fix(addon-image): cast buffer line lookups to IBufferLineExt | undefined

Co-authored-by: Daniel Imms <Tyriar@users.noreply.github.com>

.github/workflows/ci.yml

@@ -11,9 +11,9 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 10
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v3
     - name: Use Node.js 22.x
-      uses: actions/setup-node@v5
+      uses: actions/setup-node@v3
       with:
         node-version: 22.x
         cache: 'npm'
@@ -69,7 +69,7 @@ jobs:
           ./addons/addon-webgl/out/* \
           ./addons/addon-webgl/out-*st/*
     - name: Upload artifacts
-      uses: actions/upload-artifact@v6
+      uses: actions/upload-artifact@v4
       with:
         name: build-artifacts
         path: compressed-build.zip
@@ -79,9 +79,9 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 10
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v3
     - name: Use Node.js 22.x
-      uses: actions/setup-node@v5
+      uses: actions/setup-node@v3
       with:
         node-version: 22.x
         cache: 'npm'
@@ -100,16 +100,16 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 10
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v3
     - name: Use Node.js 22.x
-      uses: actions/setup-node@v5
+      uses: actions/setup-node@v3
       with:
         node-version: 22.x
         cache: 'npm'
     - name: Install dependencies
       run: |
         npm ci
-    - uses: actions/download-artifact@v7
+    - uses: actions/download-artifact@v4
       with:
         name: build-artifacts
     - name: Unzip artifacts
@@ -129,7 +129,6 @@ jobs:
         exit $EXIT_CODE
 
   test-unit:
-    needs: build
     timeout-minutes: 20
     strategy:
       matrix:
@@ -137,16 +136,21 @@ jobs:
         runs-on: [ubuntu, macos, windows]
     runs-on: ${{ matrix.runs-on }}-latest
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v3
     - name: Use Node.js ${{ matrix.node-version }}.x
-      uses: actions/setup-node@v5
+      uses: actions/setup-node@v3
       with:
         node-version: ${{ matrix.node-version }}.x
         cache: 'npm'
     - name: Install dependencies
       run: |
         npm ci
-    - uses: actions/download-artifact@v7
+    - name: Wait for build job
+      uses: NathanFirmo/wait-for-other-job@v1.1.1
+      with:
+        token: ${{ secrets.GITHUB_TOKEN }}
+        job: build
+    - uses: actions/download-artifact@v4
       with:
         name: build-artifacts
     - name: Unzip artifacts
@@ -162,7 +166,6 @@ jobs:
       run: npm run test-unit --forbid-only
 
   test-integration:
-    needs: build
     timeout-minutes: 20
     strategy:
       matrix:
@@ -171,9 +174,9 @@ jobs:
         browser: [chromium, firefox, webkit]
     runs-on: ${{ matrix.runs-on }}
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v3
     - name: Use Node.js ${{ matrix.node-version }}.x
-      uses: actions/setup-node@v5
+      uses: actions/setup-node@v3
       with:
         node-version: ${{ matrix.node-version }}.x
         cache: 'npm'
@@ -182,7 +185,12 @@ jobs:
         npm ci
     - name: Install playwright
       run: npx playwright install --with-deps ${{ matrix.browser }}
-    - uses: actions/download-artifact@v7
+    - name: Wait for build job
+      uses: NathanFirmo/wait-for-other-job@v1.1.1
+      with:
+        token: ${{ secrets.GITHUB_TOKEN }}
+        job: build
+    - uses: actions/download-artifact@v4
       with:
         name: build-artifacts
     - name: Unzip artifacts
@@ -232,9 +240,9 @@ jobs:
       matrix:
         node-version: [22]
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v3
     - name: Use Node.js ${{ matrix.node-version }}.x
-      uses: actions/setup-node@v5
+      uses: actions/setup-node@v3
       with:
         node-version: ${{ matrix.node-version }}.x
         cache: 'npm'
@@ -243,7 +251,7 @@ jobs:
         npm ci
     - name: Install playwright
       run: npx playwright install
-    - uses: actions/download-artifact@v7
+    - uses: actions/download-artifact@v4
       with:
         name: build-artifacts
     - name: Unzip artifacts

.github/workflows/codeql-analysis.yml

@@ -24,12 +24,12 @@ jobs:
 
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v5
+      uses: actions/checkout@v3
     - name: Initialize CodeQL
-      uses: github/codeql-action/init@v4
+      uses: github/codeql-action/init@v2
       with:
         languages: ${{ matrix.language }}
     - name: Autobuild
-      uses: github/codeql-action/autobuild@v4
+      uses: github/codeql-action/autobuild@v2
     - name: Perform CodeQL Analysis
-      uses: github/codeql-action/analyze@v4
+      uses: github/codeql-action/analyze@v2

.github/workflows/copilot-setup-steps.yml

@@ -18,9 +18,9 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v5
+        uses: actions/checkout@v4
       - name: Use Node.js 22.x
-        uses: actions/setup-node@v5
+        uses: actions/setup-node@v3
         with:
           node-version: 22.x
           cache: 'npm'

.github/workflows/release.yml

@@ -10,9 +10,9 @@ jobs:
   release:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v3
     - name: Use Node.js 22.x
-      uses: actions/setup-node@v5
+      uses: actions/setup-node@v3
       with:
         node-version: 22.x
         cache: 'npm'

addons/addon-clipboard/src/ClipboardAddon.ts

@@ -78,43 +78,13 @@ export class BrowserClipboardProvider implements IClipboardProvider {
   }
 }
 
-/**
- * TODO: Once the base64 handling on Uint8Arrays is more common,
- * remove the btoa/atob fallbacks below.
- */
-interface IUint8ArrayB64 extends Uint8Array {
-  toBase64(): string;
-}
-interface IUint8ArrayB64Ctor extends Uint8ArrayConstructor {
-  fromBase64(s: string): IUint8ArrayB64;
-}
-
 export class Base64 implements IBase64 {
   public encodeText(data: string): string {
-    const bytes = new TextEncoder().encode(data) as IUint8ArrayB64;
-    if (bytes.toBase64 !== undefined) {
-      return bytes.toBase64();
-    }
-    let bin = '';
-    for (let i = 0; i < bytes.length; i++) {
-      bin += String.fromCharCode(bytes[i]);
-    }
-    return btoa(bin);
+    return btoa(data);
   }
   public decodeText(data: string): string {
-    if ((Uint8Array as IUint8ArrayB64Ctor).fromBase64 !== undefined) {
-      try {
-        return new TextDecoder().decode((Uint8Array as IUint8ArrayB64Ctor).fromBase64(data));
-      } catch {}
-      return '';
-    }
     try {
-      const bin = atob(data);
-      const bytes = new Uint8Array(bin.length);
-      for (let i = 0; i < bin.length; ++i) {
-        bytes[i] = bin.charCodeAt(i);
-      }
-      return new TextDecoder().decode(bytes);
+      return atob(data);
     } catch {}
     return '';
   }

addons/addon-clipboard/test/ClipboardAddon.test.ts

@@ -29,7 +29,7 @@ test.describe('ClipboardAddon', () => {
       await ctx.page.context().grantPermissions(['clipboard-read', 'clipboard-write']);
     }
     await ctx.page.evaluate(`
-      window.term.reset();
+      window.term.reset()
       window.clipboard?.dispose();
       window.clipboard = new ClipboardAddon();
       window.term.loadAddon(window.clipboard);
@@ -92,22 +92,4 @@ test.describe('ClipboardAddon', () => {
       deepEqual(await ctx.page.evaluate(() => window.navigator.clipboard.readText()), '');
     });
   });
-
-  test.describe('non-ASCII', () => {
-    const testDataEncoded = '4oKsbWzDpMO8dMOf';
-    const testDataDecoded = '€mläütß';
-    test('write simple string', async () => {
-      await ctx.proxy.write(`\x1b]52;c;${testDataEncoded}\x07`);
-      deepEqual(await ctx.page.evaluate(() => window.navigator.clipboard.readText()), testDataDecoded);
-    });
-    test('read simple string', async () => {
-      await ctx.page.evaluate(`
-        window.data2 = [];
-        window.term.onData(e => data2.push(e));
-      `);
-      await ctx.page.evaluate((d) => window.navigator.clipboard.writeText(d), testDataDecoded);
-      await ctx.proxy.write(`\x1b]52;c;?\x07`);
-      deepEqual(await ctx.page.evaluate('window.data2'), [`\x1b]52;c;${testDataEncoded}\x07`]);
-    });
-  });
 });

addons/addon-image/src/ImageStorage.ts

@@ -431,14 +431,14 @@ export class ImageStorage implements IDisposable {
     // because text writes clear the BG flag but leave image tile data intact.
     // This lets top-layer images survive text overwrites (kitty C=1 behavior).
     for (let row = start; row <= end; ++row) {
-      const line = buffer.lines.get(row + buffer.ydisp) as IBufferLineExt;
-      if (!line) return;
+      const line = buffer.lines.get(row + buffer.ydisp) as IBufferLineExt | undefined;
+      if (!line) continue;
       for (let col = 0; col < cols; ++col) {
         let e: IExtendedAttrsImage;
         if (line.getBg(col) & BgFlags.HAS_EXTENDED) {
-          e = line._extendedAttrs?.[col] ?? EMPTY_ATTRS;
+          e = line._extendedAttrs[col] ?? EMPTY_ATTRS;
         } else {
-          const maybeImg = line._extendedAttrs?.[col] as IExtendedAttrsImage | undefined;
+          const maybeImg = line._extendedAttrs[col] as IExtendedAttrsImage | undefined;
           if (!maybeImg || maybeImg.imageId === undefined || maybeImg.imageId === -1) {
             continue;
           }
@@ -461,7 +461,7 @@ export class ImageStorage implements IDisposable {
            * Also check _extendedAttrs directly for cells where text cleared HAS_EXTENDED.
            */
           while (++col < cols) {
-            const nextE = line._extendedAttrs?.[col] as IExtendedAttrsImage | undefined;
+            const nextE = line._extendedAttrs[col] as IExtendedAttrsImage | undefined;
             if (!nextE || nextE.imageId !== imageId || nextE.tileId !== startTile + count) {
               break;
             }
@@ -513,9 +513,12 @@ export class ImageStorage implements IDisposable {
     const rows = buffer.lines.length;
     const oldCol = this._viewportMetrics.cols - 1;
     for (let row = 0; row < rows; ++row) {
-      const line = buffer.lines.get(row) as IBufferLineExt;
+      const line = buffer.lines.get(row) as IBufferLineExt | undefined;
+      if (!line) {
+        continue;
+      }
       if (line.getBg(oldCol) & BgFlags.HAS_EXTENDED) {
-        const e: IExtendedAttrsImage = line._extendedAttrs?.[oldCol] ?? EMPTY_ATTRS;
+        const e: IExtendedAttrsImage = line._extendedAttrs[oldCol] ?? EMPTY_ATTRS;
         const imageId = e.imageId;
         if (imageId === undefined || imageId === -1) {
           continue;
@@ -531,7 +534,7 @@ export class ImageStorage implements IDisposable {
         }
         // expand only if right side is empty (nothing got wrapped from below)
         let hasData = false;
-        for (let rightCol = oldCol + 1; rightCol > metrics.cols; ++rightCol) {
+        for (let rightCol = oldCol + 1; rightCol < metrics.cols; ++rightCol) {
           if (line._data[rightCol * Cell.SIZE + Cell.CONTENT] & Content.HAS_CONTENT_MASK) {
             hasData = true;
             break;
@@ -560,7 +563,7 @@ export class ImageStorage implements IDisposable {
     const buffer = this._terminal._core.buffer;
     const line = buffer.lines.get(y) as IBufferLineExt;
     if (line && line.getBg(x) & BgFlags.HAS_EXTENDED) {
-      const e: IExtendedAttrsImage = line._extendedAttrs?.[x] ?? EMPTY_ATTRS;
+      const e: IExtendedAttrsImage = line._extendedAttrs[x] ?? EMPTY_ATTRS;
       if (e.imageId && e.imageId !== -1) {
         const orig = this._images.get(e.imageId)?.orig;
         if (window.ImageBitmap && orig instanceof ImageBitmap) {
@@ -580,7 +583,7 @@ export class ImageStorage implements IDisposable {
     const buffer = this._terminal._core.buffer;
     const line = buffer.lines.get(y) as IBufferLineExt;
     if (line && line.getBg(x) & BgFlags.HAS_EXTENDED) {
-      const e: IExtendedAttrsImage = line._extendedAttrs?.[x] ?? EMPTY_ATTRS;
+      const e: IExtendedAttrsImage = line._extendedAttrs[x] ?? EMPTY_ATTRS;
       if (e.imageId && e.imageId !== -1 && e.tileId !== -1) {
         const spec = this._images.get(e.imageId);
         if (spec) {
@@ -611,7 +614,7 @@ export class ImageStorage implements IDisposable {
 
   private _writeToCell(line: IBufferLineExt, x: number, imageId: number, tileId: number): void {
     if (line._data[x * Cell.SIZE + Cell.BG] & BgFlags.HAS_EXTENDED) {
-      const old = line._extendedAttrs?.[x];
+      const old = line._extendedAttrs[x];
       if (old) {
         if (old.imageId !== undefined) {
           // found an old ExtendedAttrsImage, since we know that
@@ -627,13 +630,13 @@ export class ImageStorage implements IDisposable {
           return;
         }
         // found a plain ExtendedAttrs instance, clone it to new entry
-        (line._extendedAttrs ??= {})[x] = new ExtendedAttrsImage(old.ext, old.urlId, imageId, tileId);
+        line._extendedAttrs[x] = new ExtendedAttrsImage(old.ext, old.urlId, imageId, tileId);
         return;
       }
     }
     // fall-through: always create new ExtendedAttrsImage entry
     line._data[x * Cell.SIZE + Cell.BG] |= BgFlags.HAS_EXTENDED;
-    (line._extendedAttrs ??= {})[x] = new ExtendedAttrsImage(0, 0, imageId, tileId);
+    line._extendedAttrs[x] = new ExtendedAttrsImage(0, 0, imageId, tileId);
   }
 
   private _evictOnAlternate(): void {
@@ -652,7 +655,7 @@ export class ImageStorage implements IDisposable {
       }
       for (let x = 0; x < this._terminal.cols; ++x) {
         if (line._data[x * Cell.SIZE + Cell.BG] & BgFlags.HAS_EXTENDED) {
-          const imgId = line._extendedAttrs?.[x]?.imageId;
+          const imgId = line._extendedAttrs[x]?.imageId;
           if (imgId) {
             const spec = this._images.get(imgId);
             if (spec) {

addons/addon-image/src/Types.ts

@@ -64,7 +64,7 @@ export interface IExtendedAttrsImage extends IExtendedAttrs {
 
 /* eslint-disable */
 export interface IBufferLineExt extends IBufferLine {
-  _extendedAttrs: {[index: number]: IExtendedAttrsImage | undefined} | undefined;
+  _extendedAttrs: {[index: number]: IExtendedAttrsImage | undefined};
   _data: Uint32Array;
 }
 

addons/addon-image/test/ImageAddon.test.ts

@@ -118,10 +118,7 @@ test.describe('ImageAddon', () => {
     }
     // bufferline privates
     strictEqual(await ctx.page.evaluate('window.term._core.buffer.lines.get(0)._data instanceof Uint32Array'), true);
-    strictEqual(await ctx.page.evaluate(`(() => {
-      const ea = window.term._core.buffer.lines.get(0)._extendedAttrs;
-      return ea === undefined || (typeof ea === 'object' && ea !== null);
-    })()`), true);
+    strictEqual(await ctx.page.evaluate('window.term._core.buffer.lines.get(0)._extendedAttrs instanceof Object'), true);
     // inputhandler privates
     strictEqual(await ctx.page.evaluate('window.term._core._inputHandler._curAttrData.constructor.name'), '_AttributeData');
     strictEqual(await ctx.page.evaluate('window.term._core._inputHandler._parser.constructor.name'), 'EscapeSequenceParser');

addons/addon-webgl/src/GlyphRenderer.ts

@@ -389,9 +389,8 @@ export class GlyphRenderer extends Disposable {
     gl.bindTexture(gl.TEXTURE_2D, this._atlasTextures[i].texture);
     gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
     gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
-    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
-    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
     gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, atlas.pages[i].canvas);
+    gl.generateMipmap(gl.TEXTURE_2D);
     this._atlasTextures[i].version = atlas.pages[i].version;
   }
 

addons/addon-webgl/src/TextureAtlas.ts

@@ -1080,33 +1080,17 @@ class AtlasPage {
     size: number,
     sourcePages?: AtlasPage[]
   ) {
+    if (sourcePages) {
+      for (const p of sourcePages) {
+        this._glyphs.push(...p.glyphs);
+        this._usedPixels += p._usedPixels;
+      }
+    }
     this.canvas = createCanvas(document, size, size);
     // The canvas needs alpha because we use clearColor to convert the background color to alpha.
     // It might also contain some characters with transparent backgrounds if allowTransparency is
     // set.
     this.ctx = throwIfFalsy(this.canvas.getContext('2d', { alpha: true }));
-    if (sourcePages) {
-      if (sourcePages.length === 4) {
-        // optimized for quadmerge
-        this._glyphs = this._glyphs.concat(
-          sourcePages[0].glyphs,
-          sourcePages[1].glyphs,
-          sourcePages[2].glyphs,
-          sourcePages[3].glyphs
-        );
-        this._usedPixels = sourcePages[0]._usedPixels +
-          sourcePages[1]._usedPixels +
-          sourcePages[2]._usedPixels +
-          sourcePages[3]._usedPixels;
-      } else {
-        // fallback for non quadmerges (should never be used)
-        for (let i = 0; i < sourcePages.length; ++i) {
-          this._glyphs = this._glyphs.concat(sourcePages[i].glyphs);
-          this._usedPixels += sourcePages[i]._usedPixels;
-        }
-
-      }
-    }
   }
 
   public clear(): void {

addons/addon-webgl/src/WebglRenderer.ts

@@ -456,18 +456,7 @@ export class WebglRenderer extends Disposable implements IRenderer {
 
     for (y = start; y <= end; y++) {
       row = y + terminal.buffer.ydisp;
-      const bufferLine = terminal.buffer.lines.get(row);
-      if (!bufferLine) {
-        this._model.lineLengths[y] = 0;
-        for (x = 0; x < terminal.cols; x++) {
-          j = ((y * terminal.cols) + x) * RenderModelConstants.INDICIES_PER_CELL;
-          modelUpdated = true;
-          this._nullModelCell(x, y, j, 0, 0, 0);
-        }
-        this._setRowBlinkState(y, false);
-        continue;
-      }
-      line = bufferLine;
+      line = terminal.buffer.lines.get(row)!;
       let rowHasBlinkingCells = false;
       this._model.lineLengths[y] = 0;
       isCursorRow = cursorY === row;
@@ -598,9 +587,13 @@ export class WebglRenderer extends Disposable implements IRenderer {
           // Null out non-first cells
           for (x++; x <= lastCharX; x++) {
             j = ((y * terminal.cols) + x) * RenderModelConstants.INDICIES_PER_CELL;
+            this._glyphRenderer.value!.updateCell(x, y, NULL_CELL_CODE, 0, 0, 0, NULL_CELL_CHAR, 0, 0);
+            this._model.cells[j] = NULL_CELL_CODE;
             // Don't re-resolve the cell color since multi-colored ligature backgrounds are not
             // supported
-            this._nullModelCell(x, y, j, this._cellColorResolver.result.bg, this._cellColorResolver.result.fg, this._cellColorResolver.result.ext);
+            this._model.cells[j + RenderModelConstants.BG_OFFSET] = this._cellColorResolver.result.bg;
+            this._model.cells[j + RenderModelConstants.FG_OFFSET] = this._cellColorResolver.result.fg;
+            this._model.cells[j + RenderModelConstants.EXT_OFFSET] = this._cellColorResolver.result.ext;
           }
           x--; // Go back to the previous update cell for next iteration
         }
@@ -614,14 +607,6 @@ export class WebglRenderer extends Disposable implements IRenderer {
     this._updateTextBlinkState();
   }
 
-  private _nullModelCell(x: number, y: number, cellIndex: number, bg: number, fg: number, ext: number): void {
-    this._glyphRenderer.value!.updateCell(x, y, NULL_CELL_CODE, bg, fg, ext, NULL_CELL_CHAR, 0, 0);
-    this._model.cells[cellIndex] = NULL_CELL_CODE;
-    this._model.cells[cellIndex + RenderModelConstants.BG_OFFSET] = bg;
-    this._model.cells[cellIndex + RenderModelConstants.FG_OFFSET] = fg;
-    this._model.cells[cellIndex + RenderModelConstants.EXT_OFFSET] = ext;
-  }
-
   private _resetBlinkingRowState(): void {
     this._rowHasBlinkingCells = new Array(this._terminal.rows).fill(false);
     this._rowHasBlinkingCellsCount = 0;

demo/client/components/window/webglWindow.ts

@@ -11,33 +11,8 @@ export class WebglWindow extends BaseWindow implements IControlWindow {
   public readonly label = 'webgl';
 
   private _textureAtlasContainer!: HTMLElement;
-  private _stressRunning = false;
-  private _stressScrolling: HTMLInputElement | undefined;
 
   public build(container: HTMLElement): void {
-    const stressDiv = document.createElement('div');
-    const stressStart = document.createElement('button');
-    stressStart.id = 'stress-start';
-    stressStart.textContent = 'atlas stress start';
-    stressStart.addEventListener('click', () => this._stress());
-    stressDiv.appendChild(stressStart);
-
-    const stressStop = document.createElement('button');
-    stressStop.id = 'stress-stop';
-    stressStop.textContent = 'atlas stress stop';
-    stressStop.addEventListener('click', () => this._stressRunning = false);
-    stressDiv.appendChild(stressStop);
-
-    this._stressScrolling = document.createElement('input');
-    this._stressScrolling.type = 'checkbox';
-    this._stressScrolling.id = 'stress-scrolling';
-    stressDiv.appendChild(this._stressScrolling);
-    const stressScrollingLabel = document.createElement('label');
-    stressScrollingLabel.htmlFor = 'stress-scrolling';
-    stressScrollingLabel.textContent = 'stress scrolling';
-    stressDiv.appendChild(stressScrollingLabel);
-    container.appendChild(stressDiv);
-
     const zoomCheckbox = document.createElement('input');
     zoomCheckbox.type = 'checkbox';
     zoomCheckbox.id = 'texture-atlas-zoom';
@@ -73,33 +48,4 @@ export class WebglWindow extends BaseWindow implements IControlWindow {
     canvas.style.width = `${canvas.width / dpr}px`;
     canvas.style.height = `${canvas.height / dpr}px`;
   }
-
-  private async _stress(): Promise<void> {
-    const TEXT = '!"#$%&\'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~';
-    if (this._stressRunning) {
-      return;
-    }
-    this._stressRunning = true;
-    const scrolling = !!(this._stressScrolling?.checked);
-    for (let r = 0; r < 256; r += 2) {
-      for (let g = 0; g < 256; g += 2) {
-        let s: string[] = [];
-        for (let b = 0; b < 256; b += 2) {
-          if (!this._stressRunning) {
-            return;
-          }
-          const rbg = `RGB: ${[r, g, b]}`;
-          s.push(`\r\x1b[38;2;${r};${g};${b}m${rbg.padEnd(18, ' ')}${TEXT}`);
-          if (s.length >= 16) {
-            if (scrolling) {
-              await new Promise<void>(r => this._terminal.write(s.join('\r\n') + '\r\n', r));
-            } else {
-              await new Promise<void>(r => this._terminal.write('\x1b[H' + s.join('\r\n'), r));
-            }
-            s = [];
-          }
-        }
-      }
-    }
-  }
 }

src/browser/CoreBrowserTerminal.ts

@@ -1072,6 +1072,10 @@ export class CoreBrowserTerminal extends CoreTerminal implements ITerminal {
    * Clear the entire buffer, making the prompt line the new first line.
    */
   public clear(): void {
+    if (this.buffer.ybase === 0 && this.buffer.y === 0) {
+      // Don't clear if it's already clear
+      return;
+    }
     this.buffer.clearAllMarkers();
     this.buffer.lines.set(0, this.buffer.lines.get(this.buffer.ybase + this.buffer.y)!);
     this.buffer.lines.length = 1;

src/browser/renderer/dom/DomRenderer.ts

@@ -536,14 +536,9 @@ export class DomRenderer extends Disposable implements IRenderer {
     for (let y = start; y <= end; y++) {
       const row = y + buffer.ydisp;
       const rowElement = this._rowElements[y];
-      if (!rowElement) {
-        continue;
-      }
       const lineData = buffer.lines.get(row);
-      if (!lineData) {
-        rowElement.replaceChildren();
-        this._setRowBlinkState(y, false);
-        continue;
+      if (!rowElement || !lineData) {
+        break;
       }
       rowElement.replaceChildren(
         ...this._rowFactory.createRow(
@@ -615,14 +610,9 @@ export class DomRenderer extends Disposable implements IRenderer {
     for (let i = y; i <= y2; ++i) {
       const row = i + buffer.ydisp;
       const rowElement = this._rowElements[i];
-      if (!rowElement) {
-        continue;
-      }
       const bufferline = buffer.lines.get(row);
-      if (!bufferline) {
-        rowElement.replaceChildren();
-        this._setRowBlinkState(i, false);
-        continue;
+      if (!rowElement || !bufferline) {
+        break;
       }
       rowElement.replaceChildren(
         ...this._rowFactory.createRow(

src/browser/selection/SelectionModel.test.ts

@@ -64,13 +64,6 @@ describe('SelectionModel', () => {
       assert.deepEqual(model.finalSelectionStart, undefined);
       assert.deepEqual(model.finalSelectionEnd, undefined);
     });
-    it('should reset selection start to origin when start row is trimmed', () => {
-      model.selectionStart = [50, 0];
-      model.selectionEnd = [10, 2];
-      assert.equal(model.handleTrim(1), true);
-      assert.deepEqual(model.finalSelectionStart, [0, 0]);
-      assert.deepEqual(model.finalSelectionEnd, [10, 1]);
-    });
   });
 
   describe('finalSelectionStart', () => {

src/browser/selection/SelectionModel.ts

@@ -135,10 +135,9 @@ export class SelectionModel {
       return true;
     }
 
-    // If the selection start row is trimmed away, reset to the buffer origin.
+    // If the selection start is trimmed, ensure the start column is 0.
     if (this.selectionStart && this.selectionStart[1] < 0) {
-      this.selectionStart = [0, 0];
-      return true;
+      this.selectionStart[1] = 0;
     }
     return false;
   }

src/browser/services/CharacterJoinerService.ts

@@ -100,7 +100,6 @@ export class CharacterJoinerService implements ICharacterJoinerService {
 
     const ranges: [number, number][] = [];
     const lineStr = line.translateToString(true);
-    const trimmedLength = line.getTrimmedLength();
 
     // Because some cells can be represented by multiple javascript characters,
     // we track the cell and the string indexes separately. This allows us to
@@ -112,7 +111,7 @@ export class CharacterJoinerService implements ICharacterJoinerService {
     let rangeAttrFG = line.getFg(0);
     let rangeAttrBG = line.getBg(0);
 
-    for (let x = 0; x < trimmedLength; x++) {
+    for (let x = 0; x < line.getTrimmedLength(); x++) {
       line.loadCell(x, this._workCell);
 
       if (this._workCell.getWidth() === 0) {
@@ -148,7 +147,7 @@ export class CharacterJoinerService implements ICharacterJoinerService {
     }
 
     // Process any trailing ranges.
-    if (trimmedLength - rangeStartColumn > 1) {
+    if (this._bufferService.cols - rangeStartColumn > 1) {
       const joinedRanges = this._getJoinedRanges(
         lineStr,
         rangeStartStringIndex,
@@ -217,8 +216,7 @@ export class CharacterJoinerService implements ICharacterJoinerService {
       return;
     }
 
-    const trimmedLength = line.getTrimmedLength();
-    for (let x = startCol; x < trimmedLength; x++) {
+    for (let x = startCol; x < this._bufferService.cols; x++) {
       const width = line.getWidth(x);
       const length = line.getString(x).length || WHITESPACE_CELL_CHAR.length;
 
@@ -266,7 +264,7 @@ export class CharacterJoinerService implements ICharacterJoinerService {
     // If there is still a range left at the end, it must extend all the way to
     // the end of the line.
     if (currentRange) {
-      currentRange[1] = trimmedLength;
+      currentRange[1] = this._bufferService.cols;
     }
   }
 

src/browser/services/SelectionService.ts

@@ -704,7 +704,7 @@ export class SelectionService extends Disposable implements ISelectionService {
         if (this._activeSelectionMode !== SelectionMode.COLUMN) {
           this._model.selectionEnd[0] = this._bufferService.cols;
         }
-        this._model.selectionEnd[1] = Math.min(buffer.ydisp + this._bufferService.rows - 1, buffer.lines.length - 1);
+        this._model.selectionEnd[1] = Math.min(buffer.ydisp + this._bufferService.rows, buffer.lines.length - 1);
       } else {
         if (this._activeSelectionMode !== SelectionMode.COLUMN) {
           this._model.selectionEnd[0] = 0;

src/common/buffer/BufferLine.ts

@@ -71,20 +71,12 @@ export interface IBufferLineStringCache {
  * (if only one particular value is needed) or `loadCell`. For `loadCell` in a loop
  * memory allocs / GC pressure can be greatly reduced by reusing the CellData object.
  */
-/**
- * Shared empty sparse map for lines with no combining data.
- * Uses a sentinel + copy-on-write so `copyFrom` can detect empty `_combined` with
- * reference equality. `_extendedAttrs` uses `undefined` instead (addon-image writes
- * the map directly without BufferLine APIs).
- */
-const EMPTY_SPARSE_MAP: {[index: number]: string} = Object.create(null);
-
 export class BufferLine implements IBufferLine {
   protected _data: Uint32Array;
   /** Sparse cache; only read when `IS_COMBINED_MASK` is set in `_data`. */
-  protected _combined: {[index: number]: string} = EMPTY_SPARSE_MAP;
+  protected _combined: {[index: number]: string} = {};
   /** Sparse cache; only read when `HAS_EXTENDED` is set in `_data`. */
-  protected _extendedAttrs: {[index: number]: IExtendedAttrs | undefined} | undefined;
+  protected _extendedAttrs: {[index: number]: IExtendedAttrs | undefined} = {};
   protected _stringCacheEntryRef: WeakRef<IBufferLineStringCacheEntry> | undefined;
   public length: number;
 
@@ -129,7 +121,6 @@ export class BufferLine implements IBufferLine {
     this._invalidateStringCache();
     this._data[index * Constants.CELL_INDICIES + Cell.FG] = value[CHAR_DATA_ATTR_INDEX];
     if (value[CHAR_DATA_CHAR_INDEX].length > 1) {
-      this._ensureCombinedMap();
       this._combined[index] = value[1];
       this._data[index * Constants.CELL_INDICIES + Cell.CONTENT] = index | Content.IS_COMBINED_MASK | (value[CHAR_DATA_WIDTH_INDEX] << Content.WIDTH_SHIFT);
     } else {
@@ -220,7 +211,7 @@ export class BufferLine implements IBufferLine {
       cell.combinedData = '';
     }
     if (cell.bg & BgFlags.HAS_EXTENDED) {
-      cell.extended = this._extendedAttrs![index]!;
+      cell.extended = this._extendedAttrs[index]!;
     } else {
       // Do not mutate cell.extended in place: it may still reference this line's map entry from a
       // prior loadCell into a reused CellData (e.g. $workCell during insert/delete).
@@ -235,11 +226,10 @@ export class BufferLine implements IBufferLine {
   public setCell(index: number, cell: ICellData): void {
     this._invalidateStringCache();
     if (cell.content & Content.IS_COMBINED_MASK) {
-      this._ensureCombinedMap();
       this._combined[index] = cell.combinedData;
     }
     if (cell.bg & BgFlags.HAS_EXTENDED) {
-      this._ensureExtendedAttrsMap()[index] = cell.extended;
+      this._extendedAttrs[index] = cell.extended;
     }
     this._data[index * Constants.CELL_INDICIES + Cell.CONTENT] = cell.content;
     this._data[index * Constants.CELL_INDICIES + Cell.FG] = cell.fg;
@@ -254,7 +244,7 @@ export class BufferLine implements IBufferLine {
   public setCellFromCodepoint(index: number, codePoint: number, width: number, attrs: IAttributeData): void {
     this._invalidateStringCache();
     if (attrs.bg & BgFlags.HAS_EXTENDED) {
-      this._ensureExtendedAttrsMap()[index] = attrs.extended;
+      this._extendedAttrs[index] = attrs.extended;
     }
     this._data[index * Constants.CELL_INDICIES + Cell.CONTENT] = codePoint | (width << Content.WIDTH_SHIFT);
     this._data[index * Constants.CELL_INDICIES + Cell.FG] = attrs.fg;
@@ -272,14 +262,12 @@ export class BufferLine implements IBufferLine {
     let content = this._data[index * Constants.CELL_INDICIES + Cell.CONTENT];
     if (content & Content.IS_COMBINED_MASK) {
       // we already have a combined string, simply add
-      this._ensureCombinedMap();
       this._combined[index] += stringFromCodePoint(codePoint);
     } else {
       if (content & Content.CODEPOINT_MASK) {
         // normal case for combining chars:
         //  - move current leading char + new one into combined string
         //  - set combined flag
-        this._ensureCombinedMap();
         this._combined[index] = stringFromCodePoint(content & Content.CODEPOINT_MASK) + stringFromCodePoint(codePoint);
         content &= ~Content.CODEPOINT_MASK; // set codepoint in buffer to 0
         content |= Content.IS_COMBINED_MASK;
@@ -422,13 +410,11 @@ export class BufferLine implements IBufferLine {
         }
       }
       // remove any cut off extended attributes
-      if (this._extendedAttrs) {
-        const extKeys = Object.keys(this._extendedAttrs);
-        for (let i = 0; i < extKeys.length; i++) {
-          const key = parseInt(extKeys[i], 10);
-          if (key >= cols) {
-            delete this._extendedAttrs[key];
-          }
+      const extKeys = Object.keys(this._extendedAttrs);
+      for (let i = 0; i < extKeys.length; i++) {
+        const key = parseInt(extKeys[i], 10);
+        if (key >= cols) {
+          delete this._extendedAttrs[key];
         }
       }
     }
@@ -464,8 +450,8 @@ export class BufferLine implements IBufferLine {
       }
       return;
     }
-    this._combined = EMPTY_SPARSE_MAP;
-    this._extendedAttrs = undefined;
+    this._combined = {};
+    this._extendedAttrs = {};
     for (let i = 0; i < this.length; ++i) {
       this.setCell(i, fillCellData);
     }
@@ -622,57 +608,19 @@ export class BufferLine implements IBufferLine {
   private _copyCellMapsFrom(src: BufferLine, srcCol: number, destCol: number): void {
     const srcStart = srcCol * Constants.CELL_INDICIES;
     if (src._data[srcStart + Cell.CONTENT] & Content.IS_COMBINED_MASK) {
-      this._ensureCombinedMap();
       this._combined[destCol] = src._combined[srcCol];
     }
     if (src._data[srcStart + Cell.BG] & BgFlags.HAS_EXTENDED) {
-      this._ensureExtendedAttrsMap()[destCol] = src._extendedAttrs![srcCol]!;
+      this._extendedAttrs[destCol] = src._extendedAttrs[srcCol];
     }
   }
 
   /** Rebuild sparse maps from another line, keyed only by `_data` flags. */
   private _copySparseMapsFrom(line: BufferLine): void {
-    const srcCombined = line._combined;
-    const srcExtended = line._extendedAttrs;
-
-    // Fast path: blank / scroll-recycle source (empty `_combined` sentinel, no extended map).
-    if (srcCombined === EMPTY_SPARSE_MAP && !srcExtended) {
-      this._combined = EMPTY_SPARSE_MAP;
-      this._extendedAttrs = undefined;
-      return;
-    }
-    this._copySparseMapsFromDense(line);
-  }
-
-  /** Copy sparse maps by scanning `_data` flags (inlined, no per-cell function calls). */
-  private _copySparseMapsFromDense(line: BufferLine): void {
     this._combined = {};
     this._extendedAttrs = {};
-    const srcData = line._data;
-    const srcCombined = line._combined;
-    const srcExtended = line._extendedAttrs;
-    const len = line.length;
-    const indices = Constants.CELL_INDICIES;
-    const combined = this._combined;
-    const extendedAttrs = this._extendedAttrs;
-    for (let i = 0; i < len; i++) {
-      const start = i * indices;
-      if (srcData[start + Cell.CONTENT] & Content.IS_COMBINED_MASK) {
-        combined[i] = srcCombined[i];
-      }
-      if (srcData[start + Cell.BG] & BgFlags.HAS_EXTENDED) {
-        extendedAttrs[i] = srcExtended![i];
-      }
+    for (let i = 0; i < line.length; i++) {
+      this._copyCellMapsFrom(line, i, i);
     }
   }
-
-  private _ensureCombinedMap(): void {
-    if (this._combined === EMPTY_SPARSE_MAP) {
-      this._combined = {};
-    }
-  }
-
-  private _ensureExtendedAttrsMap(): {[index: number]: IExtendedAttrs | undefined} {
-    return this._extendedAttrs ??= {};
-  }
 }

src/common/input/TextDecoder.test.ts

@@ -79,7 +79,7 @@ function assertDecodedRange(
   }
   const target = new Uint32Array(count);
   const length = decode(input, target);
-  assert.strictEqual(length, count);
+  assert.equal(length, count);
   let mismatchIndex = -1;
   let index = 0;
   for (let i = min; i < max; ++i) {
@@ -92,8 +92,8 @@ function assertDecodedRange(
     }
     index++;
   }
-  assert.strictEqual(mismatchIndex, -1);
-  assert.strictEqual(outputToString(target, length), input);
+  assert.equal(mismatchIndex, -1);
+  assert.equal(outputToString(target, length), input);
 }
 
 const BATCH_SIZE = 8192;
@@ -116,9 +116,9 @@ describe('text encodings', () => {
     const data = new Uint32Array(s.length);
     for (let i = 0; i < s.length; ++i) {
       data[i] = s.charCodeAt(i);
-      assert.strictEqual(stringFromCodePoint(data[i]), s[i]);
+      assert.equal(stringFromCodePoint(data[i]), s[i]);
     }
-    assert.strictEqual(utf32ToString(data), s);
+    assert.equal(utf32ToString(data), s);
   });
 
   describe('StringToUtf32 decoder', () => {
@@ -159,7 +159,7 @@ describe('text encodings', () => {
         const decoder = new StringToUtf32();
         const target = new Uint32Array(5);
         const length = decoder.decode(String.fromCharCode(0xFEFF), target);
-        assert.strictEqual(length, 0);
+        assert.equal(length, 0);
         decoder.clear();
       });
     });
@@ -169,7 +169,7 @@ describe('text encodings', () => {
       const target = new Uint32Array(500);
       for (let i = 0; i < TEST_STRINGS.length; ++i) {
         const length = decoder.decode(TEST_STRINGS[i], target);
-        assert.strictEqual(toString(target, length), TEST_STRINGS[i]);
+        assert.equal(toString(target, length), TEST_STRINGS[i]);
         decoder.clear();
       }
     });
@@ -184,7 +184,7 @@ describe('text encodings', () => {
           const written = decoder.decode(input[i], target);
           decoded += toString(target, written);
         }
-        assert.strictEqual(decoded, 'Ä€𝄞Ö𝄞€Ü𝄞€');
+        assert(decoded, 'Ä€𝄞Ö𝄞€Ü𝄞€');
       });
     });
   });
@@ -226,7 +226,7 @@ describe('text encodings', () => {
         const target = new Uint32Array(5);
         const utf8Data = stringToUtf8Bytes(String.fromCharCode(0xFEFF));
         const length = decoder.decode(utf8Data, target);
-        assert.strictEqual(length, 0);
+        assert.equal(length, 0);
         decoder.clear();
       });
     });
@@ -237,7 +237,7 @@ describe('text encodings', () => {
       for (let i = 0; i < TEST_STRINGS.length; ++i) {
         const utf8Data = stringToUtf8Bytes(TEST_STRINGS[i]);
         const length = decoder.decode(utf8Data, target);
-        assert.strictEqual(toString(target, length), TEST_STRINGS[i]);
+        assert.equal(toString(target, length), TEST_STRINGS[i]);
         decoder.clear();
       }
     });
@@ -252,7 +252,7 @@ describe('text encodings', () => {
           const written = decoder.decode(utf8Data.slice(i, i + 1), target);
           decoded += toString(target, written);
         }
-        assert.strictEqual(decoded, 'ÄÖÜßöäü');
+        assert(decoded, 'ÄÖÜßöäü');
       });
 
       it('2/3 byte sequences - advance by 1', () => {
@@ -264,7 +264,7 @@ describe('text encodings', () => {
           const written = decoder.decode(utf8Data.slice(i, i + 1), target);
           decoded += toString(target, written);
         }
-        assert.strictEqual(decoded, 'Āր܀߀ö€ä€ü');
+        assert(decoded, 'Āր܀߀ö€ä€ü');
       });
 
       it('2/3/4 byte sequences - advance by 1', () => {
@@ -276,7 +276,7 @@ describe('text encodings', () => {
           const written = decoder.decode(utf8Data.slice(i, i + 1), target);
           decoded += toString(target, written);
         }
-        assert.strictEqual(decoded, 'Ä€𝄞Ö𝄞€Ü𝄞€');
+        assert(decoded, 'Ä€𝄞Ö𝄞€Ü𝄞€');
       });
 
       it('2/3/4 byte sequences - advance by 2', () => {
@@ -288,7 +288,7 @@ describe('text encodings', () => {
           const written = decoder.decode(utf8Data.slice(i, i + 2), target);
           decoded += toString(target, written);
         }
-        assert.strictEqual(decoded, 'Ä€𝄞Ö𝄞€Ü𝄞€');
+        assert(decoded, 'Ä€𝄞Ö𝄞€Ü𝄞€');
       });
 
       it('2/3/4 byte sequences - advance by 3', () => {
@@ -300,7 +300,7 @@ describe('text encodings', () => {
           const written = decoder.decode(utf8Data.slice(i, i + 3), target);
           decoded += toString(target, written);
         }
-        assert.strictEqual(decoded, 'Ä€𝄞Ö𝄞€Ü𝄞€');
+        assert(decoded, 'Ä€𝄞Ö𝄞€Ü𝄞€');
       });
 
       it('BOMs (3 byte sequences) - advance by 2', () => {
@@ -312,7 +312,7 @@ describe('text encodings', () => {
           const written = decoder.decode(utf8Data.slice(i, i + 2), target);
           decoded += toString(target, written);
         }
-        assert.strictEqual(decoded, '');
+        assert.equal(decoded, '');
       });
 
       it('test break after 3 bytes - issue #2495', () => {
@@ -320,37 +320,11 @@ describe('text encodings', () => {
         const target = new Uint32Array(5);
         const utf8Data = fromByteString('\xf0\xa0\x9c\x8e');
         let written = decoder.decode(utf8Data.slice(0, 3), target);
-        assert.strictEqual(written, 0);
+        assert.equal(written, 0);
         written = decoder.decode(utf8Data.slice(3), target);
-        assert.strictEqual(written, 1);
-        assert.strictEqual(toString(target, written), '𠜎');
+        assert.equal(written, 1);
+        assert(toString(target, written), '𠜎');
       });
-
-      describe('0x80 not swallowed in continuation', () => {
-        it('A—B', () => {
-          const decoder = new Utf8ToUtf32();
-          const target = new Uint32Array(5);
-          const utf8Data = new TextEncoder().encode('A—BA—BA—BA—BA—B');
-          let decoded = '';
-          for (let i = 0; i < utf8Data.length; i += 2) {
-            const written = decoder.decode(utf8Data.slice(i, i + 2), target);
-            decoded += toString(target, written);
-          }
-          assert.strictEqual(decoded, 'A—BA—BA—BA—BA—B');
-        });
-        it('A𐀀B', () => {
-          const decoder = new Utf8ToUtf32();
-          const target = new Uint32Array(5);
-          const utf8Data = new TextEncoder().encode('A𐀀BA𐀀BA𐀀BA𐀀BA𐀀B');
-          let decoded = '';
-          for (let i = 0; i < utf8Data.length; i += 2) {
-            const written = decoder.decode(utf8Data.slice(i, i + 2), target);
-            decoded += toString(target, written);
-          }
-          assert.strictEqual(decoded, 'A𐀀BA𐀀BA𐀀BA𐀀BA𐀀B');
-        });
-      });
-
     });
   });
 });

src/common/input/TextDecoder.ts

@@ -158,9 +158,9 @@ export class Utf8ToUtf32 {
       cp &= ((((cp & 0xE0) === 0xC0)) ? 0x1F : (((cp & 0xF0) === 0xE0)) ? 0x0F : 0x07);
       let pos = 0;
       let tmp: number;
-      while ((tmp = this.interim[++pos]) && pos < 4) {
+      while ((tmp = this.interim[++pos] & 0x3F) && pos < 4) {
         cp <<= 6;
-        cp |= tmp & 0x3F;
+        cp |= tmp;
       }
       // missing bytes - read ahead from input
       const type = (((this.interim[0] & 0xE0) === 0xC0)) ? 2 : (((this.interim[0] & 0xF0) === 0xE0)) ? 3 : 4;

src/headless/Terminal.ts

@@ -99,6 +99,10 @@ export class Terminal extends CoreTerminal {
    * Clear the entire buffer, making the prompt line the new first line.
    */
   public clear(): void {
+    if (this.buffer.ybase === 0 && this.buffer.y === 0) {
+      // Don't clear if it's already clear
+      return;
+    }
     this.buffer.clearAllMarkers();
     this.buffer.lines.set(0, this.buffer.lines.get(this.buffer.ybase + this.buffer.y)!);
     this.buffer.lines.length = 1;

test/benchmark/BufferLine.benchmark.ts

@@ -1,113 +0,0 @@
-/**
- * Copyright (c) 2026 The xterm.js authors. All rights reserved.
- * @license MIT
- */
-
-import { perfContext, before, RuntimeCase } from 'xterm-benchmark';
-import { BufferLine, DEFAULT_ATTR_DATA } from 'common/buffer/BufferLine';
-import { BufferLineStringCache } from 'common/buffer/BufferLineStringCache';
-import { CellData } from 'common/buffer/CellData';
-import { BgFlags, NULL_CELL_CHAR, NULL_CELL_WIDTH, NULL_CELL_CODE, UnderlineStyle } from 'common/buffer/Constants';
-
-const ITERATIONS = 500_000;
-const stringCache = new BufferLineStringCache();
-const nullCell = CellData.fromCharData([0, NULL_CELL_CHAR, NULL_CELL_WIDTH, NULL_CELL_CODE]);
-const yCell = CellData.fromCharData([0, 'y', 1, 'y'.charCodeAt(0)]);
-
-function fillPlainY(line: BufferLine, cols: number): void {
-  for (let i = 0; i < cols; i++) {
-    line.setCellFromCodepoint(i, 'y'.charCodeAt(0), 1, DEFAULT_ATTR_DATA);
-  }
-}
-
-function setupScrollRecyclePair(cols: number): { recycled: BufferLine, blank: BufferLine } {
-  const blank = new BufferLine(stringCache, cols, nullCell, false);
-  const recycled = new BufferLine(stringCache, cols, yCell, false);
-  fillPlainY(recycled, cols);
-  return { recycled, blank };
-}
-
-/** Source line with combining chars and extended attrs spread across columns. */
-function buildSparseSourceLine(cols: number): BufferLine {
-  const line = new BufferLine(stringCache, cols, nullCell, false);
-  for (let i = 0; i < cols; i++) {
-    if (i % 10 === 0) {
-      const cell = CellData.fromCharData([0, 'a', 1, 'a'.charCodeAt(0)]);
-      cell.extended.underlineStyle = UnderlineStyle.CURLY;
-      cell.bg |= BgFlags.HAS_EXTENDED;
-      line.setCell(i, cell);
-    } else if (i % 17 === 0) {
-      line.setCell(i, CellData.fromCharData([1, 'e\u0301', 1, '\u0301'.charCodeAt(0)]));
-    } else {
-      line.setCellFromCodepoint(i, 'y'.charCodeAt(0), 1, DEFAULT_ATTR_DATA);
-    }
-  }
-  return line;
-}
-
-function setupCopyFromSparsePair(cols: number): { dest: BufferLine, src: BufferLine } {
-  const src = buildSparseSourceLine(cols);
-  const dest = new BufferLine(stringCache, cols, yCell, false);
-  fillPlainY(dest, cols);
-  return { dest, src };
-}
-
-perfContext('BufferLine.copyFrom (scroll recycle)', () => {
-  perfContext('cols=80', () => {
-    let recycled: BufferLine;
-    let blank: BufferLine;
-    before(() => {
-      ({ recycled, blank } = setupScrollRecyclePair(80));
-    });
-    new RuntimeCase('', () => {
-      for (let i = 0; i < ITERATIONS; i++) {
-        recycled.copyFrom(blank);
-      }
-      return { payloadSize: ITERATIONS };
-    }, { fork: false }).showAverageRuntime();
-  });
-
-  perfContext('cols=279', () => {
-    let recycled: BufferLine;
-    let blank: BufferLine;
-    before(() => {
-      ({ recycled, blank } = setupScrollRecyclePair(279));
-    });
-    new RuntimeCase('', () => {
-      for (let i = 0; i < ITERATIONS; i++) {
-        recycled.copyFrom(blank);
-      }
-      return { payloadSize: ITERATIONS };
-    }, { fork: false }).showAverageRuntime();
-  });
-});
-
-perfContext('BufferLine.copyFrom (sparse source: combined + extended attrs)', () => {
-  perfContext('cols=80', () => {
-    let dest: BufferLine;
-    let src: BufferLine;
-    before(() => {
-      ({ dest, src } = setupCopyFromSparsePair(80));
-    });
-    new RuntimeCase('', () => {
-      for (let i = 0; i < ITERATIONS; i++) {
-        dest.copyFrom(src);
-      }
-      return { payloadSize: ITERATIONS };
-    }, { fork: false }).showAverageRuntime();
-  });
-
-  perfContext('cols=279', () => {
-    let dest: BufferLine;
-    let src: BufferLine;
-    before(() => {
-      ({ dest, src } = setupCopyFromSparsePair(279));
-    });
-    new RuntimeCase('', () => {
-      for (let i = 0; i < ITERATIONS; i++) {
-        dest.copyFrom(src);
-      }
-      return { payloadSize: ITERATIONS };
-    }, { fork: false }).showAverageRuntime();
-  });
-});