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Unified Diff: src/effects/SkColorMatrixFilter.cpp

Issue 967943002: impl colormatrix w/ floats (Closed) Base URL: https://skia.googlesource.com/skia.git@master
Patch Set: Created 5 years, 9 months ago
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Index: src/effects/SkColorMatrixFilter.cpp
diff --git a/src/effects/SkColorMatrixFilter.cpp b/src/effects/SkColorMatrixFilter.cpp
index bb3b6dda78b462e02454e3b536519cba51bf8d75..a63666e4c0dd4d114a06510da13d2dcb01d87731 100644
--- a/src/effects/SkColorMatrixFilter.cpp
+++ b/src/effects/SkColorMatrixFilter.cpp
@@ -1,18 +1,38 @@
-
/*
* Copyright 2011 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
+
#include "SkColorMatrixFilter.h"
#include "SkColorMatrix.h"
#include "SkColorPriv.h"
+#include "SkPMFloat.h"
#include "SkReadBuffer.h"
#include "SkWriteBuffer.h"
#include "SkUnPreMultiply.h"
#include "SkString.h"
+#define SK_PMORDER_INDEX_A (SK_A32_SHIFT / 8)
+#define SK_PMORDER_INDEX_R (SK_R32_SHIFT / 8)
+#define SK_PMORDER_INDEX_G (SK_G32_SHIFT / 8)
+#define SK_PMORDER_INDEX_B (SK_B32_SHIFT / 8)
+
+static void transpose_to_pmorder(float dst[20], const float src[20]) {
+ const float* srcR = src + 0;
+ const float* srcG = src + 5;
+ const float* srcB = src + 10;
+ const float* srcA = src + 15;
+
+ for (int i = 0; i < 20; i += 4) {
+ dst[i + SK_PMORDER_INDEX_A] = *srcA++;
+ dst[i + SK_PMORDER_INDEX_R] = *srcR++;
+ dst[i + SK_PMORDER_INDEX_G] = *srcG++;
+ dst[i + SK_PMORDER_INDEX_B] = *srcB++;
+ }
+}
+
static int32_t rowmul4(const int32_t array[], unsigned r, unsigned g,
unsigned b, unsigned a) {
return array[0] * r + array[1] * g + array[2] * b + array[3] * a + array[4];
@@ -123,6 +143,8 @@ static void Add16(const SkColorMatrixFilter::State& state,
// src is [20] but some compilers won't accept __restrict__ on anything
// but an raw pointer or reference
void SkColorMatrixFilter::initState(const SkScalar* SK_RESTRICT src) {
+ transpose_to_pmorder(fTranspose, src);
+
int32_t* array = fState.fArray;
SkFixed max = 0;
for (int i = 0; i < 20; i++) {
@@ -220,12 +242,41 @@ uint32_t SkColorMatrixFilter::getFlags() const {
return this->INHERITED::getFlags() | fFlags;
}
-void SkColorMatrixFilter::filterSpan(const SkPMColor src[], int count,
- SkPMColor dst[]) const {
- Proc proc = fProc;
- const State& state = fState;
- int32_t result[4];
+/**
+ * Need inv255 = 1 / 255 as a constant, so when we premul a SkPMFloat, we can do this
+ *
+ * new_red = old_red * alpha * inv255
+ *
+ * instead of (much slower)
+ *
+ * new_red = old_red * alpha / 255
+ *
+ * However, 1.0f/255 comes to (in hex) 0x3B808081, which is slightly bigger than the "actual"
+ * value of 0x3B808080(repeat 80)... This slightly too-big value can cause us to compute
+ * new_red > alpha, which is a problem (for valid premul). To fix this, we use a
+ * hand-computed value of 0x3B808080, 1 ULP smaller. This keeps our colors valid.
+ */
+static const float gInv255 = 0.0039215683f; // (1.0f / 255) - ULP == SkBits2Float(0x3B808080)
+
+static Sk4f premul(const Sk4f& x) {
+ float scale = SkPMFloat(x).a() * gInv255;
+ Sk4f pm = x * Sk4f(scale, scale, scale, 1);
+
+#ifdef SK_DEBUG
+ SkPMFloat pmf(pm);
+ SkASSERT(pmf.isValid());
+#endif
+
+ return pm;
+}
+
+static Sk4f unpremul(const SkPMFloat& pm) {
+ float scale = 255 / pm.a(); // candidate for fast/approx invert?
+ return Sk4f(pm) * Sk4f(scale, scale, scale, 1);
+}
+void SkColorMatrixFilter::filterSpan(const SkPMColor src[], int count, SkPMColor dst[]) const {
+ Proc proc = fProc;
if (NULL == proc) {
if (src != dst) {
memcpy(dst, src, count * sizeof(SkPMColor));
@@ -233,36 +284,82 @@ void SkColorMatrixFilter::filterSpan(const SkPMColor src[], int count,
return;
}
- const SkUnPreMultiply::Scale* table = SkUnPreMultiply::GetScaleTable();
+#ifdef SK_SUPPORT_LEGACY_INT_COLORMATRIX
+ const bool use_floats = false;
+#else
+ const bool use_floats = true;
+#endif
- for (int i = 0; i < count; i++) {
- SkPMColor c = src[i];
-
- unsigned r = SkGetPackedR32(c);
- unsigned g = SkGetPackedG32(c);
- unsigned b = SkGetPackedB32(c);
- unsigned a = SkGetPackedA32(c);
-
- // need our components to be un-premultiplied
- if (255 != a) {
- SkUnPreMultiply::Scale scale = table[a];
- r = SkUnPreMultiply::ApplyScale(scale, r);
- g = SkUnPreMultiply::ApplyScale(scale, g);
- b = SkUnPreMultiply::ApplyScale(scale, b);
-
- SkASSERT(r <= 255);
- SkASSERT(g <= 255);
- SkASSERT(b <= 255);
+ if (use_floats) {
+ const Sk4f c0 = Sk4f::Load(fTranspose + 0);
+ const Sk4f c1 = Sk4f::Load(fTranspose + 4);
+ const Sk4f c2 = Sk4f::Load(fTranspose + 8);
+ const Sk4f c3 = Sk4f::Load(fTranspose + 12);
+ const Sk4f c4 = Sk4f::Load(fTranspose + 16); // translates
+
+ SkPMColor matrix_translate_pmcolor = SkPMFloat(premul(c4)).clamped();
+
+ for (int i = 0; i < count; i++) {
+ const SkPMColor src_c = src[i];
+ if (0 == src_c) {
+ dst[i] = matrix_translate_pmcolor;
+ continue;
+ }
+
+ SkPMFloat srcf(src_c);
+
+ if (0xFF != SkGetPackedA32(src_c)) {
+ srcf = unpremul(srcf);
+ }
+
+ Sk4f r4 = Sk4f(srcf.r());
+ Sk4f g4 = Sk4f(srcf.g());
+ Sk4f b4 = Sk4f(srcf.b());
+ Sk4f a4 = Sk4f(srcf.a());
+
+ // apply matrix
+ Sk4f dst4 = c0 * r4 + c1 * g4 + c2 * b4 + c3 * a4 + c4;
+
+ // pin before re-premul (convention for color-matrix???)
+ dst4 = Sk4f::Max(Sk4f(0), Sk4f::Min(Sk4f(255), dst4));
+
+ // re-premul and write
+ dst[i] = SkPMFloat(premul(dst4)).get();
}
+ } else {
+ const State& state = fState;
+ int32_t result[4];
+ const SkUnPreMultiply::Scale* table = SkUnPreMultiply::GetScaleTable();
+
+ for (int i = 0; i < count; i++) {
+ SkPMColor c = src[i];
+
+ unsigned r = SkGetPackedR32(c);
+ unsigned g = SkGetPackedG32(c);
+ unsigned b = SkGetPackedB32(c);
+ unsigned a = SkGetPackedA32(c);
+
+ // need our components to be un-premultiplied
+ if (255 != a) {
+ SkUnPreMultiply::Scale scale = table[a];
+ r = SkUnPreMultiply::ApplyScale(scale, r);
+ g = SkUnPreMultiply::ApplyScale(scale, g);
+ b = SkUnPreMultiply::ApplyScale(scale, b);
+
+ SkASSERT(r <= 255);
+ SkASSERT(g <= 255);
+ SkASSERT(b <= 255);
+ }
- proc(state, r, g, b, a, result);
+ proc(state, r, g, b, a, result);
- r = pin(result[0], SK_R32_MASK);
- g = pin(result[1], SK_G32_MASK);
- b = pin(result[2], SK_B32_MASK);
- a = pin(result[3], SK_A32_MASK);
- // re-prepremultiply if needed
- dst[i] = SkPremultiplyARGBInline(a, r, g, b);
+ r = pin(result[0], SK_R32_MASK);
+ g = pin(result[1], SK_G32_MASK);
+ b = pin(result[2], SK_B32_MASK);
+ a = pin(result[3], SK_A32_MASK);
+ // re-prepremultiply if needed
+ dst[i] = SkPremultiplyARGBInline(a, r, g, b);
+ }
}
}
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