Icon Capture Utility For Linux, Windows and Mac

chrome/browser/media/window_icon_util_x11.cc

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/media/window_icon_util.h"
+
+#include <X11/Xatom.h>
+#include <X11/Xutil.h>
+
+#include "ui/gfx/x/x11_types.h"
+
+gfx::ImageSkia GetWindowIcon(content::DesktopMediaID id) {
+  DCHECK(id.type == content::DesktopMediaID::TYPE_WINDOW);
+
+  Display* display = gfx::GetXDisplay();
+  Atom property = XInternAtom(display, "_NET_WM_ICON", True);
+  Atom actual_type;
+  int actual_format;
+  unsigned long bytes_after;  // NOLINT: type required by XGetWindowProperty
+  unsigned long size;
+  long* data;
+
+  int status = XGetWindowProperty(display, id.id, property, 0L, ~0L, False,
+                                  AnyPropertyType, &actual_type, &actual_format,
+                                  &size, &bytes_after,
+                                  reinterpret_cast<unsigned char**>(&data));
+  if (status != Success) {
+    return gfx::ImageSkia();
+  }
+
+  // The format of |data| is concatenation of sections like
+  // [width, height, pixel data of size width * height], and the total bytes
+  // number of |data| is |size|.

[Sergey Ulanov, 2016/08/20 04:24:10]

Also mention that we want to select the biggest icon.

[qiangchen, 2016/08/22 18:16:44]

Done.

+  int width = 0;
+  int height = 0;
+  int start = 0;
+  int i = 0;
+  while (i + 1 < static_cast<int>(size)) {
+    if ((i == 0 || static_cast<int>(data[i] * data[i + 1]) > width * height) &&
+        (i + 1 + data[i] * data[i + 1] < static_cast<int>(size))) {
+      width = static_cast<int>(data[i]);
+      height = static_cast<int>(data[i + 1]);
+      start = i + 2;
+    }
+    i = i + 2 + static_cast<int>(data[i] * data[i + 1]);
+  }
+
+  SkBitmap result;
+  SkImageInfo info = SkImageInfo::MakeN32(width, height, kUnpremul_SkAlphaType);
+  result.allocPixels(info);
+  result.lockPixels();
+
+  uint32_t* pixels_data = reinterpret_cast<uint32_t*>(result.getPixels());
+
+  for (long y = 0; y < height; ++y) {
+    for (long x = 0; x < width; ++x) {
+      pixels_data[result.rowBytesAsPixels() * y + x] =
+          static_cast<uint32_t>(data[start + width * y + x]);
+    }
+  }
+
+  XFree(data);
+  return gfx::ImageSkia::CreateFrom1xBitmap(result);
+}