From 0d7e18d236a85df88b60e9b528863f1a4be5b4fc Mon Sep 17 00:00:00 2001
From: Daniel Imms <2193314+Tyriar@users.noreply.github.com>
Date: Tue, 4 Oct 2022 14:41:27 -0700
Subject: [PATCH] Add CellColorResolver to share load color code

---
 .../xterm-addon-canvas/src/BaseRenderLayer.ts | 108 +----------
 addons/xterm-addon-webgl/src/WebglRenderer.ts | 170 ++++--------------
 .../renderer/shared/CellColorResolver.ts      | 136 ++++++++++++++
 3 files changed, 177 insertions(+), 237 deletions(-)
 create mode 100644 src/browser/renderer/shared/CellColorResolver.ts

diff --git a/addons/xterm-addon-canvas/src/BaseRenderLayer.ts b/addons/xterm-addon-canvas/src/BaseRenderLayer.ts
index c0e20abd..ffea9f0e 100644
--- a/addons/xterm-addon-canvas/src/BaseRenderLayer.ts
+++ b/addons/xterm-addon-canvas/src/BaseRenderLayer.ts
@@ -18,6 +18,7 @@ import { IBufferService, IDecorationService, IOptionsService } from 'common/serv
 import { ICellData } from 'common/Types';
 import { Terminal } from 'xterm';
 import { IRenderLayer } from './Types';
+import { CellColorResolver } from 'browser/renderer/shared/CellColorResolver';
 
 // Work variables to avoid garbage collection
 let $fg = 0;
@@ -40,6 +41,7 @@ export abstract class BaseRenderLayer implements IRenderLayer {
   protected _selectionEnd: [number, number] | undefined;
   protected _columnSelectMode: boolean = false;
   protected _selectionModel: ISelectionRenderModel = createSelectionRenderModel();
+  private _cellColorResolver: CellColorResolver;
 
   protected _charAtlas!: ITextureAtlas;
 
@@ -58,6 +60,7 @@ export abstract class BaseRenderLayer implements IRenderLayer {
     protected readonly _decorationService: IDecorationService,
     protected readonly _coreBrowserService: ICoreBrowserService
   ) {
+    this._cellColorResolver = new CellColorResolver(this._terminal, this._colors, this._selectionModel, this._decorationService, this._coreBrowserService);
     this._canvas = document.createElement('canvas');
     this._canvas.classList.add(`xterm-${id}-layer`);
     this._canvas.style.zIndex = zIndex.toString();
@@ -359,20 +362,18 @@ export abstract class BaseRenderLayer implements IRenderLayer {
     }
   }
 
-  private _workColors: { fg: number, bg: number, ext: number } = { fg: 0, bg: 0, ext: 0 };
-
   /**
    * Draws one or more characters at a cell. If possible this will draw using
    * the character atlas to reduce draw time.
    */
   protected _drawChars(cell: ICellData, x: number, y: number): void {
     const chars = cell.getChars();
-    this._loadColorsForCell(x, y, cell, this._workColors);
+    this._cellColorResolver.resolve(cell, x, y);
     let glyph: IRasterizedGlyph;
     if (chars && chars.length > 1) {
-      glyph = this._charAtlas.getRasterizedGlyphCombinedChar(chars, this._workColors.bg, this._workColors.fg, this._workColors.ext);
+      glyph = this._charAtlas.getRasterizedGlyphCombinedChar(chars, this._cellColorResolver.result.bg, this._cellColorResolver.result.fg, this._cellColorResolver.result.ext);
     } else {
-      glyph = this._charAtlas.getRasterizedGlyph(cell.getCode() || WHITESPACE_CELL_CODE, this._workColors.bg, this._workColors.fg, this._workColors.ext);
+      glyph = this._charAtlas.getRasterizedGlyph(cell.getCode() || WHITESPACE_CELL_CODE, this._cellColorResolver.result.bg, this._cellColorResolver.result.fg, this._cellColorResolver.result.ext);
     }
     this._ctx.save();
     this._clipRow(y);
@@ -391,103 +392,6 @@ export abstract class BaseRenderLayer implements IRenderLayer {
     // TODO: Move both renderers to use shared load color code
   }
 
-  /**
-   * Loads colors for the cell into the work colors object. This resolves overrides/inverse if
-   * necessary which is why the work cell object is not used.
-   */
-  private _loadColorsForCell(x: number, y: number, cell: ICellData, workColors: { fg: number, bg: number, ext: number }): void {
-    workColors.bg = cell.bg;
-    workColors.fg = cell.fg;
-    workColors.ext = cell.bg & BgFlags.HAS_EXTENDED ? cell.extended.ext : 0;
-    // Get any foreground/background overrides, this happens on the model to avoid spreading
-    // override logic throughout the different sub-renderers
-
-    // Reset overrides work variables
-    $bg = 0;
-    $fg = 0;
-    $hasBg = false;
-    $hasFg = false;
-    $isSelected = false;
-
-    // Apply decorations on the bottom layer
-    this._decorationService.forEachDecorationAtCell(x, y, 'bottom', d => {
-      if (d.backgroundColorRGB) {
-        $bg = d.backgroundColorRGB.rgba >> 8 & 0xFFFFFF;
-        $hasBg = true;
-      }
-      if (d.foregroundColorRGB) {
-        $fg = d.foregroundColorRGB.rgba >> 8 & 0xFFFFFF;
-        $hasFg = true;
-      }
-    });
-
-    // Apply the selection color if needed
-    $isSelected = this._selectionModel.isCellSelected(this._terminal, x, y);
-    if ($isSelected) {
-      $bg = (this._coreBrowserService.isFocused ? this._colors.selectionBackgroundOpaque : this._colors.selectionInactiveBackgroundOpaque).rgba >> 8 & 0xFFFFFF;
-      $hasBg = true;
-      if (this._colors.selectionForeground) {
-        $fg = this._colors.selectionForeground.rgba >> 8 & 0xFFFFFF;
-        $hasFg = true;
-      }
-    }
-
-    // Apply decorations on the top layer
-    this._decorationService.forEachDecorationAtCell(x, y, 'top', d => {
-      if (d.backgroundColorRGB) {
-        $bg = d.backgroundColorRGB.rgba >> 8 & 0xFFFFFF;
-        $hasBg = true;
-      }
-      if (d.foregroundColorRGB) {
-        $fg = d.foregroundColorRGB.rgba >> 8 & 0xFFFFFF;
-        $hasFg = true;
-      }
-    });
-
-    // Convert any overrides from rgba to the fg/bg packed format. This resolves the inverse flag
-    // ahead of time in order to use the correct cache key
-    if ($hasBg) {
-      if ($isSelected) {
-        // Non-RGB attributes from model + force non-dim + override + force RGB color mode
-        $bg = (cell.bg & ~Attributes.RGB_MASK & ~BgFlags.DIM) | $bg | Attributes.CM_RGB;
-      } else {
-        // Non-RGB attributes from model + override + force RGB color mode
-        $bg = (cell.bg & ~Attributes.RGB_MASK) | $bg | Attributes.CM_RGB;
-      }
-    }
-    if ($hasFg) {
-      // Non-RGB attributes from model + force disable inverse + override + force RGB color mode
-      $fg = (cell.fg & ~Attributes.RGB_MASK & ~FgFlags.INVERSE) | $fg | Attributes.CM_RGB;
-    }
-
-    // Handle case where inverse was specified by only one of bg override or fg override was set,
-    // resolving the other inverse color and setting the inverse flag if needed.
-    if (workColors.fg & FgFlags.INVERSE) {
-      if ($hasBg && !$hasFg) {
-        // Resolve bg color type (default color has a different meaning in fg vs bg)
-        if ((workColors.bg & Attributes.CM_MASK) === Attributes.CM_DEFAULT) {
-          $fg = (workColors.fg & ~(Attributes.RGB_MASK | FgFlags.INVERSE | Attributes.CM_MASK)) | ((this._colors.background.rgba >> 8 & 0xFFFFFF) & Attributes.RGB_MASK) | Attributes.CM_RGB;
-        } else {
-          $fg = (workColors.fg & ~(Attributes.RGB_MASK | FgFlags.INVERSE | Attributes.CM_MASK)) | workColors.bg & (Attributes.RGB_MASK | Attributes.CM_MASK);
-        }
-        $hasFg = true;
-      }
-      if (!$hasBg && $hasFg) {
-        // Resolve bg color type (default color has a different meaning in fg vs bg)
-        if ((workColors.fg & Attributes.CM_MASK) === Attributes.CM_DEFAULT) {
-          $bg = (workColors.bg & ~(Attributes.RGB_MASK | Attributes.CM_MASK)) | ((this._colors.foreground.rgba >> 8 & 0xFFFFFF) & Attributes.RGB_MASK) | Attributes.CM_RGB;
-        } else {
-          $bg = (workColors.bg & ~(Attributes.RGB_MASK | Attributes.CM_MASK)) | workColors.fg & (Attributes.RGB_MASK | Attributes.CM_MASK);
-        }
-        $hasBg = true;
-      }
-    }
-
-    // Use the override if it exists
-    workColors.bg = $hasBg ? $bg : workColors.bg;
-    workColors.fg = $hasFg ? $fg : workColors.fg;
-  }
-
   /**
    * Clips a row to ensure no pixels will be drawn outside the cells in the row.
    * @param y The row to clip.
diff --git a/addons/xterm-addon-webgl/src/WebglRenderer.ts b/addons/xterm-addon-webgl/src/WebglRenderer.ts
index d7512908..c7511946 100644
--- a/addons/xterm-addon-webgl/src/WebglRenderer.ts
+++ b/addons/xterm-addon-webgl/src/WebglRenderer.ts
@@ -3,34 +3,28 @@
  * @license MIT
  */
 
-import { GlyphRenderer } from './GlyphRenderer';
-import { LinkRenderLayer } from './renderLayer/LinkRenderLayer';
-import { CursorRenderLayer } from './renderLayer/CursorRenderLayer';
-import { acquireTextureAtlas, removeTerminalFromCache } from 'browser/renderer/shared/CharAtlasCache';
-import { RectangleRenderer } from './RectangleRenderer';
-import { IWebGL2RenderingContext } from './Types';
-import { RenderModel, COMBINED_CHAR_BIT_MASK, RENDER_MODEL_BG_OFFSET, RENDER_MODEL_FG_OFFSET, RENDER_MODEL_EXT_OFFSET, RENDER_MODEL_INDICIES_PER_CELL } from './RenderModel';
-import { Disposable } from 'common/Lifecycle';
-import { Attributes, BgFlags, Content, FgFlags, NULL_CELL_CHAR, NULL_CELL_CODE } from 'common/buffer/Constants';
-import { Terminal, IEvent } from 'xterm';
-import { IRenderLayer } from './renderLayer/Types';
-import { IRenderDimensions, IRenderer, IRequestRedrawEvent, ITextureAtlas } from 'browser/renderer/shared/Types';
-import { observeDevicePixelDimensions } from 'browser/renderer/shared/DevicePixelObserver';
-import { ITerminal, IColorSet } from 'browser/Types';
-import { EventEmitter, initEvent } from 'common/EventEmitter';
-import { CellData } from 'common/buffer/CellData';
 import { addDisposableDomListener } from 'browser/Lifecycle';
+import { CellColorResolver } from 'browser/renderer/shared/CellColorResolver';
+import { acquireTextureAtlas, removeTerminalFromCache } from 'browser/renderer/shared/CharAtlasCache';
+import { observeDevicePixelDimensions } from 'browser/renderer/shared/DevicePixelObserver';
+import { IRenderDimensions, IRenderer, IRequestRedrawEvent, ITextureAtlas } from 'browser/renderer/shared/Types';
 import { ICharacterJoinerService, ICoreBrowserService } from 'browser/services/Services';
-import { CharData, IBufferLine, ICellData } from 'common/Types';
+import { IColorSet, ITerminal } from 'browser/Types';
 import { AttributeData } from 'common/buffer/AttributeData';
+import { CellData } from 'common/buffer/CellData';
+import { Content, NULL_CELL_CHAR, NULL_CELL_CODE } from 'common/buffer/Constants';
+import { initEvent } from 'common/EventEmitter';
+import { Disposable } from 'common/Lifecycle';
 import { ICoreService, IDecorationService } from 'common/services/Services';
-
-// Work variables to avoid garbage collection
-let $fg = 0;
-let $bg = 0;
-let $hasFg = false;
-let $hasBg = false;
-let $isSelected = false;
+import { CharData, IBufferLine, ICellData } from 'common/Types';
+import { Terminal } from 'xterm';
+import { GlyphRenderer } from './GlyphRenderer';
+import { RectangleRenderer } from './RectangleRenderer';
+import { CursorRenderLayer } from './renderLayer/CursorRenderLayer';
+import { LinkRenderLayer } from './renderLayer/LinkRenderLayer';
+import { IRenderLayer } from './renderLayer/Types';
+import { COMBINED_CHAR_BIT_MASK, RenderModel, RENDER_MODEL_BG_OFFSET, RENDER_MODEL_EXT_OFFSET, RENDER_MODEL_FG_OFFSET, RENDER_MODEL_INDICIES_PER_CELL } from './RenderModel';
+import { IWebGL2RenderingContext } from './Types';
 
 export class WebglRenderer extends Disposable implements IRenderer {
   private _renderLayers: IRenderLayer[];
@@ -39,7 +33,7 @@ export class WebglRenderer extends Disposable implements IRenderer {
 
   private _model: RenderModel = new RenderModel();
   private _workCell: CellData = new CellData();
-  private _workColors: { fg: number, bg: number, ext: number } = { fg: 0, bg: 0, ext: 0 };
+  private _cellColorResolver: CellColorResolver;
 
   private _canvas: HTMLCanvasElement;
   private _gl: IWebGL2RenderingContext;
@@ -67,6 +61,8 @@ export class WebglRenderer extends Disposable implements IRenderer {
   ) {
     super();
 
+    this._cellColorResolver = new CellColorResolver(this._terminal, this._colors, this._model.selection, this._decorationService, this._coreBrowserService);
+
     this._core = (this._terminal as any)._core;
 
     this._renderLayers = [
@@ -155,6 +151,7 @@ export class WebglRenderer extends Disposable implements IRenderer {
       l.reset(this._terminal);
     }
 
+    this._cellColorResolver.setColors(colors);
     this._rectangleRenderer.setColors();
 
     this._refreshCharAtlas();
@@ -372,11 +369,11 @@ export class WebglRenderer extends Disposable implements IRenderer {
       this._model.lineLengths[y] = 0;
       joinedRanges = this._characterJoinerService.getJoinedCharacters(row);
       for (x = 0; x < terminal.cols; x++) {
-        lastBg = this._workColors.bg;
+        lastBg = this._cellColorResolver.result.bg;
         line.loadCell(x, cell);
 
         if (x === 0) {
-          lastBg = this._workColors.bg;
+          lastBg = this._cellColorResolver.result.bg;
         }
 
         // If true, indicates that the current character(s) to draw were joined.
@@ -407,7 +404,7 @@ export class WebglRenderer extends Disposable implements IRenderer {
         i = ((y * terminal.cols) + x) * RENDER_MODEL_INDICIES_PER_CELL;
 
         // Load colors/resolve overrides into work colors
-        this._loadColorsForCell(x, row);
+        this._cellColorResolver.resolve(cell, x, row);
 
         if (code !== NULL_CELL_CODE) {
           this._model.lineLengths[y] = x + 1;
@@ -415,9 +412,9 @@ export class WebglRenderer extends Disposable implements IRenderer {
 
         // Nothing has changed, no updates needed
         if (this._model.cells[i] === code &&
-          this._model.cells[i + RENDER_MODEL_BG_OFFSET] === this._workColors.bg &&
-          this._model.cells[i + RENDER_MODEL_FG_OFFSET] === this._workColors.fg &&
-          this._model.cells[i + RENDER_MODEL_EXT_OFFSET] === this._workColors.ext) {
+          this._model.cells[i + RENDER_MODEL_BG_OFFSET] === this._cellColorResolver.result.bg &&
+          this._model.cells[i + RENDER_MODEL_FG_OFFSET] === this._cellColorResolver.result.fg &&
+          this._model.cells[i + RENDER_MODEL_EXT_OFFSET] === this._cellColorResolver.result.ext) {
           continue;
         }
 
@@ -428,11 +425,11 @@ export class WebglRenderer extends Disposable implements IRenderer {
 
         // Cache the results in the model
         this._model.cells[i] = code;
-        this._model.cells[i + RENDER_MODEL_BG_OFFSET] = this._workColors.bg;
-        this._model.cells[i + RENDER_MODEL_FG_OFFSET] = this._workColors.fg;
-        this._model.cells[i + RENDER_MODEL_EXT_OFFSET] = this._workColors.ext;
+        this._model.cells[i + RENDER_MODEL_BG_OFFSET] = this._cellColorResolver.result.bg;
+        this._model.cells[i + RENDER_MODEL_FG_OFFSET] = this._cellColorResolver.result.fg;
+        this._model.cells[i + RENDER_MODEL_EXT_OFFSET] = this._cellColorResolver.result.ext;
 
-        this._glyphRenderer.updateCell(x, y, code, this._workColors.bg, this._workColors.fg, this._workColors.ext, chars, lastBg);
+        this._glyphRenderer.updateCell(x, y, code, this._cellColorResolver.result.bg, this._cellColorResolver.result.fg, this._cellColorResolver.result.ext, chars, lastBg);
 
         if (isJoined) {
           // Restore work cell
@@ -443,9 +440,9 @@ export class WebglRenderer extends Disposable implements IRenderer {
             j = ((y * terminal.cols) + x) * RENDER_MODEL_INDICIES_PER_CELL;
             this._glyphRenderer.updateCell(x, y, NULL_CELL_CODE, 0, 0, 0, NULL_CELL_CHAR, 0);
             this._model.cells[j] = NULL_CELL_CODE;
-            this._model.cells[j + RENDER_MODEL_BG_OFFSET] = this._workColors.bg;
-            this._model.cells[j + RENDER_MODEL_FG_OFFSET] = this._workColors.fg;
-            this._model.cells[j + RENDER_MODEL_EXT_OFFSET] = this._workColors.ext;
+            this._model.cells[j + RENDER_MODEL_BG_OFFSET] = this._cellColorResolver.result.bg;
+            this._model.cells[j + RENDER_MODEL_FG_OFFSET] = this._cellColorResolver.result.fg;
+            this._model.cells[j + RENDER_MODEL_EXT_OFFSET] = this._cellColorResolver.result.ext;
           }
         }
       }
@@ -453,103 +450,6 @@ export class WebglRenderer extends Disposable implements IRenderer {
     this._rectangleRenderer.updateBackgrounds(this._model);
   }
 
-  /**
-   * Loads colors for the cell into the work colors object. This resolves overrides/inverse if
-   * necessary which is why the work cell object is not used.
-   */
-  private _loadColorsForCell(x: number, y: number): void {
-    this._workColors.bg = this._workCell.bg;
-    this._workColors.fg = this._workCell.fg;
-    this._workColors.ext = this._workCell.bg & BgFlags.HAS_EXTENDED ? this._workCell.extended.ext : 0;
-    // Get any foreground/background overrides, this happens on the model to avoid spreading
-    // override logic throughout the different sub-renderers
-
-    // Reset overrides work variables
-    $bg = 0;
-    $fg = 0;
-    $hasBg = false;
-    $hasFg = false;
-    $isSelected = false;
-
-    // Apply decorations on the bottom layer
-    this._decorationService.forEachDecorationAtCell(x, y, 'bottom', d => {
-      if (d.backgroundColorRGB) {
-        $bg = d.backgroundColorRGB.rgba >> 8 & 0xFFFFFF;
-        $hasBg = true;
-      }
-      if (d.foregroundColorRGB) {
-        $fg = d.foregroundColorRGB.rgba >> 8 & 0xFFFFFF;
-        $hasFg = true;
-      }
-    });
-
-    // Apply the selection color if needed
-    $isSelected = this._model.selection.isCellSelected(this._terminal, x, y);
-    if ($isSelected) {
-      $bg = (this._coreBrowserService.isFocused ? this._colors.selectionBackgroundOpaque : this._colors.selectionInactiveBackgroundOpaque).rgba >> 8 & 0xFFFFFF;
-      $hasBg = true;
-      if (this._colors.selectionForeground) {
-        $fg = this._colors.selectionForeground.rgba >> 8 & 0xFFFFFF;
-        $hasFg = true;
-      }
-    }
-
-    // Apply decorations on the top layer
-    this._decorationService.forEachDecorationAtCell(x, y, 'top', d => {
-      if (d.backgroundColorRGB) {
-        $bg = d.backgroundColorRGB.rgba >> 8 & 0xFFFFFF;
-        $hasBg = true;
-      }
-      if (d.foregroundColorRGB) {
-        $fg = d.foregroundColorRGB.rgba >> 8 & 0xFFFFFF;
-        $hasFg = true;
-      }
-    });
-
-    // Convert any overrides from rgba to the fg/bg packed format. This resolves the inverse flag
-    // ahead of time in order to use the correct cache key
-    if ($hasBg) {
-      if ($isSelected) {
-        // Non-RGB attributes from model + force non-dim + override + force RGB color mode
-        $bg = (this._workCell.bg & ~Attributes.RGB_MASK & ~BgFlags.DIM) | $bg | Attributes.CM_RGB;
-      } else {
-        // Non-RGB attributes from model + override + force RGB color mode
-        $bg = (this._workCell.bg & ~Attributes.RGB_MASK) | $bg | Attributes.CM_RGB;
-      }
-    }
-    if ($hasFg) {
-      // Non-RGB attributes from model + force disable inverse + override + force RGB color mode
-      $fg = (this._workCell.fg & ~Attributes.RGB_MASK & ~FgFlags.INVERSE) | $fg | Attributes.CM_RGB;
-    }
-
-    // Handle case where inverse was specified by only one of bg override or fg override was set,
-    // resolving the other inverse color and setting the inverse flag if needed.
-    if (this._workColors.fg & FgFlags.INVERSE) {
-      if ($hasBg && !$hasFg) {
-        // Resolve bg color type (default color has a different meaning in fg vs bg)
-        if ((this._workColors.bg & Attributes.CM_MASK) === Attributes.CM_DEFAULT) {
-          $fg = (this._workColors.fg & ~(Attributes.RGB_MASK | FgFlags.INVERSE | Attributes.CM_MASK)) | ((this._colors.background.rgba >> 8 & 0xFFFFFF) & Attributes.RGB_MASK) | Attributes.CM_RGB;
-        } else {
-          $fg = (this._workColors.fg & ~(Attributes.RGB_MASK | FgFlags.INVERSE | Attributes.CM_MASK)) | this._workColors.bg & (Attributes.RGB_MASK | Attributes.CM_MASK);
-        }
-        $hasFg = true;
-      }
-      if (!$hasBg && $hasFg) {
-        // Resolve bg color type (default color has a different meaning in fg vs bg)
-        if ((this._workColors.fg & Attributes.CM_MASK) === Attributes.CM_DEFAULT) {
-          $bg = (this._workColors.bg & ~(Attributes.RGB_MASK | Attributes.CM_MASK)) | ((this._colors.foreground.rgba >> 8 & 0xFFFFFF) & Attributes.RGB_MASK) | Attributes.CM_RGB;
-        } else {
-          $bg = (this._workColors.bg & ~(Attributes.RGB_MASK | Attributes.CM_MASK)) | this._workColors.fg & (Attributes.RGB_MASK | Attributes.CM_MASK);
-        }
-        $hasBg = true;
-      }
-    }
-
-    // Use the override if it exists
-    this._workColors.bg = $hasBg ? $bg : this._workColors.bg;
-    this._workColors.fg = $hasFg ? $fg : this._workColors.fg;
-  }
-
   /**
    * Recalculates the character and canvas dimensions.
    */
diff --git a/src/browser/renderer/shared/CellColorResolver.ts b/src/browser/renderer/shared/CellColorResolver.ts
new file mode 100644
index 00000000..b29475b9
--- /dev/null
+++ b/src/browser/renderer/shared/CellColorResolver.ts
@@ -0,0 +1,136 @@
+import { ISelectionRenderModel } from 'browser/renderer/shared/Types';
+import { ICoreBrowserService } from 'browser/services/Services';
+import { IColorSet } from 'browser/Types';
+import { Attributes, BgFlags, FgFlags } from 'common/buffer/Constants';
+import { IDecorationService } from 'common/services/Services';
+import { ICellData } from 'common/Types';
+import { Terminal } from 'xterm';
+
+// Work variables to avoid garbage collection
+let $fg = 0;
+let $bg = 0;
+let $hasFg = false;
+let $hasBg = false;
+let $isSelected = false;
+
+export class CellColorResolver {
+  /**
+   * The shared result of the {@link resolve} call. This is only safe to use immediately after as
+   * any other calls will share object.
+   */
+  public readonly result: { fg: number, bg: number, ext: number } = {
+    fg: 0,
+    bg: 0,
+    ext: 0
+  };
+
+  constructor(
+    private readonly _terminal: Terminal,
+    private _colors: IColorSet,
+    private readonly _selectionRenderModel: ISelectionRenderModel,
+    private readonly _decorationService: IDecorationService,
+    private readonly _coreBrowserService: ICoreBrowserService
+  ) {
+  }
+
+  public setColors(colors: IColorSet): void {
+    this._colors = colors;
+  }
+
+  /**
+   * Resolves colors for the cell, putting the result into the shared {@link result}. This resolves
+   * overrides, inverse and selection for the cell which can then be used to feed into the renderer.
+   */
+  public resolve(cell: ICellData, x: number, y: number): void {
+    this.result.bg = cell.bg;
+    this.result.fg = cell.fg;
+    this.result.ext = cell.bg & BgFlags.HAS_EXTENDED ? cell.extended.ext : 0;
+    // Get any foreground/background overrides, this happens on the model to avoid spreading
+    // override logic throughout the different sub-renderers
+
+    // Reset overrides work variables
+    $bg = 0;
+    $fg = 0;
+    $hasBg = false;
+    $hasFg = false;
+    $isSelected = false;
+
+    // Apply decorations on the bottom layer
+    this._decorationService.forEachDecorationAtCell(x, y, 'bottom', d => {
+      if (d.backgroundColorRGB) {
+        $bg = d.backgroundColorRGB.rgba >> 8 & 0xFFFFFF;
+        $hasBg = true;
+      }
+      if (d.foregroundColorRGB) {
+        $fg = d.foregroundColorRGB.rgba >> 8 & 0xFFFFFF;
+        $hasFg = true;
+      }
+    });
+
+    // Apply the selection color if needed
+    $isSelected = this._selectionRenderModel.isCellSelected(this._terminal, x, y);
+    if ($isSelected) {
+      $bg = (this._coreBrowserService.isFocused ? this._colors.selectionBackgroundOpaque : this._colors.selectionInactiveBackgroundOpaque).rgba >> 8 & 0xFFFFFF;
+      $hasBg = true;
+      if (this._colors.selectionForeground) {
+        $fg = this._colors.selectionForeground.rgba >> 8 & 0xFFFFFF;
+        $hasFg = true;
+      }
+    }
+
+    // Apply decorations on the top layer
+    this._decorationService.forEachDecorationAtCell(x, y, 'top', d => {
+      if (d.backgroundColorRGB) {
+        $bg = d.backgroundColorRGB.rgba >> 8 & 0xFFFFFF;
+        $hasBg = true;
+      }
+      if (d.foregroundColorRGB) {
+        $fg = d.foregroundColorRGB.rgba >> 8 & 0xFFFFFF;
+        $hasFg = true;
+      }
+    });
+
+    // Convert any overrides from rgba to the fg/bg packed format. This resolves the inverse flag
+    // ahead of time in order to use the correct cache key
+    if ($hasBg) {
+      if ($isSelected) {
+        // Non-RGB attributes from model + force non-dim + override + force RGB color mode
+        $bg = (cell.bg & ~Attributes.RGB_MASK & ~BgFlags.DIM) | $bg | Attributes.CM_RGB;
+      } else {
+        // Non-RGB attributes from model + override + force RGB color mode
+        $bg = (cell.bg & ~Attributes.RGB_MASK) | $bg | Attributes.CM_RGB;
+      }
+    }
+    if ($hasFg) {
+      // Non-RGB attributes from model + force disable inverse + override + force RGB color mode
+      $fg = (cell.fg & ~Attributes.RGB_MASK & ~FgFlags.INVERSE) | $fg | Attributes.CM_RGB;
+    }
+
+    // Handle case where inverse was specified by only one of bg override or fg override was set,
+    // resolving the other inverse color and setting the inverse flag if needed.
+    if (this.result.fg & FgFlags.INVERSE) {
+      if ($hasBg && !$hasFg) {
+        // Resolve bg color type (default color has a different meaning in fg vs bg)
+        if ((this.result.bg & Attributes.CM_MASK) === Attributes.CM_DEFAULT) {
+          $fg = (this.result.fg & ~(Attributes.RGB_MASK | FgFlags.INVERSE | Attributes.CM_MASK)) | ((this._colors.background.rgba >> 8 & 0xFFFFFF) & Attributes.RGB_MASK) | Attributes.CM_RGB;
+        } else {
+          $fg = (this.result.fg & ~(Attributes.RGB_MASK | FgFlags.INVERSE | Attributes.CM_MASK)) | this.result.bg & (Attributes.RGB_MASK | Attributes.CM_MASK);
+        }
+        $hasFg = true;
+      }
+      if (!$hasBg && $hasFg) {
+        // Resolve bg color type (default color has a different meaning in fg vs bg)
+        if ((this.result.fg & Attributes.CM_MASK) === Attributes.CM_DEFAULT) {
+          $bg = (this.result.bg & ~(Attributes.RGB_MASK | Attributes.CM_MASK)) | ((this._colors.foreground.rgba >> 8 & 0xFFFFFF) & Attributes.RGB_MASK) | Attributes.CM_RGB;
+        } else {
+          $bg = (this.result.bg & ~(Attributes.RGB_MASK | Attributes.CM_MASK)) | this.result.fg & (Attributes.RGB_MASK | Attributes.CM_MASK);
+        }
+        $hasBg = true;
+      }
+    }
+
+    // Use the override if it exists
+    this.result.bg = $hasBg ? $bg : this.result.bg;
+    this.result.fg = $hasFg ? $fg : this.result.fg;
+  }
+}