split extremely wide ligature glyphs to fit atlas #4386
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LabhanshAgrawal
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@meganrogge @Tyriar can you please review this and let me know if you have any suggestions for webgl renderer? |
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long ligatures render wider than the cells
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got webgl to also work a bit. It's working only when there's something else at the end e.g. '=====================a' but the last char disappears. Needs some more work I guess, but still not fully clear on how the webgl renderer works. @Tyriar any suggestions? |
| // split the image into multiple images to fit into the texture | ||
| const images: ImageData[] = []; |
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Returning an array of images here will complicate things a lot, can we instead force glyphs to have a maximum width of _textureSize? 512px is a lot even on a high device pixel ratio and seems like a reasonable place to stop
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for most glyphs, it'd be an array with a single item, we will have splits only when the image is bigger than texture size. Limiting glyphs to texture size would work mostly, but what to do with the huge ligatures, then?
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To do one step back - is the potentially endless stacking into a bigger and bigger glyph the expected behavior from ligatures, is that transporting the right sematics? How do other output systems (TEs or editors) deal with that?
If its indeed intended, then we have only one "natural" upper bound - the current width of the viewport. Not sure how much hassles it imports - could those big glyphs be rendered from a slow path (eg. skipping the texture atlas logic, instead doing on-the-fly composition)?
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Considering how unimportant a ligature for ================================================> seems to be, I think we should just not support that case and revert to disabling ligatures when it would exceed the width of a texture atlas page. Too much complexity would be introduced (particularly dealing with the special texture in webgl) having a special path that creates a new larger special texture just for this obscure case.
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Sorry, was caught up with things, I will try to update the pr this week to limit ligature size instead.
Thanks
Fixes #4362
Have fixed it for the canvas renderer, got confused with the webgl code, can try it again if someone can give few pointers on how to go about it.