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>

6 files changed, 42 insertions, 29 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;
 }
 
 /*!
diff --git a/src/quick/scenegraph/qsgcontext_p.h b/src/quick/scenegraph/qsgcontext_p.h
index d1897f20f9..49b6f6e2a0 100644
--- a/src/quick/scenegraph/qsgcontext_p.h
+++ b/src/quick/scenegraph/qsgcontext_p.h
@@ -88,6 +88,12 @@ class Q_QUICK_PRIVATE_EXPORT QSGRenderContext : public QObject
 {
     Q_OBJECT
 public:
+    enum CreateTextureFlags {
+        CreateTexture_Alpha       = 0x1,
+        CreateTexture_Atlas       = 0x2,
+        CreateTexture_Mipmap      = 0x4
+    };
+
     QSGRenderContext(QSGContext *context);
     ~QSGRenderContext();
 
@@ -107,8 +113,8 @@ public:
     virtual QSGDistanceFieldGlyphCache *distanceFieldGlyphCache(const QRawFont &font);
     QSGTexture *textureForFactory(QQuickTextureFactory *factory, QQuickWindow *window);
 
-    virtual QSGTexture *createTexture(const QImage &image) const;
-    virtual QSGTexture *createTextureNoAtlas(const QImage &image) const;
+    virtual QSGTexture *createTexture(const QImage &image, uint flags = CreateTexture_Alpha) const;
+
     virtual QSGRenderer *createRenderer();
 
     virtual void compile(QSGMaterialShader *shader, QSGMaterial *material, const char *vertexCode = 0, const char *fragmentCode = 0);
diff --git a/src/quick/scenegraph/util/qsgatlastexture.cpp b/src/quick/scenegraph/util/qsgatlastexture.cpp
index 076b068f27..7a2587dacd 100644
--- a/src/quick/scenegraph/util/qsgatlastexture.cpp
+++ b/src/quick/scenegraph/util/qsgatlastexture.cpp
@@ -112,13 +112,15 @@ void Manager::invalidate()
     }
 }
 
-QSGTexture *Manager::create(const QImage &image)
+QSGTexture *Manager::create(const QImage &image, bool hasAlphaChannel)
 {
-    QSGTexture *t = 0;
+    Texture *t = 0;
     if (image.width() < m_atlas_size_limit && image.height() < m_atlas_size_limit) {
         if (!m_atlas)
             m_atlas = new Atlas(m_atlas_size);
         t = m_atlas->create(image);
+        if (!hasAlphaChannel && t->hasAlphaChannel())
+            t->setHasAlphaChannel(false);
     }
     return t;
 }
diff --git a/src/quick/scenegraph/util/qsgatlastexture_p.h b/src/quick/scenegraph/util/qsgatlastexture_p.h
index 399d5fd669..c0f6ab912d 100644
--- a/src/quick/scenegraph/util/qsgatlastexture_p.h
+++ b/src/quick/scenegraph/util/qsgatlastexture_p.h
@@ -58,7 +58,7 @@ public:
     Manager();
     ~Manager();
 
-    QSGTexture *create(const QImage &image);
+    QSGTexture *create(const QImage &image, bool hasAlphaChannel);
     void invalidate();
 
 private:
@@ -114,6 +114,7 @@ public:
 
     int textureId() const { return m_atlas->textureId(); }
     QSize textureSize() const { return atlasSubRectWithoutPadding().size(); }
+    void setHasAlphaChannel(bool alpha) { m_has_alpha = alpha; }
     bool hasAlphaChannel() const { return m_has_alpha; }
     bool hasMipmaps() const { return false; }
     bool isAtlasTexture() const { return true; }
diff --git a/src/quick/scenegraph/util/qsgengine.cpp b/src/quick/scenegraph/util/qsgengine.cpp
index c0ddf25765..8622f8edc1 100644
--- a/src/quick/scenegraph/util/qsgengine.cpp
+++ b/src/quick/scenegraph/util/qsgengine.cpp
@@ -150,7 +150,7 @@ QSGAbstractRenderer *QSGEngine::createRenderer() const
 /*!
     Creates a texture using the data of \a image
 
-    Valid \a options are TextureCanUseAtlas
+    Valid \a options are TextureCanUseAtlas and TextureIsOpaque.
 
     The caller takes ownership of the texture and the
     texture should only be used with this engine.
@@ -160,13 +160,12 @@ QSGAbstractRenderer *QSGEngine::createRenderer() const
 QSGTexture *QSGEngine::createTextureFromImage(const QImage &image, CreateTextureOptions options) const
 {
     Q_D(const QSGEngine);
-    if (!d->sgRenderContext->isValid())
-        return 0;
-
-    if (options & TextureCanUseAtlas)
-        return d->sgRenderContext->createTexture(image);
-    else
-        return d->sgRenderContext->createTextureNoAtlas(image);
+     if (!d->sgRenderContext->isValid())
+         return 0;
+    uint flags = 0;
+    if (options & TextureCanUseAtlas)     flags |= QSGRenderContext::CreateTexture_Atlas;
+    if (!(options & TextureIsOpaque))     flags |= QSGRenderContext::CreateTexture_Alpha;
+    return d->sgRenderContext->createTexture(image, flags);
 }
 
 /*!
diff --git a/src/quick/scenegraph/util/qsgengine.h b/src/quick/scenegraph/util/qsgengine.h
index 9a74a02aa1..325d3a9ca2 100644
--- a/src/quick/scenegraph/util/qsgengine.h
+++ b/src/quick/scenegraph/util/qsgengine.h
@@ -52,7 +52,8 @@ public:
     enum CreateTextureOption {
         TextureHasAlphaChannel  = 0x0001,
         TextureOwnsGLTexture    = 0x0004,
-        TextureCanUseAtlas      = 0x0008
+        TextureCanUseAtlas      = 0x0008,
+        TextureIsOpaque         = 0x0010
     };
     Q_DECLARE_FLAGS(CreateTextureOptions, CreateTextureOption)