Revert of remove unused SkAvoidXfermode

src/effects/SkAvoidXfermode.cpp

Index: src/effects/SkAvoidXfermode.cpp
diff --git a/src/effects/SkAvoidXfermode.cpp b/src/effects/SkAvoidXfermode.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..41c4e9646df4078ae0139ee2d559b6f9f68d1b67
--- /dev/null
+++ b/src/effects/SkAvoidXfermode.cpp
@@ -0,0 +1,178 @@
+/*
+ * Copyright 2006 The Android Open Source Project
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkAvoidXfermode.h"
+#include "SkColorPriv.h"
+#include "SkReadBuffer.h"
+#include "SkWriteBuffer.h"
+#include "SkString.h"
+
+SkAvoidXfermode::SkAvoidXfermode(SkColor opColor, U8CPU tolerance, Mode mode) {
+    if (tolerance > 255) {
+        tolerance = 255;
+    }
+    fTolerance = SkToU8(tolerance);
+    fOpColor = opColor;
+    fDistMul = (256 << 14) / (tolerance + 1);
+    fMode = mode;
+}
+
+SkFlattenable* SkAvoidXfermode::CreateProc(SkReadBuffer& buffer) {
+    const SkColor color = buffer.readColor();
+    const unsigned tolerance = buffer.readUInt();
+    const unsigned mode = buffer.readUInt();
+    return Create(color, tolerance, (Mode)mode);
+}
+
+void SkAvoidXfermode::flatten(SkWriteBuffer& buffer) const {
+    buffer.writeColor(fOpColor);
+    buffer.writeUInt(fTolerance);
+    buffer.writeUInt(fMode);
+}
+
+// returns 0..31
+static unsigned color_dist16(uint16_t c, unsigned r, unsigned g, unsigned b) {
+    SkASSERT(r <= SK_R16_MASK);
+    SkASSERT(g <= SK_G16_MASK);
+    SkASSERT(b <= SK_B16_MASK);
+
+    unsigned dr = SkAbs32(SkGetPackedR16(c) - r);
+    unsigned dg = SkAbs32(SkGetPackedG16(c) - g) >> (SK_G16_BITS - SK_R16_BITS);
+    unsigned db = SkAbs32(SkGetPackedB16(c) - b);
+
+    return SkMax32(dr, SkMax32(dg, db));
+}
+
+// returns 0..255
+static unsigned color_dist32(SkPMColor c, U8CPU r, U8CPU g, U8CPU b) {
+    SkASSERT(r <= 0xFF);
+    SkASSERT(g <= 0xFF);
+    SkASSERT(b <= 0xFF);
+
+    unsigned dr = SkAbs32(SkGetPackedR32(c) - r);
+    unsigned dg = SkAbs32(SkGetPackedG32(c) - g);
+    unsigned db = SkAbs32(SkGetPackedB32(c) - b);
+
+    return SkMax32(dr, SkMax32(dg, db));
+}
+
+static int scale_dist_14(int dist, uint32_t mul, uint32_t sub) {
+    int tmp = dist * mul - sub;
+    int result = (tmp + (1 << 13)) >> 14;
+
+    return result;
+}
+
+static inline unsigned Accurate255To256(unsigned x) {
+    return x + (x >> 7);
+}
+
+void SkAvoidXfermode::xfer32(SkPMColor dst[], const SkPMColor src[], int count,
+                             const SkAlpha aa[]) const {
+    unsigned    opR = SkColorGetR(fOpColor);
+    unsigned    opG = SkColorGetG(fOpColor);
+    unsigned    opB = SkColorGetB(fOpColor);
+    uint32_t    mul = fDistMul;
+    uint32_t    sub = (fDistMul - (1 << 14)) << 8;
+
+    int MAX, mask;
+
+    if (kTargetColor_Mode == fMode) {
+        mask = -1;
+        MAX = 255;
+    } else {
+        mask = 0;
+        MAX = 0;
+    }
+
+    for (int i = 0; i < count; i++) {
+        int d = color_dist32(dst[i], opR, opG, opB);
+        // now reverse d if we need to
+        d = MAX + (d ^ mask) - mask;
+        SkASSERT((unsigned)d <= 255);
+        d = Accurate255To256(d);
+
+        d = scale_dist_14(d, mul, sub);
+        SkASSERT(d <= 256);
+
+        if (d > 0) {
+            if (aa) {
+                d = SkAlphaMul(d, Accurate255To256(*aa++));
+                if (0 == d) {
+                    continue;
+                }
+            }
+            dst[i] = SkFourByteInterp256(src[i], dst[i], d);
+        }
+    }
+}
+
+static inline U16CPU SkBlend3216(SkPMColor src, U16CPU dst, unsigned scale) {
+    SkASSERT(scale <= 32);
+    scale <<= 3;
+
+    return SkPackRGB16( SkAlphaBlend(SkPacked32ToR16(src), SkGetPackedR16(dst), scale),
+                        SkAlphaBlend(SkPacked32ToG16(src), SkGetPackedG16(dst), scale),
+                        SkAlphaBlend(SkPacked32ToB16(src), SkGetPackedB16(dst), scale));
+}
+
+void SkAvoidXfermode::xfer16(uint16_t dst[], const SkPMColor src[], int count,
+                             const SkAlpha aa[]) const {
+    unsigned    opR = SkColorGetR(fOpColor) >> (8 - SK_R16_BITS);
+    unsigned    opG = SkColorGetG(fOpColor) >> (8 - SK_G16_BITS);
+    unsigned    opB = SkColorGetB(fOpColor) >> (8 - SK_R16_BITS);
+    uint32_t    mul = fDistMul;
+    uint32_t    sub = (fDistMul - (1 << 14)) << SK_R16_BITS;
+
+    int MAX, mask;
+
+    if (kTargetColor_Mode == fMode) {
+        mask = -1;
+        MAX = 31;
+    } else {
+        mask = 0;
+        MAX = 0;
+    }
+
+    for (int i = 0; i < count; i++) {
+        int d = color_dist16(dst[i], opR, opG, opB);
+        // now reverse d if we need to
+        d = MAX + (d ^ mask) - mask;
+        SkASSERT((unsigned)d <= 31);
+        // convert from 0..31 to 0..32
+        d += d >> 4;
+        d = scale_dist_14(d, mul, sub);
+        SkASSERT(d <= 32);
+
+        if (d > 0) {
+            if (aa) {
+                d = SkAlphaMul(d, Accurate255To256(*aa++));
+                if (0 == d) {
+                    continue;
+                }
+            }
+            dst[i] = SkBlend3216(src[i], dst[i], d);
+        }
+    }
+}
+
+void SkAvoidXfermode::xferA8(SkAlpha dst[], const SkPMColor src[], int count,
+                             const SkAlpha aa[]) const {
+    // override in subclass
+}
+
+#ifndef SK_IGNORE_TO_STRING
+void SkAvoidXfermode::toString(SkString* str) const {
+    str->append("SkAvoidXfermode: opColor: ");
+    str->appendHex(fOpColor);
+    str->appendf("distMul: %d ", fDistMul);
+
+    static const char* gModeStrings[] = { "Avoid", "Target" };
+
+    str->appendf("mode: %s", gModeStrings[fMode]);
+}
+#endif