exclude box and block glyphs from contrast ratio demands (#3844)

src/browser/renderer/BaseRenderLayer.ts

@@ -14,7 +14,7 @@ import { AttributeData } from 'common/buffer/AttributeData';
 import { IColorSet } from 'browser/Types';
 import { CellData } from 'common/buffer/CellData';
 import { IBufferService, IDecorationService, IOptionsService } from 'common/services/Services';
-import { isPowerlineGlyph, throwIfFalsy } from 'browser/renderer/RendererUtils';
+import { excludeFromContrastRatioDemands, throwIfFalsy } from 'browser/renderer/RendererUtils';
 import { channels, color, rgba } from 'common/Color';
 import { removeElementFromParent } from 'browser/Dom';
 import { tryDrawCustomChar } from 'browser/renderer/CustomGlyphs';
@@ -473,7 +473,7 @@ export abstract class BaseRenderLayer implements IRenderLayer {
       }
     }
 
-    if (!bgOverride && !fgOverride && (this._optionsService.rawOptions.minimumContrastRatio === 1 || isPowerlineGlyph(cell.getCode()))) {
+    if (!bgOverride && !fgOverride && (this._optionsService.rawOptions.minimumContrastRatio === 1 || excludeFromContrastRatioDemands(cell.getCode()))) {
       return undefined;
     }
 

src/browser/renderer/RendererUtils.ts

@@ -14,5 +14,13 @@ export function isPowerlineGlyph(codepoint: number): boolean {
   // Only return true for Powerline symbols which require
   // different padding and should be excluded from minimum contrast
   // ratio standards
-  return 0xE0A0 <= codepoint && codepoint <=  0xE0D6;
+  return 0xE0A4 <= codepoint && codepoint <=  0xE0D6;
+}
+
+function isBoxOrBlockGlyph(codepoint: number): boolean {
+  return (0x2500 <= codepoint && codepoint <= 0x259F);
+}
+
+export function excludeFromContrastRatioDemands(codepoint: number): boolean {
+  return isPowerlineGlyph(codepoint) || isBoxOrBlockGlyph(codepoint);
 }

src/browser/renderer/dom/DomRendererRowFactory.ts

@@ -12,7 +12,7 @@ import { color, rgba } from 'common/Color';
 import { IColorSet } from 'browser/Types';
 import { ICharacterJoinerService, ISelectionService } from 'browser/services/Services';
 import { JoinedCellData } from 'browser/services/CharacterJoinerService';
-import { isPowerlineGlyph } from 'browser/renderer/RendererUtils';
+import { excludeFromContrastRatioDemands } from 'browser/renderer/RendererUtils';
 
 export const BOLD_CLASS = 'xterm-bold';
 export const DIM_CLASS = 'xterm-dim';
@@ -281,7 +281,7 @@ export class DomRendererRowFactory {
   }
 
   private _applyMinimumContrast(element: HTMLElement, bg: IColor, fg: IColor, cell: ICellData, bgOverride: IColor | undefined, fgOverride: IColor | undefined): boolean {
-    if (this._optionsService.rawOptions.minimumContrastRatio === 1 || isPowerlineGlyph(cell.getCode())) {
+    if (this._optionsService.rawOptions.minimumContrastRatio === 1 || excludeFromContrastRatioDemands(cell.getCode())) {
       return false;
     }