Bug 824965: Implement a method of getting correct CaretPosition from within anonymous content nodes. [r=ehsan]

content/base/public/nsContentUtils.h

@@ -97,6 +97,7 @@ class nsScriptObjectTracer;
 class nsStringHashKey;
 class nsTextFragment;
 class nsViewportInfo;
+class nsIFrame;
 
 struct JSContext;
 struct JSPropertyDescriptor;
@@ -2115,6 +2116,21 @@ public:
                                         int32_t& aOutStartOffset,
                                         int32_t& aOutEndOffset);
 
+  /**
+   * Takes a frame for anonymous content within a text control (<input> or
+   * <textarea>), and returns an offset in the text content, adjusted for a
+   * trailing <br> frame.
+   *
+   * @param aOffsetFrame      Frame for the text content in which the offset
+   *                          lies
+   * @param aOffset           Offset as calculated by GetContentOffsetsFromPoint
+   * @param aOutOffset        Output adjusted offset
+   *
+   * @see GetSelectionInTextControl for the original basis of this function.
+   */
+  static int32_t GetAdjustedOffsetInTextControl(nsIFrame* aOffsetFrame,
+                                                int32_t aOffset);
+
   static nsIEditor* GetHTMLEditor(nsPresContext* aPresContext);
 
   /**

content/base/src/nsContentUtils.cpp

@@ -101,6 +101,7 @@
 #include "nsIFormControl.h"
 #include "nsIForm.h"
 #include "nsIFragmentContentSink.h"
+#include "nsIFrame.h"
 #include "nsIHTMLDocument.h"
 #include "nsIIdleService.h"
 #include "nsIImageLoadingContent.h"
@@ -6750,6 +6751,40 @@ nsContentUtils::TraceWrapper(nsWrapperCache* aCache, TraceCallback aCallback,
   }
 }
 
+// static
+int32_t
+nsContentUtils::GetAdjustedOffsetInTextControl(nsIFrame* aOffsetFrame,
+                                               int32_t aOffset)
+{
+  // The structure of the anonymous frames within a text control frame is
+  // an optional block frame, followed by an optional br frame.
+
+  // If the offset frame has a child, then this frame is the block which
+  // has the text frames (containing the content) as its children. This will
+  // be the case if we click to the right of any of the text frames, or at the
+  // bottom of the text area.
+  nsIFrame* firstChild = aOffsetFrame->GetFirstPrincipalChild();
+  if (firstChild) {
+    // In this case, the passed-in offset is incorrect, and we want the length
+    // of the entire content in the text control frame.
+    return firstChild->GetContent()->Length();
+  }
+
+  if (aOffsetFrame->GetPrevSibling() &&
+      !aOffsetFrame->GetNextSibling()) {
+    // In this case, we're actually within the last frame, which is a br
+    // frame. Our offset should therefore be the length of the first child of
+    // our parent.
+    int32_t aOutOffset =
+      aOffsetFrame->GetParent()->GetFirstPrincipalChild()->GetContent()->Length();
+    return aOutOffset;
+  }
+
+  // Otherwise, we're within one of the text frames, in which case our offset
+  // has already been correctly calculated.
+  return aOffset;
+}
+
 // static
 void
 nsContentUtils::GetSelectionInTextControl(Selection* aSelection,

content/base/src/nsDocument.cpp

@@ -202,6 +202,9 @@
 #include "nsDOMEvent.h"
 #include "nsIContentPermissionPrompt.h"
 #include "mozilla/StaticPtr.h"
+#include "nsITextControlElement.h"
+#include "nsIDOMNSEditableElement.h"
+#include "nsIEditor.h"
 
 using namespace mozilla;
 using namespace mozilla::dom;
@@ -9318,7 +9321,10 @@ nsIDocument::CaretPositionFromPoint(float aX, float aY)
 
   nsCOMPtr<nsIContent> node = offsets.content;
   uint32_t offset = offsets.offset;
-  if (node && node->IsInNativeAnonymousSubtree()) {
+  nsCOMPtr<nsIContent> anonNode = node;
+  bool nodeIsAnonymous = node && node->IsInNativeAnonymousSubtree();
+  if (nodeIsAnonymous) {
+    node = ptFrame->GetContent();
     nsIContent* nonanon = node->FindFirstNonChromeOnlyAccessContent();
     nsCOMPtr<nsIDOMHTMLInputElement> input = do_QueryInterface(nonanon);
     nsCOMPtr<nsIDOMHTMLTextAreaElement> textArea = do_QueryInterface(nonanon);
@@ -9326,6 +9332,7 @@ nsIDocument::CaretPositionFromPoint(float aX, float aY)
     if (textArea || (input &&
                      NS_SUCCEEDED(input->MozIsTextField(false, &isText)) &&
                      isText)) {
+      offset = nsContentUtils::GetAdjustedOffsetInTextControl(ptFrame, offset);
       node = nonanon;
     } else {
       node = nullptr;

content/base/test/test_caretPositionFromPoint.html

@@ -21,17 +21,31 @@
       border: 8px solid black;
       width: 600px;
     }
+
+    #dp {
+      position: absolute;
+      width: 2px;
+      height: 2px;
+      left: 0px;
+      top: 0px;
+      background-color: orange;
+    }
   </style>
 <script>
+  function displayPoint(aX, aY) {
+    document.getElementById('dp').style['left'] = aX + "px";
+    document.getElementById('dp').style['top'] = aY + "px";
+  }
+
   function convertEmToPx(aEm) {
     // Assumes our base font size is 16px = 12pt = 1.0em.
     var pxPerEm = 16.0 / 1.0;
     return pxPerEm * aEm;
   }
 
-  function checkOffsetsFromPoint(aX, aY, aExpected) {
+  function checkOffsetsFromPoint(aX, aY, aExpected, aElementName='no-name') {
     var cp = document.caretPositionFromPoint(aX, aY);
-    ok(aExpected == cp.offset, 'expected offset at (' + aX + ', ' + aY + '): ' + aExpected + ', got: ' + cp.offset);
+    ok(aExpected == cp.offset, 'expected offset at (' + aX + ', ' + aY + ') [' + aElementName + ']: ' + aExpected + ', got: ' + cp.offset);
   }
 
   function doTesting() {
@@ -39,8 +53,8 @@
     var test1Rect = test1Element.getBoundingClientRect();
 
     // Check the first and last characters of the basic div.
-    checkOffsetsFromPoint(Math.round(test1Rect.left + 1), Math.round(test1Rect.top + 1), 0);
-    checkOffsetsFromPoint(Math.round(test1Rect.left + test1Rect.width - 1), Math.round(test1Rect.top + 1), 13);
+    checkOffsetsFromPoint(Math.round(test1Rect.left + 1), Math.round(test1Rect.top + 1), 0, 'test1');
+    checkOffsetsFromPoint(Math.round(test1Rect.left + test1Rect.width - 1), Math.round(test1Rect.top + 1), 13, 'test1');
 
     // Check a middle character in the second line of the div.
     // To do this, we calculate 7em in from the left of the bounding
@@ -49,20 +63,19 @@
     var pixelsLeft = convertEmToPx(7);
     var test2Element = document.getElementById("test2");
     var test2Rect = test2Element.getBoundingClientRect();
-    checkOffsetsFromPoint(Math.round(test2Rect.left + pixelsLeft + 1), Math.round(test2Rect.top + 1), 7);
+    checkOffsetsFromPoint(Math.round(test2Rect.left + pixelsLeft + 1), Math.round(test2Rect.top + 1), 7, 'test2');
 
     // Check the first and last characters of the textarea.
     var test3Element = document.getElementById('test3');
     var test3Rect = test3Element.getBoundingClientRect();
-    checkOffsetsFromPoint(test3Rect.left + 1, test3Rect.top + 1, 0);
-    // xxxTODO: This test is disabled due to bug 824965.
-    //checkOffsetsFromPoint(Math.round(test3Rect.left + test3Rect.width - 1), Math.round(test3Rect.top + 1), 0);
+    checkOffsetsFromPoint(test3Rect.left + 5, test3Rect.top + 5, 0, 'test3');
+    checkOffsetsFromPoint(Math.round(test3Rect.left + test3Rect.width - 15), Math.round(test3Rect.top + 5), 3, 'test3');
 
     // Check the first and last characters of the input.
     var test4Element = document.getElementById('test4');
     var test4Rect = test4Element.getBoundingClientRect();
-    checkOffsetsFromPoint(test4Rect.left + 1, test4Rect.top + 1, 0);
-    checkOffsetsFromPoint(Math.round(test4Rect.left + convertEmToPx(3)), Math.round(test4Rect.top + 10), 3);
+    checkOffsetsFromPoint(test4Rect.left + 5, test4Rect.top + 5, 0, 'test4');
+    checkOffsetsFromPoint(Math.round(test4Rect.left + test4Rect.width - 10), Math.round(test4Rect.top + 10), 6, 'test4');
 
     // Check to make sure that x or y outside the viewport returns null.
     var nullCp1 = document.caretPositionFromPoint(-10, 0);
@@ -82,9 +95,10 @@
 </script>
 </head>
 <body onload="doTesting();">
+<div id="dp"></div>
 <div id="a" contenteditable><span id="test1">abc, abc, abc</span><br>
 <span id="test2" style="color: blue;">abc, abc, abc</span><br>
-<textarea id="test3">abc</textarea><input id="test4" value="abc"><br><br>
+<textarea id="test3">abc</textarea><input id="test4" value="abcdef"><br><br>
 <marquee>marquee</marquee>
 </div>
 </body>