||
      !ValidateObjectAllowDeleted("detachShader: shader", shader)) {
    return;
  }

  program.DetachShader(&shader);
}

void
WebGLContext::DepthFunc(GLenum func)
{
  if (IsContextLost())
    return;

  if (!ValidateComparisonEnum(func, "depthFunc"))
    return;

  MakeContextCurrent();
  gl->fDepthFunc(func);
}

void
WebGLContext::DepthRange(GLfloat zNear, GLfloat zFar)
{
  if (IsContextLost())
    return;

  if (zNear > zFar)
    return ErrorInvalidOperation(
      "depthRange: the near value is greater than the far value!");

  MakeContextCurrent();
  gl->fDepthRange(zNear, zFar);
}

void
WebGLContext::FramebufferRenderbuffer(GLenum target,
                                      GLenum attachment,
                                      GLenum rbtarget,
                                      WebGLRenderbuffer* wrb)
{
  const char funcName[] = "framebufferRenderbuffer";
  if (IsContextLost())
    return;

  if (!ValidateFramebufferTarget(target, funcName))
    return;

  WebGLFramebuffer* fb;
  switch (target) {
    case LOCAL_GL_FRAMEBUFFER:
    case LOCAL_GL_DRAW_FRAMEBUFFER:
      fb = mBoundDrawFramebuffer;
      break;

    case LOCAL_GL_READ_FRAMEBUFFER:
      fb = mBoundReadFramebuffer;
      break;

    default:
      MOZ_CRASH("GFX: Bad target.");
  }

  if (!fb)
    return ErrorInvalidOperation("%s: Cannot modify framebuffer 0.", funcName);

  fb->FramebufferRenderbuffer(funcName, attachment, rbtarget, wrb);
}

void
WebGLContext::FramebufferTexture2D(GLenum target,
                                   GLenum attachment,
                                   GLenum textarget,
                                   WebGLTexture* tobj,
                                   GLint level)
{
  const char funcName[] = "framebufferTexture2D";
  if (IsContextLost())
    return;

  if (!ValidateFramebufferTarget(target, funcName))
    return;

  WebGLFramebuffer* fb;
  switch (target) {
    case LOCAL_GL_FRAMEBUFFER:
    case LOCAL_GL_DRAW_FRAMEBUFFER:
      fb = mBoundDrawFramebuffer;
      break;

    case LOCAL_GL_READ_FRAMEBUFFER:
      fb = mBoundReadFramebuffer;
      break;

    default:
      MOZ_CRASH("GFX: Bad target.");
  }

  if (!fb)
    return ErrorInvalidOperation("%s: Cannot modify framebuffer 0.", funcName);

  fb->FramebufferTexture2D(funcName, attachment, textarget, tobj, level);
}

void
WebGLContext::FrontFace(GLenum mode)
{
  if (IsContextLost())
    return;

  switch (mode) {
    case LOCAL_GL_CW:
    case LOCAL_GL_CCW:
      break;
    default:
      return ErrorInvalidEnumInfo("frontFace: mode", mode);
  }

  MakeContextCurrent();
  gl->fFrontFace(mode);
}

already_AddRefed<WebGLActiveInfo>
WebGLContext::GetActiveAttrib(const WebGLProgram& prog, GLuint index)
{
  if (IsContextLost())
    return nullptr;

  if (!ValidateObject("getActiveAttrib: program", prog))
    return nullptr;

  return prog.GetActiveAttrib(index);
}

already_AddRefed<WebGLActiveInfo>
WebGLContext::GetActiveUniform(const WebGLProgram& prog, GLuint index)
{
  if (IsContextLost())
    return nullptr;

  if (!ValidateObject("getActiveUniform: program", prog))
    return nullptr;

  return prog.GetActiveUniform(index);
}

void
WebGLContext::GetAttachedShaders(
  const WebGLProgram& prog,
  dom::Nullable<nsTArray<RefPtr<WebGLShader>>>& retval)
{
  retval.SetNull();
  if (IsContextLost())
    return;

  if (!ValidateObject("getAttachedShaders", prog))
    return;

  prog.GetAttachedShaders(&retval.SetValue());
}

GLint
WebGLContext::GetAttribLocation(const WebGLProgram& prog, const nsAString& name)
{
  if (IsContextLost())
    return -1;

  if (!ValidateObject("getAttribLocation: program", prog))
    return -1;

  return prog.GetAttribLocation(name);
}

JS::Value
WebGLContext::GetBufferParameter(GLenum target, GLenum pname)
{
  const char funcName[] = "getBufferParameter";
  if (IsContextLost())
    return JS::NullValue();

  const auto& slot = ValidateBufferSlot(funcName, target);
  if (!slot)
    return JS::NullValue();
  const auto& buffer = *slot;

  if (!buffer) {
    ErrorInvalidOperation("%s: Buffer for `target` is null.", funcName);
    return JS::NullValue();
  }

  switch (pname) {
    case LOCAL_GL_BUFFER_SIZE:
      return JS::NumberValue(buffer->ByteLength());

    case LOCAL_GL_BUFFER_USAGE:
      return JS::NumberValue(buffer->Usage());

    default:
      ErrorInvalidEnumInfo("getBufferParameter: parameter", pname);
      return JS::NullValue();
  }
}

JS::Value
WebGLContext::GetFramebufferAttachmentParameter(JSContext* cx,
                                                GLenum target,
                                                GLenum attachment,
                                                GLenum pname,
                                                ErrorResult& rv)
{
  const char funcName[] = "getFramebufferAttachmentParameter";

  if (IsContextLost())
    return JS::NullValue();

  if (!ValidateFramebufferTarget(target, funcName))
    return JS::NullValue();

  WebGLFramebuffer* fb;
  switch (target) {
    case LOCAL_GL_FRAMEBUFFER:
    case LOCAL_GL_DRAW_FRAMEBUFFER:
      fb = mBoundDrawFramebuffer;
      break;

    case LOCAL_GL_READ_FRAMEBUFFER:
      fb = mBoundReadFramebuffer;
      break;

    default:
      MOZ_CRASH("GFX: Bad target.");
  }

  MakeContextCurrent();

  if (fb)
    return fb->GetAttachmentParameter(
      funcName, cx, target, attachment, pname, &rv);

  ////////////////////////////////////

  if (!IsWebGL2()) {
    ErrorInvalidOperation("%s: Querying against the default framebuffer is not"
                          " allowed in WebGL 1.",
                          funcName);
    return JS::NullValue();
  }

  switch (attachment) {
    case LOCAL_GL_BACK:
    case LOCAL_GL_DEPTH:
    case LOCAL_GL_STENCIL:
      break;

    default:
      ErrorInvalidEnum(
        "%s: For the default framebuffer, can only query COLOR, DEPTH,"
        " or STENCIL.",
        funcName);
      return JS::NullValue();
  }

  switch (pname) {
    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE:
      switch (attachment) {
        case LOCAL_GL_BACK:
          break;
        case LOCAL_GL_DEPTH:
          if (!mOptions.depth) {
            return JS::Int32Value(LOCAL_GL_NONE);
          }
          break;
        case LOCAL_GL_STENCIL:
          if (!mOptions.stencil) {
            return JS::Int32Value(LOCAL_GL_NONE);
          }
          break;
        default:
          ErrorInvalidEnum(
            "%s: With the default framebuffer, can only query COLOR, DEPTH,"
            " or STENCIL for GL_FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE",
            funcName);
          return JS::NullValue();
      }
      return JS::Int32Value(LOCAL_GL_FRAMEBUFFER_DEFAULT);

      ////////////////

    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_RED_SIZE:
    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_GREEN_SIZE:
    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_BLUE_SIZE:
      if (attachment == LOCAL_GL_BACK)
        return JS::NumberValue(8);
      return JS::NumberValue(0);

    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_ALPHA_SIZE:
      if (attachment == LOCAL_GL_BACK) {
        if (mOptions.alpha) {
          return JS::NumberValue(8);
        }
        ErrorInvalidOperation(
          "The default framebuffer doesn't contain an alpha buffer");
        return JS::NullValue();
      }
      return JS::NumberValue(0);

    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_DEPTH_SIZE:
      if (attachment == LOCAL_GL_DEPTH) {
        if (mOptions.depth) {
          return JS::NumberValue(24);
        }
        ErrorInvalidOperation(
          "The default framebuffer doesn't contain an depth buffer");
        return JS::NullValue();
      }
      return JS::NumberValue(0);

    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_STENCIL_SIZE:
      if (attachment == LOCAL_GL_STENCIL) {
        if (mOptions.stencil) {
          return JS::NumberValue(8);
        }
        ErrorInvalidOperation(
          "The default framebuffer doesn't contain an stencil buffer");
        return JS::NullValue();
      }
      return JS::NumberValue(0);

    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_COMPONENT_TYPE:
      if (attachment == LOCAL_GL_STENCIL) {
        if (mOptions.stencil) {
          return JS::NumberValue(LOCAL_GL_UNSIGNED_INT);
        }
        ErrorInvalidOperation(
          "The default framebuffer doesn't contain an stencil buffer");
      } else if (attachment == LOCAL_GL_DEPTH) {
        if (mOptions.depth) {
          return JS::NumberValue(LOCAL_GL_UNSIGNED_NORMALIZED);
        }
        ErrorInvalidOperation(
          "The default framebuffer doesn't contain an depth buffer");
      } else { // LOCAL_GL_BACK
        return JS::NumberValue(LOCAL_GL_UNSIGNED_NORMALIZED);
      }
      return JS::NullValue();

    case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_COLOR_ENCODING:
      if (attachment == LOCAL_GL_STENCIL) {
        if (!mOptions.stencil) {
          ErrorInvalidOperation(
            "The default framebuffer doesn't contain an stencil buffer");
          return JS::NullValue();
        }
      } else if (attachment == LOCAL_GL_DEPTH) {
        if (!mOptions.depth) {
          ErrorInvalidOperation(
            "The default framebuffer doesn't contain an depth buffer");
          return JS::NullValue();
        }
      }
      return JS::NumberValue(LOCAL_GL_LINEAR);
  }

  ErrorInvalidEnum("%s: Invalid pname: 0x%04x", funcName, pname);
  return JS::NullValue();
}

JS::Value
WebGLContext::GetRenderbufferParameter(GLenum target, GLenum pname)
{
  if (IsContextLost())
    return JS::NullValue();

  if (target != LOCAL_GL_RENDERBUFFER) {
    ErrorInvalidEnumInfo("getRenderbufferParameter: target", target);
    return JS::NullValue();
  }

  if (!mBoundRenderbuffer) {
    ErrorInvalidOperation(
      "getRenderbufferParameter: no render buffer is bound");
    return JS::NullValue();
  }

  MakeContextCurrent();

  switch (pname) {
    case LOCAL_GL_RENDERBUFFER_SAMPLES:
      if (!IsWebGL2())
        break;
      MOZ_FALLTHROUGH;

    case LOCAL_GL_RENDERBUFFER_WIDTH:
    case LOCAL_GL_RENDERBUFFER_HEIGHT:
    case LOCAL_GL_RENDERBUFFER_RED_SIZE:
    case LOCAL_GL_RENDERBUFFER_GREEN_SIZE:
    case LOCAL_GL_RENDERBUFFER_BLUE_SIZE:
    case LOCAL_GL_RENDERBUFFER_ALPHA_SIZE:
    case LOCAL_GL_RENDERBUFFER_DEPTH_SIZE:
    case LOCAL_GL_RENDERBUFFER_STENCIL_SIZE:
    case LOCAL_GL_RENDERBUFFER_INTERNAL_FORMAT: {
      // RB emulation means we have to ask the RB itself.
      GLint i = mBoundRenderbuffer->GetRenderbufferParameter(target, pname);
      return JS::Int32Value(i);
    }

    default:
      break;
  }

  ErrorInvalidEnumInfo("getRenderbufferParameter: parameter", pname);
  return JS::NullValue();
}

already_AddRefed<WebGLTexture>
WebGLContext::CreateTexture()
{
  if (IsContextLost())
    return nullptr;

  GLuint tex = 0;
  MakeContextCurrent();
  gl->fGenTextures(1, &tex);

  RefPtr<WebGLTexture> globj = new WebGLTexture(this, tex);
  return globj.forget();
}

static GLenum
GetAndClearError(GLenum* errorVar)
{
  MOZ_ASSERT(errorVar);
  GLenum ret = *errorVar;
  *errorVar = LOCAL_GL_NO_ERROR;
  return ret;
}

GLenum
WebGLContext::GetError()
{
  /* WebGL 1.0: Section 5.14.3: Setting and getting state:
     *   If the context's webgl context lost flag is set, returns
     *   CONTEXT_LOST_WEBGL the first time this method is called.
     *   Afterward, returns NO_ERROR until the context has been
     *   restored.
     *
     * WEBGL_lose_context:
     *   [When this extension is enabled: ] loseContext and
     *   restoreContext are allowed to generate INVALID_OPERATION errors
     *   even when the context is lost.
     */

  if (IsContextLost()) {
    if (mEmitContextLostErrorOnce) {
      mEmitContextLostErrorOnce = false;
      return LOCAL_GL_CONTEXT_LOST_WEBGL;
    }
    // Don't return yet, since WEBGL_lose_contexts contradicts the
    // original spec, and allows error generation while lost.
  }

  GLenum err = GetAndClearError(&mWebGLError);
  if (err != LOCAL_GL_NO_ERROR)
    return err;

  if (IsContextLost())
    return LOCAL_GL_NO_ERROR;

  // Either no WebGL-side error, or it's already been cleared.
  // UnderlyingGL-side errors, now.

  MakeContextCurrent();
  GetAndFlushUnderlyingGLErrors();

  err = GetAndClearError(&mUnderlyingGLError);
  return err;
}

JS::Value
WebGLContext::GetProgramParameter(const WebGLProgram& prog, GLenum pname)
{
  if (IsContextLost())
    return JS::NullValue();

  if (!ValidateObjectAllowDeleted("getProgramParameter: program", prog))
    return JS::NullValue();

  return prog.GetProgramParameter(pname);
}

void
WebGLContext::GetProgramInfoLog(const WebGLProgram& prog, nsAString& retval)
{
  retval.SetIsVoid(true);

  if (IsContextLost())
    return;

  if (!ValidateObject("getProgramInfoLog: program", prog))
    return;

  prog.GetProgramInfoLog(&retval);
}

JS::Value
WebGLContext::GetUniform(JSContext* js,
                         const WebGLProgram& prog,
                         const WebGLUniformLocation& loc)
{
  if (IsContextLost())
    return JS::NullValue();

  if (!ValidateObject("getUniform: `program`", prog))
    return JS::NullValue();

  if (!ValidateObjectAllowDeleted("getUniform: `location`", loc))
    return JS::NullValue();

  if (!loc.ValidateForProgram(&prog, "getUniform"))
    return JS::NullValue();

  return loc.GetUniform(js);
}

already_AddRefed<WebGLUniformLocation>
WebGLContext::GetUniformLocation(const WebGLProgram& prog,
                                 const nsAString& name)
{
  if (IsContextLost())
    return nullptr;

  if (!ValidateObject("getUniformLocation: program", prog))
    return nullptr;

  return prog.GetUniformLocation(name);
}

void
WebGLContext::Hint(GLenum target, GLenum mode)
{
  if (IsContextLost())
    return;

  bool isValid = false;

  switch (target) {
    case LOCAL_GL_GENERATE_MIPMAP_HINT:
      mGenerateMipmapHint = mode;

      // Deprecated and removed in desktop GL Core profiles.
      if (gl->IsCoreProfile())
        return;

      isValid = true;
      break;

    case LOCAL_GL_FRAGMENT_SHADER_DERIVATIVE_HINT:
      if (IsWebGL2() ||
          IsExtensionEnabled(WebGLExtensionID::OES_standard_derivatives)) {
        isValid = true;
      }
      break;
  }

  if (!isValid)
    return ErrorInvalidEnum("hint: invalid hint");

  MakeContextCurrent();
  gl->fHint(target, mode);
}

bool
WebGLContext::IsFramebuffer(const WebGLFramebuffer* fb)
{
  if (!ValidateIsObject("isFramebuffer", fb))
    return false;

#ifdef ANDROID
  if (gl->WorkAroundDriverBugs() &&
      gl->Renderer() == GLRenderer::AndroidEmulator) {
    return fb->mIsFB;
  }
#endif

  MakeContextCurrent();
  return gl->fIsFramebuffer(fb->mGLName);
}

bool
WebGLContext::IsProgram(const WebGLProgram* prog)
{
  if (!ValidateIsObject("isProgram", prog))
    return false;

  return true;
}

bool
WebGLContext::IsRenderbuffer(const WebGLRenderbuffer* rb)
{
  if (!ValidateIsObject("isRenderbuffer", rb))
    return false;

  return rb->mHasBeenBound;
}

bool
WebGLContext::IsShader(const WebGLShader* shader)
{
  if (!ValidateIsObject("isShader", shader))
    return false;

  return true;
}

void
WebGLContext::LinkProgram(WebGLProgram& prog)
{
  if (IsContextLost())
    return;

  if (!ValidateObject("linkProgram", prog))
    return;

  prog.LinkProgram();

  if (!prog.IsLinked()) {
    // If we failed to link, but `prog == mCurrentProgram`, we are *not* supposed to
    // null out mActiveProgramLinkInfo.
    return;
  }

  if (&prog == mCurrentProgram) {
    mActiveProgramLinkInfo = prog.LinkInfo();

    if (gl->WorkAroundDriverBugs() && gl->Vendor() == gl::GLVendor::NVIDIA) {
      gl->fUseProgram(prog.mGLName);
    }
  }
}

void
WebGLContext::PixelStorei(GLenum pname, GLint param)
{
  if (IsContextLost())
    return;

  if (IsWebGL2()) {
    uint32_t* pValueSlot = nullptr;
    switch (pname) {
      case LOCAL_GL_UNPACK_IMAGE_HEIGHT:
        pValueSlot = &mPixelStore_UnpackImageHeight;
        break;

      case LOCAL_GL_UNPACK_SKIP_IMAGES:
        pValueSlot = &mPixelStore_UnpackSkipImages;
        break;

      case LOCAL_GL_UNPACK_ROW_LENGTH:
        pValueSlot = &mPixelStore_UnpackRowLength;
        break;

      case LOCAL_GL_UNPACK_SKIP_ROWS:
        pValueSlot = &mPixelStore_UnpackSkipRows;
        break;

      case LOCAL_GL_UNPACK_SKIP_PIXELS:
        pValueSlot = &mPixelStore_UnpackSkipPixels;
        break;

      case LOCAL_GL_PACK_ROW_LENGTH:
        pValueSlot = &mPixelStore_PackRowLength;
        break;

      case LOCAL_GL_PACK_SKIP_ROWS:
        pValueSlot = &mPixelStore_PackSkipRows;
        break;

      case LOCAL_GL_PACK_SKIP_PIXELS:
        pValueSlot = &mPixelStore_PackSkipPixels;
        break;
    }

    if (pValueSlot) {
      if (param < 0) {
        ErrorInvalidValue("pixelStorei: param must be >= 0.");
        return;
      }

      MakeContextCurrent();
      gl->fPixelStorei(pname, param);
      *pValueSlot = param;
      return;
    }
  }

  switch (pname) {
    case UNPACK_FLIP_Y_WEBGL:
      mPixelStore_FlipY = bool(param);
      return;

    case UNPACK_PREMULTIPLY_ALPHA_WEBGL:
      mPixelStore_PremultiplyAlpha = bool(param);
      return;

    case UNPACK_COLORSPACE_CONVERSION_WEBGL:
      switch (param) {
        case LOCAL_GL_NONE:
        case BROWSER_DEFAULT_WEBGL:
          mPixelStore_ColorspaceConversion = param;
          return;

        default:
          ErrorInvalidEnumInfo("pixelStorei: colorspace conversion parameter",
                               param);
          return;
      }

    case UNPACK_REQUIRE_FASTPATH:
      if (IsExtensionEnabled(WebGLExtensionID::MOZ_debug)) {
        mPixelStore_RequireFastPath = bool(param);
        return;
      }
      break;

    case LOCAL_GL_PACK_ALIGNMENT:
    case LOCAL_GL_UNPACK_ALIGNMENT:
      switch (param) {
        case 1:
        case 2:
        case 4:
        case 8:
          if (pname == LOCAL_GL_PACK_ALIGNMENT)
            mPixelStore_PackAlignment = param;
          else if (pname == LOCAL_GL_UNPACK_ALIGNMENT)
            mPixelStore_UnpackAlignment = param;

          MakeContextCurrent();
          gl->fPixelStorei(pname, param);
          return;

        default:
          ErrorInvalidValue("pixelStorei: invalid pack/unpack alignment value");
          return;
      }

    default:
      break;
  }

  ErrorInvalidEnumInfo("pixelStorei: parameter", pname);
}

bool
WebGLContext::DoReadPixelsAndConvert(const webgl::FormatInfo* srcFormat,
                                     GLint x,
                                     GLint y,
                                     GLsizei width,
                                     GLsizei height,
                                     GLenum format,
                                     GLenum destType,
                                     void* dest,
                                     uint32_t destSize,
                                     uint32_t rowStride)
{
  // On at least Win+NV, we'll get PBO errors if we don't have at least
  // `rowStride * height` bytes available to read into.
  const auto naiveBytesNeeded = CheckedUint32(rowStride) * height;
  const bool isDangerCloseToEdge =
    (!naiveBytesNeeded.isValid() || naiveBytesNeeded.value() > destSize);
  const bool useParanoidHandling =
    (gl->WorkAroundDriverBugs() && isDangerCloseToEdge &&
     mBoundPixelPackBuffer);
  if (!useParanoidHandling) {
    gl->fReadPixels(x, y, width, height, format, destType, dest);
    return true;
  }

  // Read everything but the last row.
  const auto bodyHeight = height - 1;
  if (bodyHeight) {
    gl->fReadPixels(x, y, width, bodyHeight, format, destType, dest);
  }

  // Now read the last row.
  gl->fPixelStorei(LOCAL_GL_PACK_ALIGNMENT, 1);
  gl->fPixelStorei(LOCAL_GL_PACK_ROW_LENGTH, 0);
  gl->fPixelStorei(LOCAL_GL_PACK_SKIP_ROWS, 0);

  const auto tailRowOffset = (char*)dest + rowStride * bodyHeight;
  gl->fReadPixels(x, y + bodyHeight, width, 1, format, destType, tailRowOffset);

  gl->fPixelStorei(LOCAL_GL_PACK_ALIGNMENT, mPixelStore_PackAlignment);
  gl->fPixelStorei(LOCAL_GL_PACK_ROW_LENGTH, mPixelStore_PackRowLength);
  gl->fPixelStorei(LOCAL_GL_PACK_SKIP_ROWS, mPixelStore_PackSkipRows);
  return true;
}

static bool
GetJSScalarFromGLType(GLenum type, js::Scalar::Type* const out_scalarType)
{
  switch (type) {
    case LOCAL_GL_BYTE:
      *out_scalarType = js::Scalar::Int8;
      return true;

    case LOCAL_GL_UNSIGNED_BYTE:
      *out_scalarType = js::Scalar::Uint8;
      return true;

    case LOCAL_GL_SHORT:
      *out_scalarType = js::Scalar::Int16;
      return true;

    case LOCAL_GL_HALF_FLOAT:
    case LOCAL_GL_HALF_FLOAT_OES:
    case LOCAL_GL_UNSIGNED_SHORT:
    case LOCAL_GL_UNSIGNED_SHORT_4_4_4_4:
    case LOCAL_GL_UNSIGNED_SHORT_5_5_5_1:
    case LOCAL_GL_UNSIGNED_SHORT_5_6_5:
      *out_scalarType = js::Scalar::Uint16;
      return true;

    case LOCAL_GL_UNSIGNED_INT:
    case LOCAL_GL_UNSIGNED_INT_2_10_10_10_REV:
    case LOCAL_GL_UNSIGNED_INT_5_9_9_9_REV:
    case LOCAL_GL_UNSIGNED_INT_10F_11F_11F_REV:
    case LOCAL_GL_UNSIGNED_INT_24_8:
      *out_scalarType = js::Scalar::Uint32;
      return true;
    case LOCAL_GL_INT:
      *out_scalarType = js::Scalar::Int32;
      return true;

    case LOCAL_GL_FLOAT:
      *out_scalarType = js::Scalar::Float32;
      return true;

    default:
      return false;
  }
}

bool
WebGLContext::ReadPixels_SharedPrecheck(CallerType aCallerType,
                                        ErrorResult& out_error)
{
  if (IsContextLost())
    return false;

  if (mCanvasElement && mCanvasElement->IsWriteOnly() &&
      aCallerType != CallerType::System) {
    GenerateWarning("readPixels: Not allowed");
    out_error.Throw(NS_ERROR_DOM_SECURITY_ERR);
    return false;
  }

  return true;
}

bool
WebGLContext::ValidatePackSize(const char* funcName,
                               uint32_t width,
                               uint32_t height,
                               uint8_t bytesPerPixel,
                               uint32_t* const out_rowStride,
                               uint32_t* const out_endOffset)
{
  if (!width || !height) {
    *out_rowStride = 0;
    *out_endOffset = 0;
    return true;
  }

  // GLES 3.0.4, p116 (PACK_ functions like UNPACK_)

  const auto rowLength =
    (mPixelStore_PackRowLength ? mPixelStore_PackRowLength : width);
  const auto skipPixels = mPixelStore_PackSkipPixels;
  const auto skipRows = mPixelStore_PackSkipRows;
  const auto alignment = mPixelStore_PackAlignment;

  const auto usedPixelsPerRow = CheckedUint32(skipPixels) + width;
  const auto usedRowsPerImage = CheckedUint32(skipRows) + height;

  if (!usedPixelsPerRow.isValid() || usedPixelsPerRow.value() > rowLength) {
    ErrorInvalidOperation("%s: SKIP_PIXELS + width > ROW_LENGTH.", funcName);
    return false;
  }

  const auto rowLengthBytes = CheckedUint32(rowLength) * bytesPerPixel;
  const auto rowStride = RoundUpToMultipleOf(rowLengthBytes, alignment);

  const auto usedBytesPerRow = usedPixelsPerRow * bytesPerPixel;
  const auto usedBytesPerImage =
    (usedRowsPerImage - 1) * rowStride + usedBytesPerRow;

  if (!rowStride.isValid() || !usedBytesPerImage.isValid()) {
    ErrorInvalidOperation("%s: Invalid UNPACK_ params.", funcName);
    return false;
  }

  *out_rowStride = rowStride.value();
  *out_endOffset = usedBytesPerImage.value();
  return true;
}

void
WebGLContext::ReadPixels(GLint x,
                         GLint y,
                         GLsizei width,
                         GLsizei height,
                         GLenum format,
                         GLenum type,
                         const dom::ArrayBufferView& dstView,
                         GLuint dstElemOffset,
                         CallerType aCallerType,
                         ErrorResult& out_error)
{
  const char funcName[] = "readPixels";
  if (!ReadPixels_SharedPrecheck(aCallerType, out_error))
    return;

  if (mBoundPixelPackBuffer) {
    ErrorInvalidOperation("%s: PIXEL_PACK_BUFFER must be null.", funcName);
    return;
  }

  ////

  js::Scalar::Type reqScalarType;
  if (!GetJSScalarFromGLType(type, &reqScalarType)) {
    ErrorInvalidEnum("%s: Bad `type`.", funcName);
    return;
  }

  const auto& viewElemType = dstView.Type();
  if (viewElemType != reqScalarType) {
    ErrorInvalidOperation("%s: `pixels` type does not match `type`.", funcName);
    return;
  }

  ////

  uint8_t* bytes;
  size_t byteLen;
  if (!ValidateArrayBufferView(
        funcName, dstView, dstElemOffset, 0, &bytes, &byteLen))
    return;

  ////

  ReadPixelsImpl(x, y, width, height, format, type, bytes, byteLen);
}

void
WebGLContext::ReadPixels(GLint x,
                         GLint y,
                         GLsizei width,
                         GLsizei height,
                         GLenum format,
                         GLenum type,
                         WebGLsizeiptr offset,
                         CallerType aCallerType,
                         ErrorResult& out_error)
{
  const char funcName[] = "readPixels";
  if (!ReadPixels_SharedPrecheck(aCallerType, out_error))
    return;

  const auto& buffer =
    ValidateBufferSelection(funcName, LOCAL_GL_PIXEL_PACK_BUFFER);
  if (!buffer)
    return;

  //////

  if (!ValidateNonNegative(funcName, "offset", offset))
    return;

  {
    const auto bytesPerType = webgl::BytesPerPixel({ LOCAL_GL_RED, type });

    if (offset % bytesPerType != 0) {
      ErrorInvalidOperation(
        "%s: `offset` must be divisible by the size of `type`"
        " in bytes.",
        funcName);
      return;
    }
  }

  //////

  const auto bytesAvailable = buffer->ByteLength();
  const auto checkedBytesAfterOffset = CheckedUint32(bytesAvailable) - offset;

  uint32_t bytesAfterOffset = 0;
  if (checkedBytesAfterOffset.isValid()) {
    bytesAfterOffset = checkedBytesAfterOffset.value();
  }

  gl->MakeCurrent();
  const ScopedLazyBind lazyBind(gl, LOCAL_GL_PIXEL_PACK_BUFFER, buffer);

  ReadPixelsImpl(
    x, y, width, height, format, type, (void*)offset, bytesAfterOffset);
}

static webgl::PackingInfo
DefaultReadPixelPI(const webgl::FormatUsageInfo* usage)
{
  MOZ_ASSERT(usage->IsRenderable());

  switch (usage->format->componentType) {
    case webgl::ComponentType::NormUInt:
      return { LOCAL_GL_RGBA, LOCAL_GL_UNSIGNED_BYTE };

    case webgl::ComponentType::Int:
      return { LOCAL_GL_RGBA_INTEGER, LOCAL_GL_INT };

    case webgl::ComponentType::UInt:
      return { LOCAL_GL_RGBA_INTEGER, LOCAL_GL_UNSIGNED_INT };

    case webgl::ComponentType::Float:
      return { LOCAL_GL_RGBA, LOCAL_GL_FLOAT };

    default:
      MOZ_CRASH();
  }
}

static bool
ArePossiblePackEnums(const WebGLContext* webgl, const webgl::PackingInfo& pi)
{
  // OpenGL ES 2.0 $4.3.1 - IMPLEMENTATION_COLOR_READ_{TYPE/FORMAT} is a valid
  // combination for glReadPixels()...

  // So yeah, we are actually checking that these are valid as /unpack/ formats, instead
  // of /pack/ formats here, but it should cover the INVALID_ENUM cases.
  if (!webgl->mFormatUsage->AreUnpackEnumsValid(pi.format, pi.type))
    return false;

  // Only valid when pulled from:
  // * GLES 2.0.25 p105:
  //   "table 3.4, excluding formats LUMINANCE and LUMINANCE_ALPHA."
  // * GLES 3.0.4 p193:
  //   "table 3.2, excluding formats DEPTH_COMPONENT and DEPTH_STENCIL."
  switch (pi.format) {
    case LOCAL_GL_LUMINANCE:
    case LOCAL_GL_LUMINANCE_ALPHA:
    case LOCAL_GL_DEPTH_COMPONENT:
    case LOCAL_GL_DEPTH_STENCIL:
      return false;
  }

  if (pi.type == LOCAL_GL_UNSIGNED_INT_24_8)
    return false;

  return true;
}

webgl::PackingInfo
WebGLContext::ValidImplementationColorReadPI(
  const webgl::FormatUsageInfo* usage) const
{
  const auto defaultPI = DefaultReadPixelPI(usage);

  // ES2_compatibility always returns RGBA/UNSIGNED_BYTE, so branch on actual IsGLES().
  // Also OSX+NV generates an error here.
  if (!gl->IsGLES())
    return defaultPI;

  webgl::PackingInfo implPI;
  gl->fGetIntegerv(LOCAL_GL_IMPLEMENTATION_COLOR_READ_FORMAT,
                   (GLint*)&implPI.format);
  gl->fGetIntegerv(LOCAL_GL_IMPLEMENTATION_COLOR_READ_TYPE,
                   (GLint*)&implPI.type);

  if (!ArePossiblePackEnums(this, implPI))
    return defaultPI;

  return implPI;
}

static bool
ValidateReadPixelsFormatAndType(const webgl::FormatUsageInfo* srcUsage,
                                const webgl::PackingInfo& pi,
                                gl::GLContext* gl,
                                WebGLContext* webgl)
{
  const char funcName[] = "readPixels";

  if (!ArePossiblePackEnums(webgl, pi)) {
    webgl->ErrorInvalidEnum("%s: Unexpected format or type.", funcName);
    return false;
  }

  const auto defaultPI = DefaultReadPixelPI(srcUsage);
  if (pi == defaultPI)
    return true;

  ////

  // OpenGL ES 3.0.4 p194 - When the internal format of the rendering surface is
  // RGB10_A2, a third combination of format RGBA and type UNSIGNED_INT_2_10_10_10_REV
  // is accepted.

  if (webgl->IsWebGL2() &&
      srcUsage->format->effectiveFormat == webgl::EffectiveFormat::RGB10_A2 &&
      pi.format == LOCAL_GL_RGBA &&
      pi.type == LOCAL_GL_UNSIGNED_INT_2_10_10_10_REV) {
    return true;
  }

  ////

  MOZ_ASSERT(gl->IsCurrent());
  const auto implPI = webgl->ValidImplementationColorReadPI(srcUsage);
  if (pi == implPI)
    return true;

  ////

  webgl->ErrorInvalidOperation("%s: Incompatible format or type.", funcName);
  return false;
}

void
WebGLContext::ReadPixelsImpl(GLint x,
                             GLint y,
                             GLsizei rawWidth,
                             GLsizei rawHeight,
                             GLenum packFormat,
                             GLenum packType,
                             void* dest,
                             uint32_t dataLen)
{
  if (rawWidth < 0 || rawHeight < 0) {
    ErrorInvalidValue("readPixels: negative size passed");
    return;
  }

  const uint32_t width(rawWidth);
  const uint32_t height(rawHeight);

  //////

  MakeContextCurrent();

  const webgl::FormatUsageInfo* srcFormat;
  uint32_t srcWidth;
  uint32_t srcHeight;
  if (!ValidateCurFBForRead("readPixels", &srcFormat, &srcWidth, &srcHeight))
    return;

  //////

  const webgl::PackingInfo pi = { packFormat, packType };
  if (!ValidateReadPixelsFormatAndType(srcFormat, pi, gl, this))
    return;

  uint8_t bytesPerPixel;
  if (!webgl::GetBytesPerPixel(pi, &bytesPerPixel)) {
    ErrorInvalidOperation("readPixels: Unsupported format and type.");
    return;
  }

  //////

  uint32_t rowStride;
  uint32_t bytesNeeded;
  if (!ValidatePackSize(
        "readPixels", width, height, bytesPerPixel, &rowStride, &bytesNeeded)) {
    return;
  }

  if (bytesNeeded > dataLen) {
    ErrorInvalidOperation("readPixels: buffer too small");
    return;
  }

  ////

  int32_t readX, readY;
  int32_t writeX, writeY;
  int32_t rwWidth, rwHeight;
  if (!Intersect(srcWidth, x, width, &readX, &writeX, &rwWidth) ||
      !Intersect(srcHeight, y, height, &readY, &writeY, &rwHeight)) {
    ErrorOutOfMemory("readPixels: Bad subrect selection.");
    return;
  }

  ////////////////
  // Now that the errors are out of the way, on to actually reading!

  OnBeforeReadCall();

  if (!rwWidth || !rwHeight) {
    // Disjoint rects, so we're done already.
    DummyReadFramebufferOperation("readPixels");
    return;
  }

  if (uint32_t(rwWidth) == width && uint32_t(rwHeight) == height) {
    DoReadPixelsAndConvert(srcFormat->format,
                           x,
                           y,
                           width,
                           height,
                           packFormat,
                           packType,
                           dest,
                           dataLen,
                           rowStride);
    return;
  }

  // Read request contains out-of-bounds pixels. Unfortunately:
  // GLES 3.0.4 p194 "Obtaining Pixels from the Framebuffer":
  // "If any of these pixels lies outside of the window allocated to the current GL
  //  context, or outside of the image attached to the currently bound framebuffer
  //  object, then the values obtained for those pixels are undefined."

  // This is a slow-path, so warn people away!
  GenerateWarning(
    "readPixels: Out-of-bounds reads with readPixels are deprecated, and"
    " may be slow.");

  ////////////////////////////////////
  // Read only the in-bounds pixels.

  if (IsWebGL2()) {
    if (!mPixelStore_PackRowLength) {
      gl->fPixelStorei(LOCAL_GL_PACK_ROW_LENGTH,
                       mPixelStore_PackSkipPixels + width);
    }
    gl->fPixelStorei(LOCAL_GL_PACK_SKIP_PIXELS,
                     mPixelStore_PackSkipPixels + writeX);
    gl->fPixelStorei(LOCAL_GL_PACK_SKIP_ROWS,
                     mPixelStore_PackSkipRows + writeY);

    DoReadPixelsAndConvert(srcFormat->format,
                           readX,
                           readY,
                           rwWidth,
                           rwHeight,
                           packFormat,
                           packType,
                           dest,
                           dataLen,
                           rowStride);

    gl->fPixelStorei(LOCAL_GL_PACK_ROW_LENGTH, mPixelStore_PackRowLength);
    gl->fPixelStorei(LOCAL_GL_PACK_SKIP_PIXELS, mPixelStore_PackSkipPixels);
    gl->fPixelStorei(LOCAL_GL_PACK_SKIP_ROWS, mPixelStore_PackSkipRows);
  } else {
    // I *did* say "hilariously slow".

    uint8_t* row = (uint8_t*)dest + writeX * bytesPerPixel;
    row += writeY * rowStride;
    for (uint32_t j = 0; j < uint32_t(rwHeight); j++) {
      DoReadPixelsAndConvert(srcFormat->format,
                             readX,
                             readY + j,
                             rwWidth,
                             1,
                             packFormat,
                             packType,
                             row,
                             dataLen,
                             rowStride);
      row += rowStride;
    }
  }
}

void
WebGLContext::RenderbufferStorage_base(const char* funcName,
                                       GLenum target,
                                       GLsizei samples,
                                       GLenum internalFormat,
                                       GLsizei width,
                                       GLsizei height)
{
  if (IsContextLost())
    return;

  if (target != LOCAL_GL_RENDERBUFFER) {
    ErrorInvalidEnumInfo("`target`", funcName, target);
    return;
  }

  if (!mBoundRenderbuffer) {
    ErrorInvalidOperation("%s: Called on renderbuffer 0.", funcName);
    return;
  }

  if (samples < 0) {
    ErrorInvalidValue("%s: `samples` must be >= 0.", funcName);
    return;
  }

  if (width < 0 || height < 0) {
    ErrorInvalidValue("%s: `width` and `height` must be >= 0.", funcName);
    return;
  }

  mBoundRenderbuffer->RenderbufferStorage(funcName,
                                          uint32_t(samples),
                                          internalFormat,
                                          uint32_t(width),
                                          uint32_t(height));
}

void
WebGLContext::RenderbufferStorage(GLenum target,
                                  GLenum internalFormat,
                                  GLsizei width,
                                  GLsizei height)
{
  RenderbufferStorage_base(
    "renderbufferStorage", target, 0, internalFormat, width, height);
}

void
WebGLContext::Scissor(GLint x, GLint y, GLsizei width, GLsizei height)
{
  if (IsContextLost())
    return;

  if (width < 0 || height < 0)
    return ErrorInvalidValue("scissor: negative size");

  MakeContextCurrent();
  gl->fScissor(x, y, width, height);
}

void
WebGLContext::StencilFunc(GLenum func, GLint ref, GLuint mask)
{
  if (IsContextLost())
    return;

  if (!ValidateComparisonEnum(func, "stencilFunc: func"))
    return;

  mStencilRefFront = ref;
  mStencilRefBack = ref;
  mStencilValueMaskFront = mask;
  mStencilValueMaskBack = mask;

  MakeContextCurrent();
  gl->fStencilFunc(func, ref, mask);
}

void
WebGLContext::StencilFuncSeparate(GLenum face,
                                  GLenum func,
                                  GLint ref,
                                  GLuint mask)
{
  if (IsContextLost())
    return;

  if (!ValidateFaceEnum(face, "stencilFuncSeparate: face") ||
      !ValidateComparisonEnum(func, "stencilFuncSeparate: func"))
    return;

  switch (face) {
    case LOCAL_GL_FRONT_AND_BACK:
      mStencilRefFront = ref;
      mStencilRefBack = ref;
      mStencilValueMaskFront = mask;
      mStencilValueMaskBack = mask;
      break;
    case LOCAL_GL_FRONT:
      mStencilRefFront = ref;
      mStencilValueMaskFront = mask;
      break;
    case LOCAL_GL_BACK:
      mStencilRefBack = ref;
      mStencilValueMaskBack = mask;
      break;
  }

  MakeContextCurrent();
  gl->fStencilFuncSeparate(face, func, ref, mask);
}

void
WebGLContext::StencilOp(GLenum sfail, GLenum dpfail, GLenum dppass)
{
  if (IsContextLost())
    return;

  if (!ValidateStencilOpEnum(sfail, "stencilOp: sfail") ||
      !ValidateStencilOpEnum(dpfail, "stencilOp: dpfail") ||
      !ValidateStencilOpEnum(dppass, "stencilOp: dppass"))
    return;

  MakeContextCurrent();
  gl->fStencilOp(sfail, dpfail, dppass);
}

void
WebGLContext::StencilOpSeparate(GLenum face,
                                GLenum sfail,
                                GLenum dpfail,
                                GLenum dppass)
{
  if (IsContextLost())
    return;

  if (!ValidateFaceEnum(face, "stencilOpSeparate: face") ||
      !ValidateStencilOpEnum(sfail, "stencilOpSeparate: sfail") ||
      !ValidateStencilOpEnum(dpfail, "stencilOpSeparate: dpfail") ||
      !ValidateStencilOpEnum(dppass, "stencilOpSeparate: dppass"))
    return;

  MakeContextCurrent();
  gl->fStencilOpSeparate(face, sfail, dpfail, dppass);
}

////////////////////////////////////////////////////////////////////////////////
// Uniform setters.

class ValidateIfSampler
{
  const WebGLUniformLocation* const mLoc;
  const size_t mDataCount;
  const GLint* const mData;
  bool mIsValidatedSampler;

public:
  ValidateIfSampler(WebGLContext* webgl,
                    const char* funcName,
                    WebGLUniformLocation* loc,
                    size_t dataCount,
                    const GLint* data,
                    bool* const out_error)
    : mLoc(loc)
    , mDataCount(dataCount)
    , mData(data)
    , mIsValidatedSampler(false)
  {
    if (!mLoc->mInfo->mSamplerTexList) {
      *out_error = false;
      return;
    }

    for (size_t i = 0; i < mDataCount; i++) {
      const auto& val = mData[i];
      if (val < 0 || uint32_t(val) >= webgl->GLMaxTextureUnits()) {
        webgl->ErrorInvalidValue(
          "%s: This uniform location is a sampler, but %d"
          " is not a valid texture unit.",
          funcName,
          val);
        *out_error = true;
        return;
      }
    }

    mIsValidatedSampler = true;
    *out_error = false;
  }

  ~ValidateIfSampler()
  {
    if (!mIsValidatedSampler)
      return;

    auto& samplerValues = mLoc->mInfo->mSamplerValues;

    for (size_t i = 0; i < mDataCount; i++) {
      const size_t curIndex = mLoc->mArrayIndex + i;
      if (curIndex >= samplerValues.size())
        break;

      samplerValues[curIndex] = mData[i];
    }
  }
};

////////////////////

void
WebGLContext::Uniform1i(WebGLUniformLocation* loc, GLint a1)
{
  const char funcName[] = "uniform1i";
  if (!ValidateUniformSetter(loc, 1, LOCAL_GL_INT, funcName))
    return;

  bool error;
  const ValidateIfSampler validate(this, funcName, loc, 1, &a1, &error);
  if (error)
    return;

  MakeContextCurrent();
  gl->fUniform1i(loc->mLoc, a1);
}

void
WebGLContext::Uniform2i(WebGLUniformLocation* loc, GLint a1, GLint a2)
{
  const char funcName[] = "uniform2i";
  if (!ValidateUniformSetter(loc, 2, LOCAL_GL_INT, funcName))
    return;

  MakeContextCurrent();
  gl->fUniform2i(loc->mLoc, a1, a2);
}

void
WebGLContext::Uniform3i(WebGLUniformLocation* loc, GLint a1, GLint a2, GLint a3)
{
  const char funcName[] = "uniform3i";
  if (!ValidateUniformSetter(loc, 3, LOCAL_GL_INT, funcName))
    return;

  MakeContextCurrent();
  gl->fUniform3i(loc->mLoc, a1, a2, a3);
}

void
WebGLContext::Uniform4i(WebGLUniformLocation* loc,
                        GLint a1,
                        GLint a2,
                        GLint a3,
                        GLint a4)
{
  const char funcName[] = "uniform4i";
  if (!ValidateUniformSetter(loc, 4, LOCAL_GL_INT, funcName))
    return;

  MakeContextCurrent();
  gl->fUniform4i(loc->mLoc, a1, a2, a3, a4);
}

//////////

void
WebGLContext::Uniform1f(WebGLUniformLocation* loc, GLfloat a1)
{
  const char funcName[] = "uniform1f";
  if (!ValidateUniformSetter(loc, 1, LOCAL_GL_FLOAT, funcName))
    return;

  MakeContextCurrent();
  gl->fUniform1f(loc->mLoc, a1);
}

void
WebGLContext::Uniform2f(WebGLUniformLocation* loc, GLfloat a1, GLfloat a2)
{
  const char funcName[] = "uniform2f";
  if (!ValidateUniformSetter(loc, 2, LOCAL_GL_FLOAT, funcName))
    return;

  MakeContextCurrent();
  gl->fUniform2f(loc->mLoc, a1, a2);
}

void
WebGLContext::Uniform3f(WebGLUniformLocation* loc,
                        GLfloat a1,
                        GLfloat a2,
                        GLfloat a3)
{
  const char funcName[] = "uniform3f";
  if (!ValidateUniformSetter(loc, 3, LOCAL_GL_FLOAT, funcName))
    return;

  MakeContextCurrent();
  gl->fUniform3f(loc->mLoc, a1, a2, a3);
}

void
WebGLContext::Uniform4f(WebGLUniformLocation* loc,
                        GLfloat a1,
                        GLfloat a2,
                        GLfloat a3,
                        GLfloat a4)
{
  const char funcName[] = "uniform4f";
  if (!ValidateUniformSetter(loc, 4, LOCAL_GL_FLOAT, funcName))
    return;

  MakeContextCurrent();
  gl->fUniform4f(loc->mLoc, a1, a2, a3, a4);
}

////////////////////////////////////////
// Array

static bool
ValidateArrOffsetAndCount(WebGLContext* webgl,
                          const char* funcName,
                          size_t elemsAvail,
                          GLuint elemOffset,
                          GLuint elemCountOverride,
                          size_t* const out_elemCount)
{
  if (elemOffset > elemsAvail) {
    webgl->ErrorInvalidValue("%s: Bad offset into list.", funcName);
    return false;
  }
  elemsAvail -= elemOffset;

  if (elemCountOverride) {
    if (elemCountOverride > elemsAvail) {
      webgl->ErrorInvalidValue("%s: Bad count override for sub-list.",
                               funcName);
      return false;
    }
    elemsAvail = elemCountOverride;
  }

  *out_elemCount = elemsAvail;
  return true;
}

void
WebGLContext::UniformNiv(const char* funcName,
                         uint8_t N,
                         WebGLUniformLocation* loc,
                         const Int32Arr& arr,
                         GLuint elemOffset,
                         GLuint elemCountOverride)
{
  size_t elemCount;
  if (!ValidateArrOffsetAndCount(this,
                                 funcName,
                                 arr.elemCount,
                                 elemOffset,
                                 elemCountOverride,
                                 &elemCount)) {
    return;
  }
  const auto elemBytes = arr.elemBytes + elemOffset;

  uint32_t numElementsToUpload;
  if (!ValidateUniformArraySetter(
        loc, N, LOCAL_GL_INT, elemCount, funcName, &numElementsToUpload)) {
    return;
  }

  bool error;
  const ValidateIfSampler samplerValidator(
    this, funcName, loc, numElementsToUpload, elemBytes, &error);
  if (error)
    return;

  static const decltype(
    &gl::GLContext::fUniform1iv) kFuncList[] = { &gl::GLContext::fUniform1iv,
                                                 &gl::GLContext::fUniform2iv,
                                                 &gl::GLContext::fUniform3iv,
                                                 &gl::GLContext::fUniform4iv };
  const auto func = kFuncList[N - 1];

  MakeContextCurrent();
  (gl->*func)(loc->mLoc, numElementsToUpload, elemBytes);
}

void
WebGLContext::UniformNuiv(const char* funcName,
                          uint8_t N,
                          WebGLUniformLocation* loc,
                          const Uint32Arr& arr,
                          GLuint elemOffset,
                          GLuint elemCountOverride)
{
  size_t elemCount;
  if (!ValidateArrOffsetAndCount(this,
                                 funcName,
                                 arr.elemCount,
                                 elemOffset,
                                 elemCountOverride,
                                 &elemCount)) {
    return;
  }
  const auto elemBytes = arr.elemBytes + elemOffset;

  uint32_t numElementsToUpload;
  if (!ValidateUniformArraySetter(loc,
                                  N,
                                  LOCAL_GL_UNSIGNED_INT,
                                  elemCount,
                                  funcName,
                                  &numElementsToUpload)) {
    return;
  }
  MOZ_ASSERT(!loc->mInfo->mSamplerTexList, "Should not be a sampler.");

  static const decltype(&gl::GLContext::fUniform1uiv) kFuncList[] = {
    &gl::GLContext::fUniform1uiv,
    &gl::GLContext::fUniform2uiv,
    &gl::GLContext::fUniform3uiv,
    &gl::GLContext::fUniform4uiv
  };
  const auto func = kFuncList[N - 1];

  MakeContextCurrent();
  (gl->*func)(loc->mLoc, numElementsToUpload, elemBytes);
}

void
WebGLContext::UniformNfv(const char* funcName,
                         uint8_t N,
                         WebGLUniformLocation* loc,
                         const Float32Arr& arr,
                         GLuint elemOffset,
                         GLuint elemCountOverride)
{
  size_t elemCount;
  if (!ValidateArrOffsetAndCount(this,
                                 funcName,
                                 arr.elemCount,
                                 elemOffset,
                                 elemCountOverride,
                                 &elemCount)) {
    return;
  }
  const auto elemBytes = arr.elemBytes + elemOffset;

  uint32_t numElementsToUpload;
  if (!ValidateUniformArraySetter(
        loc, N, LOCAL_GL_FLOAT, elemCount, funcName, &numElementsToUpload)) {
    return;
  }
  MOZ_ASSERT(!loc->mInfo->mSamplerTexList, "Should not be a sampler.");

  static const decltype(
    &gl::GLContext::fUniform1fv) kFuncList[] = { &gl::GLContext::fUniform1fv,
                                                 &gl::GLContext::fUniform2fv,
                                                 &gl::GLContext::fUniform3fv,
                                                 &gl::GLContext::fUniform4fv };
  const auto func = kFuncList[N - 1];

  MakeContextCurrent();
  (gl->*func)(loc->mLoc, numElementsToUpload, elemBytes);
}

static inline void
MatrixAxBToRowMajor(const uint8_t width,
                    const uint8_t height,
                    const float* __restrict srcColMajor,
                    float* __restrict dstRowMajor)
{
  for (uint8_t x = 0; x < width; ++x) {
    for (uint8_t y = 0; y < height; ++y) {
      dstRowMajor[y * width + x] = srcColMajor[x * height + y];
    }
  }
}

void
WebGLContext::UniformMatrixAxBfv(const char* funcName,
                                 uint8_t A,
                                 uint8_t B,
                                 WebGLUniformLocation* loc,
                                 const bool transpose,
                                 const Float32Arr& arr,
                                 GLuint elemOffset,
                                 GLuint elemCountOverride)
{
  size_t elemCount;
  if (!ValidateArrOffsetAndCount(this,
                                 funcName,
                                 arr.elemCount,
                                 elemOffset,
                                 elemCountOverride,
                                 &elemCount)) {
    return;
  }
  const auto elemBytes = arr.elemBytes + elemOffset;

  uint32_t numMatsToUpload;
  if (!ValidateUniformMatrixArraySetter(loc,
                                        A,
                                        B,
                                        LOCAL_GL_FLOAT,
                                        elemCount,
                                        transpose,
                                        funcName,
                                        &numMatsToUpload)) {
    return;
  }
  MOZ_ASSERT(!loc->mInfo->mSamplerTexList, "Should not be a sampler.");

  ////

  bool uploadTranspose = transpose;
  const float* uploadBytes = elemBytes;

  UniqueBuffer temp;
  if (!transpose && gl->WorkAroundDriverBugs() && gl->IsANGLE() &&
      gl->IsAtLeast(gl::ContextProfile::OpenGLES, 300)) {
    // ANGLE is really slow at non-GL-transposed matrices.
    const size_t kElemsPerMat = A * B;

    temp = malloc(numMatsToUpload * kElemsPerMat * sizeof(float));
    if (!temp) {
      ErrorOutOfMemory(
        "%s: Failed to alloc temporary buffer for transposition.", funcName);
      return;
    }

    auto srcItr = (const float*)elemBytes;
    auto dstItr = (float*)temp.get();
    const auto srcEnd = srcItr + numMatsToUpload * kElemsPerMat;

    while (srcItr != srcEnd) {
      MatrixAxBToRowMajor(A, B, srcItr, dstItr);
      srcItr += kElemsPerMat;
      dstItr += kElemsPerMat;
    }

    uploadBytes = (const float*)temp.get();
    uploadTranspose = true;
  }

  ////

  static const decltype(&gl::GLContext::fUniformMatrix2fv) kFuncList[] = {
    &gl::GLContext::fUniformMatrix2fv,   &gl::GLContext::fUniformMatrix2x3fv,
    &gl::GLContext::fUniformMatrix2x4fv,

    &gl::GLContext::fUniformMatrix3x2fv, &gl::GLContext::fUniformMatrix3fv,
    &gl::GLContext::fUniformMatrix3x4fv,

    &gl::GLContext::fUniformMatrix4x2fv, &gl::GLContext::fUniformMatrix4x3fv,
    &gl::GLContext::fUniformMatrix4fv
  };
  const auto func = kFuncList[3 * (A - 2) + (B - 2)];

  MakeContextCurrent();
  (gl->*func)(loc->mLoc, numMatsToUpload, uploadTranspose, uploadBytes);
}

////////////////////////////////////////////////////////////////////////////////

void
WebGLContext::UseProgram(WebGLProgram* prog)
{
  if (IsContextLost())
    return;

  if (!prog) {
    mCurrentProgram = nullptr;
    mActiveProgramLinkInfo = nullptr;
    return;
  }

  if (!ValidateObject("useProgram", *prog))
    return;

  if (prog->UseProgram()) {
    mCurrentProgram = prog;
    mActiveProgramLinkInfo = mCurrentProgram->LinkInfo();
  }
}

void
WebGLContext::ValidateProgram(const WebGLProgram& prog)
{
  if (IsContextLost())
    return;

  if (!ValidateObject("validateProgram", prog))
    return;

  prog.ValidateProgram();
}

already_AddRefed<WebGLFramebuffer>
WebGLContext::CreateFramebuffer()
{
  if (IsContextLost())
    return nullptr;

  GLuint fbo = 0;
  MakeContextCurrent();
  gl->fGenFramebuffers(1, &fbo);

  RefPtr<WebGLFramebuffer> globj = new WebGLFramebuffer(this, fbo);
  return globj.forget();
}

already_AddRefed<WebGLRenderbuffer>
WebGLContext::CreateRenderbuffer()
{
  if (IsContextLost())
    return nullptr;

  MakeContextCurrent();
  RefPtr<WebGLRenderbuffer> globj = new WebGLRenderbuffer(this);
  return globj.forget();
}

void
WebGLContext::Viewport(GLint x, GLint y, GLsizei width, GLsizei height)
{
  if (IsContextLost())
    return;

  if (width < 0 || height < 0)
    return ErrorInvalidValue("viewport: negative size");

  width = std::min(width, (GLsizei)mImplMaxViewportDims[0]);
  height = std::min(height, (GLsizei)mImplMaxViewportDims[1]);

  MakeContextCurrent();
  gl->fViewport(x, y, width, height);

  mViewportX = x;
  mViewportY = y;
  mViewportWidth = width;
  mViewportHeight = height;
}

void
WebGLContext::CompileShader(WebGLShader& shader)
{
  if (IsContextLost())
    return;

  if (!ValidateObject("compileShader", shader))
    return;

  shader.CompileShader();
}

JS::Value
WebGLContext::GetShaderParameter(const WebGLShader& shader, GLenum pname)
{
  if (IsContextLost())
    return JS::NullValue();

  if (!ValidateObjectAllowDeleted("getShaderParameter: shader", shader))
    return JS::NullValue();

  return shader.GetShaderParameter(pname);
}

void
WebGLContext::GetShaderInfoLog(const WebGLShader& shader, nsAString& retval)
{
  retval.SetIsVoid(true);

  if (IsContextLost())
    return;

  if (!ValidateObject("getShaderInfoLog: shader", shader))
    return;

  shader.GetShaderInfoLog(&retval);
}

already_AddRefed<WebGLShaderPrecisionFormat>
WebGLContext::GetShaderPrecisionFormat(GLenum shadertype, GLenum precisiontype)
{
  if (IsContextLost())
    return nullptr;

  switch (shadertype) {
    case LOCAL_GL_FRAGMENT_SHADER:
    case LOCAL_GL_VERTEX_SHADER:
      break;
    default:
      ErrorInvalidEnumInfo("getShaderPrecisionFormat: shadertype", shadertype);
      return nullptr;
  }

  switch (precisiontype) {
    case LOCAL_GL_LOW_FLOAT:
    case LOCAL_GL_MEDIUM_FLOAT:
    case LOCAL_GL_HIGH_FLOAT:
    case LOCAL_GL_LOW_INT:
    case LOCAL_GL_MEDIUM_INT:
    case LOCAL_GL_HIGH_INT:
      break;
    default:
      ErrorInvalidEnumInfo("getShaderPrecisionFormat: precisiontype",
                           precisiontype);
      return nullptr;
  }

  MakeContextCurrent();
  GLint range[2], precision;

  if (mDisableFragHighP && shadertype == LOCAL_GL_FRAGMENT_SHADER &&
      (precisiontype == LOCAL_GL_HIGH_FLOAT ||
       precisiontype == LOCAL_GL_HIGH_INT)) {
    precision = 0;
    range[0] = 0;
    range[1] = 0;
  } else {
    gl->fGetShaderPrecisionFormat(shadertype, precisiontype, range, &precision);
  }

  RefPtr<WebGLShaderPrecisionFormat> retShaderPrecisionFormat =
    new WebGLShaderPrecisionFormat(this, range[0], range[1], precision);
  return retShaderPrecisionFormat.forget();
}

void
WebGLContext::GetShaderSource(const WebGLShader& shader, nsAString& retval)
{
  retval.SetIsVoid(true);

  if (IsContextLost())
    return;

  if (!ValidateObject("getShaderSource: shader", shader))
    return;

  shader.GetShaderSource(&retval);
}

void
WebGLContext::ShaderSource(WebGLShader& shader, const nsAString& source)
{
  if (IsContextLost())
    return;

  if (!ValidateObject("shaderSource: shader", shader))
    return;

  shader.ShaderSource(source);
}

void
WebGLContext::LoseContext()
{
  if (IsContextLost())
    return ErrorInvalidOperation("loseContext: Context is already lost.");

  ForceLoseContext(true);
}

void
WebGLContext::RestoreContext()
{
  if (!IsContextLost())
    return ErrorInvalidOperation("restoreContext: Context is not lost.");

  if (!mLastLossWasSimulated) {
    return ErrorInvalidOperation(
      "restoreContext: Context loss was not simulated."
      " Cannot simulate restore.");
  }
  // If we're currently lost, and the last loss was simulated, then
  // we're currently only simulated-lost, allowing us to call
  // restoreContext().

  if (!mAllowContextRestore)
    return ErrorInvalidOperation("restoreContext: Context cannot be restored.");

  ForceRestoreContext();
}

void
WebGLContext::BlendColor(GLfloat r, GLfloat g, GLfloat b, GLfloat a)
{
  if (IsContextLost())
    return;
  MakeContextCurrent();
  gl->fBlendColor(r, g, b, a);
}

void
WebGLContext::Flush()
{
  if (IsContextLost())
    return;
  MakeContextCurrent();
  gl->fFlush();
}

void
WebGLContext::Finish()
{
  if (IsContextLost())
    return;
  MakeContextCurrent();
  gl->fFinish();
}

void
WebGLContext::LineWidth(GLfloat width)
{
  if (IsContextLost())
    return;

  // Doing it this way instead of `if (width <= 0.0)` handles NaNs.
  const bool isValid = width > 0.0;
  if (!isValid) {
    ErrorInvalidValue("lineWidth: `width` must be positive and non-zero.");
    return;
  }

  mLineWidth = width;

  if (gl->IsCoreProfile() && width > 1.0) {
    width = 1.0;
  }

  MakeContextCurrent();
  gl->fLineWidth(width);
}

void
WebGLContext::PolygonOffset(GLfloat factor, GLfloat units)
{
  if (IsContextLost())
    return;
  MakeContextCurrent();
  gl->fPolygonOffset(factor, units);
}

void
WebGLContext::SampleCoverage(GLclampf value, WebGLboolean invert)
{
  if (IsContextLost())
    return;
  MakeContextCurrent();
  gl->fSampleCoverage(value, invert);
}

} // namespace mozilla