Add QQuickWindow::TextureIsOpaque as option to createTextureFromImage.

Opaque textures can be a lot faster, so give this option without
forcing the user to reimplement her/his own QSGTexture class.

The old behavior was that createTextureFromImage() disregarded
TextureHasAlphaChannel and looked solely at the image's format. To
keep this behavior intact, we introduce a second opt-in flag to switch
textures from auto-detect to false, namely TextureIsOpaque.

[ChangeLog][QtQuick][QQuickWindow] Add TextureIsOpaque option to
createTextureFromImage()

Change-Id: I248db4bc5f7920864b6aa8d831ce24d23ad370ef
Reviewed-by: Laszlo Agocs <laszlo.agocs@theqtcompany.com>

1 files changed, 19 insertions, 15 deletions

diff --git a/src/quick/scenegraph/qsgcontext.cpp b/src/quick/scenegraph/qsgcontext.cpp
index 2af8bc73ba..ef31151691 100644
--- a/src/quick/scenegraph/qsgcontext.cpp
+++ b/src/quick/scenegraph/qsgcontext.cpp
@@ -735,22 +735,26 @@ QSGDepthStencilBufferManager *QSGRenderContext::depthStencilBufferManager()
     will be called with \a image as argument.
  */
 
-QSGTexture *QSGRenderContext::createTexture(const QImage &image) const
-{
-    if (!openglContext())
-        return 0;
-    QSGTexture *t = m_atlasManager->create(image);
-    if (t)
-        return t;
-    return createTextureNoAtlas(image);
-}
+QSGTexture *QSGRenderContext::createTexture(const QImage &image, uint flags) const
+{
+    bool atlas = flags & CreateTexture_Atlas;
+    bool mipmap = flags & CreateTexture_Mipmap;
+    bool alpha = flags & CreateTexture_Alpha;
+
+    // The atlas implementation is only supported from the render thread and
+    // does not support mipmaps.
+    if (!mipmap && atlas && openglContext() && QThread::currentThread() == openglContext()->thread()) {
+        QSGTexture *t = m_atlasManager->create(image, alpha);
+        if (t)
+            return t;
+    }
 
-QSGTexture *QSGRenderContext::createTextureNoAtlas(const QImage &image) const
-{
-    QSGPlainTexture *t = new QSGPlainTexture();
-    if (!image.isNull())
-        t->setImage(image);
-    return t;
+    QSGPlainTexture *texture = new QSGPlainTexture();
+    texture->setImage(image);
+    if (texture->hasAlphaChannel() && !alpha)
+        texture->setHasAlphaChannel(false);
+
+    return texture;
 }
 
 /*!