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How to change background color

Posted on 1998-04-10
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Last Modified: 2010-04-16
This question is very simple, but I have searched in many documents, and I haven't found the answer. I need to change the gray background to a transparent one in my Applet. How can I do that? what method do I have to use?

Thanks in advance,
Jaime
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Question by:DaThiN
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jpk041897 earned 20 total points
ID: 1234016
Transparent backgrounds are a GIF file format property, not a windows.

An applet is a window that is running on an independant thread from the browser but maintains an intr process communication channel with the browser that invoked it.

So, your question is realy, how can I make a transparent window, and the answer is that you cant.

What you can do though is to place a canvas that covers the entire surface of the applet window and load an image that contains the section of the background that you want place on it.

Since controls can be placed over a canvas you can, with a little work, obtain the same effect.
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by:DaThiN
ID: 1234017
Thanks for the answer... now I have a problem with the canvas. I have the following in my paint( ) method (example taken from my book):


            Canvas c = new Canvas( );
            Image off = c.createImage( 200, 100 );
            Graphics offg = off.getGraphics( );

and after drawing offline, I have:
     
                                    g.drawImage( off, 0, 0, this );

When debugging, I verify that "off" contains "null" upon return from the createImage( ) method. Any suggestion?

Thanks
Jaime


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Expert Comment

by:jpk041897
ID: 1234018
Use MediaTracker to load the graphics.

Take a look at ch.2 of the online book:

Tricks of the Java Programming Gurus
by Glenn L. Vanderburg. et al.

at http://www.mcp.com

under the personal Bookshelp Programming Language library section. (Registration is free).

You will find all the docs and sample code you could need there.
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