This is practically a from scratch rewrite of AtlasEngine.
The initial approach used a very classic monospace text renderer, where
the viewport is subdivided into cells and each cell is assigned one
glyph texture, just like how real terminals used to work.
While we knew that it would have problems with overly large glyphs,
like those found in less often used languages, we didn't expect the
absolutely massive number of fonts that this approach would break.
For one, the assumption that monospace fonts are actually mostly
monospace has turned out to be a complete lie and we can't force users
to use better designed fonts. But more importantly, we can't just
design an entire Unicode fallback font collection from scratch where
every major glyph is monospace either. This is especially problematic
for vertical overhangs which are extremely difficult to handle in a
way that outperforms the much simpler alternative approach:
Just implementing a bog-standard, modern, quad-based text renderer.
Such an approach is both, less code and runs faster due to a less
complex CPU-side. The text shaping engine (in our case DirectWrite)
has to resolve text into glyph indices anyways, so using them directly
for text rendering allows reduces the effort of turning it back into
text ranges and hashing those. It's memory overhead is also reduced,
because we can now break up long ligatures into their individual glyphs.
Especially on AMD APUs I found this approach to run much faster.
A list of issues I think are either obsolete (and could be closed)
or resolved with this PR in combination with #14255:
Closes#6864Closes#6974Closes#8993Closes#9940Closes#10128Closes#12537Closes#13064Closes#13527Closes#13662Closes#13700Closes#13989Closes#14022Closes#14057Closes#14094Closes#14098Closes#14117Closes#14533Closes#14877
## PR Checklist
* Enabling software rendering enables D2D mode ✅
* Both D2D and D3D:
* Background appears correctly ✅✅
* Text appears correctly
* Cascadia Code Regular ✅✅
* Cascadia Code Bold ✅✅
* Cascadia Code Italic ✅✅
* Cascadia Code block chars leave (almost) no gaps ✅✅
* Terminus TTF at 13.5pt leaves no gaps between block chars ✅✅
* ``"`u{e0b2}`u{e0b0}"`` in Fira Code Nerd Font forms a square ✅✅
* Cursor appears correctly
* Legacy small/medium/large ✅✅
* Vertical bar ✅✅
* Underscore ✅✅
* Empty box ✅✅
* Full box ✅✅
* Double underscore ✅✅
* Changing the cursor color works ✅✅
* Selection appears correctly ✅✅
* Scrolling in various manners always renders correctly ✅✅
* Changing the text antialising mode works ✅✅
* Semi-transparent backgrounds work ✅✅
* Scroll-zooming the font size works ✅✅
* Double-size characters work ✅✅
* Resizing while text is printing works ✅✅
* DWM `+Heatmap_ShowDirtyRegions` shows that only the cursor
region is dirty when it's blinking ✅✅
* D2D
* Margins are filled with background color ❌
They're filled with the neighboring's cell background color for
convenience, as D2D doesn't support `D3D11_TEXTURE_ADDRESS_BORDER`
* D3D
* Margins are filled with background color ✅
* Soft fonts work ✅
* Custom shaders enable continous redraw if time constant is used ✅
* Retro shader appears correctly ✅
* Resizing while a custom shader is running works ✅
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