From 941cc5100d7eb8afcfe80583412ed5d9cc12fc9a Mon Sep 17 00:00:00 2001
From: Daniel Imms <2193314+Tyriar@users.noreply.github.com>
Date: Sat, 30 Jul 2022 06:53:34 -0700
Subject: [PATCH] Increase curly height when dpr <= 1

---
 .../src/atlas/WebglCharAtlas.ts               | 22 ++++++++++---------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/addons/xterm-addon-webgl/src/atlas/WebglCharAtlas.ts b/addons/xterm-addon-webgl/src/atlas/WebglCharAtlas.ts
index 93a98c98..48418c48 100644
--- a/addons/xterm-addon-webgl/src/atlas/WebglCharAtlas.ts
+++ b/addons/xterm-addon-webgl/src/atlas/WebglCharAtlas.ts
@@ -451,8 +451,10 @@ export class WebglCharAtlas implements IDisposable {
           break;
         case UnderlineStyle.CURLY:
           const xMid = padding + this._config.scaledCharWidth / 2;
-          const yMidBot = Math.ceil(padding + this._config.scaledCharHeight - lineWidth / 2) - yOffset;
-          const yMidTop = Math.ceil(padding + this._config.scaledCharHeight + lineWidth / 2) - yOffset;
+          // Choose the bezier top and bottom based on the device pixel ratio, the curly line is
+          // made taller when the line width is  as otherwise it's not very clear otherwise.
+          const yCurlyBot = lineWidth <= 1 ? yBot : Math.ceil(padding + this._config.scaledCharHeight - lineWidth / 2) - yOffset;
+          const yCurlyTop = lineWidth <= 1 ? yTop : Math.ceil(padding + this._config.scaledCharHeight + lineWidth / 2) - yOffset;
           // Clip the left and right edges of the underline such that it can be drawn just outside
           // the edge of the cell to ensure a continuous stroke when there are multiple underlined
           // glyphs adjacent to one another.
@@ -462,23 +464,23 @@ export class WebglCharAtlas implements IDisposable {
           // Start 1/2 cell before and end 1/2 cells after to ensure a smooth curve with other cells
           this._tmpCtx.moveTo(xLeft - this._config.scaledCharWidth / 2, yMid);
           this._tmpCtx.bezierCurveTo(
-            xLeft - this._config.scaledCharWidth / 2, yMidTop,
-            xLeft, yMidTop,
+            xLeft - this._config.scaledCharWidth / 2, yCurlyTop,
+            xLeft, yCurlyTop,
             xLeft, yMid
           );
           this._tmpCtx.bezierCurveTo(
-            xLeft, yMidBot,
-            xMid, yMidBot,
+            xLeft, yCurlyBot,
+            xMid, yCurlyBot,
             xMid, yMid
           );
           this._tmpCtx.bezierCurveTo(
-            xMid, yMidTop,
-            xRight, yMidTop,
+            xMid, yCurlyTop,
+            xRight, yCurlyTop,
             xRight, yMid
           );
           this._tmpCtx.bezierCurveTo(
-            xRight, yMidBot,
-            xRight + this._config.scaledCellWidth / 2, yMidBot,
+            xRight, yCurlyBot,
+            xRight + this._config.scaledCellWidth / 2, yCurlyBot,
             xRight + this._config.scaledCellWidth / 2, yMid
           );
           break;