Contents

dissolveToPoint:fraction:

Composites the entire image to the specified location using the source-over operator.

Declaration

- (void) dissolveToPoint:(NSPoint) point fraction:(CGFloat) fraction;

Parameters

  • point:

    The point at which to draw the image, specified in the current coordinate system.

  • fraction:

    The desired opacity of the image, specified as a value between 0.0 and 1.0. A value of 0.0 renders the image totally transparent while 1.0 renders it fully opaque. Values larger than 1.0 are interpreted as 1.0.

Discussion

Except for the choice of compositing operator, this method behaves in the same way as the compositeToPoint:operation: method. During printing, the delta parameter is ignored.

If the source image contains alpha information, this operation may promote the destination NSWindow object to contain alpha information.

To slowly dissolve this image onto another, you can invoke this method (or the dissolveToPoint:fromRect:fraction: method) repeatedly with an ever-increasing delta value. Because the delta parameter refers to the visible fraction of the source image, increasing the value causes the source image to replace the destination content gradually. You should generally perform this type of operation using a buffered window or other offscreen drawing environment.

See Also

Instance Methods