gfx/thebes/gfxFontMissingGlyphs.cpp
author Lee Salzman <lsalzman@mozilla.com>
Wed, 22 Aug 2018 11:12:33 -0400
changeset 490622 4621d2fd3f175f6d7441874ba2645a47aa26c86c
parent 490365 07dabfefeef1dc4e0a7263bb10a504fa8f8252a0
child 508163 6f3709b3878117466168c40affa7bca0b60cf75b
permissions -rw-r--r--
Bug 1485358 - fix purging of missing glyph WebRender users. r=me

/* -*- Mode: C++; tab-width: 20; 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 "gfxFontMissingGlyphs.h"

#include "gfxUtils.h"
#include "mozilla/gfx/2D.h"
#include "mozilla/gfx/Helpers.h"
#include "mozilla/gfx/PathHelpers.h"
#include "mozilla/LinkedList.h"
#include "mozilla/RefPtr.h"
#include "nsDeviceContext.h"
#include "nsLayoutUtils.h"
#include "TextDrawTarget.h"

using namespace mozilla;
using namespace mozilla::gfx;

#define X 255
static const uint8_t gMiniFontData[] = {
    0,X,0, 0,X,0, X,X,X, X,X,X, X,0,X, X,X,X, X,X,X, X,X,X, X,X,X, X,X,X, X,X,X, X,X,0, 0,X,X, X,X,0, X,X,X, X,X,X,
    X,0,X, 0,X,0, 0,0,X, 0,0,X, X,0,X, X,0,0, X,0,0, 0,0,X, X,0,X, X,0,X, X,0,X, X,0,X, X,0,0, X,0,X, X,0,0, X,0,0,
    X,0,X, 0,X,0, X,X,X, X,X,X, X,X,X, X,X,X, X,X,X, 0,0,X, X,X,X, X,X,X, X,X,X, X,X,0, X,0,0, X,0,X, X,X,X, X,X,X,
    X,0,X, 0,X,0, X,0,0, 0,0,X, 0,0,X, 0,0,X, X,0,X, 0,0,X, X,0,X, 0,0,X, X,0,X, X,0,X, X,0,0, X,0,X, X,0,0, X,0,0,
    0,X,0, 0,X,0, X,X,X, X,X,X, 0,0,X, X,X,X, X,X,X, 0,0,X, X,X,X, 0,0,X, X,0,X, X,X,0, 0,X,X, X,X,0, X,X,X, X,0,0,
};
#undef X

/* Parameters that control the rendering of hexboxes. They look like this:

        BMP codepoints           non-BMP codepoints
      (U+0000 - U+FFFF)         (U+10000 - U+10FFFF)

         +---------+              +-------------+
         |         |              |             |
         | HHH HHH |              | HHH HHH HHH |
         | HHH HHH |              | HHH HHH HHH |
         | HHH HHH |              | HHH HHH HHH |
         | HHH HHH |              | HHH HHH HHH |
         | HHH HHH |              | HHH HHH HHH |
         |         |              |             |
         | HHH HHH |              | HHH HHH HHH |
         | HHH HHH |              | HHH HHH HHH |
         | HHH HHH |              | HHH HHH HHH |
         | HHH HHH |              | HHH HHH HHH |
         | HHH HHH |              | HHH HHH HHH |
         |         |              |             |
         +---------+              +-------------+
*/

/** Width of a minifont glyph (see above) */
static const int MINIFONT_WIDTH = 3;
/** Height of a minifont glyph (see above) */
static const int MINIFONT_HEIGHT = 5;
/**
 * Gap between minifont glyphs (both horizontal and vertical) and also
 * the minimum desired gap between the box border and the glyphs
 */
static const int HEX_CHAR_GAP = 1;
/**
 * The amount of space between the vertical edge of the glyphbox and the
 * box border. We make this nonzero so that when multiple missing glyphs
 * occur consecutively there's a gap between their rendered boxes.
 */
static const int BOX_HORIZONTAL_INSET = 1;
/** The width of the border */
static const int BOX_BORDER_WIDTH = 1;
/**
 * The scaling factor for the border opacity; this is multiplied by the current
 * opacity being used to draw the text.
 */
static const Float BOX_BORDER_OPACITY = 0.5;

#ifndef MOZ_GFX_OPTIMIZE_MOBILE

static RefPtr<DrawTarget> gGlyphDrawTarget;
static RefPtr<SourceSurface> gGlyphMask;
static RefPtr<SourceSurface> gGlyphAtlas;
static Color gGlyphColor;

/**
 * Generates a new colored mini-font atlas from the mini-font mask.
 */
static bool
MakeGlyphAtlas(const Color& aColor)
{
    gGlyphAtlas = nullptr;
    if (!gGlyphDrawTarget) {
        gGlyphDrawTarget = gfxPlatform::GetPlatform()->CreateOffscreenContentDrawTarget(
            IntSize(MINIFONT_WIDTH * 16, MINIFONT_HEIGHT), SurfaceFormat::B8G8R8A8);
        if (!gGlyphDrawTarget) {
            return false;
        }
    }
    if (!gGlyphMask) {
        gGlyphMask = gGlyphDrawTarget->CreateSourceSurfaceFromData(
            const_cast<uint8_t*>(gMiniFontData), IntSize(MINIFONT_WIDTH * 16, MINIFONT_HEIGHT),
            MINIFONT_WIDTH * 16, SurfaceFormat::A8);
        if (!gGlyphMask) {
            return false;
        }
    }
    gGlyphDrawTarget->MaskSurface(ColorPattern(aColor), gGlyphMask, Point(0, 0),
                                  DrawOptions(1.0f, CompositionOp::OP_SOURCE));
    gGlyphAtlas = gGlyphDrawTarget->Snapshot();
    if (!gGlyphAtlas) {
        return false;
    }
    gGlyphColor = aColor;
    return true;
}

/**
 * Reuse the current mini-font atlas if the color matches, otherwise regenerate it.
 */
static inline already_AddRefed<SourceSurface>
GetGlyphAtlas(const Color& aColor)
{
    // Get the opaque color, ignoring any transparency which will be handled later.
    Color color(aColor.r, aColor.g, aColor.b);
    if ((gGlyphAtlas && gGlyphColor == color) || MakeGlyphAtlas(color)) {
        return do_AddRef(gGlyphAtlas);
    }
    return nullptr;
}

/**
 * Clear any cached glyph atlas resources.
 */
static void
PurgeGlyphAtlas()
{
    gGlyphAtlas = nullptr;
    gGlyphDrawTarget = nullptr;
    gGlyphMask = nullptr;
}

// WebRender layer manager user data that will get signaled when the layer
// manager is destroyed.
class WRUserData : public layers::LayerUserData, public LinkedListElement<WRUserData>
{
public:
    explicit WRUserData(layers::WebRenderLayerManager* aManager);

    ~WRUserData();

    static void
    Assign(layers::WebRenderLayerManager* aManager)
    {
        if (!aManager->HasUserData(&sWRUserDataKey)) {
            aManager->SetUserData(&sWRUserDataKey, new WRUserData(aManager));
        }
    }

    void
    Remove()
    {
        mManager->RemoveUserData(&sWRUserDataKey);
    }

    layers::WebRenderLayerManager* mManager;

    static UserDataKey sWRUserDataKey;
};

static RefPtr<SourceSurface> gWRGlyphAtlas[8];
static LinkedList<WRUserData> gWRUsers;
UserDataKey WRUserData::sWRUserDataKey;

/**
 * Generates a transformed WebRender mini-font atlas for a given orientation.
 */
static already_AddRefed<SourceSurface>
MakeWRGlyphAtlas(const Matrix* aMat)
{
    IntSize size(MINIFONT_WIDTH * 16, MINIFONT_HEIGHT);
    // If the orientation is transposed, width/height are swapped.
    if (aMat && aMat->_11 == 0) {
        std::swap(size.width, size.height);
    }
    RefPtr<DrawTarget> ref = gfxPlatform::GetPlatform()->ScreenReferenceDrawTarget();
    RefPtr<DrawTarget> dt = gfxPlatform::GetPlatform()->CreateSimilarSoftwareDrawTarget(
            ref, size, SurfaceFormat::B8G8R8A8);
    if (!dt) {
        return nullptr;
    }
    if (aMat) {
        // Select appropriate transform matrix based on whether the
        // orientation is transposed.
        dt->SetTransform(aMat->_11 == 0 ?
            Matrix(0.0f, copysign(1.0f, aMat->_12),
                   copysign(1.0f, aMat->_21), 0.0f,
                   aMat->_21 < 0 ? MINIFONT_HEIGHT : 0.0f,
                   aMat->_12 < 0 ? MINIFONT_WIDTH * 16 : 0.0f) :
            Matrix(copysign(1.0f, aMat->_11), 0.0f,
                   0.0f, copysign(1.0f, aMat->_22),
                   aMat->_11 < 0 ? MINIFONT_WIDTH * 16 : 0.0f,
                   aMat->_22 < 0 ? MINIFONT_HEIGHT : 0.0f));
    }
    RefPtr<SourceSurface> mask = dt->CreateSourceSurfaceFromData(
        const_cast<uint8_t*>(gMiniFontData), IntSize(MINIFONT_WIDTH * 16, MINIFONT_HEIGHT),
        MINIFONT_WIDTH * 16, SurfaceFormat::A8);
    if (!mask) {
        return nullptr;
    }
    dt->MaskSurface(ColorPattern(Color(1.0f, 1.0f, 1.0f)), mask, Point(0, 0));
    return dt->Snapshot();
}

/**
 * Clear any cached WebRender glyph atlas resources.
 */
static void
PurgeWRGlyphAtlas()
{
    // For each WR layer manager, we need go through each atlas orientation
    // and see if it has a stashed image key. If it does, remove the image
    // from the layer manager.
    for (WRUserData* user : gWRUsers) {
        auto* manager = user->mManager;
        for (size_t i = 0; i < 8; i++) {
            if (gWRGlyphAtlas[i]) {
                uint32_t handle =
                    (uint32_t)(uintptr_t)gWRGlyphAtlas[i]->GetUserData(
                        reinterpret_cast<UserDataKey*>(manager));
                if (handle) {
                    manager->AddImageKeyForDiscard(
                        wr::ImageKey{manager->WrBridge()->GetNamespace(), handle});
                }
            }
        }
    }
    // Remove the layer managers' destroy notifications only after processing
    // so as not to mess up gWRUsers iteration.
    while (!gWRUsers.isEmpty()) {
        gWRUsers.popFirst()->Remove();
    }
    // Finally, clear out the atlases.
    for (size_t i = 0; i < 8; i++) {
        gWRGlyphAtlas[i] = nullptr;
    }
}

WRUserData::WRUserData(layers::WebRenderLayerManager* aManager)
    : mManager(aManager)
{
    gWRUsers.insertFront(this);
}

WRUserData::~WRUserData()
{
    // When the layer manager is destroyed, we need go through each
    // atlas and remove any assigned image keys.
    if (isInList()) {
        for (size_t i = 0; i < 8; i++) {
            if (gWRGlyphAtlas[i]) {
                gWRGlyphAtlas[i]->RemoveUserData(reinterpret_cast<UserDataKey*>(mManager));
            }
        }
    }
}

static already_AddRefed<SourceSurface>
GetWRGlyphAtlas(DrawTarget& aDrawTarget, const Matrix* aMat)
{
    uint32_t key = 0;
    // Encode orientation in the key.
    if (aMat) {
        if (aMat->_11 == 0) {
            key |= 4 | (aMat->_12 < 0 ? 1 : 0) | (aMat->_21 < 0 ? 2 : 0);
        } else {
            key |= (aMat->_11 < 0 ? 1 : 0) | (aMat->_22 < 0 ? 2 : 0);
        }
    }
    // Check if an atlas was already created, or create one if necessary.
    RefPtr<SourceSurface> atlas = gWRGlyphAtlas[key];
    if (!atlas) {
        atlas = MakeWRGlyphAtlas(aMat);
        gWRGlyphAtlas[key] = atlas;
    }
    // The atlas may exist, but an image key may not be assigned for it to
    // the given layer manager.
    auto* tdt = static_cast<layout::TextDrawTarget*>(&aDrawTarget);
    auto* manager = tdt->WrLayerManager();
    if (!atlas->GetUserData(reinterpret_cast<UserDataKey*>(manager))) {
        // No image key, so we need to map the atlas' data for transfer to WR.
        RefPtr<DataSourceSurface> dataSurface = atlas->GetDataSurface();
        if (!dataSurface) {
            return nullptr;
        }
        DataSourceSurface::ScopedMap map(dataSurface, DataSourceSurface::READ);
        if (!map.IsMapped()) {
            return nullptr;
        }
        // Transfer the data and get an image key for it.
        Maybe<wr::ImageKey> result =
            tdt->DefineImage(atlas->GetSize(),
                             map.GetStride(),
                             atlas->GetFormat(),
                             map.GetData());
        if (!result.isSome()) {
            return nullptr;
        }
        // Assign the image key to the atlas.
        atlas->AddUserData(reinterpret_cast<UserDataKey*>(manager),
                           (void*)(uintptr_t)result.value().mHandle,
                           nullptr);
        // Create a user data notification for when the layer manager is
        // destroyed so we can clean up any assigned image keys.
        WRUserData::Assign(manager);
    }
    return atlas.forget();
}

static void
DrawHexChar(uint32_t aDigit, Float aLeft, Float aTop, DrawTarget& aDrawTarget,
            SourceSurface* aAtlas, const Color& aColor,
            const Matrix* aMat = nullptr)
{
    Rect dest(aLeft, aTop, MINIFONT_WIDTH, MINIFONT_HEIGHT);
    if (aDrawTarget.GetBackendType() == BackendType::WEBRENDER_TEXT) {
        // For WR, we need to get the image key assigned to the given WR layer manager
        // for referencing the image.
        auto* tdt = static_cast<layout::TextDrawTarget*>(&aDrawTarget);
        auto* manager = tdt->WrLayerManager();
        wr::ImageKey key = {
            manager->WrBridge()->GetNamespace(),
            (uint32_t)(uintptr_t)aAtlas->GetUserData(reinterpret_cast<UserDataKey*>(manager))
        };
        // Transform the bounds of the atlas into the given orientation, and then also transform
        // a small clip rect which will be used to select the given digit from the atlas.
        Rect bounds(aLeft - aDigit * MINIFONT_WIDTH, aTop, MINIFONT_WIDTH * 16, MINIFONT_HEIGHT);
        if (aMat) {
            // Width and height may be negative after the transform, so move the rect
            // if necessary and fix size.
            bounds = aMat->TransformRect(bounds);
            bounds.x += std::min(bounds.width, 0.0f);
            bounds.y += std::min(bounds.height, 0.0f);
            bounds.width = fabs(bounds.width);
            bounds.height = fabs(bounds.height);
            dest = aMat->TransformRect(dest);
            dest.x += std::min(dest.width, 0.0f);
            dest.y += std::min(dest.height, 0.0f);
            dest.width = fabs(dest.width);
            dest.height = fabs(dest.height);
        }
        // Finally, push the colored image with point filtering.
        tdt->PushImage(key,
                       wr::ToLayoutRect(bounds),
                       wr::ToLayoutRect(dest),
                       wr::ImageRendering::Pixelated,
                       wr::ToColorF(aColor));
    } else {
        // For the normal case, just draw the given digit from the atlas. Point filtering is used
        // to ensure the mini-font rectangles stay sharp with any scaling. Handle any transparency
        // here as well.
        aDrawTarget.DrawSurface(aAtlas,
                                dest,
                                Rect(aDigit * MINIFONT_WIDTH, 0, MINIFONT_WIDTH, MINIFONT_HEIGHT),
                                DrawSurfaceOptions(SamplingFilter::POINT),
                                DrawOptions(aColor.a, CompositionOp::OP_OVER, AntialiasMode::NONE));
    }
}

void
gfxFontMissingGlyphs::Purge()
{
    PurgeGlyphAtlas();
    PurgeWRGlyphAtlas();
}

#else // MOZ_GFX_OPTIMIZE_MOBILE

void
gfxFontMissingGlyphs::Purge()
{
}

#endif

void
gfxFontMissingGlyphs::Shutdown()
{
    Purge();
}

void
gfxFontMissingGlyphs::DrawMissingGlyph(uint32_t aChar,
                                       const Rect& aRect,
                                       DrawTarget& aDrawTarget,
                                       const Pattern& aPattern,
                                       uint32_t aAppUnitsPerDevPixel,
                                       const Matrix* aMat)
{
    Rect rect(aRect);
    // If there is an orientation transform, reorient the bounding rect.
    if (aMat) {
        rect.MoveBy(-aRect.BottomLeft());
        rect = aMat->TransformBounds(rect);
        rect.MoveBy(aRect.BottomLeft());
    }

    // If we're currently drawing with some kind of pattern, we just draw the
    // missing-glyph data in black.
    Color color = aPattern.GetType() == PatternType::COLOR ?
        static_cast<const ColorPattern&>(aPattern).mColor :
        ToDeviceColor(Color(0.f, 0.f, 0.f, 1.f));

    // Stroke a rectangle so that the stroke's left edge is inset one pixel
    // from the left edge of the glyph box and the stroke's right edge
    // is inset one pixel from the right edge of the glyph box.
    Float halfBorderWidth = BOX_BORDER_WIDTH / 2.0;
    Float borderLeft = rect.X() + BOX_HORIZONTAL_INSET + halfBorderWidth;
    Float borderRight = rect.XMost() - BOX_HORIZONTAL_INSET - halfBorderWidth;
    Rect borderStrokeRect(borderLeft, rect.Y() + halfBorderWidth,
                          borderRight - borderLeft,
                          rect.Height() - 2.0 * halfBorderWidth);
    if (!borderStrokeRect.IsEmpty()) {
        ColorPattern adjustedColor(color);
        adjustedColor.mColor.a *= BOX_BORDER_OPACITY;
#ifdef MOZ_GFX_OPTIMIZE_MOBILE
        aDrawTarget.FillRect(borderStrokeRect, adjustedColor);
#else
        StrokeOptions strokeOptions(BOX_BORDER_WIDTH);
        aDrawTarget.StrokeRect(borderStrokeRect, adjustedColor, strokeOptions);
#endif
    }

#ifndef MOZ_GFX_OPTIMIZE_MOBILE
    RefPtr<SourceSurface> atlas =
        aDrawTarget.GetBackendType() == BackendType::WEBRENDER_TEXT ?
            GetWRGlyphAtlas(aDrawTarget, aMat) :
            GetGlyphAtlas(color);
    if (!atlas) {
        return;
    }

    Point center = rect.Center();
    Float halfGap = HEX_CHAR_GAP / 2.f;
    Float top = -(MINIFONT_HEIGHT + halfGap);
    // We always want integer scaling, otherwise the "bitmap" glyphs will look
    // even uglier than usual when zoomed
    int32_t devPixelsPerCSSPx =
        std::max<int32_t>(1, AppUnitsPerCSSPixel() /
                             aAppUnitsPerDevPixel);

    Matrix tempMat;
    if (aMat) {
        // If there is an orientation transform, since draw target transforms may
        // not be supported, scale and translate it so that it can be directly used
        // for rendering the mini font without changing the draw target transform.
        tempMat = Matrix(*aMat).PostScale(devPixelsPerCSSPx, devPixelsPerCSSPx)
                               .PostTranslate(center);
        aMat = &tempMat;
    } else {
        // Otherwise, scale and translate the draw target transform assuming it
        // supports that.
        tempMat = aDrawTarget.GetTransform();
        aDrawTarget.SetTransform(
            Matrix(tempMat).PreTranslate(center)
                           .PreScale(devPixelsPerCSSPx, devPixelsPerCSSPx));
    }

    if (aChar < 0x10000) {
        if (rect.Width() >= 2 * (MINIFONT_WIDTH + HEX_CHAR_GAP) &&
            rect.Height() >= 2 * MINIFONT_HEIGHT + HEX_CHAR_GAP) {
            // Draw 4 digits for BMP
            Float left = -(MINIFONT_WIDTH + halfGap);
            DrawHexChar((aChar >> 12) & 0xF, left, top, aDrawTarget, atlas, color, aMat);
            DrawHexChar((aChar >> 8) & 0xF, halfGap, top, aDrawTarget, atlas, color, aMat);
            DrawHexChar((aChar >> 4) & 0xF, left, halfGap, aDrawTarget, atlas, color, aMat);
            DrawHexChar(aChar & 0xF, halfGap, halfGap, aDrawTarget, atlas, color, aMat);
        }
    } else {
        if (rect.Width() >= 3 * (MINIFONT_WIDTH + HEX_CHAR_GAP) &&
            rect.Height() >= 2 * MINIFONT_HEIGHT + HEX_CHAR_GAP) {
            // Draw 6 digits for non-BMP
            Float first = -(MINIFONT_WIDTH * 1.5 + HEX_CHAR_GAP);
            Float second = -(MINIFONT_WIDTH / 2.0);
            Float third = (MINIFONT_WIDTH / 2.0 + HEX_CHAR_GAP);
            DrawHexChar((aChar >> 20) & 0xF, first, top, aDrawTarget, atlas, color, aMat);
            DrawHexChar((aChar >> 16) & 0xF, second, top, aDrawTarget, atlas, color, aMat);
            DrawHexChar((aChar >> 12) & 0xF, third, top, aDrawTarget, atlas, color, aMat);
            DrawHexChar((aChar >> 8) & 0xF, first, halfGap, aDrawTarget, atlas, color, aMat);
            DrawHexChar((aChar >> 4) & 0xF, second, halfGap, aDrawTarget, atlas, color, aMat);
            DrawHexChar(aChar & 0xF, third, halfGap, aDrawTarget, atlas, color, aMat);
        }
    }

    if (!aMat) {
        // The draw target transform was changed, so it must be restored to
        // the original value.
        aDrawTarget.SetTransform(tempMat);
    }
#endif
}

Float
gfxFontMissingGlyphs::GetDesiredMinWidth(uint32_t aChar,
                                         uint32_t aAppUnitsPerDevPixel)
{
/**
 * The minimum desired width for a missing-glyph glyph box. I've laid it out
 * like this so you can see what goes where.
 */
    Float width = BOX_HORIZONTAL_INSET + BOX_BORDER_WIDTH + HEX_CHAR_GAP +
        MINIFONT_WIDTH + HEX_CHAR_GAP + MINIFONT_WIDTH +
         ((aChar < 0x10000) ? 0 : HEX_CHAR_GAP + MINIFONT_WIDTH) +
        HEX_CHAR_GAP + BOX_BORDER_WIDTH + BOX_HORIZONTAL_INSET;
    // Note that this will give us floating-point division, so the width will
    // -not- be snapped to integer multiples of its basic pixel value
    width *= Float(AppUnitsPerCSSPixel()) / aAppUnitsPerDevPixel;
    return width;
}