Retry "Factor out common code from sweep and linear."

We weren't handing failure correctly, sending radials and two point
conics and any other unsupported cases back too far out, instead of
the default SkShader::onAppendStages().

This reverts commit 02ab8cc2909d99377e4200cd426a02c0b482a040.

Change-Id: I80cb028c37071e0146ee4b48b210fc8bc87b290f
Reviewed-on: https://skia-review.googlesource.com/15481
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Mike Klein <mtklein@chromium.org>

1 files changed, 4 insertions, 142 deletions

diff --git a/src/effects/gradients/SkSweepGradient.cpp b/src/effects/gradients/SkSweepGradient.cpp
index 81fdfe481b..b3a24cd16e 100644
--- a/src/effects/gradients/SkSweepGradient.cpp
+++ b/src/effects/gradients/SkSweepGradient.cpp
@@ -311,150 +311,12 @@ void SkSweepGradient::toString(SkString* str) const {
     str->append(")");
 }
 
-bool SkSweepGradient::onAppendStages(SkRasterPipeline* p,
-                                     SkColorSpace* dstCS,
-                                     SkArenaAlloc* alloc,
-                                     const SkMatrix& ctm,
-                                     const SkPaint& paint,
-                                     const SkMatrix* localM) const {
-    // Local matrix not supported currently.  Remove once we have a generic RP wrapper.
-    if (localM || !getLocalMatrix().isIdentity()) {
-        return false;
-    }
-
-    SkMatrix dstToSrc;
-    if (!ctm.invert(&dstToSrc)) {
-        return false;
-    }
-
-    const auto dstToCenter = SkMatrix::Concat(
-            SkMatrix::MakeTrans(-fCenter.fX, -fCenter.fY), dstToSrc);
-
-    auto* m = alloc->makeArrayDefault<float>(9);
-    if (dstToCenter.asAffine(m)) {
-        // TODO: mapping y is not needed; split the matrix stages to save some math?
-        p->append(SkRasterPipeline::matrix_2x3, m);
-    } else {
-        dstToCenter.get9(m);
-        p->append(SkRasterPipeline::matrix_perspective, m);
-    }
-
+bool SkSweepGradient::adjustMatrixAndAppendStages(SkArenaAlloc* alloc,
+                                                  SkMatrix* matrix,
+                                                  SkRasterPipeline* p) const {
+    matrix->postTranslate(-fCenter.fX, -fCenter.fY);
     p->append(SkRasterPipeline::xy_to_polar_unit);
 
-    const bool premulGrad = fGradFlags & SkGradientShader::kInterpolateColorsInPremul_Flag;
-    auto prepareColor = [premulGrad, dstCS, this](int i) {
-        SkColor4f c = dstCS ? to_colorspace(fOrigColors4f[i], fColorSpace.get(), dstCS)
-                            : SkColor4f_from_SkColor(fOrigColors[i], nullptr);
-        return premulGrad ? c.premul()
-                          : SkPM4f::From4f(Sk4f::Load(&c));
-    };
-
-    // The two-stop case with stops at 0 and 1.
-    if (fColorCount == 2 && fOrigPos == nullptr) {
-        const SkPM4f c_l = prepareColor(0),
-                     c_r = prepareColor(1);
-
-        // See F and B below.
-        auto* f_and_b = alloc->makeArrayDefault<SkPM4f>(2);
-        f_and_b[0] = SkPM4f::From4f(c_r.to4f() - c_l.to4f());
-        f_and_b[1] = c_l;
-
-        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.
-
-            float dt = 1.0f / (fColorCount - 1);
-            // In the evenly distributed case, fColorCount is the number of stops. There are no
-            // dummy entries.
-            auto* stopsArray = alloc->makeArrayDefault<Stop>(fColorCount);
-
-            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(t_l, t_r, c_l, c_r, &stopsArray[i]);
-
-                t_l = t_r;
-                c_l = c_r;
-            }
-
-            // 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->n = fColorCount;
-            ctx->stops = stopsArray;
-        } else {
-            // Handle arbitrary stops.
-
-            // Remove the dummy stops inserted by SkGradientShaderBase::SkGradientShaderBase
-            // because they are naturally handled by the search method.
-            int firstStop;
-            int lastStop;
-            if (fColorCount > 2) {
-                firstStop = fOrigColors4f[0] != fOrigColors4f[1] ? 0 : 1;
-                lastStop = fOrigColors4f[fColorCount - 2] != fOrigColors4f[fColorCount - 1]
-                           ? fColorCount - 1 : fColorCount - 2;
-            } else {
-                firstStop = 0;
-                lastStop = 1;
-            }
-            int realCount = lastStop - firstStop + 1;
-
-            // This is the maximum number of stops. There may be fewer stops because the duplicate
-            // points of hard stops are removed.
-            auto* stopsArray = alloc->makeArrayDefault<Stop>(realCount);
-
-            size_t stopCount = 0;
-            float  t_l = fOrigPos[firstStop];
-            SkPM4f c_l = prepareColor(firstStop);
-            // N.B. lastStop is the index of the last stop, not one after.
-            for (int i = firstStop; i < lastStop; i++) {
-                float  t_r = fOrigPos[i + 1];
-                SkPM4f c_r = prepareColor(i + 1);
-                if (t_l < t_r) {
-                    init_stop(t_l, t_r, c_l, c_r, &stopsArray[stopCount]);
-                    stopCount += 1;
-                }
-                t_l = t_r;
-                c_l = c_r;
-            }
-
-            stopsArray[stopCount].t = fOrigPos[lastStop];
-            stopsArray[stopCount].f = SkPM4f::From4f(Sk4f{0});
-            stopsArray[stopCount].b = prepareColor(lastStop);
-            stopCount += 1;
-
-            ctx->n = stopCount;
-            ctx->stops = stopsArray;
-        }
-
-        p->append(SkRasterPipeline::linear_gradient, ctx);
-    }
-
-    if (!premulGrad && !this->colorsAreOpaque()) {
-        p->append(SkRasterPipeline::premul);
-    }
-
     return true;
 }