From 8ebf34a385ff69e4d462a39b8b23ae745aa44694 Mon Sep 17 00:00:00 2001
From: DanyaPostfactum <danya.postfactum@gmail.com>
Date: Tue, 17 Sep 2013 19:07:16 +1000
Subject: [PATCH] Add autoscroll delay

---
 lib/ace/mouse/dragdrop_handler.js | 64 +++++++++++++++++++++++++++----
 1 file changed, 56 insertions(+), 8 deletions(-)

diff --git a/lib/ace/mouse/dragdrop_handler.js b/lib/ace/mouse/dragdrop_handler.js
index 302538e1..9da78933 100644
--- a/lib/ace/mouse/dragdrop_handler.js
+++ b/lib/ace/mouse/dragdrop_handler.js
@@ -35,6 +35,10 @@ var dom = require("../lib/dom");
 var event = require("../lib/event");
 var useragent = require("../lib/useragent");
 
+var AUTOSCROLL_DELAY = 200;
+var SCROLL_CURSOR_DELAY = 200;
+var SCROLL_CURSOR_HYSTERESIS = 5;
+
 function DragdropHandler(mouseHandler) {
 
     var editor = mouseHandler.editor;
@@ -62,6 +66,9 @@ function DragdropHandler(mouseHandler) {
     var timerId, range;
     var dragCursor, counter = 0;
     var dragOperation;
+    var autoScrollStartTime;
+    var cursorMovedTime;
+    var cursorPointOnCaretMoved;
 
     this.onDragStart = function(e) {
         // webkit workaround, see this.onMouseDown
@@ -185,8 +192,29 @@ function DragdropHandler(mouseHandler) {
     event.addListener(mouseTarget, "dragleave", this.onDragLeave.bind(mouseHandler));
     event.addListener(mouseTarget, "drop", this.onDrop.bind(mouseHandler));
 
-    function onDragInterval() {
-        dragCursor = editor.renderer.screenToTextCoordinates(x, y);
+    function scrollCursorIntoView(cursor, prevCursor) {
+        var now = new Date().getTime();
+        var vMovement = !prevCursor || cursor.row != prevCursor.row;
+        var hMovement = !prevCursor || cursor.column != prevCursor.column;
+        if (!cursorMovedTime || vMovement || hMovement) {
+            editor.$blockScrolling += 1;
+            editor.moveCursorToPosition(cursor);
+            editor.$blockScrolling -= 1;
+            cursorMovedTime = now;
+            cursorPointOnCaretMoved = {x: x, y: y};
+        } else {
+            var distance = calcDistance(cursorPointOnCaretMoved.x, cursorPointOnCaretMoved.y, x, y);
+            if (distance > SCROLL_CURSOR_HYSTERESIS) {
+                cursorMovedTime = null;
+            } else if (now - cursorMovedTime >= SCROLL_CURSOR_DELAY) {
+                editor.renderer.scrollCursorIntoView();
+                cursorMovedTime = null;
+            }
+        }
+    }
+
+    function autoScroll(cursor, prevCursor) {
+        var now = new Date().getTime();
         var lineHeight = editor.renderer.layerConfig.lineHeight;
         var characterWidth = editor.renderer.layerConfig.characterWidth;
         var editorRect = editor.renderer.scroller.getBoundingClientRect();
@@ -202,15 +230,31 @@ function DragdropHandler(mouseHandler) {
         };
         var nearestXOffset = Math.min(offsets.x.left, offsets.x.right);
         var nearestYOffset = Math.min(offsets.y.top, offsets.y.bottom);
-        var scrollCursor = {row: dragCursor.row, column: dragCursor.column};
+        var scrollCursor = {row: cursor.row, column: cursor.column};
         if (nearestXOffset / characterWidth <= 2) {
             scrollCursor.column += (offsets.x.left < offsets.x.right ? -3 : +2);
         }
         if (nearestYOffset / lineHeight <= 1) {
             scrollCursor.row += (offsets.y.top < offsets.y.bottom ? -1 : +1);
         }
-        editor.moveCursorToPosition(dragCursor);
-        editor.renderer.scrollCursorIntoView(scrollCursor);
+        var vScroll = cursor.row != scrollCursor.row;
+        var hScroll = cursor.column != scrollCursor.column;
+        var vMovement = !prevCursor || cursor.row != prevCursor.row;
+        if (vScroll || (hScroll && !vMovement)) {
+            if (!autoScrollStartTime)
+                autoScrollStartTime = now;
+            else if (now - autoScrollStartTime >= AUTOSCROLL_DELAY)
+                editor.renderer.scrollCursorIntoView(scrollCursor);
+        } else {
+            autoScrollStartTime = null;
+        }
+    }
+
+    function onDragInterval() {
+        var prevCursor = dragCursor;
+        dragCursor = editor.renderer.screenToTextCoordinates(x, y);
+        scrollCursorIntoView(dragCursor, prevCursor);
+        autoScroll(dragCursor, prevCursor);
     }
 
     function addDragMarker() {
@@ -232,6 +276,8 @@ function DragdropHandler(mouseHandler) {
         editor.$blockScrolling -= 1;
         range = null;
         counter = 0;
+        autoScrollStartTime = null;
+        cursorMovedTime = null;
         event.removeListener(document, "mousemove", onMouseMove);
     }
 
@@ -355,11 +401,13 @@ function DragdropHandler(mouseHandler) {
         }
     };
 
-    function calcDistance(ax, ay, bx, by) {
-        return Math.sqrt(Math.pow(bx - ax, 2) + Math.pow(by - ay, 2));
-    }
 }).call(DragdropHandler.prototype);
 
+
+function calcDistance(ax, ay, bx, by) {
+    return Math.sqrt(Math.pow(bx - ax, 2) + Math.pow(by - ay, 2));
+}
+
 exports.DragdropHandler = DragdropHandler;
 
 });
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