/*

     File: TransparentButtonCell.m 

 Abstract: This NSButtonCell subclass knows how to draw the button frame transparent, while

 the actual content stays non-transparent.  It does this by rendering the button

 into an NSImage, drawing the image with transparancy back into the control view,

 and then drawing the button contents again. 

  Version: 1.1 

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 */

#import "TransparentButtonCell.h"

@implementation TransparentButtonCell

- (void)drawWithFrame:(NSRect)cellFrame inView:(NSView *)controlView

{

    NSImage *alphaImage;

    NSRect alphaImageRect = { NSZeroPoint, cellFrame.size };

    alphaImage = [[NSImage alloc] initWithSize:alphaImageRect.size];

    [alphaImage setFlipped:[controlView isFlipped]];

    [alphaImage lockFocus];

    BOOL wasEnabled = [self isEnabled];

    [self setEnabled:YES];

        // Draw the default button cell frame in the image

    [super drawWithFrame:alphaImageRect inView:controlView];

    [self setEnabled:wasEnabled];

    [alphaImage unlockFocus];

        // Draw the image with partial transparency into the control view

    [alphaImage drawAtPoint:cellFrame.origin fromRect:alphaImageRect operation:NSCompositeSourceOver fraction:0.75];

        // Draw the contents of the interior button image again, this time without transparency

    [self drawInteriorWithFrame:cellFrame inView:controlView];

    [alphaImage release];

}

@end