Since 6.5.2 for transparency to work with TBitmapImage it's newly necessary to set BackColor := clNone

[mpri...@gmail.com]

Hello,

I'm loading transparent .bmp files to TBitmapImage with AlphaFormat := afDefined.

Since Inno Setup 6.5.2 it stopped working for custom TBitmapImages.

But it still worked for images loaded into SelectDirBitmapImage.

Obviously because it is initialized with InitializeFromStockIcon, which sets BackColor := clNone. After applying the same to my custom TBitmapImages, the transparency started working again. It wasn't necessary before 6.5.2.

Martin

[Martijn Laan]

Hi,

The default BackColor of a TBitmapImage is clBtnFace (grey). This is not new. The CodeClasses.iss example script shows setting BackColor to clNone when you want transparency. This is also not new.

I do not know why before 6.5.2 your bitmaps were transparent anyway, but it might be because partially transparent bitmap images barely worked before that version, and you may have gotten lucky somehow.

In general, I recommend always following the example scripts, and being explicit when setting the properties you need, instead of depending on undocumented behavior.

Greetings,
Martijn

Op 30-1-2026 om 12:01 schreef mpri...@gmail.com:

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