Tk Source Code

 *
 *	Scroll a rectangle of the specified window and accumulate a damage
 *	region.
 *
 * Results:
 *	Returns 0 if the scroll generated no additional damage. Otherwise, sets
 *	the region that needs to be repainted after scrolling and returns 1.
 *      When drawRect was in use, this function used the now deprecated
 *      scrollRect method of NSView.  With the current updateLayer
 *      implementation, using a CGImage as the view's backing layer, we are
 *      able to use XCopyArea.  But both implementations are incomplete.
 *      They return a damage area which is just the source rectangle minus
 *      destination rectangle.  Other platforms, e.g. Windows, where
 *      this function is essentially provided by the windowing system,
 *      are able to add to the damage region the bounding rectangles of
 *      all subwindows which meet the source rectangle, even if they are
 *      contained in the destination rectangle.  The information needed
 *      to do that is not available in this module, as far as I know.
 *
 *      In fact, the Text widget is the only one which calls this
 *      function, and  textDisp.c compensates for this defect by using
 *      macOS-specific code.  This is possible because access to the
 *      list of all embedded windows in a Text widget is available in
 *      that module.
 *
 * Side effects:
 *	Scrolls the bits in the window.
 *
 *----------------------------------------------------------------------
 */

		TK_SIZE_CHANGED | TK_MACOSX_HANDLE_EVENT_IMMEDIATELY);
    	oldProc = Tk_RestrictEvents(ConfigureRestrictProc, NULL, &oldArg);
    	Tk_RestrictEvents(oldProc, oldArg, &oldArg);

	/*
	 * To make the reconfiguration actually happen we need to process
	 * idle tasks generated when processing the ConfigureNotify events.
	 * We also process timer events - without that there were crashes
	 * when embedded windows in a Text widget were mapped for the first
	 * time during a live resize.  This is unexplained.
	 */

	while (Tcl_DoOneEvent(TCL_TIMER_EVENTS|TCL_IDLE_EVENTS|TCL_DONT_WAIT)) {}

	/*
	 * Now that Tk has configured all subwindows, create the clip regions.
	 */

	TkMacOSXInvalClipRgns(tkwin);
	TkMacOSXUpdateClipRgn(winPtr);