macOS: Use sRGB when doing native font rendering into FBO

Otherwise text appears too dark.
A similar bug was fixed in the past for QQuickWidget (which also uses FBO).

Now this fixes it for ShaderEffectSource and QQuickItem::grabImage() too.

Change-Id: Ia0e176372b9ba8282972f8d60f87f02747291ffe
Task-Id: QTBUG-52906
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>

1 files changed, 27 insertions, 4 deletions

diff --git a/src/quick/scenegraph/qsgdefaultlayer.cpp b/src/quick/scenegraph/qsgdefaultlayer.cpp
index fa69f911dd..99735564ef 100644
--- a/src/quick/scenegraph/qsgdefaultlayer.cpp
+++ b/src/quick/scenegraph/qsgdefaultlayer.cpp
@@ -42,6 +42,29 @@ DEFINE_BOOL_CONFIG_OPTION(qmlFboOverlay, QML_FBO_OVERLAY)
 #endif
 DEFINE_BOOL_CONFIG_OPTION(qmlFboFlushBeforeDetach, QML_FBO_FLUSH_BEFORE_DETACH)
 
+
+
+static QOpenGLFramebufferObject *createFramebuffer(const QSize &size,
+                                                   QOpenGLFramebufferObjectFormat format)
+{
+#ifdef Q_OS_MACOS
+    QOpenGLContext *context = QOpenGLContext::currentContext();
+    if (context->hasExtension("GL_ARB_framebuffer_sRGB")
+        && context->hasExtension("GL_EXT_texture_sRGB")
+        && context->hasExtension("GL_EXT_texture_sRGB_decode"))
+        format.setInternalTextureFormat(GL_SRGB8_ALPHA8_EXT);
+#endif
+    QOpenGLFramebufferObject *fbo = new QOpenGLFramebufferObject(size, format);
+#ifdef Q_OS_MACOS
+    if (format.internalTextureFormat() == GL_SRGB8_ALPHA8_EXT) {
+        QOpenGLFunctions *funcs = context->functions();
+        funcs->glBindTexture(GL_TEXTURE_2D, fbo->texture());
+        funcs->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_SRGB_DECODE_EXT, GL_SKIP_DECODE_EXT);
+    }
+#endif
+    return fbo;
+}
+
 namespace
 {
     class BindableFbo : public QSGBindable
@@ -324,7 +347,7 @@ void QSGDefaultLayer::grab()
 
             format.setInternalTextureFormat(m_format);
             format.setSamples(m_context->openglContext()->format().samples());
-            m_secondaryFbo = new QOpenGLFramebufferObject(m_size, format);
+            m_secondaryFbo = createFramebuffer(m_size, format);
             m_depthStencilBuffer = m_context->depthStencilBufferForFbo(m_secondaryFbo);
         } else {
             QOpenGLFramebufferObjectFormat format;
@@ -333,14 +356,14 @@ void QSGDefaultLayer::grab()
             if (m_recursive) {
                 deleteFboLater = true;
                 delete m_secondaryFbo;
-                m_secondaryFbo = new QOpenGLFramebufferObject(m_size, format);
+                m_secondaryFbo = createFramebuffer(m_size, format);
                 funcs->glBindTexture(GL_TEXTURE_2D, m_secondaryFbo->texture());
                 updateBindOptions(true);
                 m_depthStencilBuffer = m_context->depthStencilBufferForFbo(m_secondaryFbo);
             } else {
                 delete m_fbo;
                 delete m_secondaryFbo;
-                m_fbo = new QOpenGLFramebufferObject(m_size, format);
+                m_fbo = createFramebuffer(m_size, format);
                 m_secondaryFbo = 0;
                 funcs->glBindTexture(GL_TEXTURE_2D, m_fbo->texture());
                 updateBindOptions(true);
@@ -354,7 +377,7 @@ void QSGDefaultLayer::grab()
         Q_ASSERT(m_fbo);
         Q_ASSERT(!m_multisampling);
 
-        m_secondaryFbo = new QOpenGLFramebufferObject(m_size, m_fbo->format());
+        m_secondaryFbo = createFramebuffer(m_size, m_fbo->format());
         funcs->glBindTexture(GL_TEXTURE_2D, m_secondaryFbo->texture());
         updateBindOptions(true);
     }