From 4f49b16079b27d7ce633619e4cddfdf2bffbc952 Mon Sep 17 00:00:00 2001
From: cashmere <cashmere@autistici.org>
Date: Fri, 4 Sep 2026 09:05:24 +0200
Subject: initial commit

---
 src/diff.js | 73 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 73 insertions(+)
 create mode 100644 src/diff.js

(limited to 'src/diff.js')

diff --git a/src/diff.js b/src/diff.js
new file mode 100644
index 0000000..b0d09da
--- /dev/null
+++ b/src/diff.js
@@ -0,0 +1,73 @@
+/* Refinements to the display of unified and side-by-side diffs.
+**
+** In all cases, the table columns tagged with "difftxt" are expanded,
+** where possible, to fill the width of the screen.
+**
+** For a side-by-side diff, if either column is two wide to fit on the
+** display, scrollbars are added.  The scrollbars are linked, so that
+** both sides scroll together.  Left and right arrows also scroll.
+*/
+window.addEventListener('load',function(){
+  var SCROLL_LEN = 25;
+  function initDiff(diff){
+    var txtCols = diff.querySelectorAll('td.difftxt');
+    var txtPres = diff.querySelectorAll('td.difftxt pre');
+    var width = 0;
+    if(txtPres.length>=2){
+      width = Math.max(txtPres[0].scrollWidth, txtPres[1].scrollWidth);
+    }
+    var i;
+    for(i=0; i<txtCols.length; i++){
+      txtCols[i].style.width = width + 'px';
+      txtPres[i].style.maxWidth = width + 'px';
+      txtPres[i].style.width = width + 'px';
+      txtPres[i].onscroll = function(e){
+        for(var j=0; j<txtPres.length; j++) txtPres[j].scrollLeft = this.scrollLeft;
+      };
+    }
+    diff.tabIndex = 0;
+    diff.onkeydown = function(e){
+      e = e || event;
+      var len = {37: -SCROLL_LEN, 39: SCROLL_LEN}[e.keyCode];
+      if( !len ) return;
+      txtPres[0].scrollLeft += len;
+      return false;
+    };
+  }
+  var i, diffs = document.querySelectorAll('table.splitdiff')
+  for(i=0; i<diffs.length; i++){
+    initDiff(diffs[i]);
+  }
+  const checkWidth = function f(){
+    if(undefined === f.lastWidth){
+      f.lastWidth = 0;
+    }
+    if( document.body.clientWidth===f.lastWidth ) return;
+    f.lastWidth = document.body.clientWidth;
+    var w = f.lastWidth*0.5 - 100;
+    if(!f.colsL){
+      f.colsL = document.querySelectorAll('td.difftxtl pre');
+    }
+    for(let i=0; i<f.colsL.length; i++){
+      f.colsL[i].style.width = w + "px";
+      f.colsL[i].style.maxWidth = w + "px";
+    }
+    if(!f.colsR){
+      f.colsR = document.querySelectorAll('td.difftxtr pre');
+    }
+    for(let i=0; i<f.colsR.length; i++){
+      f.colsR[i].style.width = w + "px";
+      f.colsR[i].style.maxWidth = w + "px";
+    }
+    if(!f.allDiffs){
+      f.allDiffs = document.querySelectorAll('table.diff');
+    }
+    w = f.lastWidth;
+    for(let i=0; i<f.allDiffs.length; i++){
+      f.allDiffs[i].style.width = '100%'; // setting to w causes unsightly horiz. scrollbar
+      f.allDiffs[i].style.maxWidth = w + "px";
+    }
+  };
+  checkWidth();
+  window.addEventListener('resize', checkWidth);
+}, false);
-- 
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