From 2e31f716eda3a40fe86ac50547f6aef3c2b68fee Mon Sep 17 00:00:00 2001
From: ahocevar <andreas.hocevar@gmail.com>
Date: Wed, 15 May 2019 15:01:12 +0200
Subject: [PATCH] Avoid cut off labels for italic text

---
 src/ol/render/canvas/Executor.js | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/ol/render/canvas/Executor.js b/src/ol/render/canvas/Executor.js
index be254c38e3..7f87089c79 100644
--- a/src/ol/render/canvas/Executor.js
+++ b/src/ol/render/canvas/Executor.js
@@ -193,9 +193,10 @@ class Executor extends Disposable {
       const width = measureTextWidths(textState.font, lines, widths);
       const lineHeight = measureTextHeight(textState.font);
       const height = lineHeight * numLines;
-      const renderWidth = (width + strokeWidth);
+      const renderWidth = width + strokeWidth;
       const context = createCanvasContext2D(
-        Math.ceil(renderWidth * scale),
+        // make canvas 2 pixels wider to account for italic text width measurement errors
+        Math.ceil((renderWidth + 2) * scale),
         Math.ceil((height + strokeWidth) * scale));
       label = context.canvas;
       labelCache.set(key, label);
@@ -220,7 +221,7 @@ class Executor extends Disposable {
       context.textBaseline = 'middle';
       context.textAlign = 'center';
       const leftRight = (0.5 - align);
-      const x = align * label.width / scale + leftRight * strokeWidth;
+      const x = align * renderWidth + leftRight * strokeWidth;
       let i;
       if (strokeKey) {
         for (i = 0; i < numLines; ++i) {
@@ -471,7 +472,9 @@ class Executor extends Disposable {
     const baseline = TEXT_ALIGN[textState.textBaseline || defaultTextBaseline];
     const strokeWidth = strokeState && strokeState.lineWidth ? strokeState.lineWidth : 0;
 
-    const anchorX = align * label.width / pixelRatio + 2 * (0.5 - align) * strokeWidth;
+    // Remove the 2 pixels we added in getTextImage() for the anchor
+    const width = label.width / pixelRatio - 2 * textState.scale;
+    const anchorX = align * width + 2 * (0.5 - align) * strokeWidth;
     const anchorY = baseline * label.height / pixelRatio + 2 * (0.5 - baseline) * strokeWidth;
 
     return {