Add QWindowCapure and QCapturableWindow for window capturing

The design of QMediaCaptureSession already uses different types and
setters/gettes for each video source, like QCamera, QImageCapture,
and QScreenCapture, so a new source type, QWindowCapure, has been
added instead of extending QScreenCapture.

For now we only cover the case of capturing windows enumerated though
the capturing API itself, via a list of QCapturableWindow instances,
as this is considered the primary use-case for such an API.

An extension to this would be to add a QWindow overload to either
QCapturableWindow's constructor or QWindowCapture::setWindow, to
allow capturing of windows in the application itself, either created
by Qt, or via QWindow::fromWinId(), but this has been left out
for the initial API to keep things minimal.

A WId overload has been intentionally left out of this API, as
the path for capturing by WId should go via QWindow::fromWinId().

Finally, capture of windows from other applications without
enumerating them via QWindowCapure is left out, as adding such
an API would require us to build a more generic WId replacement
that isn't tied to a single type for each OS, like WId is (it's
a NSView* on macOS e.g., but windows can also be represented by
CGWindowID).

Task-number: QTBUG-103226
Change-Id: I99e3b8bde62250aba35abcedbc8680a299a3cbb2
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

3 files changed, 10 insertions, 2 deletions

diff --git a/src/multimedia/platform/qplatformmediaintegration_p.h b/src/multimedia/platform/qplatformmediaintegration_p.h
index 27f00cdc0..6f60208de 100644
--- a/src/multimedia/platform/qplatformmediaintegration_p.h
+++ b/src/multimedia/platform/qplatformmediaintegration_p.h
@@ -16,6 +16,7 @@
 
 #include <private/qtmultimediaglobal_p.h>
 #include <private/qmultimediautils_p.h>
+#include <qcapturablewindow.h>
 #include <qmediarecorder.h>
 #include <qstring.h>
 
@@ -47,6 +48,7 @@ class QAudioOutput;
 class QPlatformAudioInput;
 class QPlatformAudioOutput;
 class QPlatformVideoDevices;
+class QCapturableWindow;
 
 class Q_MULTIMEDIA_EXPORT QPlatformMediaIntegration
 {
@@ -76,6 +78,10 @@ public:
 
     virtual QMaybe<QPlatformVideoSink *> createVideoSink(QVideoSink *) { return notAvailable; }
 
+    virtual QList<QCapturableWindow> capturableWindows() { return {}; };
+
+    bool isCapturableWindowValid(const QCapturableWindowPrivate &) { return false; }
+
 protected:
     std::unique_ptr<QPlatformVideoDevices> m_videoDevices;
 };
diff --git a/src/multimedia/platform/qplatformscreencapture.cpp b/src/multimedia/platform/qplatformscreencapture.cpp
index de7f74d9d..afb1a6c78 100644
--- a/src/multimedia/platform/qplatformscreencapture.cpp
+++ b/src/multimedia/platform/qplatformscreencapture.cpp
@@ -16,7 +16,7 @@ QPlatformScreenCapture::QPlatformScreenCapture(QScreenCapture *screenCapture)
 void QPlatformScreenCapture::setWindow(QWindow *w)
 {
     if (w) {
-        emit m_screenCapture->errorOccurred(QScreenCapture::WindowCapturingNotSupported,
+        emit m_screenCapture->errorOccurred(QScreenCapture::InternalError,
                                             QLatin1String("Window capture is not supported"));
     }
 }
@@ -29,7 +29,7 @@ QWindow *QPlatformScreenCapture::window() const
 void QPlatformScreenCapture::setWindowId(WId id)
 {
     if (id) {
-        emit m_screenCapture->errorOccurred(QScreenCapture::WindowCapturingNotSupported,
+        emit m_screenCapture->errorOccurred(QScreenCapture::InternalError,
                                             QLatin1String("Window capture is not supported"));
     }
 }
diff --git a/src/multimedia/platform/qplatformscreencapture_p.h b/src/multimedia/platform/qplatformscreencapture_p.h
index b5a865e22..a162fc7e6 100644
--- a/src/multimedia/platform/qplatformscreencapture_p.h
+++ b/src/multimedia/platform/qplatformscreencapture_p.h
@@ -32,9 +32,11 @@ public:
     virtual void setScreen(QScreen *s) = 0;
     virtual QScreen *screen() const = 0;
 
+    // TODO: move the methods and implementations to QPlatformWindowCapture
     virtual void setWindow(QWindow *w);
     virtual QWindow *window() const;
 
+    // to be removed
     virtual void setWindowId(WId id);
     virtual WId windowId() const;