Add API to grab a surface's content

This patch adds a new QWaylandSurfaceGrabber class. The user can use it
to grab a surface's content, and get a QImage with the data.

Change-Id: I25dd72a8ba39201cd91addbfc976b93ca1e05112
Reviewed-by: Pier Luigi Fiorini <pierluigi.fiorini@gmail.com>

1 files changed, 54 insertions, 0 deletions

diff --git a/src/compositor/compositor_api/qwaylandcompositor.cpp b/src/compositor/compositor_api/qwaylandcompositor.cpp
index 57e8397b9..17b089dcf 100644
--- a/src/compositor/compositor_api/qwaylandcompositor.cpp
+++ b/src/compositor/compositor_api/qwaylandcompositor.cpp
@@ -46,6 +46,7 @@
 #include <QtWaylandCompositor/qwaylandkeyboard.h>
 #include <QtWaylandCompositor/qwaylandpointer.h>
 #include <QtWaylandCompositor/qwaylandtouch.h>
+#include <QtWaylandCompositor/qwaylandsurfacegrabber.h>
 
 #include <QtWaylandCompositor/private/qwaylandkeyboard_p.h>
 #include <QtWaylandCompositor/private/qwaylandsurface_p.h>
@@ -75,6 +76,13 @@
 #include <QtGui/qpa/qplatformnativeinterface.h>
 #include <QtGui/private/qguiapplication_p.h>
 
+#ifdef QT_COMPOSITOR_WAYLAND_GL
+#   include <QtGui/private/qopengltextureblitter_p.h>
+#   include <QOpenGLContext>
+#   include <QOpenGLFramebufferObject>
+#   include <QMatrix4x4>
+#endif
+
 QT_BEGIN_NAMESPACE
 
 namespace QtWayland {
@@ -819,4 +827,50 @@ void QWaylandCompositor::setUseHardwareIntegrationExtension(bool use)
     useHardwareIntegrationExtensionChanged();
 }
 
+/*!
+ * Grab the surface content from the given \a buffer.
+ * The default implementation requires a OpenGL context to be bound to the current thread
+ * to work. If this is not possible reimplement this function in your compositor subclass
+ * to implement custom logic.
+ * The default implementation only grabs SHM and OpenGL buffers, reimplement this in your
+ * compositor subclass to handle more buffer types.
+ * You should not call this manually, but rather use \a QWaylandSurfaceGrabber.
+ */
+void QWaylandCompositor::grabSurface(QWaylandSurfaceGrabber *grabber, const QWaylandBufferRef &buffer)
+{
+    if (buffer.isShm()) {
+        emit grabber->success(buffer.image());
+    } else {
+#ifdef QT_COMPOSITOR_WAYLAND_GL
+        if (QOpenGLContext::currentContext()) {
+            QOpenGLFramebufferObject fbo(buffer.size());
+            fbo.bind();
+            QOpenGLTextureBlitter blitter;
+            blitter.create();
+            blitter.bind();
+
+            glViewport(0, 0, buffer.size().width(), buffer.size().height());
+
+            QOpenGLTextureBlitter::Origin surfaceOrigin =
+                buffer.origin() == QWaylandSurface::OriginTopLeft
+                ? QOpenGLTextureBlitter::OriginTopLeft
+                : QOpenGLTextureBlitter::OriginBottomLeft;
+
+            GLuint texture;
+            glGenTextures(1, &texture);
+            glBindTexture(GL_TEXTURE_2D, texture);
+            glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+            buffer.bindToTexture();
+            blitter.blit(texture, QMatrix4x4(), surfaceOrigin);
+
+            blitter.release();
+            glDeleteTextures(1, &texture);
+
+            emit grabber->success(fbo.toImage());
+        } else
+#endif
+        emit grabber->failed(QWaylandSurfaceGrabber::UnknownBufferType);
+    }
+}
+
 QT_END_NAMESPACE