gfx/src/nsRect.cpp
author Matt Woodrow <mwoodrow@mozilla.com>
Wed, 09 Feb 2011 09:35:54 +1300
changeset 62161 5ed6c4935486d1aee52f9edcd96043b0fab86fb8
parent 54095 173e878ad96a842e5baf0e9aec488afdffae156a
child 62162 b0512b9a8c11ae974391a714753aca994857a391
permissions -rw-r--r--
Bug 586683 - Part 1 - Add resolution handling to BasicLayers. r=roc a=blocking2.0

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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#include "nsRect.h"
#include "nsString.h"
#include "nsIDeviceContext.h"
#include "prlog.h"
#include <limits.h>

// the mozilla::css::Side sequence must match the nsMargin nscoord sequence
PR_STATIC_ASSERT((NS_SIDE_TOP == 0) && (NS_SIDE_RIGHT == 1) && (NS_SIDE_BOTTOM == 2) && (NS_SIDE_LEFT == 3));


/* static */
const nsIntRect nsIntRect::kMaxSizedIntRect(0, 0, INT_MAX, INT_MAX);

// Containment
PRBool nsRect::Contains(nscoord aX, nscoord aY) const
{
  return (PRBool) ((aX >= x) && (aY >= y) &&
                   (aX < XMost()) && (aY < YMost()));
}

//Also Returns true if aRect is Empty
PRBool nsRect::Contains(const nsRect &aRect) const
{
  return aRect.IsEmpty() ||
          ((PRBool) ((aRect.x >= x) && (aRect.y >= y) &&
                    (aRect.XMost() <= XMost()) && (aRect.YMost() <= YMost())));
}

// Intersection. Returns TRUE if the receiver overlaps aRect and
// FALSE otherwise
PRBool nsRect::Intersects(const nsRect &aRect) const
{
  return (PRBool) ((x < aRect.XMost()) && (y < aRect.YMost()) &&
                   (aRect.x < XMost()) && (aRect.y < YMost()));
}

// Computes the area in which aRect1 and aRect2 overlap and fills 'this' with
// the result. Returns FALSE if the rectangles don't intersect.
PRBool nsRect::IntersectRect(const nsRect &aRect1, const nsRect &aRect2)
{
  nscoord  xmost1 = aRect1.XMost();
  nscoord  ymost1 = aRect1.YMost();
  nscoord  xmost2 = aRect2.XMost();
  nscoord  ymost2 = aRect2.YMost();
  nscoord  temp;

  x = PR_MAX(aRect1.x, aRect2.x);
  y = PR_MAX(aRect1.y, aRect2.y);

  // Compute the destination width
  temp = PR_MIN(xmost1, xmost2);
  if (temp <= x) {
    width = 0;
  } else {
    width = temp - x;
  }

  // Compute the destination height
  temp = PR_MIN(ymost1, ymost2);
  if (temp <= y) {
    height = 0;
  } else {
    height = temp - y;
  }

  return !IsEmpty();
}

// Computes the smallest rectangle that contains both aRect1 and aRect2 and
// fills 'this' with the result. Returns FALSE if both aRect1 and aRect2 are
// empty and TRUE otherwise
PRBool nsRect::UnionRect(const nsRect &aRect1, const nsRect &aRect2)
{
  PRBool  result = PR_TRUE;

  // Is aRect1 empty?
  if (aRect1.IsEmpty()) {
    if (aRect2.IsEmpty()) {
      // Both rectangles are empty which is an error
      Empty();
      result = PR_FALSE;
    } else {
      // aRect1 is empty so set the result to aRect2
      *this = aRect2;
    }
  } else if (aRect2.IsEmpty()) {
    // aRect2 is empty so set the result to aRect1
    *this = aRect1;
  } else {
    UnionRectIncludeEmpty(aRect1, aRect2);
  }

  return result;
}

void nsRect::UnionRectIncludeEmpty(const nsRect &aRect1, const nsRect &aRect2)
{
  nscoord xmost1 = aRect1.XMost();
  nscoord xmost2 = aRect2.XMost();
  nscoord ymost1 = aRect1.YMost();
  nscoord ymost2 = aRect2.YMost();

  // Compute the origin
  x = PR_MIN(aRect1.x, aRect2.x);
  y = PR_MIN(aRect1.y, aRect2.y);

  // Compute the size
  width = PR_MAX(xmost1, xmost2) - x;
  height = PR_MAX(ymost1, ymost2) - y;
}

// Inflate the rect by the specified width and height
void nsRect::Inflate(nscoord aDx, nscoord aDy)
{
  x -= aDx;
  y -= aDy;
  width += 2 * aDx;
  height += 2 * aDy;
}

// Inflate the rect by the specified margin
void nsRect::Inflate(const nsMargin &aMargin)
{
  x -= aMargin.left;
  y -= aMargin.top;
  width += aMargin.left + aMargin.right;
  height += aMargin.top + aMargin.bottom;
}

// Deflate the rect by the specified width and height
void nsRect::Deflate(nscoord aDx, nscoord aDy)
{
  x += aDx;
  y += aDy;
  width = PR_MAX(0, width - 2 * aDx);
  height = PR_MAX(0, height - 2 * aDy);
}

// Deflate the rect by the specified margin
void nsRect::Deflate(const nsMargin &aMargin)
{
  x += aMargin.left;
  y += aMargin.top;
  width = PR_MAX(0, width - aMargin.LeftRight());
  height = PR_MAX(0, height - aMargin.TopBottom());
}

// Find difference between rects as an nsMargin
nsMargin nsRect::operator-(const nsRect& aRect) const
{
  nsMargin margin;
  margin.left = aRect.x - x;
  margin.right = XMost() - aRect.XMost();
  margin.top = aRect.y - y;
  margin.bottom = YMost() - aRect.YMost();
  return margin;
}

// scale the rect but round to smallest containing rect
nsRect& nsRect::ScaleRoundOut(float aXScale, float aYScale)
{
  nscoord right = NSToCoordCeil(float(XMost()) * aXScale);
  nscoord bottom = NSToCoordCeil(float(YMost()) * aYScale);
  x = NSToCoordFloor(float(x) * aXScale);
  y = NSToCoordFloor(float(y) * aYScale);
  width = (right - x);
  height = (bottom - y);
  return *this;
}

static bool IsFloatInteger(float aFloat)
{
  return fabs(aFloat - NS_round(aFloat)) < 1e-6;
}

nsRect& nsRect::ExtendForScaling(float aXMult, float aYMult)
{
  NS_ASSERTION((IsFloatInteger(aXMult) || IsFloatInteger(1/aXMult)) &&
               (IsFloatInteger(aYMult) || IsFloatInteger(1/aYMult)),
               "Multiplication factors must be integers or 1/integer");
               
  // Scale rect by multiplier, snap outwards to integers and then unscale.
  // We round the results to the nearest integer to prevent floating point errors.
  if (aXMult < 1) {
    nscoord right = NSToCoordRound(ceil(float(XMost()) * aXMult) / aXMult);
    x = NSToCoordRound(floor(float(x) * aXMult) / aXMult);
    width = right - x;
  }
  if (aYMult < 1) {
    nscoord bottom = NSToCoordRound(ceil(float(YMost()) * aYMult) / aYMult);
    y = NSToCoordRound(floor(float(y) * aYMult) / aYMult);
    height = bottom - y;
  }
  return *this;
}

#ifdef DEBUG
// Diagnostics

FILE* operator<<(FILE* out, const nsRect& rect)
{
  nsAutoString tmp;

  // Output the coordinates in fractional pixels so they're easier to read
  tmp.AppendLiteral("{");
  tmp.AppendFloat(NSAppUnitsToFloatPixels(rect.x,
                       nsIDeviceContext::AppUnitsPerCSSPixel()));
  tmp.AppendLiteral(", ");
  tmp.AppendFloat(NSAppUnitsToFloatPixels(rect.y,
                       nsIDeviceContext::AppUnitsPerCSSPixel()));
  tmp.AppendLiteral(", ");
  tmp.AppendFloat(NSAppUnitsToFloatPixels(rect.width,
                       nsIDeviceContext::AppUnitsPerCSSPixel()));
  tmp.AppendLiteral(", ");
  tmp.AppendFloat(NSAppUnitsToFloatPixels(rect.height,
                       nsIDeviceContext::AppUnitsPerCSSPixel()));
  tmp.AppendLiteral("}");
  fputs(NS_LossyConvertUTF16toASCII(tmp).get(), out);
  return out;
}

#endif // DEBUG

// Computes the area in which aRect1 and aRect2 overlap and fills 'this' with
// the result. Returns FALSE if the rectangles don't intersect.
PRBool nsIntRect::IntersectRect(const nsIntRect &aRect1, const nsIntRect &aRect2)
{
  PRInt32  xmost1 = aRect1.XMost();
  PRInt32  ymost1 = aRect1.YMost();
  PRInt32  xmost2 = aRect2.XMost();
  PRInt32  ymost2 = aRect2.YMost();
  PRInt32  temp;

  x = PR_MAX(aRect1.x, aRect2.x);
  y = PR_MAX(aRect1.y, aRect2.y);

  // Compute the destination width
  temp = PR_MIN(xmost1, xmost2);
  if (temp <= x) {
    Empty();
    return PR_FALSE;
  }
  width = temp - x;

  // Compute the destination height
  temp = PR_MIN(ymost1, ymost2);
  if (temp <= y) {
    Empty();
    return PR_FALSE;
  }
  height = temp - y;

  return PR_TRUE;
}

// Computes the smallest rectangle that contains both aRect1 and aRect2 and
// fills 'this' with the result. Returns FALSE if both aRect1 and aRect2 are
// empty and TRUE otherwise
PRBool nsIntRect::UnionRect(const nsIntRect &aRect1, const nsIntRect &aRect2)
{
  PRBool  result = PR_TRUE;

  // Is aRect1 empty?
  if (aRect1.IsEmpty()) {
    if (aRect2.IsEmpty()) {
      // Both rectangles are empty which is an error
      Empty();
      result = PR_FALSE;
    } else {
      // aRect1 is empty so set the result to aRect2
      *this = aRect2;
    }
  } else if (aRect2.IsEmpty()) {
    // aRect2 is empty so set the result to aRect1
    *this = aRect1;
  } else {
    PRInt32 xmost1 = aRect1.XMost();
    PRInt32 xmost2 = aRect2.XMost();
    PRInt32 ymost1 = aRect1.YMost();
    PRInt32 ymost2 = aRect2.YMost();

    // Compute the origin
    x = PR_MIN(aRect1.x, aRect2.x);
    y = PR_MIN(aRect1.y, aRect2.y);

    // Compute the size
    width = PR_MAX(xmost1, xmost2) - x;
    height = PR_MAX(ymost1, ymost2) - y;
  }

  return result;
}