diff --git a/tests/WritePixelsTest.cpp b/tests/WritePixelsTest.cpp
new file mode 100644
index 0000000..8244fb1
--- /dev/null
+++ b/tests/WritePixelsTest.cpp
@@ -0,0 +1,419 @@
+
+/*
+ * 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 "Test.h"
+#include "SkCanvas.h"
+#include "SkRegion.h"
+#include "SkGpuDevice.h"
+
+static const int DEV_W = 100, DEV_H = 100;
+static const SkIRect DEV_RECT = SkIRect::MakeWH(DEV_W, DEV_H);
+static const SkRect DEV_RECT_S = SkRect::MakeWH(DEV_W * SK_Scalar1, 
+                                                DEV_H * SK_Scalar1);
+static const U8CPU DEV_PAD = 0xee;
+
+namespace {
+SkPMColor getCanvasColor(int x, int y) {
+    SkASSERT(x >= 0 && x < DEV_W);
+    SkASSERT(y >= 0 && y < DEV_H);
+
+    U8CPU r = x;
+    U8CPU g = y;
+    U8CPU b = 0xc;
+
+    U8CPU a = 0xff;
+    switch ((x+y) % 5) {
+        case 0:
+            a = 0xff;
+            break;
+        case 1:
+            a = 0x80;
+            break;
+        case 2:
+            a = 0xCC;
+            break;
+        case 4:
+            a = 0x01;
+            break;
+        case 3:
+            a = 0x00;
+            break;
+    }
+    return SkPremultiplyARGBInline(a, r, g, b);
+}
+
+bool config8888IsPremul(SkCanvas::Config8888 config8888) {
+    switch (config8888) {
+        case SkCanvas::kNative_Premul_Config8888:
+        case SkCanvas::kBGRA_Premul_Config8888:
+        case SkCanvas::kRGBA_Premul_Config8888:
+            return true;
+        case SkCanvas::kNative_Unpremul_Config8888:
+        case SkCanvas::kBGRA_Unpremul_Config8888:
+        case SkCanvas::kRGBA_Unpremul_Config8888:
+            return false;
+        default:
+            SkASSERT(0);
+            return false;
+    }
+}
+
+// assumes any premu/.unpremul has been applied
+uint32_t packConfig8888(SkCanvas::Config8888 config8888,
+                        U8CPU a, U8CPU r, U8CPU g, U8CPU b) {
+    uint32_t r32;
+    uint8_t* result = reinterpret_cast<uint8_t*>(&r32);
+    switch (config8888) {
+        case SkCanvas::kNative_Premul_Config8888:
+        case SkCanvas::kNative_Unpremul_Config8888:
+            r32 = SkPackARGB32NoCheck(a, r, g, b);
+            break;
+        case SkCanvas::kBGRA_Premul_Config8888:
+        case SkCanvas::kBGRA_Unpremul_Config8888:
+            result[0] = b;
+            result[1] = g;
+            result[2] = r;
+            result[3] = a;
+            break;
+        case SkCanvas::kRGBA_Premul_Config8888:
+        case SkCanvas::kRGBA_Unpremul_Config8888:
+            result[0] = r;
+            result[1] = g;
+            result[2] = b;
+            result[3] = a;
+            break;
+        default:
+            SkASSERT(0);
+            return 0;
+    }
+    return r32;
+}
+
+uint32_t getBitmapColor(int x, int y, int w, int h, SkCanvas::Config8888 config8888) {
+    int n = y * w + x;
+    U8CPU b = n & 0xff;
+    U8CPU g = (n >> 8) & 0xff;
+    U8CPU r = (n >> 16) & 0xff;
+    U8CPU a;
+    switch ((x+y) % 5) {
+        case 4:
+            a = 0xff;
+            break;
+        case 3:
+            a = 0x80;
+            break;
+        case 2:
+            a = 0xCC;
+            break;
+        case 1:
+            a = 0x01;
+            break;
+        case 0:
+            a = 0x00;
+            break;
+    }
+    if (config8888IsPremul(config8888)) {
+        r = SkMulDiv255Ceiling(r, a);
+        g = SkMulDiv255Ceiling(g, a);
+        b = SkMulDiv255Ceiling(b, a);
+    }
+    return packConfig8888(config8888, a, r, g , b);
+}
+
+void fillCanvas(SkCanvas* canvas) {
+    static SkBitmap bmp;
+    if (bmp.isNull()) {
+        bmp.setConfig(SkBitmap::kARGB_8888_Config, DEV_W, DEV_H);
+        bool alloc = bmp.allocPixels();
+        SkASSERT(alloc);
+        SkAutoLockPixels alp(bmp);
+        intptr_t pixels = reinterpret_cast<intptr_t>(bmp.getPixels());
+        for (int y = 0; y < DEV_H; ++y) {
+            for (int x = 0; x < DEV_W; ++x) {
+                SkPMColor* pixel = reinterpret_cast<SkPMColor*>(pixels + y * bmp.rowBytes() + x * bmp.bytesPerPixel());
+                *pixel = getCanvasColor(x, y);
+            }
+        }
+    }
+    canvas->save();
+    canvas->setMatrix(SkMatrix::I());
+    canvas->clipRect(DEV_RECT_S, SkRegion::kReplace_Op);
+    SkPaint paint;
+    paint.setXfermodeMode(SkXfermode::kSrc_Mode);
+    canvas->drawBitmap(bmp, 0, 0, &paint);
+    canvas->restore();
+}
+
+SkPMColor convertConfig8888ToPMColor(SkCanvas::Config8888 config8888,
+                                     uint32_t color,
+                                     bool* premul) {
+    const uint8_t* c = reinterpret_cast<uint8_t*>(&color);
+    U8CPU a,r,g,b;
+    *premul = false;
+    switch (config8888) {
+        case SkCanvas::kNative_Premul_Config8888:
+            return color;
+        case SkCanvas::kNative_Unpremul_Config8888:
+            *premul = true;
+            a = SkGetPackedA32(color);
+            r = SkGetPackedR32(color);
+            g = SkGetPackedG32(color);
+            b = SkGetPackedB32(color);
+            break;
+        case SkCanvas::kBGRA_Unpremul_Config8888:
+            *premul = true; // fallthru
+        case SkCanvas::kBGRA_Premul_Config8888:
+            a = static_cast<U8CPU>(c[3]);
+            r = static_cast<U8CPU>(c[2]);
+            g = static_cast<U8CPU>(c[1]);
+            b = static_cast<U8CPU>(c[0]);
+            break;
+        case SkCanvas::kRGBA_Unpremul_Config8888:
+            *premul = true; // fallthru
+        case SkCanvas::kRGBA_Premul_Config8888:
+            a = static_cast<U8CPU>(c[3]);
+            r = static_cast<U8CPU>(c[0]);
+            g = static_cast<U8CPU>(c[1]);
+            b = static_cast<U8CPU>(c[2]);
+            break;
+        default:
+            GrCrash("Unexpected Config8888");
+    }
+    if (*premul) {
+        r = SkMulDiv255Ceiling(r, a);
+        g = SkMulDiv255Ceiling(g, a);
+        b = SkMulDiv255Ceiling(b, a);
+    }
+    return SkPackARGB32(a, r, g, b);
+}
+
+bool checkPixel(SkPMColor a, SkPMColor b, bool didPremulConversion) {
+    if (!didPremulConversion) {
+        return a == b;
+    }
+    int32_t aA = static_cast<int32_t>(SkGetPackedA32(a));
+    int32_t aR = static_cast<int32_t>(SkGetPackedR32(a));
+    int32_t aG = static_cast<int32_t>(SkGetPackedG32(a));
+    int32_t aB = SkGetPackedB32(a);
+
+    int32_t bA = static_cast<int32_t>(SkGetPackedA32(b));
+    int32_t bR = static_cast<int32_t>(SkGetPackedR32(b));
+    int32_t bG = static_cast<int32_t>(SkGetPackedG32(b));
+    int32_t bB = static_cast<int32_t>(SkGetPackedB32(b));
+
+    return aA == bA &&
+           SkAbs32(aR - bR) <= 1 &&
+           SkAbs32(aG - bG) <= 1 &&
+           SkAbs32(aB - bB) <= 1;
+}
+
+bool checkWrite(skiatest::Reporter* reporter,
+                SkCanvas* canvas,
+                const SkBitmap& bitmap,
+                int writeX, int writeY,
+                SkCanvas::Config8888 config8888) {
+    SkDevice* dev = canvas->getDevice();
+    if (!dev) {
+        return false;
+    }
+    SkBitmap devBmp = dev->accessBitmap(false);
+    if (devBmp.width() != DEV_W ||
+        devBmp.height() != DEV_H ||
+        devBmp.config() != SkBitmap::kARGB_8888_Config ||
+        devBmp.isNull()) {
+        return false;
+    }
+    SkAutoLockPixels alp(devBmp);
+
+    intptr_t canvasPixels = reinterpret_cast<intptr_t>(devBmp.getPixels());
+    size_t canvasRowBytes = devBmp.rowBytes();
+    SkIRect writeRect = SkIRect::MakeXYWH(writeX, writeY, bitmap.width(), bitmap.height());
+    bool success = true;
+    for (int cy = 0; cy < DEV_H; ++cy) {
+        const SkPMColor* canvasRow = reinterpret_cast<const SkPMColor*>(canvasPixels);
+        for (int cx = 0; cx < DEV_W; ++cx) {
+            SkPMColor canvasPixel = canvasRow[cx];
+            if (writeRect.contains(cx, cy)) {
+                int bx = cx - writeX;
+                int by = cy - writeY;
+                uint32_t bmpColor8888 = getBitmapColor(bx, by, bitmap.width(), bitmap.height(), config8888);
+                bool mul;
+                SkPMColor bmpPMColor = convertConfig8888ToPMColor(config8888, bmpColor8888, &mul);
+                bool check;
+                // do we need fuzzy test?
+                REPORTER_ASSERT(reporter, check = checkPixel(bmpPMColor, canvasPixel, mul));
+                if (!check) {
+                    success = false;
+                }
+            } else {
+                bool check;
+                SkPMColor testColor = getCanvasColor(cx, cy);
+                REPORTER_ASSERT(reporter, check = (canvasPixel == testColor));
+                if (!check) {
+                    success = false;
+                }
+            }
+        }
+        if (cy != DEV_H -1) {
+            const char* pad = reinterpret_cast<const char*>(canvasPixels + 4 * DEV_W);
+            for (size_t px = 0; px < canvasRowBytes - 4 * DEV_W; ++px) {
+                bool check;
+                REPORTER_ASSERT(reporter, check = (pad[px] == static_cast<char>(DEV_PAD)));
+                if (!check) {
+                    success = false;
+                }
+            }
+        }
+        canvasPixels += canvasRowBytes;
+    }
+
+    return success;
+}
+
+enum DevType {
+    kRaster_DevType,
+    kGpu_DevType,
+};
+
+struct CanvasConfig {
+    DevType fDevType;
+    bool fTightRowBytes;
+};
+
+static const CanvasConfig gCanvasConfigs[] = {
+    {kRaster_DevType, true},
+    {kRaster_DevType, false},
+    {kGpu_DevType, true}, // row bytes has no meaning on gpu devices
+};
+
+bool setupCanvas(SkCanvas* canvas, const CanvasConfig& c, GrContext* grCtx) {
+    switch (c.fDevType) {
+        case kRaster_DevType: {
+            SkBitmap bmp;
+            size_t rowBytes = c.fTightRowBytes ? 0 : 4 * DEV_W + 100;
+            bmp.setConfig(SkBitmap::kARGB_8888_Config, DEV_W, DEV_H, rowBytes);
+            if (!bmp.allocPixels()) {
+                return false;
+            }
+            // if rowBytes isn't tight then set the padding to a known value
+            if (rowBytes) {
+                SkAutoLockPixels alp(bmp);
+                memset(bmp.getPixels(), DEV_PAD, bmp.getSafeSize());
+            }
+            canvas->setDevice(new SkDevice(bmp))->unref();
+            } break;
+        case kGpu_DevType:
+            canvas->setDevice(new SkGpuDevice(grCtx,
+                                              SkBitmap::kARGB_8888_Config,
+                                              DEV_W, DEV_H))->unref();
+            break;
+    }
+    return true;
+}
+
+bool setupBitmap(SkBitmap* bitmap,
+              SkCanvas::Config8888 config8888,
+              int w, int h,
+              bool tightRowBytes) {
+    size_t rowBytes = tightRowBytes ? 0 : 4 * w + 60;
+    bitmap->setConfig(SkBitmap::kARGB_8888_Config, w, h, rowBytes);
+    if (!bitmap->allocPixels()) {
+        return false;
+    }
+    SkAutoLockPixels alp(*bitmap);
+    intptr_t pixels = reinterpret_cast<intptr_t>(bitmap->getPixels());
+    for (int y = 0; y < h; ++y) {
+        for (int x = 0; x < w; ++x) {
+            uint32_t* pixel = reinterpret_cast<uint32_t*>(pixels + y * bitmap->rowBytes() + x * 4);
+            *pixel = getBitmapColor(x, y, w, h, config8888);
+        }
+    }
+    return true;
+}
+
+void WritePixelsTest(skiatest::Reporter* reporter, GrContext* context) {
+    SkCanvas canvas;
+    
+    const SkIRect testRects[] = {
+        // entire thing
+        DEV_RECT,
+        // larger on all sides
+        SkIRect::MakeLTRB(-10, -10, DEV_W + 10, DEV_H + 10),
+        // fully contained
+        SkIRect::MakeLTRB(DEV_W / 4, DEV_H / 4, 3 * DEV_W / 4, 3 * DEV_H / 4),
+        // outside top left
+        SkIRect::MakeLTRB(-10, -10, -1, -1),
+        // touching top left corner
+        SkIRect::MakeLTRB(-10, -10, 0, 0),
+        // overlapping top left corner
+        SkIRect::MakeLTRB(-10, -10, DEV_W / 4, DEV_H / 4),
+        // overlapping top left and top right corners
+        SkIRect::MakeLTRB(-10, -10, DEV_W  + 10, DEV_H / 4),
+        // touching entire top edge
+        SkIRect::MakeLTRB(-10, -10, DEV_W  + 10, 0),
+        // overlapping top right corner
+        SkIRect::MakeLTRB(3 * DEV_W / 4, -10, DEV_W  + 10, DEV_H / 4),
+        // contained in x, overlapping top edge
+        SkIRect::MakeLTRB(DEV_W / 4, -10, 3 * DEV_W  / 4, DEV_H / 4),
+        // outside top right corner
+        SkIRect::MakeLTRB(DEV_W + 1, -10, DEV_W + 10, -1),
+        // touching top right corner
+        SkIRect::MakeLTRB(DEV_W, -10, DEV_W + 10, 0),
+        // overlapping top left and bottom left corners
+        SkIRect::MakeLTRB(-10, -10, DEV_W / 4, DEV_H + 10),
+        // touching entire left edge
+        SkIRect::MakeLTRB(-10, -10, 0, DEV_H + 10),
+        // overlapping bottom left corner
+        SkIRect::MakeLTRB(-10, 3 * DEV_H / 4, DEV_W / 4, DEV_H + 10),
+        // contained in y, overlapping left edge
+        SkIRect::MakeLTRB(-10, DEV_H / 4, DEV_W / 4, 3 * DEV_H / 4),
+        // outside bottom left corner
+        SkIRect::MakeLTRB(-10, DEV_H + 1, -1, DEV_H + 10),
+        // touching bottom left corner
+        SkIRect::MakeLTRB(-10, DEV_H, 0, DEV_H + 10),
+        // overlapping bottom left and bottom right corners
+        SkIRect::MakeLTRB(-10, 3 * DEV_H / 4, DEV_W + 10, DEV_H + 10),
+        // touching entire left edge
+        SkIRect::MakeLTRB(0, DEV_H, DEV_W, DEV_H + 10),
+        // overlapping bottom right corner
+        SkIRect::MakeLTRB(3 * DEV_W / 4, 3 * DEV_H / 4, DEV_W + 10, DEV_H + 10),
+        // overlapping top right and bottom right corners
+        SkIRect::MakeLTRB(3 * DEV_W / 4, -10, DEV_W + 10, DEV_H + 10),
+    };
+
+    for (size_t i = 0; i < SK_ARRAY_COUNT(gCanvasConfigs); ++i) {
+        REPORTER_ASSERT(reporter, setupCanvas(&canvas, gCanvasConfigs[i], context));
+
+        static const SkCanvas::Config8888 gReadConfigs[] = {
+            SkCanvas::kNative_Premul_Config8888,
+            SkCanvas::kNative_Unpremul_Config8888,
+            SkCanvas::kBGRA_Premul_Config8888,
+            SkCanvas::kBGRA_Unpremul_Config8888,
+            SkCanvas::kRGBA_Premul_Config8888,
+            SkCanvas::kRGBA_Unpremul_Config8888,
+        };
+        for (int r = 0; r < SK_ARRAY_COUNT(testRects); ++r) {
+            const SkIRect& rect = testRects[r];
+            for (int tightBmp = 0; tightBmp < 2; ++tightBmp) {
+                for (int c = 0; c < SK_ARRAY_COUNT(gReadConfigs); ++c) {
+                    fillCanvas(&canvas);
+                    SkCanvas::Config8888 config8888 = gReadConfigs[c];
+                    SkBitmap bmp;
+                    REPORTER_ASSERT(reporter, setupBitmap(&bmp, config8888, rect.width(), rect.height(), SkToBool(tightBmp)));
+                    canvas.writePixels(bmp, rect.fLeft, rect.fTop, config8888);
+                    REPORTER_ASSERT(reporter, checkWrite(reporter, &canvas, bmp, rect.fLeft, rect.fTop, config8888));
+                }
+            }
+        }
+    }
+}
+}
+
+#include "TestClassDef.h"
+DEFINE_GPUTESTCLASS("WritePixels", WritePixelsTestClass, WritePixelsTest)
+