Add opacity decoration option

Adds a new opacity option for text decorations. This controls the opacity of the text (it does not effect the border or background added by the decoration since those already have alpha channels)

Fixes #43004

src/vs/editor/browser/services/codeEditorServiceImpl.ts

@@ -194,6 +194,7 @@ class DecorationTypeOptionsProvider implements IModelDecorationOptionsProvider {
 
 const _CSS_MAP = {
 	color: 'color:{0} !important;',
+	opacity: 'opacity:{0};',
 	backgroundColor: 'background-color:{0};',
 
 	outline: 'outline:{0};',
@@ -357,7 +358,7 @@ class DecorationCSSRules {
 			return '';
 		}
 		let cssTextArr: string[] = [];
-		this.collectCSSText(opts, ['fontStyle', 'fontWeight', 'textDecoration', 'cursor', 'color', 'letterSpacing'], cssTextArr);
+		this.collectCSSText(opts, ['fontStyle', 'fontWeight', 'textDecoration', 'cursor', 'color', 'opacity', 'letterSpacing'], cssTextArr);
 		return cssTextArr.join('');
 	}
 
@@ -385,7 +386,7 @@ class DecorationCSSRules {
 
 				cssTextArr.push(strings.format(_CSS_MAP.contentText, escaped));
 			}
-			this.collectCSSText(opts, ['fontStyle', 'fontWeight', 'textDecoration', 'color', 'backgroundColor', 'margin'], cssTextArr);
+			this.collectCSSText(opts, ['fontStyle', 'fontWeight', 'textDecoration', 'color', 'opacity', 'backgroundColor', 'margin'], cssTextArr);
 			if (this.collectCSSText(opts, ['width', 'height'], cssTextArr)) {
 				cssTextArr.push('display:inline-block;');
 			}

src/vs/editor/common/editorCommon.ts

@@ -509,6 +509,7 @@ export interface IThemeDecorationRenderOptions {
 	textDecoration?: string;
 	cursor?: string;
 	color?: string | ThemeColor;
+	opacity?: number;
 	letterSpacing?: string;
 
 	gutterIconPath?: string | UriComponents;

src/vs/vscode.d.ts

@@ -893,6 +893,11 @@ declare module 'vscode' {
 		 */
 		color?: string | ThemeColor;
 
+		/**
+		 * CSS styling property that will be applied to text enclosed by a decoration.
+		 */
+		opacity?: string;
+
 		/**
 		 * CSS styling property that will be applied to text enclosed by a decoration.
 		 */