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Date Posted: 07:44:44 05/14/01 Mon
Author: Michel
Subject: Re: The loaded image is not a DIB?
In reply to: wto 's message, "The loaded image is not a DIB?" on 09:41:38 05/12/01 Sat


I am not sure I understand completely. Instead of using a TPicture, you can use a TJpegGraphic object directly.

When you write, "But I found the drawing process does not change the system palette", I am not quite sure what you mean. Are you using a 256 color or less video mode? Envision does not handle well 256 or less color video modes, generally for this reason, because interacting with the system palette is quite involved. A JPEG image does not have a palette, so changing the system palette would involve color quantization to find the best colors.

Envision does store the image in DIB. TDibGraphic class creates the undering DIB using the windows API CreateDIBSection call.

Best regards,


> I declared a TPicture variable named FPicture, and
>use it
>to load a JPEG file by FPicture.LoadFromFile('a.jpg');
>The graphic class processing the JPEG file is
>TJPEGGraphic. And then I use TForm.Canvas.Draw(0,0,
>FPicture.Graphic) to draw
>the picture to my form. But I found the drawing
>process does not change the system palette, so I think
>your FPicture.Graphic is not a DIB. How can I do?(I
>not want to
>use the TImage)

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