Implement window capturer for OS X.

R=wez@chromium.org

Review URL: https://webrtc-codereview.appspot.com/2055005

git-svn-id: http://webrtc.googlecode.com/svn/trunk@4599 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/modules/desktop_capture/window_capturer_mac.cc

@@ -11,13 +11,59 @@
 #include "webrtc/modules/desktop_capture/window_capturer.h"
 
 #include <assert.h>
+#include <ApplicationServices/ApplicationServices.h>
+#include <CoreFoundation/CoreFoundation.h>
 
 #include "webrtc/modules/desktop_capture/desktop_frame.h"
+#include "webrtc/system_wrappers/interface/logging.h"
 
 namespace webrtc {
 
 namespace {
 
+bool CFStringRefToUtf8(const CFStringRef string, std::string* str_utf8) {
+  assert(string);
+  assert(str_utf8);
+  CFIndex length = CFStringGetLength(string);
+  size_t max_length_utf8 =
+      CFStringGetMaximumSizeForEncoding(length, kCFStringEncodingUTF8);
+  str_utf8->resize(max_length_utf8);
+  CFIndex used_bytes;
+  int result = CFStringGetBytes(
+      string, CFRangeMake(0, length), kCFStringEncodingUTF8, 0, false,
+      reinterpret_cast<UInt8*>(&*str_utf8->begin()), max_length_utf8,
+      &used_bytes);
+  if (result != length) {
+    str_utf8->clear();
+    return false;
+  }
+  str_utf8->resize(used_bytes);
+  return true;
+}
+
+// DesktopFrame that stores data in CFData.
+class CFDataDesktopFrame : public DesktopFrame {
+ public:
+  // Consumes |cf_data| reference.
+  //
+  // TODO(sergeyu): Here we const_cast<> the buffer used in CFDataRef. CFDataRef
+  // buffer is immutable, but DesktopFrame is always mutable. This shouldn't be
+  // a problem because frames generated by WindowCapturers are normally not
+  // mutated. To avoid this hack consider making DesktopFrame immutable and add
+  // MutableDesktopFrame.
+  CFDataDesktopFrame(DesktopSize size, int stride, CFDataRef cf_data)
+      : DesktopFrame(size, stride,
+                     const_cast<uint8_t*>(CFDataGetBytePtr(cf_data)), NULL),
+        cf_data_(cf_data) {
+  }
+  virtual ~CFDataDesktopFrame() {
+    CFRelease(cf_data_);
+  }
+
+ private:
+  CFDataRef cf_data_;
+};
+
 class WindowCapturerMac : public WindowCapturer {
  public:
   WindowCapturerMac();
@@ -33,25 +79,81 @@ class WindowCapturerMac : public WindowCapturer {
 
  private:
   Callback* callback_;
+  CGWindowID window_id_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowCapturerMac);
 };
 
 WindowCapturerMac::WindowCapturerMac()
-    : callback_(NULL) {
+    : callback_(NULL),
+      window_id_(0) {
 }
 
 WindowCapturerMac::~WindowCapturerMac() {
 }
 
 bool WindowCapturerMac::GetWindowList(WindowList* windows) {
-  // Not implemented yet.
-  return false;
+  // Only get on screen, non-desktop windows.
+  CFArrayRef window_array = CGWindowListCopyWindowInfo(
+      kCGWindowListOptionOnScreenOnly | kCGWindowListExcludeDesktopElements,
+      kCGNullWindowID);
+  if (!window_array)
+    return false;
+
+  // Check windows to make sure they have an id, title, and use window layer
+  // other than 0.
+  CFIndex count = CFArrayGetCount(window_array);
+  for (CFIndex i = 0; i < count; ++i) {
+    CFDictionaryRef window = reinterpret_cast<CFDictionaryRef>(
+        CFArrayGetValueAtIndex(window_array, i));
+    CFStringRef window_title = reinterpret_cast<CFStringRef>(
+        CFDictionaryGetValue(window, kCGWindowName));
+    CFNumberRef window_id = reinterpret_cast<CFNumberRef>(
+        CFDictionaryGetValue(window, kCGWindowNumber));
+    CFNumberRef window_layer = reinterpret_cast<CFNumberRef>(
+        CFDictionaryGetValue(window, kCGWindowLayer));
+    if (window_title && window_id && window_layer) {
+      // Skip windows with layer=0 (menu, dock).
+      int layer;
+      CFNumberGetValue(window_layer, kCFNumberIntType, &layer);
+      if (layer != 0)
+        continue;
+
+      int id;
+      CFNumberGetValue(window_id, kCFNumberIntType, &id);
+      WindowCapturer::Window window;
+      window.id = id;
+      if (!CFStringRefToUtf8(window_title, &(window.title)) ||
+          window.title.empty()) {
+        continue;
+      }
+      windows->push_back(window);
+    }
+  }
+
+  CFRelease(window_array);
+  return true;
 }
 
 bool WindowCapturerMac::SelectWindow(WindowId id) {
-  // Not implemented yet.
-  return false;
+  // Request description for the specified window to make sure |id| is valid.
+  CGWindowID ids[1];
+  ids[0] = id;
+  CFArrayRef window_id_array =
+      CFArrayCreate(NULL, reinterpret_cast<const void **>(&ids), 1, NULL);
+  CFArrayRef window_array =
+      CGWindowListCreateDescriptionFromArray(window_id_array);
+  int results_count = window_array ? CFArrayGetCount(window_array) : 0;
+  CFRelease(window_id_array);
+  CFRelease(window_array);
+
+  if (results_count == 0) {
+    // Could not find the window. It might have been closed.
+    return false;
+  }
+
+  window_id_ = id;
+  return true;
 }
 
 void WindowCapturerMac::Start(Callback* callback) {
@@ -62,8 +164,33 @@ void WindowCapturerMac::Start(Callback* callback) {
 }
 
 void WindowCapturerMac::Capture(const DesktopRegion& region) {
-  // Not implemented yet.
-  callback_->OnCaptureCompleted(NULL);
+  CGImageRef window_image = CGWindowListCreateImage(
+      CGRectNull, kCGWindowListOptionIncludingWindow,
+      window_id_, kCGWindowImageBoundsIgnoreFraming);
+
+  if (!window_image) {
+    CFRelease(window_image);
+    callback_->OnCaptureCompleted(NULL);
+    return;
+  }
+
+  int bits_per_pixel = CGImageGetBitsPerPixel(window_image);
+  if (bits_per_pixel != 32) {
+    LOG(LS_ERROR) << "Unsupported window image depth: " << bits_per_pixel;
+    CFRelease(window_image);
+    callback_->OnCaptureCompleted(NULL);
+    return;
+  }
+
+  int width = CGImageGetWidth(window_image);
+  int height = CGImageGetHeight(window_image);
+  CGDataProviderRef provider = CGImageGetDataProvider(window_image);
+  DesktopFrame* frame = new CFDataDesktopFrame(
+      DesktopSize(width, height), CGImageGetBytesPerRow(window_image),
+      CGDataProviderCopyData(provider));
+  CFRelease(window_image);
+
+  callback_->OnCaptureCompleted(frame);
 }
 
 }  // namespace

webrtc/modules/desktop_capture/window_capturer_unittest.cc

@@ -42,16 +42,13 @@ class WindowCapturerTest : public testing::Test,
   scoped_ptr<DesktopFrame> frame_;
 };
 
-#if defined(WEBRTC_WIN)
+#if defined(WEBRTC_WIN) || defined(WEBRTC_MAC)
 
 // Verify that we can enumerate windows.
 TEST_F(WindowCapturerTest, Enumerate) {
   WindowCapturer::WindowList windows;
   EXPECT_TRUE(capturer_->GetWindowList(&windows));
 
-  // Assume that there is at least one window.
-  EXPECT_GT(windows.size(), 0U);
-
   // Verify that window titles are set.
   for (WindowCapturer::WindowList::iterator it = windows.begin();
        it != windows.end(); ++it) {
@@ -95,6 +92,6 @@ TEST_F(WindowCapturerTest, Capture) {
   }
 }
 
-#endif  // defined(WEBRTC_WIN)
+#endif  // defined(WEBRTC_WIN) || defined(WEBRTC_MAC)
 
 }  // namespace webrtc