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Bug 1274624 - Speed up tiled axis-aligned linear gradient painting - r=mstange

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This commit is contained in:
Edwin Flores
2016-07-27 16:57:53 +01:00
parent 1359267ec4
commit db7f97c65f
1 changed files with 122 additions and 14 deletions
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136
layout/base/nsCSSRendering.cpp
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@@ -2532,6 +2532,79 @@ ResolvePremultipliedAlpha(nsTArray<ColorStop>& aStops)
}
}
static ColorStop
InterpolateColorStop(const ColorStop& aFirst, const ColorStop& aSecond,
double aPosition, const Color& aDefault)
{
MOZ_ASSERT(aFirst.mPosition <= aPosition);
MOZ_ASSERT(aPosition <= aSecond.mPosition);
double delta = aSecond.mPosition - aFirst.mPosition;
if (delta < 1e-6) {
return ColorStop(aPosition, false, aDefault);
}
return ColorStop(aPosition, false,
Unpremultiply(InterpolateColor(Premultiply(aFirst.mColor),
Premultiply(aSecond.mColor),
(aPosition - aFirst.mPosition) / delta)));
}
// Clamp and extend the given ColorStop array in-place to fit exactly into the
// range [0, 1].
static void
ClampColorStops(nsTArray<ColorStop>& aStops)
{
MOZ_ASSERT(aStops.Length() > 0);
// If all stops are outside the range, then get rid of everything and replace
// with a single colour.
if (aStops.Length() < 2 || aStops[0].mPosition > 1 ||
aStops.LastElement().mPosition < 0) {
Color c = aStops[0].mPosition > 1 ? aStops[0].mColor : aStops.LastElement().mColor;
aStops.Clear();
aStops.AppendElement(ColorStop(0, false, c));
return;
}
// Create the 0 and 1 points if they fall in the range of |aStops|, and discard
// all stops outside the range [0, 1].
// XXX: If we have stops positioned at 0 or 1, we only keep the innermost of
// those stops. This should be fine for the current user(s) of this function.
for (size_t i = aStops.Length() - 1; i > 0; i--) {
if (aStops[i - 1].mPosition < 1 && aStops[i].mPosition >= 1) {
// Add a point to position 1.
aStops[i] = InterpolateColorStop(aStops[i - 1], aStops[i],
/* aPosition = */ 1,
aStops[i - 1].mColor);
// Remove all the elements whose position is greater than 1.
aStops.RemoveElementsAt(i + 1, aStops.Length() - (i + 1));
}
if (aStops[i - 1].mPosition <= 0 && aStops[i].mPosition > 0) {
// Add a point to position 0.
aStops[i - 1] = InterpolateColorStop(aStops[i - 1], aStops[i],
/* aPosition = */ 0,
aStops[i].mColor);
// Remove all of the preceding stops -- they are all negative.
aStops.RemoveElementsAt(0, i - 1);
break;
}
}
MOZ_ASSERT(aStops[0].mPosition >= 0);
MOZ_ASSERT(aStops.LastElement().mPosition <= 1);
// The end points won't exist yet if they don't fall in the original range of
// |aStops|. Create them if needed.
if (aStops[0].mPosition > 0) {
aStops.InsertElementAt(0, ColorStop(0, false, aStops[0].mColor));
}
if (aStops.LastElement().mPosition < 1) {
aStops.AppendElement(ColorStop(1, false, aStops.LastElement().mColor));
}
}
void
nsCSSRendering::PaintGradient(nsPresContext* aPresContext,
nsRenderingContext& aRenderingContext,
@@ -2646,6 +2719,55 @@ nsCSSRendering::PaintGradient(nsPresContext* aPresContext,
}
}
// If a non-repeating linear gradient is axis-aligned and there are no gaps
// between tiles, we can optimise away most of the work by converting to a
// repeating linear gradient and filling the whole destination rect at once.
bool forceRepeatToCoverTiles =
aGradient->mShape == NS_STYLE_GRADIENT_SHAPE_LINEAR &&
(lineStart.x == lineEnd.x) != (lineStart.y == lineEnd.y) &&
aRepeatSize.width == aDest.width && aRepeatSize.height == aDest.height &&
!aGradient->mRepeating && !cellContainsFill;
gfxMatrix matrix;
if (forceRepeatToCoverTiles) {
// Length of the source rectangle along the gradient axis.
double rectLen;
// The position of the start of the rectangle along the gradient.
double offset;
// The gradient line is "backwards". Flip the line upside down to make
// things easier, and then rotate the matrix to turn everything back the
// right way up.
if (lineStart.x > lineEnd.x || lineStart.y > lineEnd.y) {
std::swap(lineStart, lineEnd);
matrix.Scale(-1, -1);
}
// Fit the gradient line exactly into the source rect.
if (lineStart.x != lineEnd.x) {
rectLen = srcSize.width;
offset = ((double)aSrc.x - lineStart.x) / lineLength;
lineStart.x = aSrc.x;
lineEnd.x = aSrc.x + srcSize.width;
} else {
rectLen = srcSize.height;
offset = ((double)aSrc.y - lineStart.y) / lineLength;
lineStart.y = aSrc.y;
lineEnd.y = aSrc.y + srcSize.height;
}
// Adjust gradient stop positions for the new gradient line.
double scale = lineLength / rectLen;
for (size_t i = 0; i < stops.Length(); i++) {
stops[i].mPosition = (stops[i].mPosition - offset) * fabs(scale);
}
// Clamp or extrapolate gradient stops to exactly [0, 1].
ClampColorStops(stops);
lineLength = rectLen;
}
// Eliminate negative-position stops if the gradient is radial.
double firstStop = stops[0].mPosition;
if (aGradient->mShape != NS_STYLE_GRADIENT_SHAPE_LINEAR && firstStop < 0.0) {
@@ -2745,8 +2867,6 @@ nsCSSRendering::PaintGradient(nsPresContext* aPresContext,
// Create the gradient pattern.
RefPtr<gfxPattern> gradientPattern;
bool forceRepeatToCoverTiles = false;
gfxMatrix matrix;
gfxPoint gradientStart;
gfxPoint gradientEnd;
if (aGradient->mShape == NS_STYLE_GRADIENT_SHAPE_LINEAR) {
@@ -2770,18 +2890,6 @@ nsCSSRendering::PaintGradient(nsPresContext* aPresContext,
gradientPattern = new gfxPattern(gradientStart.x, gradientStart.y,
gradientEnd.x, gradientEnd.y);
// When the gradient line is parallel to the x axis from the left edge
// to the right edge of a tile, then we can repeat by just repeating the
// gradient.
if (!cellContainsFill &&
stopDelta != 0.0 && // if 0.0, gradientStopEnd is bogus (see above)
((gradientStopStart.y == gradientStopEnd.y && gradientStopStart.x == 0 &&
gradientStopEnd.x == srcSize.width) ||
(gradientStopStart.x == gradientStopEnd.x && gradientStopStart.y == 0 &&
gradientStopEnd.y == srcSize.height))) {
forceRepeatToCoverTiles = true;
}
} else {
NS_ASSERTION(firstStop >= 0.0,
"Negative stops not allowed for radial gradients");