Fix horizontal scrolling bugs in AtlasEngine/DxEngine #15707

lhecker · 2023-07-14T12:38:55Z

This commit fixes a number of issues around horizontal scrolling.
DxEngine only had one bug, where the clip rect would cause any content
outside of the actual viewport to be invisible. AtlasEngine had more
bugs, mostly around the conversion from textbuffer-relative coordinates
to viewport-relative coordinates, since AtlasEngine stores things like
the cursor position, attributes, etc., relative to the viewport.

It also renames cellCount to viewportCellCount, because I realized
that it might have to deal with a textBufferCellCount or similar in
the future. I hope that the new name is more descriptive of what it
refers to.

Future improvements to AtlasEngine in particular would be to not copy
the entire Settings struct every time the horizontal scroll offset
changes, and to trim trailing whitespace before shaping text.

This is in preparation for #1860

Validation Steps Performed

Patch RenderingTests to run in the main (and not alt) buffer
Horizontal scrolling of line renditions and attributes works ✅
Selection retains its position (mostly) ✅

lhecker · 2023-07-14T12:39:51Z

src/renderer/atlas/AtlasEngine.api.cpp

@@ -119,7 +119,7 @@ constexpr HRESULT vec2_narrow(U x, U y, vec2<T>& out) noexcept
        if (delta < 0)
        {
            _api.invalidatedRows.start = gsl::narrow_cast<u16>(clamp<int>(_api.invalidatedRows.start + delta, u16min, u16max));
-            _api.invalidatedRows.end = _api.s->cellCount.y;
+            _api.invalidatedRows.end = _api.s->viewportCellCount.y;


It also renames cellCount to viewportCellCount, because I realized that it might have to deal with a textBufferCellCount or similar in the future. I hope that the new name is more descriptive of what it refers to.

lhecker · 2023-07-14T12:40:17Z

src/renderer/atlas/AtlasEngine.api.cpp

+        gsl::narrow<u16>(std::max(1, srNewViewport.right - srNewViewport.left + 1)),
+        gsl::narrow<u16>(std::max(1, srNewViewport.bottom - srNewViewport.top + 1)),


I hope that this makes it a little bit safer than before.

lhecker · 2023-07-14T12:43:28Z

src/renderer/atlas/AtlasEngine.cpp

+    const auto x = std::max(0, coordTarget.x - (_p.s->viewportOffset.x >> shift));
+    const auto y = gsl::narrow_cast<u16>(clamp<til::CoordType>(coordTarget.y, 0, _p.s->viewportCellCount.y));
+    const auto from = gsl::narrow_cast<u16>(clamp<til::CoordType>(x << shift, 0, _p.s->viewportCellCount.x - 1));
+    const auto to = gsl::narrow_cast<u16>(clamp<size_t>((x + cchLine) << shift, from, _p.s->viewportCellCount.x));


Here, the only change is that coordTarget.x is replaced with x.
coordTarget.x is in textbuffer-relative coordinates (so when you scroll horizontally, the left edge of the viewport might be something non-0), but we need viewport relative coordinates where the left edge is always 0.
To do so we first need to horizontal scroll-offset viewportOffset.x from the coordTarget.x, but this breaks with line renditions, because the caller already divides coordTarget.x by 2, whereas viewportOffset.x is not being divided by 2.

And so we first shift viewportOffset.x to the right, then subtract and then finally shift it to the left again to get viewport-relative, unshifted coordinates.

lhecker · 2023-07-14T12:44:53Z

src/renderer/atlas/AtlasEngine.cpp

-        auto right = std::max(left + cursorWidth, 0);
-
-        if (_p.rows[top]->lineRendition != LineRendition::SingleWidth)
+        if (_p.cursorRect)


Just like above we need to shift to the right, subtract and and then shift to the left. The only additional difference here is that we now need to check if the cursorRect is empty (out of bounds), because the cursor might be on, but simply scrolled off to the side.

zadjii-msft · 2023-07-17T12:32:39Z

src/renderer/dx/CustomTextRenderer.cpp

@@ -509,7 +509,7 @@ CATCH_RETURN()
    clipRect.top = origin.y + drawingContext->topClipOffset;
    clipRect.bottom = origin.y + drawingContext->cellSize.height - drawingContext->bottomClipOffset;
    clipRect.left = 0;
-    clipRect.right = drawingContext->targetSize.width;
+    clipRect.right = FLT_MAX;


👀

This seems... interesting. Any chance this breaks something by not clipping on the right side anymore? My attempted fix was (I believe)

clipRect.left = origin.x;

on the line above, but I don't know which is better

Hmm... I think that would work as well, but only if we also do clipRect.right = origin.x + width.
I believe FLT_MAX is correct, because we never limited the left border of the clip-rect either.
This implies to me that the clipRect.right = drawingContext->targetSize.width; is just a hold-over from when we didn't draw entire rows at a time.

DHowett · 2023-07-18T18:32:02Z

src/renderer/atlas/AtlasEngine.cpp

        const auto cursorWidth = 1 + (options.fIsDoubleWidth & (options.cursorType != CursorType::VerticalBar));
+        const auto top = options.coordCursor.y;


The todo from 437L is no longer valid?

This commit fixes a number of issues around horizontal scrolling. DxEngine only had one bug, where the clip rect would cause any content outside of the actual viewport to be invisible. AtlasEngine had more bugs, mostly around the conversion from textbuffer-relative coordinates to viewport-relative coordinates, since AtlasEngine stores things like the cursor position, attributes, etc., relative to the viewport. It also renames `cellCount` to `viewportCellCount`, because I realized that it might have to deal with a `textBufferCellCount` or similar in the future. I hope that the new name is more descriptive of what it refers to. Future improvements to AtlasEngine in particular would be to not copy the entire `Settings` struct every time the horizontal scroll offset changes, and to trim trailing whitespace before shaping text. This is in preparation for #1860 ## Validation Steps Performed * Patch `RenderingTests` to run in the main (and not alt) buffer * Horizontal scrolling of line renditions and attributes works ✅ * Selection retains its position (mostly) ✅ (cherry picked from commit 89c39b0) Service-Card-Id: 90625739 Service-Version: 1.18

This regressed in #15707. By having the `viewportOffset` on the `Settings` object we accidentally invalidate the entire viewport every time it scrolls. That doesn't break anything of course, but it's better to prevent this. This PR additionally contains a fix for clamping the y coordinates coming from `Renderer`: Since `viewportCellCount.y` is a count and thus exclusive, but clamp's max is inclusive, we must subtract 1.

Fix horizontal scrolling bugs in AtlasEngine/DxEngine

cec12bc

lhecker added Area-Rendering Text rendering, emoji, complex glyph & font-fallback issues Issue-Bug It either shouldn't be doing this or needs an investigation. Priority-3 A description (P3) labels Jul 14, 2023

lhecker commented Jul 14, 2023

View reviewed changes

zadjii-msft approved these changes Jul 17, 2023

View reviewed changes

DHowett approved these changes Jul 18, 2023

View reviewed changes

DHowett merged commit 89c39b0 into main Jul 18, 2023
15 checks passed

DHowett deleted the dev/lhecker/1860-fix-hor-scroll branch July 18, 2023 18:35

AloisKraus mentioned this pull request Oct 2, 2023

Terminal desperately needs a horizontal scrollbar (similar to Command Prompt) #1860

Open

lhecker mentioned this pull request Jul 18, 2024

AtlasEngine: Fix dirty rects during scrolling #17583

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Fix horizontal scrolling bugs in AtlasEngine/DxEngine #15707

Fix horizontal scrolling bugs in AtlasEngine/DxEngine #15707

lhecker commented Jul 14, 2023 •

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DHowett Jul 18, 2023

DHowett Jul 18, 2023

		gsl::narrow<u16>(std::max(1, srNewViewport.right - srNewViewport.left + 1)),
		gsl::narrow<u16>(std::max(1, srNewViewport.bottom - srNewViewport.top + 1)),

		const auto cursorWidth = 1 + (options.fIsDoubleWidth & (options.cursorType != CursorType::VerticalBar));
		const auto top = options.coordCursor.y;

Fix horizontal scrolling bugs in AtlasEngine/DxEngine #15707

Fix horizontal scrolling bugs in AtlasEngine/DxEngine #15707

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lhecker commented Jul 14, 2023 • edited Loading

Validation Steps Performed

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lhecker commented Jul 14, 2023 •

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