Clean up QScreen::grabWindow()

Handle 0 WId parameter as meaning "desktop window"/whole screen.
Also, re-add the default values for the grab area, both for
convenience and compatibility with QPixmap::grabWindow() in Qt4.
Update the screenshot example so it doesn't comlain about usage of
deprecated QPixmap::grabWindow().

Change-Id: I2ad229113ddb8ded0388f2ebc0e8c703c6657f1f
Reviewed-by: Gunnar Sletta <gunnar.sletta@nokia.com>

1 files changed, 7 insertions, 8 deletions

diff --git a/doc/src/examples/screenshot.qdoc b/doc/src/examples/screenshot.qdoc
index cf6e68b6df..4723d3d43c 100644
--- a/doc/src/examples/screenshot.qdoc
+++ b/doc/src/examples/screenshot.qdoc
@@ -172,16 +172,15 @@
 
     \snippet examples/desktop/screenshot/screenshot.cpp 5
 
-    We take the screenshot using the static QPixmap::grabWindow()
+    Using the static function QApplication::primaryScreen(), we
+    obtain the QScreen object for the application's main screen.
+
+    We take the screenshot using the QScreen::grabWindow()
     function. The function grabs the contents of the window passed as
     an argument, makes a pixmap out of it and returns that pixmap.
-
-    We identify the argument window using the QWidget::winID()
-    function which returns the window system identifier. Here it
-    returns the identifier of the current QDesktopWidget retrieved by
-    the QApplication::desktop() function. The QDesktopWidget class
-    provides access to screen information, and inherits
-    QWidget::winID().
+    The window id can be obtained with QWidget::winId() or QWindow::winId().
+    Here, however, we just pass 0 as the window id, indicating that we
+    want to grab the entire screen.
 
     We update the screenshot preview label using the private \c
     updateScreenshotLabel() function. Then we enable the \uicontrol {New