1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
5 #include "chrome/browser/ui/libgtk2ui/skia_utils_gtk2.h"
9 #include "base/basictypes.h"
10 #include "base/logging.h"
11 #include "third_party/skia/include/core/SkBitmap.h"
12 #include "third_party/skia/include/core/SkUnPreMultiply.h"
16 // GDK_COLOR_RGB multiplies by 257 (= 0x10001) to distribute the bits evenly
17 // See: http://www.mindcontrol.org/~hplus/graphics/expand-bits.html
18 // To get back, we can just right shift by eight
19 // (or, formulated differently, i == (i*257)/256 for all i < 256).
21 SkColor GdkColorToSkColor(GdkColor color) {
22 return SkColorSetRGB(color.red >> 8, color.green >> 8, color.blue >> 8);
25 GdkColor SkColorToGdkColor(SkColor color) {
26 GdkColor gdk_color = {
28 static_cast<guint16>(SkColorGetR(color) * kSkiaToGDKMultiplier),
29 static_cast<guint16>(SkColorGetG(color) * kSkiaToGDKMultiplier),
30 static_cast<guint16>(SkColorGetB(color) * kSkiaToGDKMultiplier)
35 const SkBitmap GdkPixbufToImageSkia(GdkPixbuf* pixbuf) {
36 // TODO(erg): What do we do in the case where the pixbuf fails these dchecks?
37 // I would prefer to use our gtk based canvas, but that would require
38 // recompiling half of our skia extensions with gtk support, which we can't
40 DCHECK_EQ(GDK_COLORSPACE_RGB, gdk_pixbuf_get_colorspace(pixbuf));
42 int n_channels = gdk_pixbuf_get_n_channels(pixbuf);
43 int w = gdk_pixbuf_get_width(pixbuf);
44 int h = gdk_pixbuf_get_height(pixbuf);
47 ret.setConfig(SkBitmap::kARGB_8888_Config, w, h);
51 uint32_t* skia_data = static_cast<uint32_t*>(ret.getAddr(0, 0));
53 if (n_channels == 4) {
54 int total_length = w * h;
55 guchar* gdk_pixels = gdk_pixbuf_get_pixels(pixbuf);
57 // Now here's the trick: we need to convert the gdk data (which is RGBA and
58 // isn't premultiplied) to skia (which can be anything and premultiplied).
59 for (int i = 0; i < total_length; ++i, gdk_pixels += 4) {
60 const unsigned char& red = gdk_pixels[0];
61 const unsigned char& green = gdk_pixels[1];
62 const unsigned char& blue = gdk_pixels[2];
63 const unsigned char& alpha = gdk_pixels[3];
65 skia_data[i] = SkPreMultiplyARGB(alpha, red, green, blue);
67 } else if (n_channels == 3) {
68 // Because GDK makes rowstrides word aligned, we need to do something a bit
69 // more complex when a pixel isn't perfectly a word of memory.
70 int rowstride = gdk_pixbuf_get_rowstride(pixbuf);
71 guchar* gdk_pixels = gdk_pixbuf_get_pixels(pixbuf);
72 for (int y = 0; y < h; ++y) {
73 int row = y * rowstride;
75 for (int x = 0; x < w; ++x) {
76 guchar* pixel = gdk_pixels + row + (x * 3);
77 const unsigned char& red = pixel[0];
78 const unsigned char& green = pixel[1];
79 const unsigned char& blue = pixel[2];
81 skia_data[y * w + x] = SkPreMultiplyARGB(255, red, green, blue);
91 GdkPixbuf* GdkPixbufFromSkBitmap(const SkBitmap& bitmap) {
95 SkAutoLockPixels lock_pixels(bitmap);
97 int width = bitmap.width();
98 int height = bitmap.height();
101 gdk_pixbuf_new(GDK_COLORSPACE_RGB, // The only colorspace gtk supports.
102 TRUE, // There is an alpha channel.
107 // SkBitmaps are premultiplied, we need to unpremultiply them.
108 const int kBytesPerPixel = 4;
109 uint8* divided = gdk_pixbuf_get_pixels(pixbuf);
111 for (int y = 0, i = 0; y < height; y++) {
112 for (int x = 0; x < width; x++) {
113 uint32 pixel = bitmap.getAddr32(0, y)[x];
115 int alpha = SkColorGetA(pixel);
116 if (alpha != 0 && alpha != 255) {
117 SkColor unmultiplied = SkUnPreMultiply::PMColorToColor(pixel);
118 divided[i + 0] = SkColorGetR(unmultiplied);
119 divided[i + 1] = SkColorGetG(unmultiplied);
120 divided[i + 2] = SkColorGetB(unmultiplied);
121 divided[i + 3] = alpha;
123 divided[i + 0] = SkColorGetR(pixel);
124 divided[i + 1] = SkColorGetG(pixel);
125 divided[i + 2] = SkColorGetB(pixel);
126 divided[i + 3] = alpha;
135 } // namespace libgtk2ui