diff --git a/css/xterm.css b/css/xterm.css
index 74acc26708..e97b643905 100644
--- a/css/xterm.css
+++ b/css/xterm.css
@@ -140,7 +140,7 @@
     cursor: crosshair;
 }
 
-.xterm .xterm-accessibility,
+.xterm .xterm-accessibility:not(.debug),
 .xterm .xterm-message {
     position: absolute;
     left: 0;
@@ -152,6 +152,15 @@
     pointer-events: none;
 }
 
+.xterm .xterm-accessibility-tree:not(.debug) *::selection {
+  color: transparent;
+}
+
+.xterm .xterm-accessibility-tree {
+  user-select: text;
+  white-space: pre;
+}
+
 .xterm .live-region {
     position: absolute;
     left: -9999px;
diff --git a/src/browser/AccessibilityManager.ts b/src/browser/AccessibilityManager.ts
index 5f52958924..68c65ebd87 100644
--- a/src/browser/AccessibilityManager.ts
+++ b/src/browser/AccessibilityManager.ts
@@ -10,6 +10,7 @@ import { Disposable, toDisposable } from 'common/Lifecycle';
 import { ICoreBrowserService, IRenderService } from 'browser/services/Services';
 import { IBuffer } from 'common/buffer/Types';
 import { IInstantiationService } from 'common/services/Services';
+import { addDisposableDomListener } from 'browser/Lifecycle';
 
 const MAX_ROWS_TO_READ = 20;
 
@@ -18,11 +19,17 @@ const enum BoundaryPosition {
   BOTTOM
 }
 
+// Turn this on to unhide the accessibility tree and display it under
+// (instead of overlapping with) the terminal.
+const DEBUG = false;
+
 export class AccessibilityManager extends Disposable {
+  private _debugRootContainer: HTMLElement | undefined;
   private _accessibilityContainer: HTMLElement;
 
   private _rowContainer: HTMLElement;
   private _rowElements: HTMLElement[];
+  private _rowColumns: WeakMap<HTMLElement, number[]> = new WeakMap();
 
   private _liveRegion: HTMLElement;
   private _liveRegionLineCount: number = 0;
@@ -80,7 +87,23 @@ export class AccessibilityManager extends Disposable {
     if (!this._terminal.element) {
       throw new Error('Cannot enable accessibility before Terminal.open');
     }
-    this._terminal.element.insertAdjacentElement('afterbegin', this._accessibilityContainer);
+
+    if (DEBUG) {
+      this._accessibilityContainer.classList.add('debug');
+      this._rowContainer.classList.add('debug');
+
+      // Use a `<div class="xterm">` container so that the css will still apply.
+      this._debugRootContainer = document.createElement('div');
+      this._debugRootContainer.classList.add('xterm');
+
+      this._debugRootContainer.appendChild(document.createTextNode('------start a11y------'));
+      this._debugRootContainer.appendChild(this._accessibilityContainer);
+      this._debugRootContainer.appendChild(document.createTextNode('------end a11y------'));
+
+      this._terminal.element.insertAdjacentElement('afterend', this._debugRootContainer);
+    } else {
+      this._terminal.element.insertAdjacentElement('afterbegin', this._accessibilityContainer);
+    }
 
     this.register(this._terminal.onResize(e => this._handleResize(e.rows)));
     this.register(this._terminal.onRender(e => this._refreshRows(e.start, e.end)));
@@ -92,11 +115,16 @@ export class AccessibilityManager extends Disposable {
     this.register(this._terminal.onKey(e => this._handleKey(e.key)));
     this.register(this._terminal.onBlur(() => this._clearLiveRegion()));
     this.register(this._renderService.onDimensionsChange(() => this._refreshRowsDimensions()));
+    this.register(addDisposableDomListener(document, 'selectionchange', () => this._handleSelectionChange()));
     this.register(this._coreBrowserService.onDprChange(() => this._refreshRowsDimensions()));
 
     this._refreshRows();
     this.register(toDisposable(() => {
-      this._accessibilityContainer.remove();
+      if (DEBUG) {
+        this._debugRootContainer!.remove();
+      } else {
+        this._accessibilityContainer.remove();
+      }
       this._rowElements.length = 0;
     }));
   }
@@ -149,14 +177,18 @@ export class AccessibilityManager extends Disposable {
     const buffer: IBuffer = this._terminal.buffer;
     const setSize = buffer.lines.length.toString();
     for (let i = start; i <= end; i++) {
-      const lineData = buffer.translateBufferLineToString(buffer.ydisp + i, true);
+      const line = buffer.lines.get(buffer.ydisp + i);
+      const columns: number[] = [];
+      const lineData = line?.translateToString(true, undefined, undefined, columns) || '';
       const posInSet = (buffer.ydisp + i + 1).toString();
       const element = this._rowElements[i];
       if (element) {
         if (lineData.length === 0) {
           element.innerText = '\u00a0';
+          this._rowColumns.set(element, [0, 1]);
         } else {
           element.textContent = lineData;
+          this._rowColumns.set(element, columns);
         }
         element.setAttribute('aria-posinset', posInSet);
         element.setAttribute('aria-setsize', setSize);
@@ -233,6 +265,103 @@ export class AccessibilityManager extends Disposable {
     e.stopImmediatePropagation();
   }
 
+  private _handleSelectionChange(): void {
+    if (this._rowElements.length === 0) {
+      return;
+    }
+
+    const selection = document.getSelection();
+    if (!selection) {
+      return;
+    }
+
+    if (selection.isCollapsed) {
+      // Only do something when the anchorNode is inside the row container. This
+      // behavior mirrors what we do with mouse --- if the mouse clicks
+      // somewhere outside of the terminal, we don't clear the selection.
+      if (this._rowContainer.contains(selection.anchorNode)) {
+        this._terminal.clearSelection();
+      }
+      return;
+    }
+
+    if (!selection.anchorNode || !selection.focusNode) {
+      console.error('anchorNode and/or focusNode are null');
+      return;
+    }
+
+    // Sort the two selection points in document order.
+    let begin = { node: selection.anchorNode, offset: selection.anchorOffset };
+    let end = { node: selection.focusNode, offset: selection.focusOffset };
+    if ((begin.node.compareDocumentPosition(end.node) & Node.DOCUMENT_POSITION_PRECEDING) || (begin.node === end.node && begin.offset > end.offset) ) {
+      [begin, end] = [end, begin];
+    }
+
+    // Clamp begin/end to the inside of the row container.
+    if (begin.node.compareDocumentPosition(this._rowElements[0]) & (Node.DOCUMENT_POSITION_CONTAINED_BY | Node.DOCUMENT_POSITION_FOLLOWING)) {
+      begin = { node: this._rowElements[0].childNodes[0], offset: 0 };
+    }
+    if (!this._rowContainer.contains(begin.node)) {
+      // This happens when `begin` is below the last row.
+      return;
+    }
+    const lastRowElement = this._rowElements.slice(-1)[0];
+    if (end.node.compareDocumentPosition(lastRowElement) & (Node.DOCUMENT_POSITION_CONTAINED_BY | Node.DOCUMENT_POSITION_PRECEDING)) {
+      end = {
+        node: lastRowElement,
+        offset: lastRowElement.textContent?.length ?? 0
+      };
+    }
+    if (!this._rowContainer.contains(end.node)) {
+      // This happens when `end` is above the first row.
+      return;
+    }
+
+    const toRowColumn = ({ node, offset }: typeof begin): {row: number, column: number} | null => {
+      // `node` is either the row element or the Text node inside it.
+      const rowElement: any = node instanceof Text ? node.parentNode : node;
+      let row = parseInt(rowElement?.getAttribute('aria-posinset'), 10) - 1;
+      if (isNaN(row)) {
+        console.warn('row is invalid. Race condition?');
+        return null;
+      }
+
+      const columns = this._rowColumns.get(rowElement);
+      if (!columns) {
+        console.warn('columns is null. Race condition?');
+        return null;
+      }
+
+      let column = offset < columns.length ? columns[offset] : columns.slice(-1)[0] + 1;
+      if (column >= this._terminal.cols) {
+        ++row;
+        column = 0;
+      }
+      return {
+        row,
+        column
+      };
+    };
+
+    const beginRowColumn = toRowColumn(begin);
+    const endRowColumn = toRowColumn(end);
+
+    if (!beginRowColumn || !endRowColumn) {
+      return;
+    }
+
+    if (beginRowColumn.row > endRowColumn.row || (beginRowColumn.row === endRowColumn.row && beginRowColumn.column >= endRowColumn.column)) {
+      // This should not happen unless we have some bugs.
+      throw new Error('invalid range');
+    }
+
+    this._terminal.select(
+      beginRowColumn.column,
+      beginRowColumn.row,
+      (endRowColumn.row - beginRowColumn.row) * this._terminal.cols - beginRowColumn.column + endRowColumn.column
+    );
+  }
+
   private _handleResize(rows: number): void {
     // Remove bottom boundary listener
     this._rowElements[this._rowElements.length - 1].removeEventListener('focus', this._bottomBoundaryFocusListener);
diff --git a/src/common/Types.d.ts b/src/common/Types.d.ts
index 244f30b442..175c47c318 100644
--- a/src/common/Types.d.ts
+++ b/src/common/Types.d.ts
@@ -247,7 +247,7 @@ export interface IBufferLine {
   clone(): IBufferLine;
   getTrimmedLength(): number;
   getNoBgTrimmedLength(): number;
-  translateToString(trimRight?: boolean, startCol?: number, endCol?: number): string;
+  translateToString(trimRight?: boolean, startCol?: number, endCol?: number, outColumns?: number[]): string;
 
   /* direct access to cell attrs */
   getWidth(index: number): number;
diff --git a/src/common/buffer/BufferLine.test.ts b/src/common/buffer/BufferLine.test.ts
index 8b9ec63e46..9d08c2bef6 100644
--- a/src/common/buffer/BufferLine.test.ts
+++ b/src/common/buffer/BufferLine.test.ts
@@ -343,56 +343,75 @@ describe('BufferLine', function(): void {
   describe('translateToString with and w\'o trimming', function(): void {
     it('empty line', function(): void {
       const line = new TestBufferLine(10, CellData.fromCharData([DEFAULT_ATTR, NULL_CELL_CHAR, NULL_CELL_WIDTH, NULL_CELL_CODE]), false);
-      assert.equal(line.translateToString(false), '          ');
-      assert.equal(line.translateToString(true), '');
+      const columns: number[] = [];
+      assert.equal(line.translateToString(false, undefined, undefined, columns), '          ');
+      assert.deepEqual(columns, [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]);
+      assert.equal(line.translateToString(true, undefined, undefined, columns), '');
+      assert.deepEqual(columns, [0]);
     });
     it('ASCII', function(): void {
+      const columns: number[] = [];
       const line = new TestBufferLine(10, CellData.fromCharData([DEFAULT_ATTR, NULL_CELL_CHAR, NULL_CELL_WIDTH, NULL_CELL_CODE]), false);
       line.setCell(0, CellData.fromCharData([1, 'a', 1, 'a'.charCodeAt(0)]));
       line.setCell(2, CellData.fromCharData([1, 'a', 1, 'a'.charCodeAt(0)]));
       line.setCell(4, CellData.fromCharData([1, 'a', 1, 'a'.charCodeAt(0)]));
       line.setCell(5, CellData.fromCharData([1, 'a', 1, 'a'.charCodeAt(0)]));
-      assert.equal(line.translateToString(false), 'a a aa    ');
-      assert.equal(line.translateToString(true), 'a a aa');
-      assert.equal(line.translateToString(false, 0, 5), 'a a a');
-      assert.equal(line.translateToString(false, 0, 4), 'a a ');
-      assert.equal(line.translateToString(false, 0, 3), 'a a');
-      assert.equal(line.translateToString(true, 0, 5), 'a a a');
-      assert.equal(line.translateToString(true, 0, 4), 'a a ');
-      assert.equal(line.translateToString(true, 0, 3), 'a a');
+      assert.equal(line.translateToString(false, undefined, undefined, columns), 'a a aa    ');
+      assert.deepEqual(columns, [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]);
+      assert.equal(line.translateToString(true, undefined, undefined, columns), 'a a aa');
+      assert.deepEqual(columns, [0, 1, 2, 3, 4, 5, 6]);
+      for (const trimRight of [true, false]) {
+        assert.equal(line.translateToString(trimRight, 0, 5, columns), 'a a a');
+        assert.deepEqual(columns, [0, 1, 2, 3, 4, 5]);
+        assert.equal(line.translateToString(trimRight, 0, 4, columns), 'a a ');
+        assert.deepEqual(columns, [0, 1, 2, 3, 4]);
+        assert.equal(line.translateToString(trimRight, 0, 3, columns), 'a a');
+        assert.deepEqual(columns, [0, 1, 2, 3]);
+      }
 
     });
     it('surrogate', function(): void {
+      const columns: number[] = [];
       const line = new TestBufferLine(10, CellData.fromCharData([DEFAULT_ATTR, NULL_CELL_CHAR, NULL_CELL_WIDTH, NULL_CELL_CODE]), false);
       line.setCell(0, CellData.fromCharData([1, 'a', 1, 'a'.charCodeAt(0)]));
       line.setCell(2, CellData.fromCharData([1, '𝄞', 1, '𝄞'.charCodeAt(0)]));
       line.setCell(4, CellData.fromCharData([1, '𝄞', 1, '𝄞'.charCodeAt(0)]));
       line.setCell(5, CellData.fromCharData([1, '𝄞', 1, '𝄞'.charCodeAt(0)]));
-      assert.equal(line.translateToString(false), 'a 𝄞 𝄞𝄞    ');
-      assert.equal(line.translateToString(true), 'a 𝄞 𝄞𝄞');
-      assert.equal(line.translateToString(false, 0, 5), 'a 𝄞 𝄞');
-      assert.equal(line.translateToString(false, 0, 4), 'a 𝄞 ');
-      assert.equal(line.translateToString(false, 0, 3), 'a 𝄞');
-      assert.equal(line.translateToString(true, 0, 5), 'a 𝄞 𝄞');
-      assert.equal(line.translateToString(true, 0, 4), 'a 𝄞 ');
-      assert.equal(line.translateToString(true, 0, 3), 'a 𝄞');
+      assert.equal(line.translateToString(false, undefined, undefined, columns), 'a 𝄞 𝄞𝄞    ');
+      assert.deepEqual(columns, [0, 1, 2, 2, 3, 4, 4, 5, 5, 6, 7, 8, 9, 10]);
+      assert.equal(line.translateToString(true, undefined, undefined, columns), 'a 𝄞 𝄞𝄞');
+      assert.deepEqual(columns, [0, 1, 2, 2, 3, 4, 4, 5, 5, 6]);
+      for (const trimRight of [true, false]) {
+        assert.equal(line.translateToString(trimRight, 0, 5, columns), 'a 𝄞 𝄞');
+        assert.deepEqual(columns, [0, 1, 2, 2, 3, 4, 4, 5]);
+        assert.equal(line.translateToString(trimRight, 0, 4, columns), 'a 𝄞 ');
+        assert.deepEqual(columns, [0, 1, 2, 2, 3, 4]);
+        assert.equal(line.translateToString(trimRight, 0, 3, columns), 'a 𝄞');
+        assert.deepEqual(columns, [0, 1, 2, 2, 3]);
+      }
     });
     it('combining', function(): void {
+      const columns: number[] = [];
       const line = new TestBufferLine(10, CellData.fromCharData([DEFAULT_ATTR, NULL_CELL_CHAR, NULL_CELL_WIDTH, NULL_CELL_CODE]), false);
       line.setCell(0, CellData.fromCharData([1, 'a', 1, 'a'.charCodeAt(0)]));
       line.setCell(2, CellData.fromCharData([1, 'e\u0301', 1, '\u0301'.charCodeAt(0)]));
       line.setCell(4, CellData.fromCharData([1, 'e\u0301', 1, '\u0301'.charCodeAt(0)]));
       line.setCell(5, CellData.fromCharData([1, 'e\u0301', 1, '\u0301'.charCodeAt(0)]));
-      assert.equal(line.translateToString(false), 'a e\u0301 e\u0301e\u0301    ');
-      assert.equal(line.translateToString(true), 'a e\u0301 e\u0301e\u0301');
-      assert.equal(line.translateToString(false, 0, 5), 'a e\u0301 e\u0301');
-      assert.equal(line.translateToString(false, 0, 4), 'a e\u0301 ');
-      assert.equal(line.translateToString(false, 0, 3), 'a e\u0301');
-      assert.equal(line.translateToString(true, 0, 5), 'a e\u0301 e\u0301');
-      assert.equal(line.translateToString(true, 0, 4), 'a e\u0301 ');
-      assert.equal(line.translateToString(true, 0, 3), 'a e\u0301');
+      assert.equal(line.translateToString(false, undefined, undefined, columns), 'a e\u0301 e\u0301e\u0301    ');
+      assert.deepEqual(columns, [0, 1, 2, 2, 3, 4, 4, 5, 5, 6, 7, 8, 9, 10]);
+      assert.equal(line.translateToString(true, undefined, undefined, columns), 'a e\u0301 e\u0301e\u0301');
+      assert.deepEqual(columns, [0, 1, 2, 2, 3, 4, 4, 5, 5, 6]);
+      for (const trimRight of [true, false]) {
+        assert.equal(line.translateToString(trimRight, 0, 5, columns), 'a e\u0301 e\u0301');
+        assert.deepEqual(columns, [0, 1, 2, 2, 3, 4, 4, 5]);
+        assert.equal(line.translateToString(trimRight, 0, 4, columns), 'a e\u0301 ');
+        assert.deepEqual(columns, [0, 1, 2, 2, 3, 4]);
+        assert.equal(line.translateToString(trimRight, 0, 3, columns), 'a e\u0301');
+        assert.deepEqual(columns, [0, 1, 2, 2, 3]);
+      }
     });
     it('fullwidth', function(): void {
+      const columns: number[] = [];
       const line = new TestBufferLine(10, CellData.fromCharData([DEFAULT_ATTR, NULL_CELL_CHAR, NULL_CELL_WIDTH, NULL_CELL_CODE]), false);
       line.setCell(0, CellData.fromCharData([1, 'a', 1, 'a'.charCodeAt(0)]));
       line.setCell(2, CellData.fromCharData([1, '１', 2, '１'.charCodeAt(0)]));
@@ -401,43 +420,55 @@ describe('BufferLine', function(): void {
       line.setCell(6, CellData.fromCharData([0, '', 0, 0]));
       line.setCell(7, CellData.fromCharData([1, '１', 2, '１'.charCodeAt(0)]));
       line.setCell(8, CellData.fromCharData([0, '', 0, 0]));
-      assert.equal(line.translateToString(false), 'a １ １１ ');
-      assert.equal(line.translateToString(true), 'a １ １１');
-      assert.equal(line.translateToString(false, 0, 7), 'a １ １');
-      assert.equal(line.translateToString(false, 0, 6), 'a １ １');
-      assert.equal(line.translateToString(false, 0, 5), 'a １ ');
-      assert.equal(line.translateToString(false, 0, 4), 'a １');
-      assert.equal(line.translateToString(false, 0, 3), 'a １');
-      assert.equal(line.translateToString(false, 0, 2), 'a ');
-      assert.equal(line.translateToString(true, 0, 7), 'a １ １');
-      assert.equal(line.translateToString(true, 0, 6), 'a １ １');
-      assert.equal(line.translateToString(true, 0, 5), 'a １ ');
-      assert.equal(line.translateToString(true, 0, 4), 'a １');
-      assert.equal(line.translateToString(true, 0, 3), 'a １');
-      assert.equal(line.translateToString(true, 0, 2), 'a ');
+      assert.equal(line.translateToString(false, undefined, undefined, columns), 'a １ １１ ');
+      assert.deepEqual(columns, [0, 1, 2, 4, 5, 7, 9, 10]);
+      assert.equal(line.translateToString(true, undefined, undefined, columns), 'a １ １１');
+      assert.deepEqual(columns, [0, 1, 2, 4, 5, 7, 9]);
+      for (const trimRight of [true, false]) {
+        assert.equal(line.translateToString(trimRight, 0, 7, columns), 'a １ １');
+        assert.deepEqual(columns, [0, 1, 2, 4, 5, 7]);
+        assert.equal(line.translateToString(trimRight, 0, 6, columns), 'a １ １');
+        assert.deepEqual(columns, [0, 1, 2, 4, 5, 7]);
+        assert.equal(line.translateToString(trimRight, 0, 5, columns), 'a １ ');
+        assert.deepEqual(columns, [0, 1, 2, 4, 5]);
+        assert.equal(line.translateToString(trimRight, 0, 4, columns), 'a １');
+        assert.deepEqual(columns, [0, 1, 2, 4]);
+        assert.equal(line.translateToString(trimRight, 0, 3, columns), 'a １');
+        assert.deepEqual(columns, [0, 1, 2, 4]);
+        assert.equal(line.translateToString(trimRight, 0, 2, columns), 'a ');
+        assert.deepEqual(columns, [0, 1, 2]);
+      }
     });
     it('space at end', function(): void {
+      const columns: number[] = [];
       const line = new TestBufferLine(10, CellData.fromCharData([DEFAULT_ATTR, NULL_CELL_CHAR, NULL_CELL_WIDTH, NULL_CELL_CODE]), false);
       line.setCell(0, CellData.fromCharData([1, 'a', 1, 'a'.charCodeAt(0)]));
       line.setCell(2, CellData.fromCharData([1, 'a', 1, 'a'.charCodeAt(0)]));
       line.setCell(4, CellData.fromCharData([1, 'a', 1, 'a'.charCodeAt(0)]));
       line.setCell(5, CellData.fromCharData([1, 'a', 1, 'a'.charCodeAt(0)]));
       line.setCell(6, CellData.fromCharData([1, ' ', 1, ' '.charCodeAt(0)]));
-      assert.equal(line.translateToString(false), 'a a aa    ');
-      assert.equal(line.translateToString(true), 'a a aa ');
+      assert.equal(line.translateToString(false, undefined, undefined, columns), 'a a aa    ');
+      assert.deepEqual(columns, [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]);
+      assert.equal(line.translateToString(true, undefined, undefined, columns), 'a a aa ');
+      assert.deepEqual(columns, [0, 1, 2, 3, 4, 5, 6, 7]);
     });
     it('should always return some sane value', function(): void {
+      const columns: number[] = [];
       // sanity check - broken line with invalid out of bound null width cells
       // this can atm happen with deleting/inserting chars in inputhandler by "breaking"
       // fullwidth pairs --> needs to be fixed after settling BufferLine impl
       const line = new TestBufferLine(10, CellData.fromCharData([DEFAULT_ATTR, NULL_CELL_CHAR, 0, NULL_CELL_CODE]), false);
-      assert.equal(line.translateToString(false), '          ');
-      assert.equal(line.translateToString(true), '');
+      assert.equal(line.translateToString(false, undefined, undefined, columns), '          ');
+      assert.deepEqual(columns, [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]);
+      assert.equal(line.translateToString(true, undefined, undefined, columns), '');
+      assert.deepEqual(columns, [0]);
     });
     it('should work with endCol=0', () => {
+      const columns: number[] = [];
       const line = new TestBufferLine(10, CellData.fromCharData([DEFAULT_ATTR, NULL_CELL_CHAR, 0, NULL_CELL_CODE]), false);
       line.setCell(0, CellData.fromCharData([1, 'a', 1, 'a'.charCodeAt(0)]));
-      assert.equal(line.translateToString(true, 0, 0), '');
+      assert.equal(line.translateToString(true, 0, 0, columns), '');
+      assert.deepEqual(columns, [0]);
     });
   });
   describe('addCharToCell', () => {
diff --git a/src/common/buffer/BufferLine.ts b/src/common/buffer/BufferLine.ts
index 2852c7f169..ee3481a24e 100644
--- a/src/common/buffer/BufferLine.ts
+++ b/src/common/buffer/BufferLine.ts
@@ -508,16 +508,43 @@ export class BufferLine implements IBufferLine {
     }
   }
 
-  public translateToString(trimRight: boolean = false, startCol: number = 0, endCol: number = this.length): string {
+  /**
+   * Translates the buffer line to a string.
+   *
+   * @param trimRight Whether to trim any empty cells on the right.
+   * @param startCol The column to start the string (0-based inclusive).
+   * @param endCol The column to end the string (0-based exclusive).
+   * @param outColumns if specified, this array will be filled with column numbers such that
+   * `returnedString[i]` is displayed at `outColumns[i]` column. `outColumns[returnedString.length]`
+   * is where the character following `returnedString` will be displayed.
+   *
+   * When a single cell is translated to multiple UTF-16 code units (e.g. surrogate pair) in the
+   * returned string, the corresponding entries in `outColumns` will have the same column number.
+   */
+  public translateToString(trimRight?: boolean, startCol?: number, endCol?: number, outColumns?: number[]): string {
+    startCol = startCol ?? 0;
+    endCol = endCol ?? this.length;
     if (trimRight) {
       endCol = Math.min(endCol, this.getTrimmedLength());
     }
+    if (outColumns) {
+      outColumns.length = 0;
+    }
     let result = '';
     while (startCol < endCol) {
       const content = this._data[startCol * CELL_SIZE + Cell.CONTENT];
       const cp = content & Content.CODEPOINT_MASK;
-      result += (content & Content.IS_COMBINED_MASK) ? this._combined[startCol] : (cp) ? stringFromCodePoint(cp) : WHITESPACE_CELL_CHAR;
-      startCol += (content >> Content.WIDTH_SHIFT) || 1; // always advance by 1
+      const chars = (content & Content.IS_COMBINED_MASK) ? this._combined[startCol] : (cp) ? stringFromCodePoint(cp) : WHITESPACE_CELL_CHAR;
+      result += chars;
+      if (outColumns) {
+        for (let i = 0; i < chars.length; ++i) {
+          outColumns.push(startCol);
+        }
+      }
+      startCol += (content >> Content.WIDTH_SHIFT) || 1; // always advance by at least 1
+    }
+    if (outColumns) {
+      outColumns.push(startCol);
     }
     return result;
   }