Ensure replacement color is positive #505
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nohe427
approved these changes
Apr 20, 2021
PEConn
reviewed
Apr 20, 2021
| @@ -47,7 +47,7 @@ export class ImageHelper { | |||
| // See https://github.com/GoogleChromeLabs/bubblewrap/issues/488#issuecomment-806560923. | |||
| if (backgroundColor && image.hasAlpha()) { | |||
| // The replacement colour is the same as the background colour, but fully transparent. | |||
| const replacementColor = (backgroundColor.rgbNumber() << 8) & 0xFFFFFF00; | |||
| const replacementColor = ((backgroundColor.rgbNumber() << 8) & 0xFFFFFF00) >>> 0; | |||
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This reads like magic to me (combined with there being no commit message). I'm assuming it's something to do with promoting the integer type?
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TL;DR - bitten by the lack of unsigned integers :D.
0xFFFFFF00is4294967040, right?- However, if you do
0xFFFFFF << 8, you get-256. - So, we force it to be interpreted as a positive int with
(0xFFFFFF << 8) >>> 0
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What is the data type before and after the >>> 0?
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