Re: Example needed to show how to overlay images upon a single view
Re: Example needed to show how to overlay images upon a single view
- Subject: Re: Example needed to show how to overlay images upon a single view
- From: "Frederick C. Lee" <email@hidden>
- Date: Wed, 12 Jan 2005 09:33:19 -0800
Thanks for the response!
I don't want to draw onto the background image, but to place an
'overlay' or a virtual 'plastic' layer to draw upon and maneuver.
That way, I can customize the collection without changing the parts.
I want to be able keep each layer independent and modifiable.
An example would be a weather map: You can draw/erase weather symbols
upon the map of the U.S., without actually affecting the map itself.
Each layer would have its own data storage.
I'll play with your idea to see if that is what I can do.
I was thinking that it would be necessary to stack NSImageViews and
work with each separately; since each NSImageView works with one (1)
image. Perhaps this takes too much overhead. I don't know.
BTW: I've read that TIFF images can store multiple images as well.
I'm not a Graphic Artist so I'm currently clueless.
Regards,
Ric.
On Jan 11, 2005, at 7:47 PM, Louis C. Sacha wrote:
Hello...
In the drawRect: method of your NSView subclass, after drawing the
background you could use the NSImage
drawInRect:fromRect:operation:fraction: instance method to draw each
of the images, starting with most distant / bottom layers.
You can use the destination rect (in your NSView) and the source rect
(from the NSImage) to dynamically scale the image as you draw it into
your NSView. Generally, you will want to use the NSCompositeSourceOver
compositing operation, and to draw an image with a fraction of it's
normal opacity you would change the value passed as the fraction:
argument.
No sample code handy at the moment, but hopefully enough words to do
the job :)
Louis
Greetings:
I would like to create a variable stack of images upon a single
NSView with each image acting as layers or gels upon a solid
background. These layers should be available programmatically to
alter their respective transparencies, etc. I good analogy is a
cartoon with a solid background and characters in the separate
layers. Another example is what OmniGraffle does: provide a canvas
with various layers per user option.
I'm banging around here I know it should be a straight forward
design. An example is worth more than a thousand words.
Regards,
Ric.
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