blob: 2e9a513bb59141b2e064ddba6419cb50c04631d9 [file] [log] [blame]
* Copyright 2018 Google Inc.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
// This top-level effect implements clamping on the layout coordinate and requires specifying the
// border colors that are used when outside the clamped boundary. Gradients with the
// SkShader::kClamp_TileMode should use the colors at their first and last stop (after adding dummy
// stops for t=0,t=1) as the border color. This will automatically replicate the edge color, even if
// when there is a hard stop.
// The SkShader::kDecal_TileMode can be produced by specifying transparent black as the border
// colors, regardless of the gradient's stop colors.
in fragmentProcessor colorizer;
in fragmentProcessor gradLayout;
layout(ctype=SkPMColor4f, tracked) in uniform half4 leftBorderColor; // t < 0.0
layout(ctype=SkPMColor4f, tracked) in uniform half4 rightBorderColor; // t > 1.0
layout(key) in bool makePremul;
// Trust the creator that this matches the color spec of the gradient
in bool colorsAreOpaque;
half4 main() {
half4 t = sample(gradLayout);
half4 outColor;
// If t.x is below 0, use the left border color without invoking the child processor. If any t.x
// is above 1, use the right border color. Otherwise, t is in the [0, 1] range assumed by the
// colorizer FP, so delegate to the child processor.
if (!gradLayout.preservesOpaqueInput && t.y < 0) {
// layout has rejected this fragment (rely on sksl to remove this branch if the layout FP
// preserves opacity is false)
outColor = half4(0);
} else if (t.x < 0) {
outColor = leftBorderColor;
} else if (t.x > 1.0) {
outColor = rightBorderColor;
} else {
// Always sample from (x, 0), discarding y, since the layout FP can use y as a side-channel.
outColor = sample(colorizer, t.x0);
@if (makePremul) {
outColor.rgb *= outColor.a;
return outColor;
// If the layout does not preserve opacity, remove the opaque optimization,
// but otherwise respect the provided color opacity state (which should take
// into account the opacity of the border colors).
@optimizationFlags {
kCompatibleWithCoverageAsAlpha_OptimizationFlag |
(colorsAreOpaque && gradLayout->preservesOpaqueInput() ? kPreservesOpaqueInput_OptimizationFlag
: kNone_OptimizationFlags)