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Canvas and Panel

Posted on 2002-06-30
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Last Modified: 2012-05-04
Since you can use the Graphics methods on a Panel, what is the advantage of using a Canvas instead of a Panel to display an image, for example?
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Question by:HanRui
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by:Ovi
ID: 7121081
Panel is a container, canvas is a component. Of course both of them have as superclass Component, but they coming from different class tree paths(roots). On a Panel you can add components which meens that you can overlap what are you doing in the paint method; this can be a good think, or a bad one, depending on your application type/design. Canvas on the other hand is "specialized" for graphic operations. Basically there is no difference from the paint method point of view. All is very depending of your application specifications and needs.
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by:HanRui
ID: 7121511
Thanks, but this still this doesn't explain to me the need for a Canvas class since Panel can do everything that Canvas can do.
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allie earned 100 total points
ID: 7122218
The advantage of using a Canvas for graphics (as opposed to a Panel), is that Canvas allows more flexible graphics programming.  For example, you can set a GraphicsConfiguration when creating a Canvas (whereas in a Panel you could set the Layout).  Canvas allows you to use more advanced graphics, utilize more periphery interaction (like with printers, moniters, and mulit-screen environments), and have better (optimal) trapping of input events from the user related to graphics.  (Like letting the user draw lines in the graphics area.)  I've never even tried to let a user draw using the mouse on a Panel (for instance), and if you can even do it I'm sure you'd need some extra code to handle it that would be unnecessary in Canvas.

allie
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