From 46d8e24afa2c9972bf972043e8dc19938d032c1b Mon Sep 17 00:00:00 2001
From: Jim Mathies <jmathies@mozilla.com>
Date: Thu, 11 Jul 2013 04:29:27 -0500
Subject: [PATCH] Bug 891805 - Cache caret position at the start of a drag in
 text edits, and use that when initiating selection. r=rsilveira

---
 .../content/helperui/SelectionHelperUI.js     | 20 +++++++++++++++++--
 .../browser_selection_contenteditable.js      |  2 +-
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/browser/metro/base/content/helperui/SelectionHelperUI.js b/browser/metro/base/content/helperui/SelectionHelperUI.js
index fc9c67c527f..2ed06fb5216 100644
--- a/browser/metro/base/content/helperui/SelectionHelperUI.js
+++ b/browser/metro/base/content/helperui/SelectionHelperUI.js
@@ -610,6 +610,16 @@ var SelectionHelperUI = {
     this.startMark.position(targetMark.xPos, targetMark.yPos);
     this.endMark.position(targetMark.xPos, targetMark.yPos);
 
+    // We delay transitioning until we know which direction the user is dragging
+    // based on a hysteresis value in the drag marker code. Down in our caller, we
+    // cache the first drag position in _cachedCaretPos so we can select from the
+    // initial caret drag position. Use those values if we have them. (Note
+    // _cachedCaretPos has already been translated in _getMarkerBaseMessage.)
+    let xpos = this._cachedCaretPos ? this._cachedCaretPos.xPos :
+      this._msgTarget.ctobx(targetMark.xPos, true);
+    let ypos = this._cachedCaretPos ? this._cachedCaretPos.yPos :
+      this._msgTarget.ctoby(targetMark.yPos, true);
+
     // Start the selection monocle drag. SelectionHandler relies on this
     // for getting initialized. This will also trigger a message back for
     // monocle positioning. Note, markerDragMove is still on the stack in
@@ -617,8 +627,8 @@ var SelectionHelperUI = {
     this._sendAsyncMessage("Browser:SelectionSwitchMode", {
       newMode: "selection",
       change: targetMark.tag,
-      xPos: this._msgTarget.ctobx(targetMark.xPos, true),
-      yPos: this._msgTarget.ctoby(targetMark.yPos, true),
+      xPos: xpos,
+      yPos: ypos,
     });
   },
 
@@ -1097,6 +1107,7 @@ var SelectionHelperUI = {
   markerDragStart: function markerDragStart(aMarker) {
     let json = this._getMarkerBaseMessage(aMarker.tag);
     if (aMarker.tag == "caret") {
+      this._cachedCaretPos = null;
       this._sendAsyncMessage("Browser:CaretMove", json);
       return;
     }
@@ -1123,8 +1134,13 @@ var SelectionHelperUI = {
         this._transitionFromCaretToSelection(aDirection);
         return false;
       }
+      // Cache for when we start the drag in _transitionFromCaretToSelection.
+      if (!this._cachedCaretPos) {
+        this._cachedCaretPos = this._getMarkerBaseMessage(aMarker.tag).caret;
+      }
       return true;
     }
+    this._cachedCaretPos = null;
 
     // We'll re-display these after the drag is complete.
     this._hideMonocles();
diff --git a/browser/metro/base/tests/mochitest/browser_selection_contenteditable.js b/browser/metro/base/tests/mochitest/browser_selection_contenteditable.js
index 0a32a90a379..8fd00719ca8 100644
--- a/browser/metro/base/tests/mochitest/browser_selection_contenteditable.js
+++ b/browser/metro/base/tests/mochitest/browser_selection_contenteditable.js
@@ -38,7 +38,7 @@ gTests.push({
     let div = gWindow.document.getElementById("testdiv");
     ok(div, "have the div");
 
-    sendElementTap(gWindow, div, 295); // end of 'outlook.com'
+    sendElementTap(gWindow, div, 287); // end of 'outlook.com'
 
     yield waitForCondition(function () {
         return SelectionHelperUI.isCaretUIVisible;