explain specifically how to make a transparent window

Change-Id: I136d8d9709d4fae914f12919e513641a6e76e3f0
Task-number: QTBUG-20768
Reviewed-by: Samuel Rødal <samuel.rodal@nokia.com>

diff --git a/src/gui/kernel/qwindow.cpp b/src/gui/kernel/qwindow.cpp
index 44f3bc4..2dc62d6 100644 (file)
--- a/src/gui/kernel/qwindow.cpp
+++ b/src/gui/kernel/qwindow.cpp
@@ -435,8 +435,16 @@ void QWindow::setWindowModality(Qt::WindowModality modality)
 /*!
     Sets the window's surface \a format.
 
-    The format determines properties such as color depth, alpha,
-    depth and stencil buffer size, etc.
+    The format determines properties such as color depth, alpha, depth and
+    stencil buffer size, etc. For example, to give a window a transparent
+    background (provided that the window system supports compositing, and
+    provided that other content in the window does not make it opaque again):
+
+    \code
+    QSurfaceFormat format;
+    format.setAlphaBufferSize(8);
+    window.setFormat(format);
+    \endcode
 
     The surface format will be resolved in the create() function. Calling
     this function after create() has been called will not re-resolve the