This is the third part of a technical note series about creating interactive graphic interfaces with 4D Draw.
Part III focuses on one example of a 4D Draw interactive graphic interface: the "Image Data" page of the "BMP Picture Properties" window in the example database. It features a BMP picture displayed in a 4D Draw area. The user can click on any pixel in the picture, and information about the pixel is displayed on the form. This technical note answers questions such as:
- How can you configure a 4D Draw area so its code detects when a user clicks in the area?
- How can you detect which pixel the user clicked in a picture displayed in a 4D Draw area?
- How can you display a cursor over the clicked pixel?
- How can you read color information about that pixel from the BMP document?
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.
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