WebKit merge 40668:40722 part 1.

third_party/WebKit/WebCore/platform/image-encoders/skia/PNGImageEncoder.cpp

Index: third_party/WebKit/WebCore/platform/image-encoders/skia/PNGImageEncoder.cpp
===================================================================
--- third_party/WebKit/WebCore/platform/image-encoders/skia/PNGImageEncoder.cpp	(revision 0)
+++ third_party/WebKit/WebCore/platform/image-encoders/skia/PNGImageEncoder.cpp	(revision 0)
@@ -0,0 +1,172 @@
+/*
+ * Copyright (c) 2006-2009, Google Inc. All rights reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ * 
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "config.h"
+
+#include "IntSize.h"
+#include "OwnArrayPtr.h"
+#include "PNGImageEncoder.h"
+#include "Vector.h"
+
+#include "SkBitmap.h"
+
+extern "C" {
+#include "png.h"
+}
+
+namespace WebCore {
+
+// Converts BGRA->RGBA and RGBA->BGRA.
+static void convertBetweenBGRAandRGBA(const unsigned char* input, int numberOfPixels,
+                                      unsigned char* output)
+{
+    for (int x = 0; x < numberOfPixels; x++) {
+        const unsigned char* pixelIn = &input[x * 4];
+        unsigned char* pixelOut = &output[x * 4];
+        pixelOut[0] = pixelIn[2];
+        pixelOut[1] = pixelIn[1];
+        pixelOut[2] = pixelIn[0];
+        pixelOut[3] = pixelIn[3];
+    }
+}
+
+// Encoder --------------------------------------------------------------------
+//
+// This section of the code is based on nsPNGEncoder.cpp in Mozilla
+// (Copyright 2005 Google Inc.)
+
+// Passed around as the io_ptr in the png structs so our callbacks know where
+// to write data.
+struct PNGEncoderState {
+    PNGEncoderState(Vector<unsigned char>* o) : m_out(o) {}
+    Vector<unsigned char>* m_out;
+};
+
+// Called by libpng to flush its internal buffer to ours.
+void encoderWriteCallback(png_structp png, png_bytep data, png_size_t size)
+{
+    PNGEncoderState* state = static_cast<PNGEncoderState*>(png_get_io_ptr(png));
+    ASSERT(state->m_out);
+
+    size_t oldSize = state->m_out->size();
+    state->m_out->resize(oldSize + size);
+    memcpy(&(*state->m_out)[oldSize], data, size);
+}
+
+// Automatically destroys the given write structs on destruction to make
+// cleanup and error handling code cleaner.
+class PNGWriteStructDestroyer {
+public:
+    PNGWriteStructDestroyer(png_struct** ps, png_info** pi)
+        : m_pngStruct(ps)
+        , m_pngInfo(pi) {
+    }
+
+    ~PNGWriteStructDestroyer() {
+        png_destroy_write_struct(m_pngStruct, m_pngInfo);
+    }
+
+private:
+    png_struct** m_pngStruct;
+    png_info** m_pngInfo;
+};
+
+// static
+bool PNGImageEncoder::encode(const SkBitmap& image, Vector<unsigned char>* output)
+{
+    if (image.config() != SkBitmap::kARGB_8888_Config)
+        return false;  // Only support ARGB at 8 bpp now.
+
+    image.lockPixels();
+    bool result = PNGImageEncoder::encode(static_cast<unsigned char*>(
+        image.getPixels()), IntSize(image.width(), image.height()),
+        image.rowBytes(), output);
+    image.unlockPixels();
+    return result;
+}
+
+// static
+bool PNGImageEncoder::encode(const unsigned char* input, const IntSize& size,
+                             int bytesPerRow,
+                             Vector<unsigned char>* output)
+{
+    int inputColorComponents = 4;
+    int outputColorComponents = 4;
+    int pngOutputColorType = PNG_COLOR_TYPE_RGB_ALPHA;
+    IntSize imageSize(size);
+    imageSize.clampNegativeToZero();
+
+    // Row stride should be at least as long as the length of the data.
+    if (inputColorComponents * imageSize.width() > bytesPerRow) {
+        ASSERT(false);
+        return false;
+    }
+
+    png_struct* pngPtr = png_create_write_struct(PNG_LIBPNG_VER_STRING,
+                                                 png_voidp_NULL,
+                                                 png_error_ptr_NULL,
+                                                 png_error_ptr_NULL);
+    if (!pngPtr)
+        return false;
+
+    png_info* infoPtr = png_create_info_struct(pngPtr);
+    if (!infoPtr) {
+        png_destroy_write_struct(&pngPtr, NULL);
+        return false;
+    }
+    PNGWriteStructDestroyer destroyer(&pngPtr, &infoPtr);
+
+    if (setjmp(png_jmpbuf(pngPtr))) {
+        // The destroyer will ensure that the structures are cleaned up in this
+        // case, even though we may get here as a jump from random parts of the
+        // PNG library called below.
+        return false;
+    }
+
+    // Set our callback for libpng to give us the data.
+    PNGEncoderState state(output);
+    png_set_write_fn(pngPtr, &state, encoderWriteCallback, NULL);
+
+    png_set_IHDR(pngPtr, infoPtr, imageSize.width(), imageSize.height(), 8, pngOutputColorType,
+                 PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT,
+                 PNG_FILTER_TYPE_DEFAULT);
+    png_write_info(pngPtr, infoPtr);
+
+    OwnArrayPtr<unsigned char> rowPixels(new unsigned char[imageSize.width() * outputColorComponents]);
+    for (int y = 0; y < imageSize.height(); y ++) {
+        convertBetweenBGRAandRGBA(&input[y * bytesPerRow], imageSize.width(), rowPixels.get());
+        png_write_row(pngPtr, rowPixels.get());
+    }
+
+    png_write_end(pngPtr, infoPtr);
+    return true;
+}
+
+}  // namespace WebCore