implement readPixels and writePixels natively, w/o using the (deprecated)

SkCanvas::Config8888 enum.

Revert "Revert "hide Config8888 entirely". Broke a bunch of builds."

This reverts commit 763277ba157fef0f651004bb98a189e9f1ac730b.

Needs chrome to remove the READPIXELS guard from skia's .gyp

Review URL: https://codereview.chromium.org/199733016

git-svn-id: http://skia.googlecode.com/svn/trunk@13931 2bbb7eff-a529-9590-31e7-b0007b416f81

6 files changed, 171 insertions, 434 deletions

diff --git a/src/core/SkBitmapDevice.cpp b/src/core/SkBitmapDevice.cpp
index f0f4df41f1..d968cb850b 100644
--- a/src/core/SkBitmapDevice.cpp
+++ b/src/core/SkBitmapDevice.cpp
@@ -221,47 +221,27 @@ static void rect_memcpy(void* dst, size_t dstRB, const void* src, size_t srcRB,
     }
 }
 
-static bool info2config8888(const SkImageInfo& info, SkCanvas::Config8888* config) {
-    bool pre;
-    switch (info.alphaType()) {
-        case kPremul_SkAlphaType:
-        case kOpaque_SkAlphaType:
-            pre = true;
-            break;
-        case kUnpremul_SkAlphaType:
-            pre = false;
-            break;
-        default:
-            return false;
-    }
-    switch (info.colorType()) {
-        case kRGBA_8888_SkColorType:
-            *config = pre ? SkCanvas::kRGBA_Premul_Config8888 : SkCanvas::kRGBA_Unpremul_Config8888;
-            return true;
-        case kBGRA_8888_SkColorType:
-            *config = pre ? SkCanvas::kBGRA_Premul_Config8888 : SkCanvas::kBGRA_Unpremul_Config8888;
-            return true;
-        default:
-            return false;
-    }
-}
-
-// TODO: make this guy real, and not rely on legacy config8888 utility
 #include "SkConfig8888.h"
+
 static bool copy_pixels(const SkImageInfo& dstInfo, void* dstPixels, size_t dstRowBytes,
                         const SkImageInfo& srcInfo, const void* srcPixels, size_t srcRowBytes) {
     if (srcInfo.dimensions() != dstInfo.dimensions()) {
         return false;
     }
     if (4 == srcInfo.bytesPerPixel() && 4 == dstInfo.bytesPerPixel()) {
-        SkCanvas::Config8888 srcConfig, dstConfig;
-        if (!info2config8888(srcInfo, &srcConfig) || !info2config8888(dstInfo, &dstConfig)) {
-            return false;
-        }
-        SkConvertConfig8888Pixels((uint32_t*)dstPixels, dstRowBytes, dstConfig,
-                                  (const uint32_t*)srcPixels, srcRowBytes, srcConfig,
-                                  srcInfo.width(), srcInfo.height());
-        return true;
+        SkDstPixelInfo dstPI;
+        dstPI.fColorType = dstInfo.colorType();
+        dstPI.fAlphaType = dstInfo.alphaType();
+        dstPI.fPixels = dstPixels;
+        dstPI.fRowBytes = dstRowBytes;
+
+        SkSrcPixelInfo srcPI;
+        srcPI.fColorType = srcInfo.colorType();
+        srcPI.fAlphaType = srcInfo.alphaType();
+        srcPI.fPixels = srcPixels;
+        srcPI.fRowBytes = srcRowBytes;
+
+        return srcPI.convertPixelsTo(&dstPI, srcInfo.width(), srcInfo.height());
     }
     if (srcInfo.colorType() == dstInfo.colorType()) {
         switch (srcInfo.colorType()) {
diff --git a/src/core/SkConfig8888.cpp b/src/core/SkConfig8888.cpp
index dd5cbc4724..189309dae6 100644
--- a/src/core/SkConfig8888.cpp
+++ b/src/core/SkConfig8888.cpp
@@ -1,280 +1,117 @@
 #include "SkConfig8888.h"
+#include "SkColorPriv.h"
 #include "SkMathPriv.h"
 #include "SkUnPreMultiply.h"
 
-namespace {
+enum AlphaVerb {
+    kNothing_AlphaVerb,
+    kPremul_AlphaVerb,
+    kUnpremul_AlphaVerb,
+};
 
-template <int A_IDX, int R_IDX, int G_IDX, int B_IDX>
-inline uint32_t pack_config8888(uint32_t a, uint32_t r,
-                                uint32_t g, uint32_t b) {
-#ifdef SK_CPU_LENDIAN
-    return (a << (A_IDX * 8)) | (r << (R_IDX * 8)) |
-           (g << (G_IDX * 8)) | (b << (B_IDX * 8));
-#else
-    return (a << ((3-A_IDX) * 8)) | (r << ((3-R_IDX) * 8)) |
-           (g << ((3-G_IDX) * 8)) | (b << ((3-B_IDX) * 8));
-#endif
-}
-
-template <int A_IDX, int R_IDX, int G_IDX, int B_IDX>
-inline void unpack_config8888(uint32_t color,
-                              uint32_t* a, uint32_t* r,
-                              uint32_t* g, uint32_t* b) {
-#ifdef SK_CPU_LENDIAN
-    *a = (color >> (A_IDX * 8)) & 0xff;
-    *r = (color >> (R_IDX * 8)) & 0xff;
-    *g = (color >> (G_IDX * 8)) & 0xff;
-    *b = (color >> (B_IDX * 8)) & 0xff;
-#else
-    *a = (color >> ((3 - A_IDX) * 8)) & 0xff;
-    *r = (color >> ((3 - R_IDX) * 8)) & 0xff;
-    *g = (color >> ((3 - G_IDX) * 8)) & 0xff;
-    *b = (color >> ((3 - B_IDX) * 8)) & 0xff;
-#endif
-}
-
-#ifdef SK_CPU_LENDIAN
-    static const int SK_NATIVE_A_IDX = SK_A32_SHIFT / 8;
-    static const int SK_NATIVE_R_IDX = SK_R32_SHIFT / 8;
-    static const int SK_NATIVE_G_IDX = SK_G32_SHIFT / 8;
-    static const int SK_NATIVE_B_IDX = SK_B32_SHIFT / 8;
-#else
-    static const int SK_NATIVE_A_IDX = 3 - (SK_A32_SHIFT / 8);
-    static const int SK_NATIVE_R_IDX = 3 - (SK_R32_SHIFT / 8);
-    static const int SK_NATIVE_G_IDX = 3 - (SK_G32_SHIFT / 8);
-    static const int SK_NATIVE_B_IDX = 3 - (SK_B32_SHIFT / 8);
-#endif
-
-/**
- * convert_pixel<OUT_CFG, IN_CFG converts a pixel value from one Config8888 to
- * another. It is implemented by first expanding OUT_CFG to r, g, b, a indices
- * and an is_premul bool as params to another template function. Then IN_CFG is
- * expanded via another function call.
- */
-
-template <bool OUT_PM, int OUT_A_IDX, int OUT_R_IDX, int OUT_G_IDX, int OUT_B_IDX,
-          bool IN_PM,  int IN_A_IDX,  int IN_R_IDX,  int IN_G_IDX,  int IN_B_IDX>
-inline uint32_t convert_pixel(uint32_t pixel) {
-    uint32_t a, r, g, b;
-    unpack_config8888<IN_A_IDX, IN_R_IDX, IN_G_IDX, IN_B_IDX>(pixel, &a, &r, &g, &b);
-    if (IN_PM && !OUT_PM) {
-        // Using SkUnPreMultiply::ApplyScale is faster than (value * 0xff) / a.
-        if (a) {
-            SkUnPreMultiply::Scale scale = SkUnPreMultiply::GetScale(a);
-            r = SkUnPreMultiply::ApplyScale(scale, r);
-            g = SkUnPreMultiply::ApplyScale(scale, g);
-            b = SkUnPreMultiply::ApplyScale(scale, b);
-        } else {
-            return 0;
-        }
-    } else if (!IN_PM && OUT_PM) {
-        // This matches SkUnPreMultiply conversion which we are replacing.
-        r = SkMulDiv255Round(r, a);
-        g = SkMulDiv255Round(g, a);
-        b = SkMulDiv255Round(b, a);
+template <bool doSwapRB, AlphaVerb doAlpha> uint32_t convert32(uint32_t c) {
+    if (doSwapRB) {
+        c = SkSwizzle_RB(c);
     }
-    return pack_config8888<OUT_A_IDX, OUT_R_IDX, OUT_G_IDX, OUT_B_IDX>(a, r, g, b);
-}
 
-template <bool OUT_PM, int OUT_A_IDX, int OUT_R_IDX, int OUT_G_IDX, int OUT_B_IDX, SkCanvas::Config8888 IN_CFG>
-inline uint32_t convert_pixel(uint32_t pixel) {
-    switch(IN_CFG) {
-        case SkCanvas::kNative_Premul_Config8888:
-            return convert_pixel<OUT_PM, OUT_A_IDX,       OUT_R_IDX,       OUT_G_IDX,       OUT_B_IDX,
-                                 true,  SK_NATIVE_A_IDX,  SK_NATIVE_R_IDX, SK_NATIVE_G_IDX, SK_NATIVE_B_IDX>(pixel);
-            break;
-        case SkCanvas::kNative_Unpremul_Config8888:
-            return convert_pixel<OUT_PM, OUT_A_IDX,       OUT_R_IDX,       OUT_G_IDX,       OUT_B_IDX,
-                                 false,  SK_NATIVE_A_IDX, SK_NATIVE_R_IDX, SK_NATIVE_G_IDX, SK_NATIVE_B_IDX>(pixel);
-            break;
-        case SkCanvas::kBGRA_Premul_Config8888:
-            return convert_pixel<OUT_PM, OUT_A_IDX, OUT_R_IDX, OUT_G_IDX, OUT_B_IDX,
-                                 true,  3,         2,         1,         0>(pixel);
-            break;
-        case SkCanvas::kBGRA_Unpremul_Config8888:
-            return convert_pixel<OUT_PM, OUT_A_IDX, OUT_R_IDX, OUT_G_IDX, OUT_B_IDX,
-                                 false,  3,         2,         1,         0>(pixel);
-            break;
-        case SkCanvas::kRGBA_Premul_Config8888:
-            return convert_pixel<OUT_PM, OUT_A_IDX, OUT_R_IDX, OUT_G_IDX, OUT_B_IDX,
-                                 true,  3,         0,         1,         2>(pixel);
+    // Lucky for us, in both RGBA and BGRA, the alpha component is always in the same place, so
+    // we can perform premul or unpremul the same way without knowing the swizzles for RGB.
+    switch (doAlpha) {
+        case kNothing_AlphaVerb:
+            // no change
             break;
-        case SkCanvas::kRGBA_Unpremul_Config8888:
-            return convert_pixel<OUT_PM, OUT_A_IDX, OUT_R_IDX, OUT_G_IDX, OUT_B_IDX,
-                                 false,  3,         0,         1,         2>(pixel);
+        case kPremul_AlphaVerb:
+            c = SkPreMultiplyARGB(SkGetPackedA32(c), SkGetPackedR32(c),
+                                  SkGetPackedG32(c), SkGetPackedB32(c));
             break;
-        default:
-            SkDEBUGFAIL("Unexpected config8888");
-            return 0;
+        case kUnpremul_AlphaVerb:
+            c = SkUnPreMultiply::UnPreMultiplyPreservingByteOrder(c);
             break;
     }
+    return c;
 }
 
-template <SkCanvas::Config8888 OUT_CFG, SkCanvas::Config8888 IN_CFG>
-inline uint32_t convert_pixel(uint32_t pixel) {
-    switch(OUT_CFG) {
-        case SkCanvas::kNative_Premul_Config8888:
-            return convert_pixel<true,  SK_NATIVE_A_IDX,  SK_NATIVE_R_IDX, SK_NATIVE_G_IDX, SK_NATIVE_B_IDX, IN_CFG>(pixel);
-            break;
-        case SkCanvas::kNative_Unpremul_Config8888:
-            return convert_pixel<false,  SK_NATIVE_A_IDX,  SK_NATIVE_R_IDX, SK_NATIVE_G_IDX, SK_NATIVE_B_IDX, IN_CFG>(pixel);
-            break;
-        case SkCanvas::kBGRA_Premul_Config8888:
-            return convert_pixel<true, 3, 2, 1, 0, IN_CFG>(pixel);
-            break;
-        case SkCanvas::kBGRA_Unpremul_Config8888:
-            return convert_pixel<false, 3, 2, 1, 0, IN_CFG>(pixel);
-            break;
-        case SkCanvas::kRGBA_Premul_Config8888:
-            return convert_pixel<true, 3, 0, 1, 2, IN_CFG>(pixel);
-            break;
-        case SkCanvas::kRGBA_Unpremul_Config8888:
-            return convert_pixel<false, 3, 0, 1, 2, IN_CFG>(pixel);
-            break;
-        default:
-            SkDEBUGFAIL("Unexpected config8888");
-            return 0;
-            break;
+template <bool doSwapRB, AlphaVerb doAlpha>
+void convert32_row(uint32_t* dst, const uint32_t* src, int count) {
+    // This has to be correct if src == dst (but not partial overlap)
+    for (int i = 0; i < count; ++i) {
+        dst[i] = convert32<doSwapRB, doAlpha>(src[i]);
     }
 }
 
-/**
- * SkConvertConfig8888Pixels has 6 * 6 possible combinations of src and dst
- * configs. Each is implemented as an instantiation templated function. Two
- * levels of switch statements are used to select the correct instantiation, one
- * for the src config and one for the dst config.
- */
+static bool is_32bit_colortype(SkColorType ct) {
+    return kRGBA_8888_SkColorType == ct || kBGRA_8888_SkColorType == ct;
+}
 
-template <SkCanvas::Config8888 DST_CFG, SkCanvas::Config8888 SRC_CFG>
-inline void convert_config8888(uint32_t* dstPixels,
-                               size_t dstRowBytes,
-                               const uint32_t* srcPixels,
-                               size_t srcRowBytes,
-                               int width,
-                               int height) {
-    intptr_t dstPix = reinterpret_cast<intptr_t>(dstPixels);
-    intptr_t srcPix = reinterpret_cast<intptr_t>(srcPixels);
+static AlphaVerb compute_AlphaVerb(SkAlphaType src, SkAlphaType dst) {
+    SkASSERT(kIgnore_SkAlphaType != src);
+    SkASSERT(kIgnore_SkAlphaType != dst);
 
-    for (int y = 0; y < height; ++y) {
-        srcPixels = reinterpret_cast<const uint32_t*>(srcPix);
-        dstPixels = reinterpret_cast<uint32_t*>(dstPix);
-        for (int x = 0; x < width; ++x) {
-            dstPixels[x] = convert_pixel<DST_CFG, SRC_CFG>(srcPixels[x]);
-        }
-        dstPix += dstRowBytes;
-        srcPix += srcRowBytes;
+    if (kOpaque_SkAlphaType == src || kOpaque_SkAlphaType == dst || src == dst) {
+        return kNothing_AlphaVerb;
     }
-}
-
-template <SkCanvas::Config8888 SRC_CFG>
-inline void convert_config8888(uint32_t* dstPixels,
-                               size_t dstRowBytes,
-                               SkCanvas::Config8888 dstConfig,
-                               const uint32_t* srcPixels,
-                               size_t srcRowBytes,
-                               int width,
-                               int height) {
-    switch(dstConfig) {
-        case SkCanvas::kNative_Premul_Config8888:
-            convert_config8888<SkCanvas::kNative_Premul_Config8888, SRC_CFG>(dstPixels, dstRowBytes, srcPixels, srcRowBytes, width, height);
-            break;
-        case SkCanvas::kNative_Unpremul_Config8888:
-            convert_config8888<SkCanvas::kNative_Unpremul_Config8888, SRC_CFG>(dstPixels, dstRowBytes, srcPixels, srcRowBytes, width, height);
-            break;
-        case SkCanvas::kBGRA_Premul_Config8888:
-            convert_config8888<SkCanvas::kBGRA_Premul_Config8888, SRC_CFG>(dstPixels, dstRowBytes, srcPixels, srcRowBytes, width, height);
-            break;
-        case SkCanvas::kBGRA_Unpremul_Config8888:
-            convert_config8888<SkCanvas::kBGRA_Unpremul_Config8888, SRC_CFG>(dstPixels, dstRowBytes, srcPixels, srcRowBytes, width, height);
-            break;
-        case SkCanvas::kRGBA_Premul_Config8888:
-            convert_config8888<SkCanvas::kRGBA_Premul_Config8888, SRC_CFG>(dstPixels, dstRowBytes, srcPixels, srcRowBytes, width, height);
-            break;
-        case SkCanvas::kRGBA_Unpremul_Config8888:
-            convert_config8888<SkCanvas::kRGBA_Unpremul_Config8888, SRC_CFG>(dstPixels, dstRowBytes, srcPixels, srcRowBytes, width, height);
-            break;
-        default:
-            SkDEBUGFAIL("Unexpected config8888");
-            break;
+    if (kPremul_SkAlphaType == dst) {
+        SkASSERT(kUnpremul_SkAlphaType == src);
+        return kPremul_AlphaVerb;
+    } else {
+        SkASSERT(kPremul_SkAlphaType == src);
+        SkASSERT(kUnpremul_SkAlphaType == dst);
+        return kUnpremul_AlphaVerb;
     }
 }
 
+static void memcpy32_row(uint32_t* dst, const uint32_t* src, int count) {
+    memcpy(dst, src, count * 4);
 }
 
-void SkConvertConfig8888Pixels(uint32_t* dstPixels,
-                               size_t dstRowBytes,
-                               SkCanvas::Config8888 dstConfig,
-                               const uint32_t* srcPixels,
-                               size_t srcRowBytes,
-                               SkCanvas::Config8888 srcConfig,
-                               int width,
-                               int height) {
-    if (srcConfig == dstConfig) {
-        if (srcPixels == dstPixels) {
-            return;
-        }
-        if (dstRowBytes == srcRowBytes &&
-            4U * width == srcRowBytes) {
-            memcpy(dstPixels, srcPixels, srcRowBytes * height);
-            return;
-        } else {
-            intptr_t srcPix = reinterpret_cast<intptr_t>(srcPixels);
-            intptr_t dstPix = reinterpret_cast<intptr_t>(dstPixels);
-            for (int y = 0; y < height; ++y) {
-                srcPixels = reinterpret_cast<const uint32_t*>(srcPix);
-                dstPixels = reinterpret_cast<uint32_t*>(dstPix);
-                memcpy(dstPixels, srcPixels, 4 * width);
-                srcPix += srcRowBytes;
-                dstPix += dstRowBytes;
-            }
-            return;
-        }
+bool SkSrcPixelInfo::convertPixelsTo(SkDstPixelInfo* dst, int width, int height) const {
+    if (width <= 0 || height <= 0) {
+        return false;
     }
-    switch(srcConfig) {
-        case SkCanvas::kNative_Premul_Config8888:
-            convert_config8888<SkCanvas::kNative_Premul_Config8888>(dstPixels, dstRowBytes, dstConfig, srcPixels, srcRowBytes, width, height);
-            break;
-        case SkCanvas::kNative_Unpremul_Config8888:
-            convert_config8888<SkCanvas::kNative_Unpremul_Config8888>(dstPixels, dstRowBytes, dstConfig, srcPixels, srcRowBytes, width, height);
-            break;
-        case SkCanvas::kBGRA_Premul_Config8888:
-            convert_config8888<SkCanvas::kBGRA_Premul_Config8888>(dstPixels, dstRowBytes, dstConfig, srcPixels, srcRowBytes, width, height);
-            break;
-        case SkCanvas::kBGRA_Unpremul_Config8888:
-            convert_config8888<SkCanvas::kBGRA_Unpremul_Config8888>(dstPixels, dstRowBytes, dstConfig, srcPixels, srcRowBytes, width, height);
-            break;
-        case SkCanvas::kRGBA_Premul_Config8888:
-            convert_config8888<SkCanvas::kRGBA_Premul_Config8888>(dstPixels, dstRowBytes, dstConfig, srcPixels, srcRowBytes, width, height);
+
+    if (!is_32bit_colortype(fColorType) || !is_32bit_colortype(dst->fColorType)) {
+        return false;
+    }
+
+    void (*proc)(uint32_t* dst, const uint32_t* src, int count);
+    AlphaVerb doAlpha = compute_AlphaVerb(fAlphaType, dst->fAlphaType);
+    bool doSwapRB = fColorType != dst->fColorType;
+
+    switch (doAlpha) {
+        case kNothing_AlphaVerb:
+            if (doSwapRB) {
+                proc = convert32_row<true, kNothing_AlphaVerb>;
+            } else {
+                if (fPixels == dst->fPixels) {
+                    return true;
+                }
+                proc = memcpy32_row;
+            }
             break;
-        case SkCanvas::kRGBA_Unpremul_Config8888:
-            convert_config8888<SkCanvas::kRGBA_Unpremul_Config8888>(dstPixels, dstRowBytes, dstConfig, srcPixels, srcRowBytes, width, height);
+        case kPremul_AlphaVerb:
+            if (doSwapRB) {
+                proc = convert32_row<true, kPremul_AlphaVerb>;
+            } else {
+                proc = convert32_row<false, kPremul_AlphaVerb>;
+            }
             break;
-        default:
-            SkDEBUGFAIL("Unexpected config8888");
+        case kUnpremul_AlphaVerb:
+            if (doSwapRB) {
+                proc = convert32_row<true, kUnpremul_AlphaVerb>;
+            } else {
+                proc = convert32_row<false, kUnpremul_AlphaVerb>;
+            }
             break;
     }
-}
 
-uint32_t SkPackConfig8888(SkCanvas::Config8888 config,
-                          uint32_t a,
-                          uint32_t r,
-                          uint32_t g,
-                          uint32_t b) {
-    switch (config) {
-        case SkCanvas::kNative_Premul_Config8888:
-        case SkCanvas::kNative_Unpremul_Config8888:
-            return pack_config8888<SK_NATIVE_A_IDX,
-                                   SK_NATIVE_R_IDX,
-                                   SK_NATIVE_G_IDX,
-                                   SK_NATIVE_B_IDX>(a, r, g, b);
-        case SkCanvas::kBGRA_Premul_Config8888:
-        case SkCanvas::kBGRA_Unpremul_Config8888:
-            return pack_config8888<3, 2, 1, 0>(a, r, g, b);
-        case SkCanvas::kRGBA_Premul_Config8888:
-        case SkCanvas::kRGBA_Unpremul_Config8888:
-            return pack_config8888<3, 0, 1, 2>(a, r, g, b);
-        default:
-            SkDEBUGFAIL("Unexpected config8888");
-            return 0;
+    uint32_t* dstP = static_cast<uint32_t*>(dst->fPixels);
+    const uint32_t* srcP = static_cast<const uint32_t*>(fPixels);
+    size_t srcInc = fRowBytes >> 2;
+    size_t dstInc = dst->fRowBytes >> 2;
+    for (int y = 0; y < height; ++y) {
+        proc(dstP, srcP, width);
+        dstP += dstInc;
+        srcP += srcInc;
     }
+    return true;
 }
diff --git a/src/core/SkConfig8888.h b/src/core/SkConfig8888.h
index 041773e6df..97a3433ad2 100644
--- a/src/core/SkConfig8888.h
+++ b/src/core/SkConfig8888.h
@@ -5,75 +5,27 @@
  * found in the LICENSE file.
  */
 
-#ifndef SkConfig8888_DEFINED
-#define SkConfig8888_DEFINED
+#ifndef SkPixelInfo_DEFINED
+#define SkPixelInfo_DEFINED
 
-#include "SkCanvas.h"
-#include "SkColorPriv.h"
+#include "SkImageInfo.h"
 
-/**
- * Converts pixels from one Config8888 to another Config8888
- */
-void SkConvertConfig8888Pixels(uint32_t* dstPixels,
-                               size_t dstRowBytes,
-                               SkCanvas::Config8888 dstConfig,
-                               const uint32_t* srcPixels,
-                               size_t srcRowBytes,
-                               SkCanvas::Config8888 srcConfig,
-                               int width,
-                               int height);
-
-/**
- * Packs a, r, g, b, values into byte order specified by config.
- */
-uint32_t SkPackConfig8888(SkCanvas::Config8888 config,
-                          uint32_t a,
-                          uint32_t r,
-                          uint32_t g,
-                          uint32_t b);
-
-///////////////////////////////////////////////////////////////////////////////
-// Implementation
-
-namespace {
+struct SkPixelInfo {
+    SkColorType fColorType;
+    SkAlphaType fAlphaType;
+    size_t      fRowBytes;
+};
 
-/**
-  Copies all pixels from a bitmap to a dst ptr with a given rowBytes and
-  Config8888. The bitmap must have kARGB_8888_Config.
- */
-
-static inline void SkCopyBitmapToConfig8888(uint32_t* dstPixels,
-                                     size_t dstRowBytes,
-                                     SkCanvas::Config8888 dstConfig8888,
-                                     const SkBitmap& srcBmp) {
-    SkASSERT(SkBitmap::kARGB_8888_Config == srcBmp.config());
-    SkAutoLockPixels alp(srcBmp);
-    int w = srcBmp.width();
-    int h = srcBmp.height();
-    size_t srcRowBytes = srcBmp.rowBytes();
-    const uint32_t* srcPixels = reinterpret_cast<uint32_t*>(srcBmp.getPixels());
-
-    SkConvertConfig8888Pixels(dstPixels, dstRowBytes, dstConfig8888, srcPixels, srcRowBytes, SkCanvas::kNative_Premul_Config8888, w, h);
-}
-
-/**
-  Copies over all pixels in a bitmap from a src ptr with a given rowBytes and
-  Config8888. The bitmap must have pixels and be kARGB_8888_Config.
- */
-static inline void SkCopyConfig8888ToBitmap(const SkBitmap& dstBmp,
-                                     const uint32_t* srcPixels,
-                                     size_t srcRowBytes,
-                                     SkCanvas::Config8888 srcConfig8888) {
-    SkASSERT(SkBitmap::kARGB_8888_Config == dstBmp.config());
-    SkAutoLockPixels alp(dstBmp);
-    int w = dstBmp.width();
-    int h = dstBmp.height();
-    size_t dstRowBytes = dstBmp.rowBytes();
-    uint32_t* dstPixels = reinterpret_cast<uint32_t*>(dstBmp.getPixels());
+struct SkDstPixelInfo : SkPixelInfo {
+    void* fPixels;
+};
 
-    SkConvertConfig8888Pixels(dstPixels, dstRowBytes, SkCanvas::kNative_Premul_Config8888, srcPixels, srcRowBytes, srcConfig8888, w, h);
-}
+struct SkSrcPixelInfo : SkPixelInfo {
+    const void* fPixels;
 
-}
+    // Guaranteed to work even if src.fPixels and dst.fPixels are the same
+    // (but not if they overlap partially)
+    bool convertPixelsTo(SkDstPixelInfo* dst, int width, int height) const;
+};
 
 #endif
diff --git a/src/core/SkDevice.cpp b/src/core/SkDevice.cpp
index ac46755013..4c75a36363 100644
--- a/src/core/SkDevice.cpp
+++ b/src/core/SkDevice.cpp
@@ -8,16 +8,6 @@
 #include "SkDevice.h"
 #include "SkMetaData.h"
 
-#if SK_PMCOLOR_BYTE_ORDER(B,G,R,A)
-    const SkCanvas::Config8888 SkBaseDevice::kPMColorAlias = SkCanvas::kBGRA_Premul_Config8888;
-#elif SK_PMCOLOR_BYTE_ORDER(R,G,B,A)
-    const SkCanvas::Config8888 SkBaseDevice::kPMColorAlias = SkCanvas::kRGBA_Premul_Config8888;
-#else
-    const SkCanvas::Config8888 SkBaseDevice::kPMColorAlias = (SkCanvas::Config8888) -1;
-#endif
-
-///////////////////////////////////////////////////////////////////////////////
-
 SkBaseDevice::SkBaseDevice()
     : fLeakyProperties(SkDeviceProperties::MakeDefault())
 #ifdef SK_DEBUG
diff --git a/src/gpu/GrContext.cpp b/src/gpu/GrContext.cpp
index c016d062ab..9a277b0591 100644
--- a/src/gpu/GrContext.cpp
+++ b/src/gpu/GrContext.cpp
@@ -25,6 +25,7 @@
 #include "GrSoftwarePathRenderer.h"
 #include "GrStencilBuffer.h"
 #include "GrTextStrike.h"
+#include "SkGr.h"
 #include "SkRTConf.h"
 #include "SkRRect.h"
 #include "SkStrokeRec.h"
@@ -1259,54 +1260,15 @@ bool GrContext::readTexturePixels(GrTexture* texture,
 
 #include "SkConfig8888.h"
 
-namespace {
-/**
- * Converts a GrPixelConfig to a SkCanvas::Config8888. Only byte-per-channel
- * formats are representable as Config8888 and so the function returns false
- * if the GrPixelConfig has no equivalent Config8888.
- */
-bool grconfig_to_config8888(GrPixelConfig config,
-                            bool unpremul,
-                            SkCanvas::Config8888* config8888) {
-    switch (config) {
-        case kRGBA_8888_GrPixelConfig:
-            if (unpremul) {
-                *config8888 = SkCanvas::kRGBA_Unpremul_Config8888;
-            } else {
-                *config8888 = SkCanvas::kRGBA_Premul_Config8888;
-            }
-            return true;
-        case kBGRA_8888_GrPixelConfig:
-            if (unpremul) {
-                *config8888 = SkCanvas::kBGRA_Unpremul_Config8888;
-            } else {
-                *config8888 = SkCanvas::kBGRA_Premul_Config8888;
-            }
-            return true;
-        default:
-            return false;
-    }
-}
-
-// It returns a configuration with where the byte position of the R & B components are swapped in
-// relation to the input config. This should only be called with the result of
-// grconfig_to_config8888 as it will fail for other configs.
-SkCanvas::Config8888 swap_config8888_red_and_blue(SkCanvas::Config8888 config8888) {
-    switch (config8888) {
-        case SkCanvas::kBGRA_Premul_Config8888:
-            return SkCanvas::kRGBA_Premul_Config8888;
-        case SkCanvas::kBGRA_Unpremul_Config8888:
-            return SkCanvas::kRGBA_Unpremul_Config8888;
-        case SkCanvas::kRGBA_Premul_Config8888:
-            return SkCanvas::kBGRA_Premul_Config8888;
-        case SkCanvas::kRGBA_Unpremul_Config8888:
-            return SkCanvas::kBGRA_Unpremul_Config8888;
-        default:
-            GrCrash("Unexpected input");
-            return SkCanvas::kBGRA_Unpremul_Config8888;;
+// toggles between RGBA and BGRA
+static SkColorType toggle_colortype32(SkColorType ct) {
+    if (kRGBA_8888_SkColorType == ct) {
+        return kBGRA_8888_SkColorType;
+    } else {
+        SkASSERT(kBGRA_8888_SkColorType == ct);
+        return kRGBA_8888_SkColorType;
     }
 }
-}
 
 bool GrContext::readRenderTargetPixels(GrRenderTarget* target,
                                        int left, int top, int width, int height,
@@ -1432,22 +1394,21 @@ bool GrContext::readRenderTargetPixels(GrRenderTarget* target,
     }
     // Perform any conversions we weren't able to perform using a scratch texture.
     if (unpremul || swapRAndB) {
-        // These are initialized to suppress a warning
-        SkCanvas::Config8888 srcC8888 = SkCanvas::kNative_Premul_Config8888;
-        SkCanvas::Config8888 dstC8888 = SkCanvas::kNative_Premul_Config8888;
+        SkDstPixelInfo dstPI;
+        if (!GrPixelConfig2ColorType(dstConfig, &dstPI.fColorType)) {
+            return false;
+        }
+        dstPI.fAlphaType = kUnpremul_SkAlphaType;
+        dstPI.fPixels = buffer;
+        dstPI.fRowBytes = rowBytes;
 
-        SkDEBUGCODE(bool c8888IsValid =) grconfig_to_config8888(dstConfig, false, &srcC8888);
-        grconfig_to_config8888(dstConfig, unpremul, &dstC8888);
+        SkSrcPixelInfo srcPI;
+        srcPI.fColorType = swapRAndB ? toggle_colortype32(dstPI.fColorType) : dstPI.fColorType;
+        srcPI.fAlphaType = kPremul_SkAlphaType;
+        srcPI.fPixels = buffer;
+        srcPI.fRowBytes = rowBytes;
 
-        if (swapRAndB) {
-            SkASSERT(c8888IsValid); // we should only do r/b swap on 8888 configs
-            srcC8888 = swap_config8888_red_and_blue(srcC8888);
-        }
-        SkASSERT(c8888IsValid);
-        uint32_t* b32 = reinterpret_cast<uint32_t*>(buffer);
-        SkConvertConfig8888Pixels(b32, rowBytes, dstC8888,
-                                  b32, rowBytes, srcC8888,
-                                  width, height);
+        return srcPI.convertPixelsTo(&dstPI, width, height);
     }
     return true;
 }
@@ -1567,18 +1528,24 @@ bool GrContext::writeRenderTargetPixels(GrRenderTarget* target,
         effect.reset(this->createUPMToPMEffect(texture, swapRAndB, textureMatrix));
         // handle the unpremul step on the CPU if we couldn't create an effect to do it.
         if (NULL == effect) {
-            SkCanvas::Config8888 srcConfig8888, dstConfig8888;
-            SkDEBUGCODE(bool success = )
-            grconfig_to_config8888(srcConfig, true, &srcConfig8888);
-            SkASSERT(success);
-            SkDEBUGCODE(success = )
-            grconfig_to_config8888(srcConfig, false, &dstConfig8888);
-            SkASSERT(success);
-            const uint32_t* src = reinterpret_cast<const uint32_t*>(buffer);
-            tmpPixels.reset(width * height);
-            SkConvertConfig8888Pixels(tmpPixels.get(), 4 * width, dstConfig8888,
-                                      src, rowBytes, srcConfig8888,
-                                      width, height);
+            SkSrcPixelInfo srcPI;
+            if (!GrPixelConfig2ColorType(srcConfig, &srcPI.fColorType)) {
+                return false;
+            }
+            srcPI.fAlphaType = kUnpremul_SkAlphaType;
+            srcPI.fPixels = buffer;
+            srcPI.fRowBytes = rowBytes;
+
+            SkDstPixelInfo dstPI;
+            dstPI.fColorType = srcPI.fColorType;
+            dstPI.fAlphaType = kPremul_SkAlphaType;
+            dstPI.fPixels = tmpPixels.get();
+            dstPI.fRowBytes = 4 * width;
+
+            if (!srcPI.convertPixelsTo(&dstPI, width, height)) {
+                return false;
+            }
+
             buffer = tmpPixels.get();
             rowBytes = 4 * width;
         }
diff --git a/src/gpu/SkGr.cpp b/src/gpu/SkGr.cpp
index 94e4c8c35d..db46b86901 100644
--- a/src/gpu/SkGr.cpp
+++ b/src/gpu/SkGr.cpp
@@ -34,11 +34,22 @@ static void build_compressed_data(void* buffer, const SkBitmap& bitmap) {
     SkColorTable* ctable = bitmap.getColorTable();
     char* dst = (char*)buffer;
 
-    uint32_t* colorTableDst = reinterpret_cast<uint32_t*>(dst);
-    const uint32_t* colorTableSrc = reinterpret_cast<const uint32_t*>(ctable->lockColors());
-    SkConvertConfig8888Pixels(colorTableDst, 0, SkCanvas::kRGBA_Premul_Config8888,
-                              colorTableSrc, 0, SkCanvas::kNative_Premul_Config8888,
-                              ctable->count(), 1);
+    const int count = ctable->count();
+
+    SkDstPixelInfo dstPI;
+    dstPI.fColorType = kRGBA_8888_SkColorType;
+    dstPI.fAlphaType = kPremul_SkAlphaType;
+    dstPI.fPixels = buffer;
+    dstPI.fRowBytes = count * sizeof(SkPMColor);
+
+    SkSrcPixelInfo srcPI;
+    srcPI.fColorType = kPMColor_SkColorType;
+    srcPI.fAlphaType = kPremul_SkAlphaType;
+    srcPI.fPixels = ctable->lockColors();
+    srcPI.fRowBytes = count * sizeof(SkPMColor);
+
+    srcPI.convertPixelsTo(&dstPI, count, 1);
+
     ctable->unlockColors();
 
     // always skip a full 256 number of entries, even if we memcpy'd fewer