Further refinement of scrolling; addresses artifacts in scrolling complex interfaces on OS X

1 files changed, 61 insertions, 34 deletions

diff --git a/macosx/tkMacOSXDraw.c b/macosx/tkMacOSXDraw.c
index 089097e..6ec3e59 100644
--- a/macosx/tkMacOSXDraw.c
+++ b/macosx/tkMacOSXDraw.c
@@ -1458,12 +1458,12 @@ 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.
  *
  *----------------------------------------------------------------------
  */
@@ -1480,59 +1480,86 @@ TkScrollWindow(
     Drawable drawable = Tk_WindowId(tkwin);
     MacDrawable *macDraw = (MacDrawable *) drawable; 
     NSView *view = TkMacOSXDrawableView(macDraw);
-    CGRect dmgRect, dstRect, visRectBL, srcRectBL, dstRectBL;
-    NSRect visible, frame;
-    HIShapeRef dmgRgn = NULL, dstRgn;
+    CGRect visRect, srcRect, dstRect, scroll_src, scroll_dst;
+    HIShapeRef dmgRgn = NULL;
+    NSRect bounds;
     int result;
 
     if ( view ) {
-	visible = [view visibleRect];
-
-	/* Find the frame for the Tk window within its NSview. */
-	frame = NSMakeRect(Tk_X(tkwin),
-			   Tk_Y(tkwin) + visible.size.height - Tk_Height(tkwin),
-			   Tk_Width(tkwin),
-			   Tk_Height(tkwin));
-
 	/*  Get the scroll area in NSView coordinates (origin at bottom left). */
-	srcRectBL = CGRectMake(frame.origin.x + x,
-			       frame.origin.y + frame.size.height - height - y,
+	bounds = [view bounds];
+	scroll_src = CGRectMake(
+				macDraw->xOff + x, 
+				bounds.size.height - height - (macDraw->yOff + y),
 				width, height);
-	dstRectBL = CGRectOffset(srcRectBL, dx, -dy);
-	
+	scroll_dst = CGRectOffset(scroll_src, dx, -dy);
 	/* Limit scrolling to the window content area. */
-	visRectBL = NSRectToCGRect(frame);
-	srcRectBL = CGRectIntersection(srcRectBL, visRectBL);
-	dstRectBL = CGRectIntersection(dstRectBL, visRectBL);
+	visRect = NSRectToCGRect([view visibleRect]);
+	scroll_src = CGRectIntersection(scroll_src, visRect);
+	scroll_dst = CGRectIntersection(scroll_dst, visRect);
 
-	if ( !CGRectIsEmpty(srcRectBL) && !CGRectIsEmpty(dstRectBL) ) {
+	if ( !CGRectIsEmpty(scroll_src) && !CGRectIsEmpty(scroll_dst) ) {
 
 	    /*
-	     * Construct the damage region.  We extend it to the top
-	     * or bottom of the window, in order to avoid artifacts when
-	     * scrolling.
+	     * Mark the difference between source and destination as damaged.
+	     * This region is described in the Tk coordinate system, after shifting by dy.
 	     */
 
-	    if ( dy < 0 ) { /* extend to bottom */
-	    	dmgRect = CGRectMake(x, y, Tk_Width(tkwin), Tk_Height(tkwin) - y);
-	    } else {         /* extend to top */
-	    	dmgRect = CGRectMake(x , 0, Tk_Width(tkwin), Tk_Height(tkwin) + y);
-	    }
-	    dstRect = CGRectMake(x+dx, y+dy, width, height);
-
-	    dmgRgn = HIShapeCreateMutableWithRect(&dmgRect);
-	    dstRgn = HIShapeCreateWithRect(&dstRect);
+	    srcRect = CGRectMake(x - macDraw->xOff, y - macDraw->yOff,
+				 width, height);
+	    dstRect = CGRectOffset(srcRect, dx, dy);
+	    dmgRgn = HIShapeCreateMutableWithRect(&srcRect);
+	    HIShapeRef dstRgn = HIShapeCreateWithRect(&dstRect);
 	    ChkErr(HIShapeDifference, dmgRgn, dstRgn, (HIMutableShapeRef) dmgRgn);
 	    CFRelease(dstRgn);
 
 	    /* Scroll the rectangle. */
-	    [view scrollRect:NSRectFromCGRect(srcRectBL) by:NSMakeSize(dx, -dy)];
+	    [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 ) {
 	dmgRgn = HIShapeCreateEmpty();
     }
+    //TkMacOSXInvalidateViewRegion(view, dmgRgn);
     TkMacOSXSetWithNativeRegion(damageRgn, dmgRgn);
     result = HIShapeIsEmpty(dmgRgn) ? 0 : 1;
     CFRelease(dmgRgn);