Add support for custom texture format in QOpenGLWidget

...in order to support sRGB framebuffers.

Add a --srgb option to the qopenglwidget example to allow testing.

[ChangeLog][QtWidgets][QOpenGLWidget] Added support for specifying
custom internal texture formats in QOpenGLWidget in order to make it
possible to have the widget backed by an sRGB-capable framebuffer.

Task-number: QTBUG-50987
Change-Id: I112e2f0ab0b1478c69e601031aa0bafaa87fa847
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

2 files changed, 8 insertions, 0 deletions

diff --git a/examples/opengl/qopenglwidget/glwidget.cpp b/examples/opengl/qopenglwidget/glwidget.cpp
index 21d922d713..bb7c952a26 100644
--- a/examples/opengl/qopenglwidget/glwidget.cpp
+++ b/examples/opengl/qopenglwidget/glwidget.cpp
@@ -61,6 +61,10 @@
 
 const int bubbleNum = 8;
 
+#ifndef GL_SRGB8_ALPHA8
+#define GL_SRGB8_ALPHA8 0x8C43
+#endif
+
 GLWidget::GLWidget(MainWindow *mw, bool button, const QColor &background)
     : m_mainWindow(mw),
       m_showBubbles(true),
@@ -75,6 +79,8 @@ GLWidget::GLWidget(MainWindow *mw, bool button, const QColor &background)
       m_background(background)
 {
     setMinimumSize(300, 250);
+    if (QCoreApplication::arguments().contains(QStringLiteral("--srgb")))
+        setTextureFormat(GL_SRGB8_ALPHA8);
 }
 
 GLWidget::~GLWidget()
diff --git a/examples/opengl/qopenglwidget/main.cpp b/examples/opengl/qopenglwidget/main.cpp
index d7aa791142..f9b5731b8f 100644
--- a/examples/opengl/qopenglwidget/main.cpp
+++ b/examples/opengl/qopenglwidget/main.cpp
@@ -61,6 +61,8 @@ int main( int argc, char ** argv )
     QSurfaceFormat format;
     format.setDepthBufferSize(24);
     format.setStencilBufferSize(8);
+    if (QCoreApplication::arguments().contains(QStringLiteral("--srgb")))
+        format.setColorSpace(QSurfaceFormat::sRGBColorSpace);
     if (QCoreApplication::arguments().contains(QStringLiteral("--multisample")))
         format.setSamples(4);
     QSurfaceFormat::setDefaultFormat(format);