Specifies the alpha blending factor used for image drawing.
This can be used for wallpaper controls to optionally reduce the image contrast, and hence improve the visibility of the controls placed on the wallpaper.
The alpha blending value is specified as a percentage. Each of the red, green and blue color components of the wallpaper image is separately blended with the corresponding value of the host control's background color according to the formula:
Color(blended) = (BlendFactor * Color(host)) + ((100 - BlendFactor) * Color(wallpaper)
where Color is the value (0 - 255) of the color component (red, green or blue), BlendFactor is the value of the BLEND attribute, and the host is the dialog or dialog element within which the wallpaper is being displayed.
Note that, from the above formula, when the alpha blending factor is set to 0, the contribution to the resulting color from the host control becomes zero and the wallpaper appears opaque. Similarly, when the alpha blending factor is set to 100, the contribution to the resulting color from the wallpaper becomes zero and the wallpaper is fully transparent and cannot be seen. Intermediate values make the wallpaper appear faded and translucent.
| Applies to | Wallpaper control. |
|---|---|
| Data Type | I4 |
| Default Value | 0 (opaque) |
| Possible Values | 0 - 100 |
