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1 /*
2  *  Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
3  *
4  *  Use of this source code is governed by a BSD-style license
5  *  that can be found in the LICENSE file in the root of the source
6  *  tree. An additional intellectual property rights grant can be found
7  *  in the file PATENTS.  All contributing project authors may
8  *  be found in the AUTHORS file in the root of the source tree.
9  */
10 
11 #include "webrtc/modules/desktop_capture/win/cursor.h"
12 
13 #include <algorithm>
14 
15 #include "webrtc/base/scoped_ptr.h"
16 #include "webrtc/modules/desktop_capture/win/scoped_gdi_object.h"
17 #include "webrtc/modules/desktop_capture/desktop_frame.h"
18 #include "webrtc/modules/desktop_capture/desktop_geometry.h"
19 #include "webrtc/modules/desktop_capture/mouse_cursor.h"
20 #include "webrtc/system_wrappers/include/logging.h"
21 #include "webrtc/typedefs.h"
22 
23 namespace webrtc {
24 
25 namespace {
26 
27 #if defined(WEBRTC_ARCH_LITTLE_ENDIAN)
28 
29 #define RGBA(r, g, b, a) \
30     ((((a) << 24) & 0xff000000) | \
31     (((b) << 16) & 0xff0000) | \
32     (((g) << 8) & 0xff00) | \
33     ((r) & 0xff))
34 
35 #else  // !defined(WEBRTC_ARCH_LITTLE_ENDIAN)
36 
37 #define RGBA(r, g, b, a) \
38     ((((r) << 24) & 0xff000000) | \
39     (((g) << 16) & 0xff0000) | \
40     (((b) << 8) & 0xff00) | \
41     ((a) & 0xff))
42 
43 #endif  // !defined(WEBRTC_ARCH_LITTLE_ENDIAN)
44 
45 const int kBytesPerPixel = DesktopFrame::kBytesPerPixel;
46 
47 // Pixel colors used when generating cursor outlines.
48 const uint32_t kPixelRgbaBlack = RGBA(0, 0, 0, 0xff);
49 const uint32_t kPixelRgbaWhite = RGBA(0xff, 0xff, 0xff, 0xff);
50 const uint32_t kPixelRgbaTransparent = RGBA(0, 0, 0, 0);
51 
52 const uint32_t kPixelRgbWhite = RGB(0xff, 0xff, 0xff);
53 
54 // Expands the cursor shape to add a white outline for visibility against
55 // dark backgrounds.
AddCursorOutline(int width,int height,uint32_t * data)56 void AddCursorOutline(int width, int height, uint32_t* data) {
57   for (int y = 0; y < height; y++) {
58     for (int x = 0; x < width; x++) {
59       // If this is a transparent pixel (bgr == 0 and alpha = 0), check the
60       // neighbor pixels to see if this should be changed to an outline pixel.
61       if (*data == kPixelRgbaTransparent) {
62         // Change to white pixel if any neighbors (top, bottom, left, right)
63         // are black.
64         if ((y > 0 && data[-width] == kPixelRgbaBlack) ||
65             (y < height - 1 && data[width] == kPixelRgbaBlack) ||
66             (x > 0 && data[-1] == kPixelRgbaBlack) ||
67             (x < width - 1 && data[1] == kPixelRgbaBlack)) {
68           *data = kPixelRgbaWhite;
69         }
70       }
71       data++;
72     }
73   }
74 }
75 
76 // Premultiplies RGB components of the pixel data in the given image by
77 // the corresponding alpha components.
AlphaMul(uint32_t * data,int width,int height)78 void AlphaMul(uint32_t* data, int width, int height) {
79   static_assert(sizeof(uint32_t) == kBytesPerPixel,
80                 "size of uint32 should be the number of bytes per pixel");
81 
82   for (uint32_t* data_end = data + width * height; data != data_end; ++data) {
83     RGBQUAD* from = reinterpret_cast<RGBQUAD*>(data);
84     RGBQUAD* to = reinterpret_cast<RGBQUAD*>(data);
85     to->rgbBlue =
86         (static_cast<uint16_t>(from->rgbBlue) * from->rgbReserved) / 0xff;
87     to->rgbGreen =
88         (static_cast<uint16_t>(from->rgbGreen) * from->rgbReserved) / 0xff;
89     to->rgbRed =
90         (static_cast<uint16_t>(from->rgbRed) * from->rgbReserved) / 0xff;
91   }
92 }
93 
94 // Scans a 32bpp bitmap looking for any pixels with non-zero alpha component.
95 // Returns true if non-zero alpha is found. |stride| is expressed in pixels.
HasAlphaChannel(const uint32_t * data,int stride,int width,int height)96 bool HasAlphaChannel(const uint32_t* data, int stride, int width, int height) {
97   const RGBQUAD* plane = reinterpret_cast<const RGBQUAD*>(data);
98   for (int y = 0; y < height; ++y) {
99     for (int x = 0; x < width; ++x) {
100       if (plane->rgbReserved != 0)
101         return true;
102       plane += 1;
103     }
104     plane += stride - width;
105   }
106 
107   return false;
108 }
109 
110 }  // namespace
111 
CreateMouseCursorFromHCursor(HDC dc,HCURSOR cursor)112 MouseCursor* CreateMouseCursorFromHCursor(HDC dc, HCURSOR cursor) {
113   ICONINFO iinfo;
114   if (!GetIconInfo(cursor, &iinfo)) {
115     LOG_F(LS_ERROR) << "Unable to get cursor icon info. Error = "
116                     << GetLastError();
117     return NULL;
118   }
119 
120   int hotspot_x = iinfo.xHotspot;
121   int hotspot_y = iinfo.yHotspot;
122 
123   // Make sure the bitmaps will be freed.
124   win::ScopedBitmap scoped_mask(iinfo.hbmMask);
125   win::ScopedBitmap scoped_color(iinfo.hbmColor);
126   bool is_color = iinfo.hbmColor != NULL;
127 
128   // Get |scoped_mask| dimensions.
129   BITMAP bitmap_info;
130   if (!GetObject(scoped_mask, sizeof(bitmap_info), &bitmap_info)) {
131     LOG_F(LS_ERROR) << "Unable to get bitmap info. Error = "
132                     << GetLastError();
133     return NULL;
134   }
135 
136   int width = bitmap_info.bmWidth;
137   int height = bitmap_info.bmHeight;
138   rtc::scoped_ptr<uint32_t[]> mask_data(new uint32_t[width * height]);
139 
140   // Get pixel data from |scoped_mask| converting it to 32bpp along the way.
141   // GetDIBits() sets the alpha component of every pixel to 0.
142   BITMAPV5HEADER bmi = {0};
143   bmi.bV5Size = sizeof(bmi);
144   bmi.bV5Width = width;
145   bmi.bV5Height = -height;  // request a top-down bitmap.
146   bmi.bV5Planes = 1;
147   bmi.bV5BitCount = kBytesPerPixel * 8;
148   bmi.bV5Compression = BI_RGB;
149   bmi.bV5AlphaMask = 0xff000000;
150   bmi.bV5CSType = LCS_WINDOWS_COLOR_SPACE;
151   bmi.bV5Intent = LCS_GM_BUSINESS;
152   if (!GetDIBits(dc,
153                  scoped_mask,
154                  0,
155                  height,
156                  mask_data.get(),
157                  reinterpret_cast<BITMAPINFO*>(&bmi),
158                  DIB_RGB_COLORS)) {
159     LOG_F(LS_ERROR) << "Unable to get bitmap bits. Error = "
160                     << GetLastError();
161     return NULL;
162   }
163 
164   uint32_t* mask_plane = mask_data.get();
165   rtc::scoped_ptr<DesktopFrame> image(
166       new BasicDesktopFrame(DesktopSize(width, height)));
167   bool has_alpha = false;
168 
169   if (is_color) {
170     image.reset(new BasicDesktopFrame(DesktopSize(width, height)));
171     // Get the pixels from the color bitmap.
172     if (!GetDIBits(dc,
173                    scoped_color,
174                    0,
175                    height,
176                    image->data(),
177                    reinterpret_cast<BITMAPINFO*>(&bmi),
178                    DIB_RGB_COLORS)) {
179       LOG_F(LS_ERROR) << "Unable to get bitmap bits. Error = "
180                       << GetLastError();
181       return NULL;
182     }
183 
184     // GetDIBits() does not provide any indication whether the bitmap has alpha
185     // channel, so we use HasAlphaChannel() below to find it out.
186     has_alpha = HasAlphaChannel(reinterpret_cast<uint32_t*>(image->data()),
187                                 width, width, height);
188   } else {
189     // For non-color cursors, the mask contains both an AND and an XOR mask and
190     // the height includes both. Thus, the width is correct, but we need to
191     // divide by 2 to get the correct mask height.
192     height /= 2;
193 
194     image.reset(new BasicDesktopFrame(DesktopSize(width, height)));
195 
196     // The XOR mask becomes the color bitmap.
197     memcpy(
198         image->data(), mask_plane + (width * height), image->stride() * height);
199   }
200 
201   // Reconstruct transparency from the mask if the color image does not has
202   // alpha channel.
203   if (!has_alpha) {
204     bool add_outline = false;
205     uint32_t* dst = reinterpret_cast<uint32_t*>(image->data());
206     uint32_t* mask = mask_plane;
207     for (int y = 0; y < height; y++) {
208       for (int x = 0; x < width; x++) {
209         // The two bitmaps combine as follows:
210         //  mask  color   Windows Result   Our result    RGB   Alpha
211         //   0     00      Black            Black         00    ff
212         //   0     ff      White            White         ff    ff
213         //   1     00      Screen           Transparent   00    00
214         //   1     ff      Reverse-screen   Black         00    ff
215         //
216         // Since we don't support XOR cursors, we replace the "Reverse Screen"
217         // with black. In this case, we also add an outline around the cursor
218         // so that it is visible against a dark background.
219         if (*mask == kPixelRgbWhite) {
220           if (*dst != 0) {
221             add_outline = true;
222             *dst = kPixelRgbaBlack;
223           } else {
224             *dst = kPixelRgbaTransparent;
225           }
226         } else {
227           *dst = kPixelRgbaBlack ^ *dst;
228         }
229 
230         ++dst;
231         ++mask;
232       }
233     }
234     if (add_outline) {
235       AddCursorOutline(
236           width, height, reinterpret_cast<uint32_t*>(image->data()));
237     }
238   }
239 
240   // Pre-multiply the resulting pixels since MouseCursor uses premultiplied
241   // images.
242   AlphaMul(reinterpret_cast<uint32_t*>(image->data()), width, height);
243 
244   return new MouseCursor(
245       image.release(), DesktopVector(hotspot_x, hotspot_y));
246 }
247 
248 }  // namespace webrtc
249