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.
4
5 #include "chrome/browser/ui/libgtk2ui/skia_utils_gtk2.h"
6
7 #include <gdk/gdk.h>
8
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"
13
14 namespace libgtk2ui {
15
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).
20
GdkColorToSkColor(GdkColor color)21 SkColor GdkColorToSkColor(GdkColor color) {
22 return SkColorSetRGB(color.red >> 8, color.green >> 8, color.blue >> 8);
23 }
24
SkColorToGdkColor(SkColor color)25 GdkColor SkColorToGdkColor(SkColor color) {
26 GdkColor gdk_color = {
27 0,
28 static_cast<guint16>(SkColorGetR(color) * kSkiaToGDKMultiplier),
29 static_cast<guint16>(SkColorGetG(color) * kSkiaToGDKMultiplier),
30 static_cast<guint16>(SkColorGetB(color) * kSkiaToGDKMultiplier)
31 };
32 return gdk_color;
33 }
34
GdkPixbufToImageSkia(GdkPixbuf * pixbuf)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
39 // do in this build.
40 DCHECK_EQ(GDK_COLORSPACE_RGB, gdk_pixbuf_get_colorspace(pixbuf));
41
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);
45
46 SkBitmap ret;
47 ret.allocN32Pixels(w, h);
48 ret.eraseColor(0);
49
50 uint32_t* skia_data = static_cast<uint32_t*>(ret.getAddr(0, 0));
51
52 if (n_channels == 4) {
53 int total_length = w * h;
54 guchar* gdk_pixels = gdk_pixbuf_get_pixels(pixbuf);
55
56 // Now here's the trick: we need to convert the gdk data (which is RGBA and
57 // isn't premultiplied) to skia (which can be anything and premultiplied).
58 for (int i = 0; i < total_length; ++i, gdk_pixels += 4) {
59 const unsigned char& red = gdk_pixels[0];
60 const unsigned char& green = gdk_pixels[1];
61 const unsigned char& blue = gdk_pixels[2];
62 const unsigned char& alpha = gdk_pixels[3];
63
64 skia_data[i] = SkPreMultiplyARGB(alpha, red, green, blue);
65 }
66 } else if (n_channels == 3) {
67 // Because GDK makes rowstrides word aligned, we need to do something a bit
68 // more complex when a pixel isn't perfectly a word of memory.
69 int rowstride = gdk_pixbuf_get_rowstride(pixbuf);
70 guchar* gdk_pixels = gdk_pixbuf_get_pixels(pixbuf);
71 for (int y = 0; y < h; ++y) {
72 int row = y * rowstride;
73
74 for (int x = 0; x < w; ++x) {
75 guchar* pixel = gdk_pixels + row + (x * 3);
76 const unsigned char& red = pixel[0];
77 const unsigned char& green = pixel[1];
78 const unsigned char& blue = pixel[2];
79
80 skia_data[y * w + x] = SkPreMultiplyARGB(255, red, green, blue);
81 }
82 }
83 } else {
84 NOTREACHED();
85 }
86
87 return ret;
88 }
89
GdkPixbufFromSkBitmap(const SkBitmap & bitmap)90 GdkPixbuf* GdkPixbufFromSkBitmap(const SkBitmap& bitmap) {
91 if (bitmap.isNull())
92 return NULL;
93
94 SkAutoLockPixels lock_pixels(bitmap);
95
96 int width = bitmap.width();
97 int height = bitmap.height();
98
99 GdkPixbuf* pixbuf =
100 gdk_pixbuf_new(GDK_COLORSPACE_RGB, // The only colorspace gtk supports.
101 TRUE, // There is an alpha channel.
102 8,
103 width,
104 height);
105
106 // SkBitmaps are premultiplied, we need to unpremultiply them.
107 const int kBytesPerPixel = 4;
108 uint8* divided = gdk_pixbuf_get_pixels(pixbuf);
109
110 for (int y = 0, i = 0; y < height; y++) {
111 for (int x = 0; x < width; x++) {
112 uint32 pixel = bitmap.getAddr32(0, y)[x];
113
114 int alpha = SkColorGetA(pixel);
115 if (alpha != 0 && alpha != 255) {
116 SkColor unmultiplied = SkUnPreMultiply::PMColorToColor(pixel);
117 divided[i + 0] = SkColorGetR(unmultiplied);
118 divided[i + 1] = SkColorGetG(unmultiplied);
119 divided[i + 2] = SkColorGetB(unmultiplied);
120 divided[i + 3] = alpha;
121 } else {
122 divided[i + 0] = SkColorGetR(pixel);
123 divided[i + 1] = SkColorGetG(pixel);
124 divided[i + 2] = SkColorGetB(pixel);
125 divided[i + 3] = alpha;
126 }
127 i += kBytesPerPixel;
128 }
129 }
130
131 return pixbuf;
132 }
133
134 } // namespace libgtk2ui
135