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## Summary of the Pull Request
This change tries to fix column size calculation when shaping return glyphs that represents multiple characters (e.g. ligature).
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## References
This should fix#696.
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## PR Checklist
* [ ] Closes #xxx
* [X] CLA signed. If not, go over [here](https://cla.opensource.microsoft.com/microsoft/Terminal) and sign the CLA
* [ ] Tests added/passed
* [ ] Requires documentation to be updated
* [ ] I've discussed this with core contributors already. If not checked, I'm ready to accept this work might be rejected in favor of a different grand plan. Issue number where discussion took place: #xxx
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## Detailed Description of the Pull Request / Additional comments
Currently, it seems like CustomTextLayout::_CorrectGlyphRun generally assumes that glyphs and characters have a 1:1 mapping relationship - which holds true for most trivial scenarios with basic western scripts, and also many, but unfortunately not all, monospace "programming" fonts with programming ligatures.
This change makes terminal correctly processes glyphs that represents multiple characters, by properly accumulating the column counts of all these characters together (which I believe is more close to what this code originally intended to do).
There are still many issues existing in both CustomTextLayout as well as the TextBuffer, and the correct solution to them will likely demand large-scale changes, at least at the scale of #3578. I wish small changes like this can serve as a stop gap solution while we take our time to work on the long-term right thing.
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## Validation Steps Performed
Builds and runs. Manual testing confirmed that it solves #696 with both LigConsalata and Fixedsys Excelsior.
* If IDWriteTextFormat1 does not exist, return directly
* We use DXGI_SCALING_NONE create SwapChain first, if failed switch to DXGI_SCALING_STRETCH
Co-Authored-By: Michael Niksa <miniksa@microsoft.com>
Co-Authored-By: Dustin L. Howett (MSFT) <duhowett@microsoft.com>
Certain DirectX features are unavailable on windows 7. The important ones as they are used in the DX renderer are color font rendering and fallback font support. Color fonts did not exist at all on windows 7 so running basic glyphrun rendering should work just fine.
Fallback font support was not exposed to the user in windows 7, making dealing with them difficult. Rather than try to get some workarounds to properly enable it I have opted to just conditionally disable the support on windows 7.
This encompasses a handful of problems with column counting.
The Terminal project didn't set a fallback column counter. Oops. I've fixed this to use the `DxEngine` as the fallback.
The `DxEngine` didn't implement its fallback method. Oops. I've fixed this to use the `CustomTextLayout` to figure out the advances based on the same font and fallback pattern as the real final layout, just without "rounding" it into cells yet.
- `CustomTextLayout` has been updated to move the advance-correction into a separate phase from glyph shaping. Previously, we corrected the advances to nice round cell counts during shaping, which is fine for drawing, but hard for column count analysis.
- Now that there are separate phases, an `Analyze` method was added to the `CustomTextLayout` which just performs the text analysis steps and the glyph shaping, but no advance correction to column boundaries nor actual drawing.
I've taken the caching code that I was working on to improve chafa, and I've brought it into this. Now that we're doing a lot of fallback and heavy lifting in terms of analysis via the layout, we should cache the results until the font changes.
I've adjusted how column counting is done overall. It's always been in these phases:
1. We used a quick-lookup of ranges of characters we knew to rapidly decide `Narrow`, `Wide` or `Invalid` (a.k.a. "I dunno")
2. If it was `Invalid`, we consulted a table based off of the Unicode standard that has either `Narrow`, `Wide`, or `Ambiguous` as a result.
3. If it's still `Ambiguous`, we consult a render engine fallback (usually GDI or now DX) to see how many columns it would take.
4. If we still don't know, then it's `Wide` to be safe.
- I've added an additional flow here. The quick-lookup can now return `Ambiguous` off the bat for some glyph characters in the x2000-x3000 range that used to just be simple shapes but have been retroactively recategorized as emoji and are frequently now using full width color glyphs.
- This new state causes the lookup to go immediately to the render engine if it is available instead of consulting the Unicode standard table first because the half/fullwidth table doesn't appear to have been updated for this nuance to reclass these characters as ambiguous, but we'd like to keep that table as a "generated from the spec" sort of table and keep our exceptions in the "quick lookup" function.
I have confirmed the following things "just work" now:
- The windows logo flag from the demo. (⚫⚪💖✅🌌😊)
- The dotted chart on the side of crossterm demo (•)
- The powerline characters that make arrows with the Consolas patched font (██)
- An accented é
- The warning and checkmark symbols appearing same size as the X. (✔⚠🔥)
Related work items: #21167256, #21237515, #21243859, #21274645, #21296827
