ResizeCustomViewOnDrag

I’m trying to create a custom size grip like that found at the bottom of Mail 2.0. I already have the one-pixel split view bar, etc. and all is working well there. I found the following example for handling continuous dragging events in the Cocoa docs and adapted it to my purposes. The problem is that it works too well. In other words, if I drag anywhere in the view, the resizing code is executed.

The mouseDown: code is as follows:

(void)mouseDown:(NSEvent *)event { BOOL keepOn = YES; BOOL isInside = YES; NSPoint mouseLoc; NSRect rect; while (keepOn) { event = self window] nextEventMatchingMask:[[NSLeftMouseUpMask | NSLeftMouseDraggedMask]; mouseLoc = [self convertPoint:[event locationInWindow] fromView:nil]; isInside = [self mouse:mouseLoc inRect:GRIPRECT];
```
  switch ([event type]) {
      case NSLeftMouseDragged:
          rect = [self frame];
          rect.size.width += [event deltaX];
          [self setFrame:rect];
          self superview] display];
          break;
      case [[NSLeftMouseUp:
          keepOn = NO;
          break;
      default:
          break;
  }   }   return; }
```

“GRIPRECT” is defined as follows:

#define GRIPRECT NSMakeRect(NSWidth([self frame]) - 17, 0, 17, BOTTOM_BAR_HEIGHT)

If I modify the case NSLeftMouseDragged: block to only execute if isInside == YES, if you drag too fast, the resize doesn’t keep up and the drag ends because it’s no longer “ isInside”. What’s wrong with my assumptions? ;-)

Never mind … ;-) I found it. I had to account for the initial mouseDown: event and react accordingly. The following seems to work.

(void)mouseDown:(NSEvent *)event { NSPoint mouseLoc = [self convertPoint:[event locationInWindow] fromView:nil]; BOOL isInside = [self mouse:mouseLoc inRect:GRIPRECT];; BOOL keepOn = isInside; NSRect rect;

if (!keepOn) { [super mouseDown:event]; //?? return; }

while (keepOn) { event = self window] nextEventMatchingMask:[[NSLeftMouseUpMask | NSLeftMouseDraggedMask]; mouseLoc = [self convertPoint:[event locationInWindow] fromView:nil]; isInside = [self mouse:mouseLoc inRect:GRIPRECT];
```
  switch ([event type]) {
      case NSLeftMouseDragged:
          rect = [self frame];
          rect.size.width += [event deltaX];
          [self setFrame:rect];
          self superview] display];
          break;
      case [[NSLeftMouseUp:
          keepOn = NO;
          break;
      default:
          [super mouseDown:event];
          break;
  }   }   return; }
```

Note the line commented as “//??” above. Is this necessary? I’ll have other controls added to this view as subviews. I thought that line might be necessary to allow normal operation for subviews. Also, is there anything else wrong above?

CocoaDev