[merge addon] Compensate for editor top offset when aligning lines

Closes #6202
codemirror · Apr 2, 2020 · caca4ff · caca4ff
1 parent e1d58e2
commit caca4ff
Showing 1 changed file with 10 additions and 6 deletions.
diff --git a/addon/merge/merge.js b/addon/merge/merge.js
@@ -443,22 +443,26 @@
       aligners[i].clear();
     aligners.length = 0;
 
-    var cm = [dv.edit, dv.orig], scroll = [];
+    var cm = [dv.edit, dv.orig], scroll = [], offset = []
     if (other) cm.push(other.orig);
-    for (var i = 0; i < cm.length; i++)
+    for (var i = 0; i < cm.length; i++) {
       scroll.push(cm[i].getScrollInfo().top);
+      offset.push(-cm[i].getScrollerElement().getBoundingClientRect().top)
+    }
 
+    if (offset[0] != offset[1] || cm.length == 3 && offset[1] != offset[2])
+      alignLines(cm, offset, [0, 0, 0], aligners)
     for (var ln = 0; ln < linesToAlign.length; ln++)
-      alignLines(cm, linesToAlign[ln], aligners);
+      alignLines(cm, offset, linesToAlign[ln], aligners);
 
     for (var i = 0; i < cm.length; i++)
       cm[i].scrollTo(null, scroll[i]);
   }
 
-  function alignLines(cm, lines, aligners) {
-    var maxOffset = 0, offset = [];
+  function alignLines(cm, cmOffset, lines, aligners) {
+    var maxOffset = -1e8, offset = [];
     for (var i = 0; i < cm.length; i++) if (lines[i] != null) {
-      var off = cm[i].heightAtLine(lines[i], "local");
+      var off = cm[i].heightAtLine(lines[i], "local") - cmOffset[i];
       offset[i] = off;
       maxOffset = Math.max(maxOffset, off);
     }