Don't always use the replacement character in minimap

When the font scale is small enough, using other ASCII characters for characters outside the supported ASCII range is preferrable.

Fixes #84264

src/vs/editor/browser/viewParts/minimap/minimap.ts

@@ -1109,7 +1109,7 @@ export class Minimap extends ViewPart {
 						if (renderMinimap === RenderMinimap.Blocks) {
 							minimapCharRenderer.blockRenderChar(target, dx, dy, tokenColor, backgroundColor, useLighterFont);
 						} else { // RenderMinimap.Text
-							minimapCharRenderer.renderChar(target, dx, dy, charCode, tokenColor, backgroundColor, useLighterFont);
+							minimapCharRenderer.renderChar(target, dx, dy, charCode, tokenColor, backgroundColor, fontScale, useLighterFont);
 						}
 
 						dx += charWidth;

src/vs/editor/browser/viewParts/minimap/minimapCharRenderer.ts

@@ -32,6 +32,7 @@ export class MinimapCharRenderer {
 		chCode: number,
 		color: RGBA8,
 		backgroundColor: RGBA8,
+		fontScale: number,
 		useLighterFont: boolean
 	): void {
 		const charWidth = Constants.BASE_CHAR_WIDTH * this.scale;
@@ -42,7 +43,7 @@ export class MinimapCharRenderer {
 		}
 
 		const charData = useLighterFont ? this.charDataLight : this.charDataNormal;
-		const charIndex = getCharIndex(chCode);
+		const charIndex = getCharIndex(chCode, fontScale);
 
 		const destWidth = target.width * Constants.RGBA_CHANNELS_CNT;
 

src/vs/editor/browser/viewParts/minimap/minimapCharSheet.ts

@@ -29,9 +29,13 @@ export const allCharCodes: ReadonlyArray<number> = (() => {
 	return v;
 })();
 
-export const getCharIndex = (chCode: number) => {
+export const getCharIndex = (chCode: number, fontScale: number) => {
 	chCode -= Constants.START_CH_CODE;
 	if (chCode < 0 || chCode > Constants.CHAR_COUNT) {
+		if (fontScale <= 2) {
+			// for smaller scales, we can get away with using any ASCII character...
+			return (chCode + Constants.CHAR_COUNT) % Constants.CHAR_COUNT;
+		}
 		return Constants.CHAR_COUNT - 1; // unknown symbol
 	}
 

src/vs/editor/test/browser/view/minimapCharRenderer.test.ts

@@ -86,7 +86,7 @@ suite('MinimapCharRenderer', () => {
 			imageData.data[4 * i + 2] = background.b;
 			imageData.data[4 * i + 3] = 255;
 		}
-		renderer.renderChar(imageData, 0, 0, 'd'.charCodeAt(0), color, background, false);
+		renderer.renderChar(imageData, 0, 0, 'd'.charCodeAt(0), color, background, 2, false);
 
 		let actual: number[] = [];
 		for (let i = 0; i < imageData.data.length; i++) {
@@ -116,7 +116,7 @@ suite('MinimapCharRenderer', () => {
 			imageData.data[4 * i + 3] = 255;
 		}
 
-		renderer.renderChar(imageData, 0, 0, 'd'.charCodeAt(0), color, background, false);
+		renderer.renderChar(imageData, 0, 0, 'd'.charCodeAt(0), color, background, 1, false);
 
 		let actual: number[] = [];
 		for (let i = 0; i < imageData.data.length; i++) {