QML: Use alpha channel for ARGB32 video frames

Added a fix to use alpha channel for ARGB32 video frames.
Previously alpha component was always ignored and used 1.0 instead.

To see transparent videos it is still needed to enable blending
by adjusting an opacity property of qml element.

Task-number: QTBUG-43098
Change-Id: If3aaf8ab695021b3a49a1790d900366e9c336b33
Reviewed-by: Christian Stromme <christian.stromme@qt.io>

1 files changed, 12 insertions, 3 deletions

diff --git a/src/qtmultimediaquicktools/qsgvideonode_texture.cpp b/src/qtmultimediaquicktools/qsgvideonode_texture.cpp
index a26d59532..f5545afc7 100644
--- a/src/qtmultimediaquicktools/qsgvideonode_texture.cpp
+++ b/src/qtmultimediaquicktools/qsgvideonode_texture.cpp
@@ -108,11 +108,19 @@ protected:
 class QSGVideoMaterialShader_Texture_swizzle : public QSGVideoMaterialShader_Texture
 {
 public:
-    QSGVideoMaterialShader_Texture_swizzle()
-        : QSGVideoMaterialShader_Texture()
+    QSGVideoMaterialShader_Texture_swizzle(bool hasAlpha)
+        : m_hasAlpha(hasAlpha)
     {
         setShaderSourceFile(QOpenGLShader::Fragment, QStringLiteral(":/qtmultimediaquicktools/shaders/rgbvideo_swizzle.frag"));
     }
+
+protected:
+    void initialize() override {
+        QSGVideoMaterialShader_Texture::initialize();
+        program()->setUniformValue(program()->uniformLocation("hasAlpha"), GLboolean(m_hasAlpha));
+    }
+
+    int m_hasAlpha;
 };
 
 
@@ -138,7 +146,8 @@ public:
     }
 
     QSGMaterialShader *createShader() const override {
-        return needsSwizzling() ? new QSGVideoMaterialShader_Texture_swizzle
+        const bool hasAlpha = m_format.pixelFormat() == QVideoFrame::Format_ARGB32;
+        return needsSwizzling() ? new QSGVideoMaterialShader_Texture_swizzle(hasAlpha)
                                 : new QSGVideoMaterialShader_Texture;
     }