This is the second part in a series of technical notes about creating interactive graphic interfaces with 4D Draw.
Part I explained the issues involved in creating the 4D Draw vector graphics needed for these interfaces, and how to convert graphics from other sources. The accompanying "v65Trace" example database demonstrated how to use 4th Dimension to auto-trace bitmapped images to create 4D Draw vector graphics.
Part II begins explaining the code of the example database, focusing on the validation of a picture: how to thoroughly check a BMP document to confirm that it really is in the specific format required by the example database, and how to make sure there won’t be any problems reading it, before you start working with it.
Other parts in this series will continue explaining the example database’s code, and describe techniques you can use to build interactive graphic interfaces with 4D Draw.
The "v65Trace" example database features four menu choices:
1. Convert Picture to BMP
2. BMP Picture Properties
3. Trace BMP Picture
4. 4D Draw Window
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