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gdigrab.c
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1 /*
2  * GDI video grab interface
3  *
4  * This file is part of FFmpeg.
5  *
6  * Copyright (C) 2013 Calvin Walton <calvin.walton@kepstin.ca>
7  * Copyright (C) 2007-2010 Christophe Gisquet <word1.word2@gmail.com>
8  *
9  * FFmpeg is free software; you can redistribute it and/or
10  * modify it under the terms of the GNU Lesser General Public License
11  * as published by the Free Software Foundation; either version 2.1
12  * of the License, or (at your option) any later version.
13  *
14  * FFmpeg is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17  * GNU Lesser General Public License for more details.
18  *
19  * You should have received a copy of the GNU Lesser General Public
20  * License along with FFmpeg; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22  */
23 
24 /**
25  * @file
26  * GDI frame device demuxer
27  * @author Calvin Walton <calvin.walton@kepstin.ca>
28  * @author Christophe Gisquet <word1.word2@gmail.com>
29  */
30 
31 #include "config.h"
32 #include "libavformat/internal.h"
33 #include "libavutil/opt.h"
34 #include "libavutil/time.h"
35 #include <windows.h>
36 
37 /**
38  * GDI Device Demuxer context
39  */
40 struct gdigrab {
41  const AVClass *class; /**< Class for private options */
42 
43  int frame_size; /**< Size in bytes of the frame pixel data */
44  int header_size; /**< Size in bytes of the DIB header */
45  AVRational time_base; /**< Time base */
46  int64_t time_frame; /**< Current time */
47 
48  int draw_mouse; /**< Draw mouse cursor (private option) */
49  int show_region; /**< Draw border (private option) */
50  AVRational framerate; /**< Capture framerate (private option) */
51  int width; /**< Width of the grab frame (private option) */
52  int height; /**< Height of the grab frame (private option) */
53  int offset_x; /**< Capture x offset (private option) */
54  int offset_y; /**< Capture y offset (private option) */
55 
56  HWND hwnd; /**< Handle of the window for the grab */
57  HDC source_hdc; /**< Source device context */
58  HDC dest_hdc; /**< Destination, source-compatible DC */
59  BITMAPINFO bmi; /**< Information describing DIB format */
60  HBITMAP hbmp; /**< Information on the bitmap captured */
61  void *buffer; /**< The buffer containing the bitmap image data */
62  RECT clip_rect; /**< The subarea of the screen or window to clip */
63 
64  HWND region_hwnd; /**< Handle of the region border window */
65 
67 };
68 
69 #define WIN32_API_ERROR(str) \
70  av_log(s1, AV_LOG_ERROR, str " (error %li)\n", GetLastError())
71 
72 #define REGION_WND_BORDER 3
73 
74 /**
75  * Callback to handle Windows messages for the region outline window.
76  *
77  * In particular, this handles painting the frame rectangle.
78  *
79  * @param hwnd The region outline window handle.
80  * @param msg The Windows message.
81  * @param wparam First Windows message parameter.
82  * @param lparam Second Windows message parameter.
83  * @return 0 success, !0 failure
84  */
85 static LRESULT CALLBACK
86 gdigrab_region_wnd_proc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam)
87 {
88  PAINTSTRUCT ps;
89  HDC hdc;
90  RECT rect;
91 
92  switch (msg) {
93  case WM_PAINT:
94  hdc = BeginPaint(hwnd, &ps);
95 
96  GetClientRect(hwnd, &rect);
97  FrameRect(hdc, &rect, GetStockObject(BLACK_BRUSH));
98 
99  rect.left++; rect.top++; rect.right--; rect.bottom--;
100  FrameRect(hdc, &rect, GetStockObject(WHITE_BRUSH));
101 
102  rect.left++; rect.top++; rect.right--; rect.bottom--;
103  FrameRect(hdc, &rect, GetStockObject(BLACK_BRUSH));
104 
105  EndPaint(hwnd, &ps);
106  break;
107  default:
108  return DefWindowProc(hwnd, msg, wparam, lparam);
109  }
110  return 0;
111 }
112 
113 /**
114  * Initialize the region outline window.
115  *
116  * @param s1 The format context.
117  * @param gdigrab gdigrab context.
118  * @return 0 success, !0 failure
119  */
120 static int
122 {
123  HWND hwnd;
124  RECT rect = gdigrab->clip_rect;
125  HRGN region = NULL;
126  HRGN region_interior = NULL;
127 
128  DWORD style = WS_POPUP | WS_VISIBLE;
129  DWORD ex = WS_EX_TOOLWINDOW | WS_EX_TOPMOST | WS_EX_TRANSPARENT;
130 
131  rect.left -= REGION_WND_BORDER; rect.top -= REGION_WND_BORDER;
132  rect.right += REGION_WND_BORDER; rect.bottom += REGION_WND_BORDER;
133 
134  AdjustWindowRectEx(&rect, style, FALSE, ex);
135 
136  // Create a window with no owner; use WC_DIALOG instead of writing a custom
137  // window class
138  hwnd = CreateWindowEx(ex, WC_DIALOG, NULL, style, rect.left, rect.top,
139  rect.right - rect.left, rect.bottom - rect.top,
140  NULL, NULL, NULL, NULL);
141  if (!hwnd) {
142  WIN32_API_ERROR("Could not create region display window");
143  goto error;
144  }
145 
146  // Set the window shape to only include the border area
147  GetClientRect(hwnd, &rect);
148  region = CreateRectRgn(0, 0,
149  rect.right - rect.left, rect.bottom - rect.top);
150  region_interior = CreateRectRgn(REGION_WND_BORDER, REGION_WND_BORDER,
151  rect.right - rect.left - REGION_WND_BORDER,
152  rect.bottom - rect.top - REGION_WND_BORDER);
153  CombineRgn(region, region, region_interior, RGN_DIFF);
154  if (!SetWindowRgn(hwnd, region, FALSE)) {
155  WIN32_API_ERROR("Could not set window region");
156  goto error;
157  }
158  // The "region" memory is now owned by the window
159  region = NULL;
160  DeleteObject(region_interior);
161 
162  SetWindowLongPtr(hwnd, GWLP_WNDPROC, (LONG_PTR) gdigrab_region_wnd_proc);
163 
164  ShowWindow(hwnd, SW_SHOW);
165 
166  gdigrab->region_hwnd = hwnd;
167 
168  return 0;
169 
170 error:
171  if (region)
172  DeleteObject(region);
173  if (region_interior)
174  DeleteObject(region_interior);
175  if (hwnd)
176  DestroyWindow(hwnd);
177  return 1;
178 }
179 
180 /**
181  * Cleanup/free the region outline window.
182  *
183  * @param s1 The format context.
184  * @param gdigrab gdigrab context.
185  */
186 static void
188 {
189  if (gdigrab->region_hwnd)
190  DestroyWindow(gdigrab->region_hwnd);
191  gdigrab->region_hwnd = NULL;
192 }
193 
194 /**
195  * Process the Windows message queue.
196  *
197  * This is important to prevent Windows from thinking the window has become
198  * unresponsive. As well, things like WM_PAINT (to actually draw the window
199  * contents) are handled from the message queue context.
200  *
201  * @param s1 The format context.
202  * @param gdigrab gdigrab context.
203  */
204 static void
206 {
207  HWND hwnd = gdigrab->region_hwnd;
208  MSG msg;
209 
210  while (PeekMessage(&msg, hwnd, 0, 0, PM_REMOVE)) {
211  DispatchMessage(&msg);
212  }
213 }
214 
215 /**
216  * Initializes the gdi grab device demuxer (public device demuxer API).
217  *
218  * @param s1 Context from avformat core
219  * @return AVERROR_IO error, 0 success
220  */
221 static int
223 {
224  struct gdigrab *gdigrab = s1->priv_data;
225 
226  HWND hwnd;
227  HDC source_hdc = NULL;
228  HDC dest_hdc = NULL;
229  BITMAPINFO bmi;
230  HBITMAP hbmp = NULL;
231  void *buffer = NULL;
232 
233  const char *filename = s1->filename;
234  const char *name = NULL;
235  AVStream *st = NULL;
236 
237  int bpp;
238  RECT virtual_rect;
239  RECT clip_rect;
240  BITMAP bmp;
241  int ret;
242 
243  if (!strncmp(filename, "title=", 6)) {
244  name = filename + 6;
245  hwnd = FindWindow(NULL, name);
246  if (!hwnd) {
247  av_log(s1, AV_LOG_ERROR,
248  "Can't find window '%s', aborting.\n", name);
249  ret = AVERROR(EIO);
250  goto error;
251  }
252  if (gdigrab->show_region) {
254  "Can't show region when grabbing a window.\n");
255  gdigrab->show_region = 0;
256  }
257  } else if (!strcmp(filename, "desktop")) {
258  hwnd = NULL;
259  } else {
260  av_log(s1, AV_LOG_ERROR,
261  "Please use \"desktop\" or \"title=<windowname>\" to specify your target.\n");
262  ret = AVERROR(EIO);
263  goto error;
264  }
265 
266  if (hwnd) {
267  GetClientRect(hwnd, &virtual_rect);
268  } else {
269  virtual_rect.left = GetSystemMetrics(SM_XVIRTUALSCREEN);
270  virtual_rect.top = GetSystemMetrics(SM_YVIRTUALSCREEN);
271  virtual_rect.right = virtual_rect.left + GetSystemMetrics(SM_CXVIRTUALSCREEN);
272  virtual_rect.bottom = virtual_rect.top + GetSystemMetrics(SM_CYVIRTUALSCREEN);
273  }
274 
275  /* If no width or height set, use full screen/window area */
276  if (!gdigrab->width || !gdigrab->height) {
277  clip_rect.left = virtual_rect.left;
278  clip_rect.top = virtual_rect.top;
279  clip_rect.right = virtual_rect.right;
280  clip_rect.bottom = virtual_rect.bottom;
281  } else {
282  clip_rect.left = gdigrab->offset_x;
283  clip_rect.top = gdigrab->offset_y;
284  clip_rect.right = gdigrab->width + gdigrab->offset_x;
285  clip_rect.bottom = gdigrab->height + gdigrab->offset_y;
286  }
287 
288  if (clip_rect.left < virtual_rect.left ||
289  clip_rect.top < virtual_rect.top ||
290  clip_rect.right > virtual_rect.right ||
291  clip_rect.bottom > virtual_rect.bottom) {
292  av_log(s1, AV_LOG_ERROR,
293  "Capture area (%li,%li),(%li,%li) extends outside window area (%li,%li),(%li,%li)",
294  clip_rect.left, clip_rect.top,
295  clip_rect.right, clip_rect.bottom,
296  virtual_rect.left, virtual_rect.top,
297  virtual_rect.right, virtual_rect.bottom);
298  ret = AVERROR(EIO);
299  goto error;
300  }
301 
302  /* This will get the device context for the selected window, or if
303  * none, the primary screen */
304  source_hdc = GetDC(hwnd);
305  if (!source_hdc) {
306  WIN32_API_ERROR("Couldn't get window device context");
307  ret = AVERROR(EIO);
308  goto error;
309  }
310  bpp = GetDeviceCaps(source_hdc, BITSPIXEL);
311 
312  if (name) {
313  av_log(s1, AV_LOG_INFO,
314  "Found window %s, capturing %lix%lix%i at (%li,%li)\n",
315  name,
316  clip_rect.right - clip_rect.left,
317  clip_rect.bottom - clip_rect.top,
318  bpp, clip_rect.left, clip_rect.top);
319  } else {
320  av_log(s1, AV_LOG_INFO,
321  "Capturing whole desktop as %lix%lix%i at (%li,%li)\n",
322  clip_rect.right - clip_rect.left,
323  clip_rect.bottom - clip_rect.top,
324  bpp, clip_rect.left, clip_rect.top);
325  }
326 
327  if (clip_rect.right - clip_rect.left <= 0 ||
328  clip_rect.bottom - clip_rect.top <= 0 || bpp%8) {
329  av_log(s1, AV_LOG_ERROR, "Invalid properties, aborting\n");
330  ret = AVERROR(EIO);
331  goto error;
332  }
333 
334  dest_hdc = CreateCompatibleDC(source_hdc);
335  if (!dest_hdc) {
336  WIN32_API_ERROR("Screen DC CreateCompatibleDC");
337  ret = AVERROR(EIO);
338  goto error;
339  }
340 
341  /* Create a DIB and select it into the dest_hdc */
342  bmi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
343  bmi.bmiHeader.biWidth = clip_rect.right - clip_rect.left;
344  bmi.bmiHeader.biHeight = -(clip_rect.bottom - clip_rect.top);
345  bmi.bmiHeader.biPlanes = 1;
346  bmi.bmiHeader.biBitCount = bpp;
347  bmi.bmiHeader.biCompression = BI_RGB;
348  bmi.bmiHeader.biSizeImage = 0;
349  bmi.bmiHeader.biXPelsPerMeter = 0;
350  bmi.bmiHeader.biYPelsPerMeter = 0;
351  bmi.bmiHeader.biClrUsed = 0;
352  bmi.bmiHeader.biClrImportant = 0;
353  hbmp = CreateDIBSection(dest_hdc, &bmi, DIB_RGB_COLORS,
354  &buffer, NULL, 0);
355  if (!hbmp) {
356  WIN32_API_ERROR("Creating DIB Section");
357  ret = AVERROR(EIO);
358  goto error;
359  }
360 
361  if (!SelectObject(dest_hdc, hbmp)) {
362  WIN32_API_ERROR("SelectObject");
363  ret = AVERROR(EIO);
364  goto error;
365  }
366 
367  /* Get info from the bitmap */
368  GetObject(hbmp, sizeof(BITMAP), &bmp);
369 
370  st = avformat_new_stream(s1, NULL);
371  if (!st) {
372  ret = AVERROR(ENOMEM);
373  goto error;
374  }
375  avpriv_set_pts_info(st, 64, 1, 1000000); /* 64 bits pts in us */
376 
377  gdigrab->frame_size = bmp.bmWidthBytes * bmp.bmHeight * bmp.bmPlanes;
378  gdigrab->header_size = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER) +
379  (bpp <= 8 ? (1 << bpp) : 0) * sizeof(RGBQUAD) /* palette size */;
380  gdigrab->time_base = av_inv_q(gdigrab->framerate);
381  gdigrab->time_frame = av_gettime() / av_q2d(gdigrab->time_base);
382 
383  gdigrab->hwnd = hwnd;
384  gdigrab->source_hdc = source_hdc;
385  gdigrab->dest_hdc = dest_hdc;
386  gdigrab->hbmp = hbmp;
387  gdigrab->bmi = bmi;
388  gdigrab->buffer = buffer;
389  gdigrab->clip_rect = clip_rect;
390 
391  gdigrab->cursor_error_printed = 0;
392 
393  if (gdigrab->show_region) {
394  if (gdigrab_region_wnd_init(s1, gdigrab)) {
395  ret = AVERROR(EIO);
396  goto error;
397  }
398  }
399 
402  st->codec->time_base = gdigrab->time_base;
403  st->codec->bit_rate = (gdigrab->header_size + gdigrab->frame_size) * 1/av_q2d(gdigrab->time_base) * 8;
404 
405  return 0;
406 
407 error:
408  if (source_hdc)
409  ReleaseDC(hwnd, source_hdc);
410  if (dest_hdc)
411  DeleteDC(dest_hdc);
412  if (hbmp)
413  DeleteObject(hbmp);
414  if (source_hdc)
415  DeleteDC(source_hdc);
416  return ret;
417 }
418 
419 /**
420  * Paints a mouse pointer in a Win32 image.
421  *
422  * @param s1 Context of the log information
423  * @param s Current grad structure
424  */
426 {
427  CURSORINFO ci = {0};
428 
429 #define CURSOR_ERROR(str) \
430  if (!gdigrab->cursor_error_printed) { \
431  WIN32_API_ERROR(str); \
432  gdigrab->cursor_error_printed = 1; \
433  }
434 
435  ci.cbSize = sizeof(ci);
436 
437  if (GetCursorInfo(&ci)) {
438  HCURSOR icon = CopyCursor(ci.hCursor);
439  ICONINFO info;
440  POINT pos;
441  RECT clip_rect = gdigrab->clip_rect;
442  HWND hwnd = gdigrab->hwnd;
443 
444  if (ci.flags != CURSOR_SHOWING)
445  return;
446 
447  if (!icon) {
448  /* Use the standard arrow cursor as a fallback.
449  * You'll probably only hit this in Wine, which can't fetch
450  * the current system cursor. */
451  icon = CopyCursor(LoadCursor(NULL, IDC_ARROW));
452  }
453 
454  if (!GetIconInfo(icon, &info)) {
455  CURSOR_ERROR("Could not get icon info");
456  goto icon_error;
457  }
458 
459  pos.x = ci.ptScreenPos.x - clip_rect.left - info.xHotspot;
460  pos.y = ci.ptScreenPos.y - clip_rect.top - info.yHotspot;
461 
462  if (hwnd) {
463  RECT rect;
464 
465  if (GetWindowRect(hwnd, &rect)) {
466  pos.x -= rect.left;
467  pos.y -= rect.top;
468  } else {
469  CURSOR_ERROR("Couldn't get window rectangle");
470  goto icon_error;
471  }
472  }
473 
474  av_log(s1, AV_LOG_DEBUG, "Cursor pos (%li,%li) -> (%li,%li)\n",
475  ci.ptScreenPos.x, ci.ptScreenPos.y, pos.x, pos.y);
476 
477  if (pos.x >= 0 && pos.x <= clip_rect.right - clip_rect.left &&
478  pos.y >= 0 && pos.y <= clip_rect.bottom - clip_rect.top) {
479  if (!DrawIcon(gdigrab->dest_hdc, pos.x, pos.y, icon))
480  CURSOR_ERROR("Couldn't draw icon");
481  }
482 
483 icon_error:
484  if (icon)
485  DestroyCursor(icon);
486  } else {
487  CURSOR_ERROR("Couldn't get cursor info");
488  }
489 }
490 
491 /**
492  * Grabs a frame from gdi (public device demuxer API).
493  *
494  * @param s1 Context from avformat core
495  * @param pkt Packet holding the grabbed frame
496  * @return frame size in bytes
497  */
499 {
500  struct gdigrab *gdigrab = s1->priv_data;
501 
502  HDC dest_hdc = gdigrab->dest_hdc;
503  HDC source_hdc = gdigrab->source_hdc;
504  RECT clip_rect = gdigrab->clip_rect;
505  AVRational time_base = gdigrab->time_base;
506  int64_t time_frame = gdigrab->time_frame;
507 
508  BITMAPFILEHEADER bfh;
509  int file_size = gdigrab->header_size + gdigrab->frame_size;
510 
511  int64_t curtime, delay;
512 
513  /* Calculate the time of the next frame */
514  time_frame += INT64_C(1000000);
515 
516  /* Run Window message processing queue */
517  if (gdigrab->show_region)
518  gdigrab_region_wnd_update(s1, gdigrab);
519 
520  /* wait based on the frame rate */
521  for (;;) {
522  curtime = av_gettime();
523  delay = time_frame * av_q2d(time_base) - curtime;
524  if (delay <= 0) {
525  if (delay < INT64_C(-1000000) * av_q2d(time_base)) {
526  time_frame += INT64_C(1000000);
527  }
528  break;
529  }
530  if (s1->flags & AVFMT_FLAG_NONBLOCK) {
531  return AVERROR(EAGAIN);
532  } else {
533  av_usleep(delay);
534  }
535  }
536 
537  if (av_new_packet(pkt, file_size) < 0)
538  return AVERROR(ENOMEM);
539  pkt->pts = curtime;
540 
541  /* Blit screen grab */
542  if (!BitBlt(dest_hdc, 0, 0,
543  clip_rect.right - clip_rect.left,
544  clip_rect.bottom - clip_rect.top,
545  source_hdc,
546  clip_rect.left, clip_rect.top, SRCCOPY | CAPTUREBLT)) {
547  WIN32_API_ERROR("Failed to capture image");
548  return AVERROR(EIO);
549  }
550  if (gdigrab->draw_mouse)
551  paint_mouse_pointer(s1, gdigrab);
552 
553  /* Copy bits to packet data */
554 
555  bfh.bfType = 0x4d42; /* "BM" in little-endian */
556  bfh.bfSize = file_size;
557  bfh.bfReserved1 = 0;
558  bfh.bfReserved2 = 0;
559  bfh.bfOffBits = gdigrab->header_size;
560 
561  memcpy(pkt->data, &bfh, sizeof(bfh));
562 
563  memcpy(pkt->data + sizeof(bfh), &gdigrab->bmi.bmiHeader, sizeof(gdigrab->bmi.bmiHeader));
564 
565  if (gdigrab->bmi.bmiHeader.biBitCount <= 8)
566  GetDIBColorTable(dest_hdc, 0, 1 << gdigrab->bmi.bmiHeader.biBitCount,
567  (RGBQUAD *) (pkt->data + sizeof(bfh) + sizeof(gdigrab->bmi.bmiHeader)));
568 
569  memcpy(pkt->data + gdigrab->header_size, gdigrab->buffer, gdigrab->frame_size);
570 
571  gdigrab->time_frame = time_frame;
572 
573  return gdigrab->header_size + gdigrab->frame_size;
574 }
575 
576 /**
577  * Closes gdi frame grabber (public device demuxer API).
578  *
579  * @param s1 Context from avformat core
580  * @return 0 success, !0 failure
581  */
583 {
584  struct gdigrab *s = s1->priv_data;
585 
586  if (s->show_region)
588 
589  if (s->source_hdc)
590  ReleaseDC(s->hwnd, s->source_hdc);
591  if (s->dest_hdc)
592  DeleteDC(s->dest_hdc);
593  if (s->hbmp)
594  DeleteObject(s->hbmp);
595  if (s->source_hdc)
596  DeleteDC(s->source_hdc);
597 
598  return 0;
599 }
600 
601 #define OFFSET(x) offsetof(struct gdigrab, x)
602 #define DEC AV_OPT_FLAG_DECODING_PARAM
603 static const AVOption options[] = {
604  { "draw_mouse", "draw the mouse pointer", OFFSET(draw_mouse), AV_OPT_TYPE_INT, {.i64 = 1}, 0, 1, DEC },
605  { "show_region", "draw border around capture area", OFFSET(show_region), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, DEC },
606  { "framerate", "set video frame rate", OFFSET(framerate), AV_OPT_TYPE_VIDEO_RATE, {.str = "ntsc"}, 0, 0, DEC },
607  { "video_size", "set video frame size", OFFSET(width), AV_OPT_TYPE_IMAGE_SIZE, {.str = NULL}, 0, 0, DEC },
608  { "offset_x", "capture area x offset", OFFSET(offset_x), AV_OPT_TYPE_INT, {.i64 = 0}, INT_MIN, INT_MAX, DEC },
609  { "offset_y", "capture area y offset", OFFSET(offset_y), AV_OPT_TYPE_INT, {.i64 = 0}, INT_MIN, INT_MAX, DEC },
610  { NULL },
611 };
612 
613 static const AVClass gdigrab_class = {
614  .class_name = "GDIgrab indev",
615  .item_name = av_default_item_name,
616  .option = options,
617  .version = LIBAVUTIL_VERSION_INT,
618 };
619 
620 /** gdi grabber device demuxer declaration */
622  .name = "gdigrab",
623  .long_name = NULL_IF_CONFIG_SMALL("GDI API Windows frame grabber"),
624  .priv_data_size = sizeof(struct gdigrab),
625  .read_header = gdigrab_read_header,
626  .read_packet = gdigrab_read_packet,
627  .read_close = gdigrab_read_close,
628  .flags = AVFMT_NOFILE,
629  .priv_class = &gdigrab_class,
630 };