non-transparent selection covers text

src/browser/Color.ts

@@ -3,7 +3,7 @@
  * @license MIT
  */
 
-import { IColor } from 'browser/Types';
+import { IColor, IColorSet } from 'browser/Types';
 
 /**
  * Helper functions where the source type is "channels" (individual color channels as numbers).
@@ -47,6 +47,17 @@ export namespace color {
     const rgba = channels.toRgba(r, g, b);
     return { css, rgba };
   }
+  export function blendSelectionWithBgWithOpacity(colors: IColorSet, opacity: number=0.3): void {
+    const [selectionR, selectionG, selectionB, selectionA] = rgba.toChannels(colors.selection.rgba);
+    // The selection color is opaque. It needs to be blended with background color at 0.3 opacity Issue #2737
+    if (selectionA === 0xFF) {
+      const newAlpha: number = Math.round(opacity*255);
+      colors.selection = {
+        css: channels.toCss(selectionR, selectionG, selectionB, newAlpha),
+        rgba: channels.toRgba(selectionR, selectionG, selectionB, newAlpha)
+      };
+    }
+  }
 
   export function ensureContrastRatio(bg: IColor, fg: IColor, ratio: number): IColor | undefined {
     const result = rgba.ensureContrastRatio(bg.rgba, fg.rgba, ratio);

src/browser/ColorManager.ts

@@ -5,7 +5,7 @@
 
 import { IColorManager, IColor, IColorSet, IColorContrastCache } from 'browser/Types';
 import { ITheme } from 'common/services/Services';
-import { channels, color, css } from 'browser/Color';
+import { channels, color, css, rgba } from 'browser/Color';
 import { ColorContrastCache } from 'browser/ColorContrastCache';
 
 const DEFAULT_FOREGROUND = css.toColor('#ffffff');

src/browser/renderer/Renderer.ts

@@ -15,6 +15,7 @@ import { ICharSizeService, ICoreBrowserService } from 'browser/services/Services
 import { IBufferService, IOptionsService, ICoreService } from 'common/services/Services';
 import { removeTerminalFromCache } from 'browser/renderer/atlas/CharAtlasCache';
 import { EventEmitter, IEvent } from 'common/EventEmitter';
+import { color } from 'browser/Color';
 
 let nextRendererId = 1;
 
@@ -44,7 +45,7 @@ export class Renderer extends Disposable implements IRenderer {
     super();
     const allowTransparency = this._optionsService.options.allowTransparency;
     this._characterJoinerRegistry = new CharacterJoinerRegistry(this._bufferService);
-
+    color.blendSelectionWithBgWithOpacity(this._colors);
     this._renderLayers = [
       new TextRenderLayer(this._screenElement, 0, this._colors, this._characterJoinerRegistry, allowTransparency, this._id, this._bufferService, _optionsService),
       new SelectionRenderLayer(this._screenElement, 1, this._colors, this._id, this._bufferService, _optionsService),
@@ -89,7 +90,6 @@ export class Renderer extends Disposable implements IRenderer {
 
   public setColors(colors: IColorSet): void {
     this._colors = colors;
-
     // Clear layers and force a full render
     for (const l of this._renderLayers) {
       l.setColors(this._colors);

src/browser/renderer/dom/DomRenderer.ts

@@ -54,7 +54,7 @@ export class DomRenderer extends Disposable implements IRenderer {
     @IBufferService private readonly _bufferService: IBufferService
   ) {
     super();
-
+    color.blendSelectionWithBgWithOpacity(this._colors);
     this._rowContainer = document.createElement('div');
     this._rowContainer.classList.add(ROW_CONTAINER_CLASS);
     this._rowContainer.style.lineHeight = 'normal';