force all colorfilters to implement 4f

high-contrast gms differ at most by 1 bit

Bug: skia:
Change-Id: I1308bd105020ea3cd5a30fd3dd322ed134fb5ed5
Reviewed-on: https://skia-review.googlesource.com/15249
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Mike Klein <mtklein@chromium.org>
Reviewed-by: Florin Malita <fmalita@chromium.org>

5 files changed, 101 insertions, 43 deletions

diff --git a/src/effects/SkHighContrastFilter.cpp b/src/effects/SkHighContrastFilter.cpp
index 5d92cdf0d0..2d827db751 100644
--- a/src/effects/SkHighContrastFilter.cpp
+++ b/src/effects/SkHighContrastFilter.cpp
@@ -6,7 +6,7 @@
 */
 
 #include "SkHighContrastFilter.h"
-
+#include "SkPM4f.h"
 #include "SkArenaAlloc.h"
 #include "SkRasterPipeline.h"
 #include "SkReadBuffer.h"
@@ -45,33 +45,18 @@ SkScalar Hue2RGB(SkScalar p, SkScalar q, SkScalar t) {
     return p;
 }
 
-uint8_t SkScalarToUint8Clamp(SkScalar f) {
-    if (f <= 0) {
-        return 0;
-    } else if (f >= 1) {
-        return 255;
-    }
-    return static_cast<unsigned char>(255 * f);
-}
-
 SkScalar IncreaseContrast(SkScalar f, SkScalar contrast) {
     SkScalar m = (1 + contrast) / (1 - contrast);
     SkScalar b = (-0.5f * m + 0.5f);
     return m * f + b;
 }
 
-static SkPMColor ApplyHighContrastFilter(const SkHighContrastConfig& config,
-                                         SkPMColor pmColor) {
-    SkColor color = SkUnPreMultiply::PMColorToColor(pmColor);
-    SkScalar rf = SkColorGetR(color) / 255.f;
-    SkScalar gf = SkColorGetG(color) / 255.f;
-    SkScalar bf = SkColorGetB(color) / 255.f;
-
+SkColor4f ApplyHighContrastFilter(const SkHighContrastConfig& config, const SkColor4f& src) {
     // Apply a gamma of 2.0 so that the rest of the calculations
     // happen roughly in linear space.
-    rf *= rf;
-    gf *= gf;
-    bf *= bf;
+    float rf = src.fR * src.fR;
+    float gf = src.fG * src.fG;
+    float bf = src.fB * src.fB;
 
     // Convert to grayscale using luminance coefficients.
     if (config.fGrayscale) {
@@ -136,14 +121,7 @@ static SkPMColor ApplyHighContrastFilter(const SkHighContrastConfig& config,
     }
 
     // Convert back from linear to a color space with a gamma of ~2.0.
-    rf = SkScalarSqrt(rf);
-    gf = SkScalarSqrt(gf);
-    bf = SkScalarSqrt(bf);
-
-    return SkPremultiplyARGBInline(SkColorGetA(color),
-                                   SkScalarToUint8Clamp(rf),
-                                   SkScalarToUint8Clamp(gf),
-                                   SkScalarToUint8Clamp(bf));
+    return SkColor4f::Pin(SkScalarSqrt(rf), SkScalarSqrt(gf), SkScalarSqrt(bf), src.fA);
 }
 
 }  // namespace
@@ -164,8 +142,8 @@ public:
     sk_sp<GrFragmentProcessor> asFragmentProcessor(GrContext*, SkColorSpace*) const override;
  #endif
 
-    void filterSpan(const SkPMColor src[], int count, SkPMColor dst[]) const
-          override;
+    void filterSpan(const SkPMColor src[], int count, SkPMColor dst[]) const override;
+    void filterSpan4f(const SkPM4f src[], int count, SkPM4f result[]) const override;
     bool onAppendStages(SkRasterPipeline* p,
                         SkColorSpace* dst,
                         SkArenaAlloc* scratch,
@@ -186,10 +164,24 @@ private:
     typedef SkColorFilter INHERITED;
 };
 
-void SkHighContrast_Filter::filterSpan(const SkPMColor src[], int count,
-                                       SkPMColor dst[]) const {
-    for (int i = 0; i < count; ++i)
-        dst[i] = ApplyHighContrastFilter(fConfig, src[i]);
+void SkHighContrast_Filter::filterSpan(const SkPMColor src[], int count, SkPMColor dst[]) const {
+    const float oneOver255 = 1.0f / 255;
+    for (int i = 0; i < count; ++i) {
+        SkColor color = SkUnPreMultiply::PMColorToColor(src[i]);
+        // be sure to NOT treat color as sRGB, as we are in legacy mode here
+        SkColor4f s4 {
+            SkColorGetR(color) * oneOver255, SkColorGetG(color) * oneOver255,
+            SkColorGetB(color) * oneOver255, SkColorGetA(color) * oneOver255,
+        };
+        SkColor4f d4 = ApplyHighContrastFilter(fConfig, s4);
+        dst[i] = d4.premul().toPMColor();
+    }
+}
+
+void SkHighContrast_Filter::filterSpan4f(const SkPM4f src[], int count, SkPM4f dst[]) const {
+    for (int i = 0; i < count; ++i) {
+        dst[i] = ApplyHighContrastFilter(fConfig, dst[i].unpremul()).premul();
+    }
 }
 
 bool SkHighContrast_Filter::onAppendStages(SkRasterPipeline* p,
diff --git a/src/effects/SkLumaColorFilter.cpp b/src/effects/SkLumaColorFilter.cpp
index 2809c8b492..b2f6b47a69 100644
--- a/src/effects/SkLumaColorFilter.cpp
+++ b/src/effects/SkLumaColorFilter.cpp
@@ -6,7 +6,7 @@
  */
 
 #include "SkLumaColorFilter.h"
-
+#include "SkPM4f.h"
 #include "SkColorPriv.h"
 #include "SkRasterPipeline.h"
 #include "SkString.h"
@@ -17,8 +17,7 @@
 #include "glsl/GrGLSLFragmentShaderBuilder.h"
 #endif
 
-void SkLumaColorFilter::filterSpan(const SkPMColor src[], int count,
-                                   SkPMColor dst[]) const {
+void SkLumaColorFilter::filterSpan(const SkPMColor src[], int count, SkPMColor dst[]) const {
     for (int i = 0; i < count; ++i) {
         SkPMColor c = src[i];
 
@@ -37,6 +36,25 @@ void SkLumaColorFilter::filterSpan(const SkPMColor src[], int count,
     }
 }
 
+void SkLumaColorFilter::filterSpan4f(const SkPM4f src[], int count, SkPM4f dst[]) const {
+    for (int i = 0; i < count; ++i) {
+        /*
+         * While LuminanceToAlpha is defined to operate on un-premultiplied
+         * inputs, due to the final alpha scaling it can be computed based on
+         * premultipled components:
+         *
+         *   LumA = (k1 * r / a + k2 * g / a + k3 * b / a) * a
+         *   LumA = (k1 * r + k2 * g + k3 * b)
+         */
+        dst[i].fVec[SkPM4f::R] = 0;
+        dst[i].fVec[SkPM4f::G] = 0;
+        dst[i].fVec[SkPM4f::B] = 0;
+        dst[i].fVec[SkPM4f::A] = src[i].r() * SK_LUM_COEFF_R +
+                                 src[i].g() * SK_LUM_COEFF_G +
+                                 src[i].b() * SK_LUM_COEFF_B;
+    }
+}
+
 bool SkLumaColorFilter::onAppendStages(SkRasterPipeline* p,
                                        SkColorSpace* dst,
                                        SkArenaAlloc* scratch,
diff --git a/src/effects/SkOverdrawColorFilter.cpp b/src/effects/SkOverdrawColorFilter.cpp
index 87bbc1069e..2bed180bcc 100644
--- a/src/effects/SkOverdrawColorFilter.cpp
+++ b/src/effects/SkOverdrawColorFilter.cpp
@@ -6,6 +6,7 @@
  */
 
 #include "SkOverdrawColorFilter.h"
+#include "SkPM4f.h"
 
 void SkOverdrawColorFilter::filterSpan(const SkPMColor src[], int count, SkPMColor dst[]) const {
     for (int x = 0; x < count; x++) {
@@ -18,6 +19,16 @@ void SkOverdrawColorFilter::filterSpan(const SkPMColor src[], int count, SkPMCol
     }
 }
 
+void SkOverdrawColorFilter::filterSpan4f(const SkPM4f src[], int count, SkPM4f dst[]) const {
+    for (int i = 0; i < count; ++i) {
+        uint8_t alpha = (int)(src[i].a() * 255);
+        if (alpha >= kNumColors) {
+            alpha = kNumColors - 1;
+        }
+        dst[i] = SkPM4f::FromPMColor(fColors[alpha]);
+    }
+}
+
 void SkOverdrawColorFilter::toString(SkString* str) const {
     str->append("SkOverdrawColorFilter (");
     for (int i = 0; i < kNumColors; i++) {
diff --git a/src/effects/SkOverdrawColorFilter.h b/src/effects/SkOverdrawColorFilter.h
index 6c5ce592f3..772e07c674 100644
--- a/src/effects/SkOverdrawColorFilter.h
+++ b/src/effects/SkOverdrawColorFilter.h
@@ -32,6 +32,7 @@ public:
 #endif
 
     void filterSpan(const SkPMColor src[], int count, SkPMColor dst[]) const override;
+    void filterSpan4f(const SkPM4f src[], int count, SkPM4f result[]) const override;
     void toString(SkString* str) const override;
 
     static sk_sp<SkFlattenable> CreateProc(SkReadBuffer& buffer);
diff --git a/src/effects/SkTableColorFilter.cpp b/src/effects/SkTableColorFilter.cpp
index 0253e60b59..d9ce98a7d8 100644
--- a/src/effects/SkTableColorFilter.cpp
+++ b/src/effects/SkTableColorFilter.cpp
@@ -1,12 +1,12 @@
 /*
-* Copyright 2015 Google Inc.
-*
-* Use of this source code is governed by a BSD-style license that can be
-* found in the LICENSE file.
-*/
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
 
 #include "SkTableColorFilter.h"
-
+#include "SkPM4f.h"
 #include "SkArenaAlloc.h"
 #include "SkBitmap.h"
 #include "SkColorPriv.h"
@@ -90,6 +90,7 @@ public:
 #endif
 
     void filterSpan(const SkPMColor src[], int count, SkPMColor dst[]) const override;
+    void filterSpan4f(const SkPM4f src[], int count, SkPM4f result[]) const override;
 
     SK_TO_STRING_OVERRIDE()
 
@@ -185,6 +186,41 @@ void SkTable_ColorFilter::filterSpan(const SkPMColor src[], int count, SkPMColor
     }
 }
 
+void SkTable_ColorFilter::filterSpan4f(const SkPM4f src[], int count, SkPM4f dst[]) const {
+    const uint8_t* table = fStorage;
+    const uint8_t* tableA = gIdentityTable;
+    const uint8_t* tableR = gIdentityTable;
+    const uint8_t* tableG = gIdentityTable;
+    const uint8_t* tableB = gIdentityTable;
+    if (fFlags & kA_Flag) {
+        tableA = table; table += 256;
+    }
+    if (fFlags & kR_Flag) {
+        tableR = table; table += 256;
+    }
+    if (fFlags & kG_Flag) {
+        tableG = table; table += 256;
+    }
+    if (fFlags & kB_Flag) {
+        tableB = table;
+    }
+
+    const float oneOver255 = 1.0f / 255;
+    for (int i = 0; i < count; ++i) {
+        SkColor4f c = src[i].unpremul();
+        int r = (int)(c.fR * 255.999) & 0xFF;
+        int g = (int)(c.fG * 255.999) & 0xFF;
+        int b = (int)(c.fB * 255.999) & 0xFF;
+        int a = (int)(c.fA * 255.999) & 0xFF;
+
+        SkColor4f d {
+            tableR[r] * oneOver255, tableG[g] * oneOver255,
+            tableB[b] * oneOver255, tableA[a] * oneOver255,
+        };
+        dst[i] = d.premul();
+    }
+}
+
 #ifndef SK_IGNORE_TO_STRING
 void SkTable_ColorFilter::toString(SkString* str) const {
     const uint8_t* table = fStorage;