Implement basic parts of hit regions on canvas2d.

Source/core/html/canvas/HitRegion.cpp

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "config.h"
+#include "core/html/canvas/HitRegion.h"
+
+#include "core/accessibility/AXObject.h"
+#include "core/accessibility/AXObjectCache.h"
+
+namespace WebCore {
+
+HitRegion::HitRegion(const HitRegionOptions& options)
+    : m_id(options.id)
+    , m_control(options.control)
+    , m_path(options.path)
+{
+}
+
+void HitRegion::updateAccessibility(Element* canvas)
+{
+    if (!m_control || !canvas || !canvas->renderer() || !m_control->isDescendantOf(canvas))
+        return;
+
+    if (AXObjectCache* axObjectCache = m_control->document().existingAXObjectCache()) {
+        if (AXObject* obj = axObjectCache->getOrCreate(m_control.get())) {

[dmazzoni, 2014/06/03 17:26:10]

Let's move some of this logic to a new function on AXObjectCache.

Something like: axObjectCache->setCanvasObjectBounds(m_control.get(),
elementRect)
then have axObjectCache do the logic of walking up the ancestors

In general we want directories outside of core/accessibility to only interact
with AXObjectCache and not with AXObject. Long-term we hope to modularize it
this way.

[zino, 2014/06/08 08:39:49]

Done.

+            LayoutRect elementRect = LayoutRect(m_path.boundingRect());
+
+            IntRect canvasRect = canvas->renderer()->absoluteBoundingBoxRect();
+            elementRect.moveBy(canvasRect.location());
+            obj->setElementRect(elementRect);
+
+            obj = obj->parentObject();
+            while (obj && obj->node() != canvas) {
+                obj->setElementRect(elementRect);

[fs, 2014/06/03 11:47:01]

This might be better answered by dmazzoni, but this looks odd to me (a later
caller could end up overwriting the rect in cases where two controls share an
ancestor.)

[dmazzoni, 2014/06/03 17:26:10]

Ideally it seems like we'd want container element bounding boxes to be the union
of their child element bounding boxes. Perhaps it'd make sense to compute them
on-demand rather than here?

[fs, 2014/06/04 08:13:40]

Computing on-demand SGTM.

[zino, 2014/06/08 08:39:49]

Done.

+                obj = obj->parentObject();
+            }
+        }
+    }
+}
+
+bool HitRegion::contains(const LayoutPoint& point) const
+{
+    // FIXME: We should avoid following boundingRect test if fillRule is evenodd.

[fs, 2014/06/03 11:47:01]

Why? AFAICT this broad-phase check is equally good for both fill-rules

[zino, 2014/06/06 06:35:16]

You're right.
Done.

+    if (!m_path.boundingRect().contains(point))
+        return false;
+
+    return m_path.contains(point, RULE_NONZERO);
+}
+
+void HitRegion::removePixels(const Path& clearArea)
+{
+    m_path.subtractPath(clearArea);
+}
+
+void HitRegionManager::addHitRegion(PassRefPtrWillBeRawPtr<HitRegion> passHitRegion)
+{
+    RefPtrWillBeRawPtr<HitRegion> hitRegion = passHitRegion;
+
+    m_hitRegionList.add(hitRegion);
+
+    if (!hitRegion->id().isEmpty())
+        m_hitRegionIdMap.set(hitRegion->id(), hitRegion);
+
+    if (hitRegion->control())
+        m_hitRegionControlMap.set(hitRegion->control(), hitRegion);
+}
+
+void HitRegionManager::removeHitRegion(HitRegion* hitRegion)
+{
+    if (!hitRegion)
+        return;
+
+    if (!hitRegion->id().isEmpty())
+        m_hitRegionIdMap.remove(hitRegion->id());
+
+    if (hitRegion->control())
+        m_hitRegionControlMap.remove(hitRegion->control());
+
+    m_hitRegionList.remove(hitRegion);
+}
+
+void HitRegionManager::removeHitRegionById(const String& id)
+{
+    if (!id.isEmpty())
+        removeHitRegion(getHitRegionById(id));
+}
+
+void HitRegionManager::removeHitRegionByControl(const Element* control)
+{
+    removeHitRegion(getHitRegionByControl(control));
+}
+
+void HitRegionManager::removeHitRegionsInRect(const FloatRect& rect, const AffineTransform& ctm)
+{
+    Path clearArea;
+    clearArea.addRect(rect);
+    clearArea.transform(ctm);
+
+    HitRegionIterator itEnd = m_hitRegionList.rend();
+
+    for (HitRegionIterator it = m_hitRegionList.rbegin(); it != itEnd; ++it) {
+        RefPtrWillBeRawPtr<HitRegion> hitRegion = *it;
+        hitRegion->removePixels(clearArea);
+        if (hitRegion->path().isEmpty())
+            removeHitRegion(hitRegion.get());
+    }
+}
+
+void HitRegionManager::removeAllHitRegions()
+{
+    m_hitRegionList.clear();
+    m_hitRegionIdMap.clear();
+}
+
+HitRegion* HitRegionManager::getHitRegionById(const String& id) const
+{
+    return m_hitRegionIdMap.get(id);
+}
+
+HitRegion* HitRegionManager::getHitRegionByControl(const Element* control) const
+{
+    if (control)
+        return m_hitRegionControlMap.get(control);
+
+    return 0;
+}
+
+HitRegion* HitRegionManager::getHitRegionAtPoint(const LayoutPoint& point) const
+{
+    HitRegionIterator itEnd = m_hitRegionList.rend();
+
+    for (HitRegionIterator it = m_hitRegionList.rbegin(); it != itEnd; ++it) {
+        RefPtrWillBeRawPtr<HitRegion> hitRegion = *it;
+        if (hitRegion->contains(point))
+            return hitRegion.get();
+    }
+
+    return 0;
+}
+
+unsigned HitRegionManager::getHitRegionsCount() const
+{
+    return m_hitRegionList.size();
+}
+
+} // namespace WebCore