Crop and zoom Bitmap Image

[nu2Cpp]

I am new to C++ and using Borland Builder 6. I am designing a GUI that will let the user select a part of an image and display/copy that into another larger window. or zooming into it. I have run into a big problem that my program is not copying the right area.

Could this be a problem with scaling or I am not copying the right area? I am completely lost..

 

[2ffat]

This is from May 2002 issue of C++Builder Developer's Journal titled "Fast Bitmap Zooming and Scrolling."

The VCL makes displaying a bitmap trivial—you simply drop a TImage control on your form and then load it with the desired bitmap. If you need to zoom in on the bitmap, set the TImage::Stretch property to true and then resize the TImage accordingly. If the bitmap is too large to display all at once, place the TImage within a TScrollBox. Unfortunately, this combination of controls (a TImage and a TScrollBox) is one of the least optimal ways to display an image with zooming and scrolling capabilities.

He recommends using WM_PAINT. The article covers it all but is too long to post here. Good e-mag, BTW. Worth every penny.

James P. Cottingham
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