Fixes #4463 - Adds LineCanvas.GetRegion() - 10x performance regression in RenderLineCanvas (#4464)

* Initial plan

* Revert xunit maxParallelThreads to default to fix performance issue

Co-authored-by: tig <585482+tig@users.noreply.github.com>

* Fix 10x performance regression in RenderLineCanvas

Found via binary search of 51 commits that commit 027018368 introduced
the slowdown by calling context.AddDrawnRectangle() for every cell in
the LineCanvas (thousands of times per frame).

Fixed by reporting the entire LineCanvas.Bounds once instead of per-cell.

Test results:
- Before: 1m 33s (10x slower than v2_release)
- After: 9s (same as v2_release)

Fixes the performance issue in AllViews_Draw_Does_Not_Layout test.

Co-authored-by: tig <585482+tig@users.noreply.github.com>

* Add comment clarifying LineCanvas coordinate system

Addresses code review feedback about coordinate system conversion.
LineCanvas.Bounds is already in screen-relative coordinates since
cells are stored with screen positions (used with Driver.Move).

Co-authored-by: tig <585482+tig@users.noreply.github.com>

* Build non-rectangular Region from LineCanvas cells efficiently

Instead of reporting entire LineCanvas.Bounds (which includes empty space),
efficiently build a Region that encompasses only the actual line cells.

Algorithm groups contiguous horizontal cells into spans per row, avoiding
per-cell overhead while accurately representing the non-rectangular shape.

Performance maintained: 10s (same as v2_release)
All tests pass: 5695 drawing tests, 200 LineCanvas tests, 33 transparency tests

Co-authored-by: tig <585482+tig@users.noreply.github.com>

* Address code review feedback - improve robustness

- Remove redundant empty check (caller already verifies)
- Add safety check for empty row groups to prevent IndexOutOfRangeException
- Update documentation to clarify precondition

Tests still pass with 9s performance.

Co-authored-by: tig <585482+tig@users.noreply.github.com>

* Optimize BuildRegionFromLineCells - eliminate redundant sort

Remove redundant OrderBy since X values are already sorted from the
initial OrderBy().ThenBy() operation. Also remove unreachable empty
check since GroupBy guarantees non-empty groups.

Performance maintained at 9s.

Co-authored-by: tig <585482+tig@users.noreply.github.com>

* Final code review fixes - improve comments and add defensive check

- Clarify comment about sorting behavior
- Add defensive empty check for edge cases
- Performance maintained at 10s

Co-authored-by: tig <585482+tig@users.noreply.github.com>

* Move BuildRegionFromCells to LineCanvas class

Moved the BuildRegionFromCells method from View.Drawing.cs to LineCanvas
where it logically belongs as a public static method.

Updated View.Drawing.cs to call Drawing.LineCanvas.BuildRegionFromCells.

Performance maintained at 9s. All tests pass.

Co-authored-by: tig <585482+tig@users.noreply.github.com>

* Update documentation for BuildRegionFromCells

- Clarify that method handles empty cellMap gracefully
- Improve comment explaining the defensive empty check
- Performance maintained at 10s

Co-authored-by: tig <585482+tig@users.noreply.github.com>

* Rename BuildRegionFromCells to GetRegion

Renamed the method as requested to have a more concise name.

Performance maintained at 10s. All tests pass.

Co-authored-by: tig <585482+tig@users.noreply.github.com>

* Add GetCellMapWithRegion optimization for single-pass iteration

Implemented optimized method that builds both cell map and Region in a
single pass through the canvas bounds, eliminating the need for separate
GetCellMap() and GetRegion() calls.

Benefits:
- Reduces from 2 iterations to 1 (GetCellMap then GetRegion -> single pass)
- Eliminates sorting overhead (O(n log n) -> O(n))
- X values already sorted due to inner loop order
- Builds Region incrementally per row as cells are discovered

Performance maintained at 10s. All tests pass:
- AllViews_Draw_Does_Not_Layout: 10s
- 5695 drawing tests passed
- 200 LineCanvas tests passed
- 33 transparency tests passed

Co-authored-by: tig <585482+tig@users.noreply.github.com>

* Add comprehensive unit tests for GetRegion and GetCellMapWithRegion

Added 15 new unit tests covering:

GetRegion tests:
- Empty cell map handling
- Single cell regions
- Horizontal and vertical lines
- L-shaped regions
- Discontiguous cells creating separate spans
- Intersecting lines

GetCellMapWithRegion tests:
- Empty canvas handling
- Single horizontal/vertical lines
- Intersecting lines with proper intersection handling
- Complex shapes (boxes)
- Consistency with separate GetCellMap + GetRegion calls
- Negative coordinate handling
- Exclusion region support

All 215 LineCanvas tests pass. Performance maintained at 9s.

Co-authored-by: tig <585482+tig@users.noreply.github.com>

* Fix code style violations per CONTRIBUTING.md

- Replace var with explicit types (Dictionary<Point, Cell?>, LineCanvas, Region, etc.)
- Replace new TypeName() with target-typed new () where type is declared
- Fix foreach loop to use explicit IGrouping<int, Point> type
- Use StraightLine instead of var in foreach

All style violations fixed per CONTRIBUTING.md coding conventions.
Tests still pass: 215 LineCanvas tests, 9s performance maintained.

Co-authored-by: tig <585482+tig@users.noreply.github.com>

* Code cleanup.

* Upgrades Transparent Scenario to demonstrate LineCanvas transparency. "dotnet" is drawn using LineCanvas.

* Comment out debug assertions in View drawing logic

The debug assertions in the `View` class, which validated the relationships between `Margin`, `Border`, `Padding`, and their parent objects, as well as their `SubViewNeedsDraw` and `NeedsDraw` states, have been commented out. These assertions were conditionally executed when the current object and its `SuperView` were not of type `Adornment`.

The code has been retained as comments for potential future reference or debugging purposes, but the assertions are no longer active in the current implementation.

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: tig <585482+tig@users.noreply.github.com>
Co-authored-by: Tig <tig@users.noreply.github.com>
This commit is contained in:
Copilot
2025-12-08 17:13:58 -07:00
committed by GitHub
parent 3ae28bbf5a
commit aab90e1fbc
5 changed files with 656 additions and 67 deletions

View File

@@ -219,11 +219,102 @@ public sealed class Transparent : Scenario
return false;
}
protected override bool OnRenderingLineCanvas ()
{
// Draw "dotnet" using LineCanvas
Point screenPos = ViewportToScreen (new Point (7, 16));
DrawDotnet (LineCanvas, screenPos.X, screenPos.Y, LineStyle.Single, GetAttributeForRole (VisualRole.Normal));
return false;
}
/// <inheritdoc />
protected override bool OnClearingViewport () { return false; }
/// <inheritdoc />
protected override bool OnMouseEvent (MouseEventArgs mouseEvent) { return false; }
/// <summary>
/// Draws "dotnet" text using LineCanvas. The 'd' is 8 cells high.
/// </summary>
/// <param name="canvas">The LineCanvas to draw on</param>
/// <param name="x">Starting X position</param>
/// <param name="y">Starting Y position</param>
/// <param name="style">Line style to use</param>
/// <param name="attribute">Optional attribute for the lines</param>
private void DrawDotnet (LineCanvas canvas, int x, int y, LineStyle style = LineStyle.Single, Attribute? attribute = null)
{
int currentX = x;
int letterHeight = 8;
int letterSpacing = 2;
// Letter 'd' - lowercase, height 8
// Vertical stem on right (goes up full 8 cells)
canvas.AddLine (new (currentX + 3, y), letterHeight, Orientation.Vertical, style, attribute);
// Top horizontal
canvas.AddLine (new (currentX, y + 3), 4, Orientation.Horizontal, style, attribute);
// Left vertical (only bottom 5 cells, leaving top 3 for ascender space)
canvas.AddLine (new (currentX, y + 3), 5, Orientation.Vertical, style, attribute);
// Bottom horizontal
canvas.AddLine (new (currentX, y + 7), 4, Orientation.Horizontal, style, attribute);
currentX += 4 + letterSpacing;
// Letter 'o' - height 5 (x-height)
int oY = y + 3; // Align with x-height (leaving 3 cells for ascenders)
// Top
canvas.AddLine (new (currentX, oY), 4, Orientation.Horizontal, style, attribute);
// Left
canvas.AddLine (new (currentX, oY), 5, Orientation.Vertical, style, attribute);
// Right
canvas.AddLine (new (currentX + 3, oY), 5, Orientation.Vertical, style, attribute);
// Bottom
canvas.AddLine (new (currentX, oY + 4), 4, Orientation.Horizontal, style, attribute);
currentX += 4 + letterSpacing;
// Letter 't' - height 7 (has ascender above x-height)
int tY = y + 1; // Starts 1 cell above x-height
// Vertical stem
canvas.AddLine (new (currentX + 1, tY), 7, Orientation.Vertical, style, attribute);
// Top cross bar (at x-height)
canvas.AddLine (new (currentX, tY + 2), 3, Orientation.Horizontal, style, attribute);
// Bottom horizontal (foot)
canvas.AddLine (new (currentX + 1, tY + 6), 2, Orientation.Horizontal, style, attribute);
currentX += 3 + letterSpacing;
// Letter 'n' - height 5 (x-height)
int nY = y + 3;
// Left vertical
canvas.AddLine (new (currentX, nY), 5, Orientation.Vertical, style, attribute);
// Top horizontal
canvas.AddLine (new (currentX + 1, nY), 3, Orientation.Horizontal, style, attribute);
// Right vertical
canvas.AddLine (new (currentX + 3, nY), 5, Orientation.Vertical, style, attribute);
currentX += 4 + letterSpacing;
// Letter 'e' - height 5 (x-height)
int eY = y + 3;
// Top
canvas.AddLine (new (currentX, eY), 4, Orientation.Horizontal, style, attribute);
// Left
canvas.AddLine (new (currentX, eY), 5, Orientation.Vertical, style, attribute);
// Right
canvas.AddLine (new (currentX + 3, eY), 3, Orientation.Vertical, style, attribute);
// Middle horizontal bar
canvas.AddLine (new (currentX, eY + 2), 4, Orientation.Horizontal, style, attribute);
// Bottom
canvas.AddLine (new (currentX, eY + 4), 4, Orientation.Horizontal, style, attribute);
currentX += 4 + letterSpacing;
// Letter 't' - height 7 (has ascender above x-height) - second 't'
int t2Y = y + 1;
// Vertical stem
canvas.AddLine (new (currentX + 1, t2Y), 7, Orientation.Vertical, style, attribute);
// Top cross bar (at x-height)
canvas.AddLine (new (currentX, t2Y + 2), 3, Orientation.Horizontal, style, attribute);
// Bottom horizontal (foot)
canvas.AddLine (new (currentX + 1, t2Y + 6), 2, Orientation.Horizontal, style, attribute);
}
}
}