make button glyph have a transparent background in delphi 7?

3
votes

I have four TSpeedButton objects, each with a BMP file assigned as a glyph for the button image. For whatever reason, delphi has decided that two of the button images should have a transparent background and two should have a white background. I created the bitmaps myself, so they are all saved at the same color depth and are using pure white (not some shade of almost white) for the background and have background color in all four corner pixels of the image.

Why would some of the glyph images show up with a transparent background and some not? What is the criterion for making the background transparent? How can I make my button images all have transparent backgrounds instead of half of them having transparent backgrounds?

2
delphidelphi-7
Delphi's glyph handling uses the pixel in the lower-left corner to determine the transparent color. All pixels that match that color should be shown as transparent. Does the lower-left pixel color match in all of the glyphs, and does it match the areas you want to be transparent? (Without the images, it's hard to tell what the problem is, but I thought I'd post this as a potential for investigation.) – Ken White
I tried a simple image with white pixels at all four corners and it worked here. – Warren P

2 Answers

2
votes

Ken's comment

Delphi's glyph handling uses the pixel in the lower-left corner to determine the transparent color. All pixels that match that color should be shown as transparent. Does the lower-left pixel color match in all of the glyphs, and does it match the areas you want to be transparent? (Without the images, it's hard to tell what the problem is, but I thought I'd post this as a potential for investigation.)

appeared to hold the correct answer (sorry, can't accept a comment as the right answer!). The image I was using had a shadow reaching to the lower left corner so it was almost white in that corner and exactly white in all the other corners.

-1
votes

I had a similar problem with D5 and I cludged a fix for this as I never found out why it was happening.

Define the image size one Row taller than the actual image/glyph is. This will force the image to be written starting at the top left and stop just before the last row. That will force the use of a non-transparent color and the extra row below the image is not visually noticeable.