From 57ad1cd7057d0a9bd8ba4ca1465a9bc44e5b20e4 Mon Sep 17 00:00:00 2001
From: Kevin Walzer <kw@codebykevin.com>
Date: Mon, 11 Aug 2014 03:12:28 +0000
Subject: Further refinement of scrolling; addresses artifacts in scrolling
 complex interfaces on OS X

---
 macosx/tkMacOSXDraw.c       | 43 ++++++++++++++++++++++++++++++++++++++++---
 macosx/tkMacOSXSubwindows.c | 14 +++++---------
 2 files changed, 45 insertions(+), 12 deletions(-)

diff --git a/macosx/tkMacOSXDraw.c b/macosx/tkMacOSXDraw.c
index 40400c2..6631b4f 100644
--- a/macosx/tkMacOSXDraw.c
+++ b/macosx/tkMacOSXDraw.c
@@ -1460,12 +1460,12 @@ XMaxRequestSize(
  *	a damage region.
  *
  * Results:
- *	Returns 0 if the scroll generated no additional damage.
+ *	Returns 0 if the scroll genereated no additional damage.
  *	Otherwise, sets the region that needs to be repainted after
  *	scrolling and returns 1.
  *
  * Side effects:
- *	Scrolls the rectangle in the window.
+ *	Scrolls the bits in the window.
  *
  *----------------------------------------------------------------------
  */
@@ -1518,9 +1518,46 @@ TkScrollWindow(
 	    /* Scroll the rectangle. */
 	    [view scrollRect:NSRectFromCGRect(scroll_src) by:NSMakeSize(dx, -dy)];
 	    [view displayRect:NSRectFromCGRect(scroll_dst)];
+
+	    /*
+	     * When a Text widget contains embedded images, scrolling generates
+	     * lots of artifacts involving multiple copies of the images
+	     * displayed on top of each other.  Extensive experimentation, with
+	     * very little help from the Apple documentation, indicates that
+	     * whenever an image is displayed it gets added as a subview, which
+	     * then gets automatically redisplayed in its original location.
+	     *
+	     * We do two things to combat this.  First, each subview that meets
+	     * the scroll area is added as a damage rectangle.  Second, we
+	     * redisplay the subviews after the scroll.
+	     */
+
+	    /*
+	     * Step 1: Find any subviews that meet the scroll area and mark
+	     * them as damaged.  Use Tk coordinates, shifted to account for the
+	     * future scrolling.
+	     */
+	    
+	    for (NSView *subview in [view subviews] ) {
+		NSRect frame = [subview frame];
+		CGRect subviewRect = CGRectMake(
+			frame.origin.x - macDraw->xOff + dx,
+			(bounds.size.height - frame.origin.y - frame.size.height) - macDraw->yOff + dy,
+			frame.size.width, frame.size.height);
+		/* Rectangles with negative coordinates seem to cause trouble. */
+		if (subviewRect.origin.y < 0 && subviewRect.origin.y + subviewRect.size.height > 0) {
+		    subviewRect.origin.y = 0;
+		}
+		CGRect intersection = CGRectIntersection(srcRect, subviewRect);
+		if (! CGRectIsEmpty(intersection) ){
+		    dstRgn = HIShapeCreateWithRect(&subviewRect);
+		    ChkErr(HIShapeUnion, dmgRgn, dstRgn, (HIMutableShapeRef) dmgRgn);
+		    CFRelease(dstRgn);
+		}
+	    }
+
 	}
     }
-	    
 
 
     if ( dmgRgn == NULL ) {
diff --git a/macosx/tkMacOSXSubwindows.c b/macosx/tkMacOSXSubwindows.c
index e4af406..9ba7100 100644
--- a/macosx/tkMacOSXSubwindows.c
+++ b/macosx/tkMacOSXSubwindows.c
@@ -651,7 +651,7 @@ XConfigureWindow(
  *
  * TkMacOSXUpdateClipRgn --
  *
- *	This function updates the clipping regions for a given window and all of
+ *	This function updates the cliping regions for a given window and all of
  *	its children. Once updated the TK_CLIP_INVALID flag in the subwindow
  *	data structure is unset. The TK_CLIP_INVALID flag should always be
  *	unset before any drawing is attempted.
@@ -677,7 +677,7 @@ TkMacOSXUpdateClipRgn(
     macWin = winPtr->privatePtr;
     if (macWin && macWin->flags & TK_CLIP_INVALID) {
 	TkWindow *win2Ptr;
-	
+
 #ifdef TK_MAC_DEBUG_CLIP_REGIONS
 	TkMacOSXDbgMsg("%s", winPtr->pathName);
 #endif
@@ -818,7 +818,7 @@ TkMacOSXUpdateClipRgn(
  *
  * TkMacOSXVisableClipRgn --
  *
- *	This function returns the Macintosh clipping region for the given
+ *	This function returns the Macintosh cliping region for the given
  *	window. The caller is responsible for disposing of the returned
  *	region via TkDestroyRegion().
  *
@@ -913,7 +913,7 @@ TkMacOSXInvalidateWindow(
 				 * TK_PARENT_WINDOW */
 {
 #ifdef TK_MAC_DEBUG_CLIP_REGIONS
-    TkMacOSXDbgMsg("%s", macWin->winPtr->pathName);
+    TkMacOSXDbgMsg("%s", winPtr->pathName);
 #endif
     if (macWin->flags & TK_CLIP_INVALID) {
 	TkMacOSXUpdateClipRgn(macWin->winPtr);
@@ -1071,7 +1071,7 @@ TkMacOSXGetRootControl(
  *	None.
  *
  * Side effects:
- *	The clipping regions for the window and its children are marked invalid.
+ *	The cliping regions for the window and its children are mark invalid.
  *	(Make sure they are valid before drawing.)
  *
  *----------------------------------------------------------------------
@@ -1090,10 +1090,6 @@ TkMacOSXInvalClipRgns(
      * be marked.
      */
 
-#ifdef TK_MAC_DEBUG_CLIP_REGIONS
-	TkMacOSXDbgMsg("%s", winPtr->pathName);
-#endif
-
     if (!macWin || macWin->flags & TK_CLIP_INVALID) {
 	return;
     }
-- 
cgit v0.12