Issue with setPatternPhase: in an NSSplitView for

问题:

I have searched around and haven't found anything regarding this particular problem. I have a window with a vertical NSSplitView. Within the right view of the splitview, I have an NSBox object set to fill the contents of the view. I am loading in custom nibs using setContentView: to swap in views to the NSBox on the righthand side of the splitview. In my custom views I'm tying to fill the views with an NSColor object that uses a NSImage to pattern the background. All of this is working as expected. I am using the code based on this article: http://www.mere-mortal-software.com/blog/details.php?d=2007-01-08 to set the phase of the pattern to the top-left corner:

[[NSGraphicsContext currentContext] saveGraphicsState];
[[NSGraphicsContext currentContext] setPatternPhase: NSMakePoint( [self bounds].origin.x, 
                                                                 [self bounds].size.height )];
[[self leatherColor] set];
NSRectFill( [self bounds] );

[[NSGraphicsContext currentContext] restoreGraphicsState];

with the intention that the pattern appears to remain constant in the upper lefthand corner of the NSBox when the views are re-sized as would be the expected behavior (via the splitview moving or the window itself being resized). I have implemented this in a stripped-down test app with just a window and a custom view and it behaves as expected.

In my project with the splitview however, it is behaving like the patternPhase is being set on the upper lefthand corner of the entire window instead of the upper lefthand corner of the right-half of the splitview (i.e. it should shift with resizing the splitview) It behaves like it's "revealing a larger image instead of shifting with it. I'm pretty certain this is an issue with multiple coordinate spaces, me misunderstanding how the coordinates of an NSSplitView work, or something to do with the view hierarchy. From the documentation on NSGraphicsContext, in the setPatternPhase: method it says: "For example, setting the pattern phase to (2,3) has the effect of moving the start of pattern cell tiling to the point (2,3) in default user space." Will the default user space correspond with the bounds of my custom view, or could it be that I am creating the point based on the right side view set of coordinates and the setPatternPhase implements it for the full width of the spitview (including the left-half)?

Any suggestions/advice/help you could provide would be greatly appreciated.

Edit: I have uploaded a copy of the project so you can see the behavior: http://dl.dropbox.com/u/6679821/ViewSwitcher.zip

回答1:

You need to adjust the phase depending on where the view sits in the window. I use this category on NSView:

@implementation NSView (RKAdditions)
- (void)rk_drawPatternImage:(NSColor*)patternColor inRect:(NSRect)rect
{
    [self rk_drawPatternImage:patternColor inBezierPath:[NSBezierPath bezierPathWithRect:rect]];
}


- (void)rk_drawPatternImage:(NSColor*)patternColor inBezierPath:(NSBezierPath*)path
{
    [NSGraphicsContext saveGraphicsState];

    CGFloat yOffset = NSMaxY([self convertRect:self.bounds toView:nil]);
    CGFloat xOffset = NSMinX([self convertRect:self.bounds toView:nil]);
    [[NSGraphicsContext currentContext] setPatternPhase:NSMakePoint(xOffset, yOffset)];

    [patternColor set];
    [path fill];
    [NSGraphicsContext restoreGraphicsState];
}

@end

In your case you'd modify -drawRect: to look like this:

-(void) drawRect: (NSRect)dirtyRect
{
    [self rk_drawPatternImage:[self leatherColor] inRect:self.bounds];
}