Kbase P115908: Does the Progress GUI client support alpha channels in images?
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
7/19/2010 |
|
Status: Verified
GOAL:
Does the Progress GUI client support alpha channels in images?
GOAL:
Does Progress support gradient transparency?
GOAL:
Why does a PNG image not appear translucent in the OpenEdge ABL client?
GOAL:
Why is the shadow effect in an image not properly displayed ?
FACT(s) (Environment):
OpenEdge 10.x
Windows
FIX:
The traditional approach of handling transparency in images is that one color is specified as the "transparent" one and all pixels of that color are replaced by the background color. The GIF file format makes use of this for example.
Alpha Channels are a feature of certain image formats (such as PNG) that allow a much greater control over transparency in images by allowing for a level of transparency to be specified.
This can be used for creating shadow affects that work on any background, for a measure of anti-aliasing and similar effects.
The image rendering libraries for the OpenEdge client do not support alpha channels, thus we can not take advantage of them when using the ABL IMAGE widget, or image properties for other controls (buttons).
Note that when using the .NET UI features, the controls commonly used for displaying images (example: the Microsoft Picturebox control) do support alpha channels.