Create new constructors and fields to support a better mouse cursor monitor

Current implementation requires MouseCursorMonitor to understand the SourceId of
a DesktopCapturer implementation. But SourceId has different meanings across
various DesktopCapturer implementations. So this change decouples the
MouseCursorMonitor from DesktopCapturer, i.e. it does not need to know
DesktopCapturer anymore, instead it always returns the absolute position of the
mouse cursor. In DesktopAndCursorComposer, it can use the newly added
DesktopFrame::top_left() to decide the relative position of mouse cursor and the
DesktopFrame.

Bug: webrtc:7950
Change-Id: Idfbde5cb0f79ff0acf4ad1e9a0ac5126f1bb2e98
Reviewed-on: https://chromium-review.googlesource.com/575315
Commit-Queue: Zijie He <zijiehe@chromium.org>
Reviewed-by: Sergey Ulanov <sergeyu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#19115}

webrtc/modules/desktop_capture/desktop_and_cursor_composer.cc

@@ -12,9 +12,13 @@
 
 #include <string.h>
 
+#include <utility>
+
 #include "webrtc/modules/desktop_capture/desktop_capturer.h"
 #include "webrtc/modules/desktop_capture/desktop_frame.h"
 #include "webrtc/modules/desktop_capture/mouse_cursor.h"
+#include "webrtc/modules/desktop_capture/mouse_cursor_monitor.h"
+#include "webrtc/rtc_base/checks.h"
 #include "webrtc/rtc_base/constructormagic.h"
 
 namespace webrtc {
@@ -130,9 +134,16 @@ DesktopAndCursorComposer::DesktopAndCursorComposer(
     MouseCursorMonitor* mouse_monitor)
     : desktop_capturer_(desktop_capturer),
       mouse_monitor_(mouse_monitor) {
+  RTC_DCHECK(desktop_capturer_);
 }
 
-DesktopAndCursorComposer::~DesktopAndCursorComposer() {}
+DesktopAndCursorComposer::DesktopAndCursorComposer(
+    std::unique_ptr<DesktopCapturer> desktop_capturer,
+    const DesktopCaptureOptions& options)
+    : DesktopAndCursorComposer(desktop_capturer.release(),
+                               MouseCursorMonitor::Create(options).release()) {}
+
+DesktopAndCursorComposer::~DesktopAndCursorComposer() = default;
 
 void DesktopAndCursorComposer::Start(DesktopCapturer::Callback* callback) {
   callback_ = callback;

webrtc/modules/desktop_capture/desktop_and_cursor_composer.h

@@ -13,6 +13,7 @@
 
 #include <memory>
 
+#include "webrtc/modules/desktop_capture/desktop_capture_options.h"
 #include "webrtc/modules/desktop_capture/desktop_capturer.h"
 #include "webrtc/modules/desktop_capture/mouse_cursor_monitor.h"
 #include "webrtc/rtc_base/constructormagic.h"
@@ -29,8 +30,16 @@ class DesktopAndCursorComposer : public DesktopCapturer,
   // renders it into the frames generated by |desktop_capturer|. If
   // |mouse_monitor| is NULL the frames are passed unmodified. Takes ownership
   // of both arguments.
+  // Deprecated: use the constructor below.
   DesktopAndCursorComposer(DesktopCapturer* desktop_capturer,
-                      MouseCursorMonitor* mouse_monitor);
+                           MouseCursorMonitor* mouse_monitor);
+
+  // Creates a new blender that captures mouse cursor using
+  // MouseCursorMonitor::Create(options) and renders it into the frames
+  // generated by |desktop_capturer|.
+  DesktopAndCursorComposer(std::unique_ptr<DesktopCapturer> desktop_capturer,
+                           const DesktopCaptureOptions& options);
+
   ~DesktopAndCursorComposer() override;
 
   // DesktopCapturer interface.
@@ -50,8 +59,8 @@ class DesktopAndCursorComposer : public DesktopCapturer,
   void OnMouseCursorPosition(MouseCursorMonitor::CursorState state,
                              const DesktopVector& position) override;
 
-  std::unique_ptr<DesktopCapturer> desktop_capturer_;
-  std::unique_ptr<MouseCursorMonitor> mouse_monitor_;
+  const std::unique_ptr<DesktopCapturer> desktop_capturer_;
+  const std::unique_ptr<MouseCursorMonitor> mouse_monitor_;
 
   DesktopCapturer::Callback* callback_;
 

webrtc/modules/desktop_capture/desktop_frame.cc

@@ -14,6 +14,7 @@
 
 #include <string.h>
 
+#include "webrtc/modules/desktop_capture/desktop_geometry.h"
 #include "webrtc/rtc_base/checks.h"
 
 namespace webrtc {
@@ -22,14 +23,23 @@ DesktopFrame::DesktopFrame(DesktopSize size,
                            int stride,
                            uint8_t* data,
                            SharedMemory* shared_memory)
+    : DesktopFrame(DesktopRect::MakeSize(size),
+                   stride,
+                   data,
+                   shared_memory) {}
+
+DesktopFrame::DesktopFrame(DesktopRect rect,
+                           int stride,
+                           uint8_t* data,
+                           SharedMemory* shared_memory)
     : data_(data),
       shared_memory_(shared_memory),
-      size_(size),
+      rect_(rect),
       stride_(stride),
       capture_time_ms_(0),
       capturer_id_(DesktopCapturerId::kUnknown) {}
 
-DesktopFrame::~DesktopFrame() {}
+DesktopFrame::~DesktopFrame() = default;
 
 void DesktopFrame::CopyPixelsFrom(const uint8_t* src_buffer, int src_stride,
                                   const DesktopRect& dest_rect) {

webrtc/modules/desktop_capture/desktop_frame.h

@@ -31,7 +31,14 @@ class DesktopFrame {
   virtual ~DesktopFrame();
 
   // Size of the frame.
-  const DesktopSize& size() const { return size_; }
+  DesktopSize size() const { return rect_.size(); }
+
+  // The top-left of the frame in full desktop coordinates. E.g. the top left
+  // monitor should start from (0, 0).
+  DesktopVector top_left() const { return rect_.top_left(); }
+
+  // Rectangle covered by the frame.
+  const DesktopRect& rect() const { return rect_; }
 
   // Distance in the buffer between two neighboring rows in bytes.
   int stride() const { return stride_; }
@@ -78,11 +85,18 @@ class DesktopFrame {
   }
 
  protected:
+  // Deprecated, use the constructor below.
   DesktopFrame(DesktopSize size,
                int stride,
                uint8_t* data,
                SharedMemory* shared_memory);
 
+  // Preferred.
+  DesktopFrame(DesktopRect rect,
+               int stride,
+               uint8_t* data,
+               SharedMemory* shared_memory);
+
   // Ownership of the buffers is defined by the classes that inherit from this
   // class. They must guarantee that the buffer is not deleted before the frame
   // is deleted.
@@ -90,7 +104,7 @@ class DesktopFrame {
   SharedMemory* const shared_memory_;
 
  private:
-  const DesktopSize size_;
+  const DesktopRect rect_;
   const int stride_;
 
   DesktopRegion updated_region_;

webrtc/modules/desktop_capture/mouse_cursor_monitor.h

@@ -11,6 +11,8 @@
 #ifndef WEBRTC_MODULES_DESKTOP_CAPTURE_MOUSE_CURSOR_MONITOR_H_
 #define WEBRTC_MODULES_DESKTOP_CAPTURE_MOUSE_CURSOR_MONITOR_H_
 
+#include <memory>
+
 #include "webrtc/modules/desktop_capture/desktop_capture_types.h"
 #include "webrtc/modules/desktop_capture/desktop_geometry.h"
 #include "webrtc/typedefs.h"
@@ -24,6 +26,7 @@ class MouseCursor;
 // Captures mouse shape and position.
 class MouseCursorMonitor {
  public:
+  // Deprecated: CursorState will not be provided.
   enum CursorState {
     // Cursor on top of the window including window decorations.
     INSIDE,
@@ -49,9 +52,19 @@ class MouseCursorMonitor {
 
     // Called in response to Capture(). |position| indicates cursor position
     // relative to the |window| specified in the constructor.
+    // Deprecated: use the following overload instead.
     virtual void OnMouseCursorPosition(CursorState state,
                                        const DesktopVector& position) = 0;
 
+    // Called in response to Capture(). |position| indicates cursor absolute
+    // position on the system in fullscreen coordinate, i.e. the top-left
+    // monitor always starts from (0, 0).
+    // TODO(zijiehe): Ensure all implementations return the absolute position.
+    // TODO(zijiehe): Make this function pure virtual after Chromium changes.
+    // TODO(zijiehe): Current this overload works correctly only when capturing
+    // mouse cursor against fullscreen.
+    virtual void OnMouseCursorPosition(const DesktopVector& position) {}
+
    protected:
     virtual ~Callback() {}
   };
@@ -60,18 +73,26 @@ class MouseCursorMonitor {
 
   // Creates a capturer that notifies of mouse cursor events while the cursor is
   // over the specified window.
+  //
+  // Deprecated: use Create() function.
   static MouseCursorMonitor* CreateForWindow(
       const DesktopCaptureOptions& options,
       WindowId window);
 
-  // Creates a capturer that monitors the mouse cursor shape and position across
-  // the entire desktop.
+  // Creates a capturer that monitors the mouse cursor shape and position over
+  // the specified screen.
   //
-  // TODO(sergeyu): Provide a way to select a specific screen.
+  // Deprecated: use Create() function.
   static MouseCursorMonitor* CreateForScreen(
       const DesktopCaptureOptions& options,
       ScreenId screen);
 
+  // Creates a capturer that monitors the mouse cursor shape and position across
+  // the entire desktop. The capturer ensures that the top-left monitor starts
+  // from (0, 0).
+  static std::unique_ptr<MouseCursorMonitor> Create(
+      const DesktopCaptureOptions& options);
+
   // Initializes the monitor with the |callback|, which must remain valid until
   // capturer is destroyed.
   virtual void Init(Callback* callback, Mode mode) = 0;

webrtc/modules/desktop_capture/mouse_cursor_monitor_mac.mm

@@ -19,6 +19,7 @@
 #include <CoreFoundation/CoreFoundation.h>
 
 #include "webrtc/modules/desktop_capture/desktop_capture_options.h"
+#include "webrtc/modules/desktop_capture/desktop_capture_types.h"
 #include "webrtc/modules/desktop_capture/desktop_frame.h"
 #include "webrtc/modules/desktop_capture/mac/desktop_configuration.h"
 #include "webrtc/modules/desktop_capture/mac/desktop_configuration_monitor.h"
@@ -244,12 +245,11 @@ void MouseCursorMonitorMac::Capture() {
       position.subtract(configuration.bounds.top_left());
     }
   }
-  if (state == INSIDE) {
-    // Convert Density Independent Pixel to physical pixel.
-    position = DesktopVector(round(position.x() * scale),
-                             round(position.y() * scale));
-  }
+  // Convert Density Independent Pixel to physical pixel.
+  position = DesktopVector(round(position.x() * scale),
+                           round(position.y() * scale));
   callback_->OnMouseCursorPosition(state, position);
+  callback_->OnMouseCursorPosition(position);
 }
 
 void MouseCursorMonitorMac::CaptureImage(float scale) {
@@ -330,4 +330,10 @@ MouseCursorMonitor* MouseCursorMonitor::CreateForScreen(
   return new MouseCursorMonitorMac(options, kCGNullWindowID, screen);
 }
 
+std::unique_ptr<MouseCursorMonitor> MouseCursorMonitor::Create(
+    const DesktopCaptureOptions& options) {
+  return std::unique_ptr<MouseCursorMonitor>(
+      CreateForScreen(options, kFullDesktopScreenId));
+}
+
 }  // namespace webrtc

webrtc/modules/desktop_capture/mouse_cursor_monitor_null.cc

@@ -12,6 +12,10 @@
 
 #include <stddef.h>
 
+#include <memory>
+
+#include "webrtc/modules/desktop_capture/desktop_capture_types.h"
+
 namespace webrtc {
 
 MouseCursorMonitor* MouseCursorMonitor::CreateForWindow(
@@ -26,4 +30,10 @@ MouseCursorMonitor* MouseCursorMonitor::CreateForScreen(
   return NULL;
 }
 
+std::unique_ptr<MouseCursorMonitor> MouseCursorMonitor::Create(
+    const DesktopCaptureOptions& options) {
+  return std::unique_ptr<MouseCursorMonitor>(
+      CreateForScreen(options, kFullDesktopScreenId));
+}
+
 }  // namespace webrtc

webrtc/modules/desktop_capture/mouse_cursor_monitor_win.cc

@@ -15,6 +15,7 @@
 
 #include <memory>
 
+#include "webrtc/modules/desktop_capture/desktop_capture_types.h"
 #include "webrtc/modules/desktop_capture/desktop_frame.h"
 #include "webrtc/modules/desktop_capture/desktop_geometry.h"
 #include "webrtc/modules/desktop_capture/mouse_cursor.h"
@@ -162,6 +163,7 @@ void MouseCursorMonitorWin::Capture() {
   }
 
   callback_->OnMouseCursorPosition(inside ? INSIDE : OUTSIDE, position);
+  callback_->OnMouseCursorPosition(position);
 }
 
 DesktopRect MouseCursorMonitorWin::GetScreenRect() {
@@ -204,4 +206,10 @@ MouseCursorMonitor* MouseCursorMonitor::CreateForScreen(
   return new MouseCursorMonitorWin(screen);
 }
 
+std::unique_ptr<MouseCursorMonitor> MouseCursorMonitor::Create(
+    const DesktopCaptureOptions& options) {
+  return std::unique_ptr<MouseCursorMonitor>(
+      CreateForScreen(options, kFullDesktopScreenId));
+}
+
 }  // namespace webrtc

webrtc/modules/desktop_capture/mouse_cursor_monitor_x11.cc

@@ -17,6 +17,7 @@
 #include <X11/Xutil.h>
 
 #include "webrtc/modules/desktop_capture/desktop_capture_options.h"
+#include "webrtc/modules/desktop_capture/desktop_capture_types.h"
 #include "webrtc/modules/desktop_capture/desktop_frame.h"
 #include "webrtc/modules/desktop_capture/mouse_cursor.h"
 #include "webrtc/modules/desktop_capture/x11/x_error_trap.h"
@@ -200,8 +201,9 @@ void MouseCursorMonitorX11::Capture() {
       }
     }
 
-    callback_->OnMouseCursorPosition(state,
-                                     webrtc::DesktopVector(win_x, win_y));
+    const DesktopVector position(win_x, win_y);
+    callback_->OnMouseCursorPosition(state, position);
+    callback_->OnMouseCursorPosition(position);
   }
 }
 
@@ -268,4 +270,10 @@ MouseCursorMonitor* MouseCursorMonitor::CreateForScreen(
       options, DefaultRootWindow(options.x_display()->display()));
 }
 
+std::unique_ptr<MouseCursorMonitor> MouseCursorMonitor::Create(
+    const DesktopCaptureOptions& options) {
+  return std::unique_ptr<MouseCursorMonitor>(
+      CreateForScreen(options, kFullDesktopScreenId));
+}
+
 }  // namespace webrtc