From 4d96cb47ad290b532dc06ed8bb6e90ff01f7fad8 Mon Sep 17 00:00:00 2001
From: Lars Jung <lrsjng@gmail.com>
Date: Tue, 9 Aug 2016 22:28:01 +0200
Subject: [PATCH] Fix drag-select on scrollable content.

---
 src/_h5ai/public/css/lib/view/content.less |  1 +
 src/_h5ai/public/js/lib/ext/select.js      | 24 +++++++++++++++-------
 2 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/src/_h5ai/public/css/lib/view/content.less b/src/_h5ai/public/css/lib/view/content.less
index 47b4194c..f4017ea9 100644
--- a/src/_h5ai/public/css/lib/view/content.less
+++ b/src/_h5ai/public/css/lib/view/content.less
@@ -2,4 +2,5 @@
     overflow: auto;
     flex: 1 1 auto;
     order: 50;
+    position: relative;
 }
diff --git a/src/_h5ai/public/js/lib/ext/select.js b/src/_h5ai/public/js/lib/ext/select.js
index 02d16097..e90acac7 100644
--- a/src/_h5ai/public/js/lib/ext/select.js
+++ b/src/_h5ai/public/js/lib/ext/select.js
@@ -68,11 +68,20 @@ const rectsDoOverlap = (rect1, rect2) => {
     return maxLeft <= minRight && maxTop <= minBottom;
 };
 
+const getPointer = ev => {
+    const content = dom('#content')[0];
+    const r = elRect(content);
+    const x = ev.pageX - r.l + content.scrollLeft;
+    const y = ev.pageY - r.t + content.scrollTop;
+    return {x, y};
+};
+
 const selectionUpdate = ev => {
-    const left = mmin(dragStartX, ev.pageX);
-    const top = mmin(dragStartY, ev.pageY);
-    const width = mabs(dragStartX - ev.pageX);
-    const height = mabs(dragStartY - ev.pageY);
+    const {x, y} = getPointer(ev);
+    const left = mmin(dragStartX, x);
+    const top = mmin(dragStartY, y);
+    const width = mabs(dragStartX - x);
+    const height = mabs(dragStartY - y);
     const isCtrlPressed = ev.ctrlKey || ev.metaKey;
 
     if (!isCtrlPressed && width < 4 && height < 4) {
@@ -125,8 +134,9 @@ const selectionStart = ev => {
         return;
     }
 
-    dragStartX = ev.pageX;
-    dragStartY = ev.pageY;
+    const {x, y} = getPointer(ev);
+    dragStartX = x;
+    dragStartY = y;
 
     $document
         .on('mousemove', selectionUpdate)
@@ -180,7 +190,7 @@ const init = () => {
     event.sub('view.changed', onViewChanged);
 
     if (settings.clickndrag) {
-        $selectionRect.hide().appTo('body');
+        $selectionRect.hide().appTo('#content');
 
         dom('#content')
             .on('mousedown', selectionStart)