Guess color format.

src/vs/editor/contrib/colorPicker/browser/colorPickerModel.ts

@@ -55,6 +55,15 @@ export class ColorPickerModel {
 		this._onDidChangeFormatter.fire(this.formatter);
 	}
 
+	guessColorFormat(color: Color, originalText: string): void {
+		for (let i = 0; i < this.formatters.length; i++) {
+			if (originalText === this.formatters[i].format(color)) {
+				this.formatterIndex = i;
+				break;
+			}
+		}
+	}
+
 	flushColor(): void {
 		this._onColorFlushed.fire(this._color);
 	}

src/vs/editor/contrib/hover/browser/modesContentHover.ts

@@ -315,6 +315,8 @@ export class ModesContentHoverWidget extends ContentHoverWidget {
 				const color = new Color(rgba);
 
 				const model = new ColorPickerModel(color, 0);
+				const originalText = this._editor.getModel().getValueInRange(msg.range);
+				model.guessColorFormat(color, originalText);
 				const widget = new ColorPickerWidget(fragment, model, this._editor.getConfiguration().pixelRatio);
 
 				const editorModel = this._editor.getModel();