Expose InlineTextBoxes in the accessibility tree.

Source/core/rendering/AbstractInlineTextBox.h

Index: Source/core/rendering/AbstractInlineTextBox.h
diff --git a/Source/core/rendering/AbstractInlineTextBox.h b/Source/core/rendering/AbstractInlineTextBox.h
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+/*
+ * Copyright (C) 2013 Google Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef AbstractInlineTextBox_h
+#define AbstractInlineTextBox_h
+
+#include "core/dom/Range.h"
+#include "core/rendering/InlineTextBox.h"
+#include "core/rendering/RenderText.h"
+#include "wtf/HashMap.h"
+#include "wtf/RefPtr.h"
+
+namespace WebCore {
+
+class InlineTextBox;
+
+enum AbstractInlineTextBoxDirection {
+    AbstractInlineTextBoxDirectionLR,

[eseidel, 2013/10/17 18:43:26]

AbstractLeftToRight,
AbstractRightToLeft,
AbstractTopToBottom,
maybe?

Donno. Seems like we're spending a lot of characters on the prefix and not much
on the content. :)  But I'm not wedded to any particular naming scheme.

I'm also OK with this just using existing enums if they fit.  The isolation
layer is more about isolating AX from object liftime troubles than it is from
keeping ABI compatibility, etc.

[dmazzoni, 2013/10/17 20:39:20]

Spelling out LeftToRight, etc. sounds good but "Abstract" as the prefix seems
unclear. How about I move it inside the class? That will make it a lot cleaner.
I can't find an existing enum that expresses this semantically - normally LTR
and RTL are a different enum than TB vs BT.

+    AbstractInlineTextBoxDirectionRL,
+    AbstractInlineTextBoxDirectionTB,
+    AbstractInlineTextBoxDirectionBT
+};
+
+// High-level abstraction of InlineTextBox to allow the accessibility module to
+// get information about InlineTextBoxes without tight coupling.
+class AbstractInlineTextBox : public RefCounted<AbstractInlineTextBox> {
+private:
+    AbstractInlineTextBox(RenderText* renderText, InlineTextBox* inlineTextBox)
+        : m_renderText(renderText)
+        , m_inlineTextBox(inlineTextBox)
+    {
+    }
+
+    static PassRefPtr<AbstractInlineTextBox> getOrCreate(RenderText*, InlineTextBox*);
+    static void willDestroy(InlineTextBox*);
+
+    friend class RenderText;
+    friend class InlineTextBox;
+
+public:
+    struct WordBoundaries {
+        WordBoundaries(int startIndex, int endIndex) : startIndex(startIndex), endIndex(endIndex) { }
+        int startIndex;
+        int endIndex;
+    };
+
+    RenderText* renderText() const { return m_renderText; }
+
+    void detach();
+
+    PassRefPtr<AbstractInlineTextBox> nextInlineTextBox() const;
+    LayoutRect bounds() const;
+    unsigned start() const;
+    unsigned len() const;
+    AbstractInlineTextBoxDirection direction() const;
+    void characterWidths(Vector<float>&) const;
+    void wordBoundaries(Vector<WordBoundaries>&) const;
+    String text() const;
+
+private:
+    RenderText* m_renderText;

[eseidel, 2013/10/17 18:43:26]

I might add a comment like:
// These are weak pointers.  ~InlineTextBox() notifies us of its destruction.
// We assume that RenderText can never be destroyed *before* its InlineTextBoxes
// and depend on ~InlineTextBox for clearing the RenderText* too.

The exact wording is up to you, just to make the lifetime assumptions clear.

[dmazzoni, 2013/10/17 20:39:20]

Done.

+    InlineTextBox* m_inlineTextBox;
+
+    static HashMap<InlineTextBox*, RefPtr<AbstractInlineTextBox> >* gAbstractInlineTextBoxMap;
+};
+
+} // namespace WebCore
+
+#endif // AbstractInlineTextBox_h