Merge pull request #4053 from Tyriar/underline_polish

Polish underline for more fonts to prevent odd overlap look

Author: Tyriar

addons/xterm-addon-webgl/src/atlas/WebglCharAtlas.ts

@@ -439,9 +439,8 @@ export class WebglCharAtlas implements IDisposable {
     if (underline) {
       this._tmpCtx.save();
       const lineWidth = Math.max(1, Math.floor(this._config.fontSize * window.devicePixelRatio / 15));
-      // When the width is odd, draw at 0.5 position. Offset by an additional 1 dpr to bring the
-      // underline closer to the character
-      const yOffset = (lineWidth % 2 === 1 ? 0.5 : 0) + window.devicePixelRatio;
+      // When the line width is odd, draw at a 0.5 position
+      const yOffset = lineWidth % 2 === 1 ? 0.5 : 0;
       this._tmpCtx.lineWidth = lineWidth;
 
       // Underline color
@@ -463,9 +462,9 @@ export class WebglCharAtlas implements IDisposable {
       this._tmpCtx.beginPath();
       const xLeft = padding;
       const xRight = padding + this._config.scaledCellWidth;
-      const yTop = Math.ceil(padding + this._config.scaledCharHeight - lineWidth) - yOffset;
-      const yMid = padding + this._config.scaledCharHeight - yOffset;
-      const yBot = Math.ceil(padding + this._config.scaledCharHeight + lineWidth) - yOffset;
+      const yTop = Math.ceil(padding + this._config.scaledCharHeight) - yOffset;
+      const yMid = padding + this._config.scaledCharHeight + lineWidth - yOffset;
+      const yBot = Math.ceil(padding + this._config.scaledCharHeight + lineWidth * 2) - yOffset;
       switch (this._workAttributeData.extended.underlineStyle) {
         case UnderlineStyle.DOUBLE:
           this._tmpCtx.moveTo(xLeft, yTop);
@@ -528,8 +527,9 @@ export class WebglCharAtlas implements IDisposable {
       this._tmpCtx.restore();
 
       // Draw stroke in the background color for non custom characters in order to give an outline
-      // between the text and the underline
-      if (!customGlyph) {
+      // between the text and the underline. Only do this when font size is >= 12 as the underline
+      // looks odd when the font size is too small
+      if (!customGlyph && this._config.fontSize >= 12) {
         // This only works when transparency is disabled because it's not clear how to clear stroked
         // text
         if (!this._config.allowTransparency && chars !== ' ') {