jix joined cell representation as overloaded CellData type

src/renderer/BaseRenderLayer.ts

@@ -10,6 +10,7 @@ import BaseCharAtlas from './atlas/BaseCharAtlas';
 import { acquireCharAtlas } from './atlas/CharAtlasCache';
 import { CellData, AttributeData } from '../BufferLine';
 import { WHITESPACE_CELL_CHAR, WHITESPACE_CELL_CODE } from '../Buffer';
+import { JoinedCellData } from './CharacterJoinerRegistry';
 
 export abstract class BaseRenderLayer implements IRenderLayer {
   private _canvas: HTMLCanvasElement;
@@ -260,8 +261,8 @@ export abstract class BaseRenderLayer implements IRenderLayer {
    */
   protected drawChars(terminal: ITerminal, cell: ICellData, x: number, y: number): void {
 
-    // skip cache right away if we draw in RGB
-    if (cell.isFgRGB() || cell.isBgRGB()) {
+    // skip cache right away if we draw in RGB or have joined cells
+    if (cell.isFgRGB() || cell.isBgRGB() || cell instanceof JoinedCellData) {
       this._drawUncachedChars(terminal, cell, x, y);
       return;
     }

src/renderer/CharacterJoinerRegistry.ts

@@ -1,8 +1,51 @@
-import { ITerminal, IBufferLine } from '../Types';
+import { ITerminal, IBufferLine, ICellData, CharData } from '../Types';
 import { ICharacterJoinerRegistry, ICharacterJoiner } from './Types';
-import { CellData } from '../BufferLine';
+import { CellData, Content } from '../BufferLine';
 import { WHITESPACE_CELL_CHAR } from '../Buffer';
 
+export class JoinedCellData extends CellData implements ICellData {
+  private _width: number = 0;
+  private _code: number = 0x1FFFFF;  // highest allowed codepoint, meant as -1
+
+  public content: number = 0;
+  public fg: number = 0;
+  public bg: number = 0;
+  public combinedData: string = '';
+
+  constructor(firstCell: ICellData, chars: string, width: number) {
+    super();
+    this.fg = firstCell.fg;
+    this.bg = firstCell.bg;
+    this.combinedData = chars;
+    this._width = width;
+  }
+
+  public isCombined(): number {
+    // always mark joined cell data as combined
+    return Content.IS_COMBINED_MASK;
+  }
+
+  public getWidth(): number {
+    return this._width;
+  }
+
+  public getChars(): string {
+    return this.combinedData;
+  }
+
+  public getCode(): number {
+    return this._code;
+  }
+
+  public setFromCharData(value: CharData): void {
+    throw new Error('not implemented');
+  }
+
+  public getAsCharData(): CharData {
+    return [this.fg, this.getChars(), this.getWidth(), this.getCode()];
+  }
+}
+
 export class CharacterJoinerRegistry implements ICharacterJoinerRegistry {
 
   private _characterJoiners: ICharacterJoiner[] = [];

src/renderer/TextRenderLayer.ts

@@ -9,6 +9,7 @@ import { CharData, ITerminal, ICellData } from '../Types';
 import { GridCache } from './GridCache';
 import { BaseRenderLayer } from './BaseRenderLayer';
 import { CellData, AttributeData, Content } from '../BufferLine';
+import { JoinedCellData } from './CharacterJoinerRegistry';
 
 /**
  * This CharData looks like a null character, which will forc a clear and render
@@ -89,15 +90,12 @@ export class TextRenderLayer extends BaseRenderLayer {
 
           // We already know the exact start and end column of the joined range,
           // so we get the string and width representing it directly
-          cell = CellData.fromCharData([
-            0,
+
+          cell = new JoinedCellData(
+            this._workCell,
             line.translateToString(true, range[0], range[1]),
-            range[1] - range[0],
-            0xFFFFFF
-          ]);
-          // hacky: patch attrs
-          cell.fg = this._workCell.fg;
-          cell.bg = this._workCell.bg;
+            range[1] - range[0]
+          );
 
           // Skip over the cells occupied by this range in the loop
           lastCharX = range[1] - 1;