Revert "Evenly space gradient stage."
This reverts commit 892501d09bc8608704362235c73a59bb23a386b3.
Reason for revert:
https://bugs.chromium.org/p/chromium/issues/detail?id=721682
:(
Original change's description:
> Evenly space gradient stage.
>
> This seems like an experiment at this point because I don't know how to do
> this kind of thing on arm.
>
>
> Numbers from Skylake...
> Before:
> ./out/Release/nanobench --config srgb \
> --match gradient_linear_clamp_3color gradient_linear_clamp_hicolor -q 19:48:13
> Timer overhead: 36.7ns
> ! -> high variance, ? -> moderate variance
> micros bench
> 439.92 ? gradient_linear_clamp_3color srgb
> 2697.60 gradient_linear_clamp_hicolor srgb
> 437.28 gradient_linear_clamp_3color_4f srgb
> 2700.50 gradient_linear_clamp_hicolor_4f srgb
>
>
> After:
> micros bench
> 382.35 gradient_linear_clamp_3color srgb
> 593.49 gradient_linear_clamp_hicolor srgb
> 382.36 gradient_linear_clamp_3color_4f srgb
> 565.60 gradient_linear_clamp_hicolor_4f srgb
>
>
> Numbers on my Mac Trashcan are about even; there is no
> speedup or slowdown between master and this change.
>
> Change-Id: I04402452e23c0888512362fd1d6d5436cea61719
> Reviewed-on: https://skia-review.googlesource.com/15960
> Commit-Queue: Herb Derby <herb@google.com>
> Reviewed-by: Mike Klein <mtklein@chromium.org>
>
TBR=mtklein@chromium.org,mtklein@google.com,herb@google.com,fmalita@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
Change-Id: Ic6a064c66686b6f238ca1417ba1abd9ce25de1b4
Reviewed-on: https://skia-review.googlesource.com/16660
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Mike Klein <mtklein@chromium.org>
diff --git a/src/effects/gradients/SkGradientShader.cpp b/src/effects/gradients/SkGradientShader.cpp
index 9e2be46..6f9b404 100644
--- a/src/effects/gradients/SkGradientShader.cpp
+++ b/src/effects/gradients/SkGradientShader.cpp
@@ -5,7 +5,6 @@
* found in the LICENSE file.
*/
-#include <algorithm>
#include "Sk4fLinearGradient.h"
#include "SkColorSpace_XYZ.h"
#include "SkGradientShaderPriv.h"
@@ -407,74 +406,51 @@
p->append(SkRasterPipeline::linear_gradient_2stops, f_and_b);
} else {
+
+ struct Stop { float t; SkPM4f f, b; };
+ struct Ctx { size_t n; Stop* stops; SkPM4f start; };
+
+ auto* ctx = alloc->make<Ctx>();
+ ctx->start = prepareColor(0);
+
+ // For each stop we calculate a bias B and a scale factor F, such that
+ // for any t between stops n and n+1, the color we want is B[n] + F[n]*t.
+ auto init_stop = [](float t_l, float t_r, SkPM4f c_l, SkPM4f c_r, Stop *stop) {
+ auto F = SkPM4f::From4f((c_r.to4f() - c_l.to4f()) / (t_r - t_l));
+ auto B = SkPM4f::From4f(c_l.to4f() - (F.to4f() * t_l));
+ *stop = {t_l, F, B};
+ };
+
if (fOrigPos == nullptr) {
// Handle evenly distributed stops.
- struct Ctx {
- size_t stopCount;
- float* fs[4];
- float* bs[4];
- };
-
- auto* ctx = alloc->make<Ctx>();
- int stopCount = fColorCount;
- float gapCount = stopCount - 1;
-
+ float dt = 1.0f / (fColorCount - 1);
// In the evenly distributed case, fColorCount is the number of stops. There are no
- // dummy entries. So, there are fColorCount - 1 FBs.
- for (int i = 0; i < 4; i++) {
+ // dummy entries.
+ auto* stopsArray = alloc->makeArrayDefault<Stop>(fColorCount);
- // Pad up to 8 in case we hit the AVX2 special case.
- ctx->fs[i] = alloc->makeArray<float>(std::max(stopCount, 8));
- ctx->bs[i] = alloc->makeArray<float>(std::max(stopCount, 8));
- }
-
- auto add_stop = [&](int stop, SkPM4f Fs, SkPM4f Bs) {
- (ctx->fs[0])[stop] = Fs.r();
- (ctx->fs[1])[stop] = Fs.g();
- (ctx->fs[2])[stop] = Fs.b();
- (ctx->fs[3])[stop] = Fs.a();
- (ctx->bs[0])[stop] = Bs.r();
- (ctx->bs[1])[stop] = Bs.g();
- (ctx->bs[2])[stop] = Bs.b();
- (ctx->bs[3])[stop] = Bs.a();
- };
- auto init_stop = [&](int stop, SkPM4f c_l, SkPM4f c_r) {
- auto Fs = SkPM4f::From4f((c_r.to4f() - c_l.to4f()) * gapCount);
- auto Bs = SkPM4f::From4f(c_l.to4f() - (Fs.to4f() * (stop / gapCount)));
- add_stop(stop, Fs, Bs);
- };
-
- SkPM4f c_l = prepareColor(0);
+ float t_l = 0;
+ SkPM4f c_l = ctx->start;
for (int i = 0; i < fColorCount - 1; i++) {
+ // Use multiply instead of accumulating error using repeated addition.
+ float t_r = (i + 1) * dt;
SkPM4f c_r = prepareColor(i + 1);
- init_stop(i, c_l, c_r);
+ init_stop(t_l, t_r, c_l, c_r, &stopsArray[i]);
+
+ t_l = t_r;
c_l = c_r;
}
- // Add the last stop.
- add_stop(stopCount - 1, SkPM4f::FromPremulRGBA(0,0,0,0), c_l);
+ // Force the last stop.
+ stopsArray[fColorCount - 1].t = 1;
+ stopsArray[fColorCount - 1].f = SkPM4f::From4f(Sk4f{0});
+ stopsArray[fColorCount - 1].b = prepareColor(fColorCount - 1);
- ctx->stopCount = stopCount;
-
- p->append(SkRasterPipeline::evenly_spaced_linear_gradient, ctx);
+ ctx->n = fColorCount;
+ ctx->stops = stopsArray;
} else {
// Handle arbitrary stops.
- struct Stop { float t; SkPM4f f, b; };
- struct Ctx { size_t n; Stop* stops; SkPM4f start; };
-
- auto* ctx = alloc->make<Ctx>();
- ctx->start = prepareColor(0);
-
- // For each stop we calculate a bias B and a scale factor F, such that
- // for any t between stops n and n+1, the color we want is B[n] + F[n]*t.
- auto init_stop = [](float t_l, float t_r, SkPM4f c_l, SkPM4f c_r, Stop *stop) {
- auto F = SkPM4f::From4f((c_r.to4f() - c_l.to4f()) / (t_r - t_l));
- auto B = SkPM4f::From4f(c_l.to4f() - (F.to4f() * t_l));
- *stop = {t_l, F, B};
- };
-
// Remove the dummy stops inserted by SkGradientShaderBase::SkGradientShaderBase
// because they are naturally handled by the search method.
int firstStop;
@@ -515,8 +491,9 @@
ctx->n = stopCount;
ctx->stops = stopsArray;
- p->append(SkRasterPipeline::linear_gradient, ctx);
}
+
+ p->append(SkRasterPipeline::linear_gradient, ctx);
}
if (!premulGrad && !this->colorsAreOpaque()) {