Issue #2135 - Bug 1430301: Implement ShadowRoot.elementFromPoint/elementsFromPoint

5 files changed, 152 insertions, 143 deletions

diff --git a/dom/base/DocumentOrShadowRoot.cpp b/dom/base/DocumentOrShadowRoot.cpp
index f8f9d5a28c..876d265cc1 100644
--- a/dom/base/DocumentOrShadowRoot.cpp
+++ b/dom/base/DocumentOrShadowRoot.cpp
@@ -10,6 +10,8 @@
 #include "nsFocusManager.h"
 #include "ShadowRoot.h"
 #include "XULDocument.h"
+#include "nsLayoutUtils.h"
+#include "nsSVGUtils.h"
 
 class nsINode;
 class nsIDocument;
@@ -180,5 +182,121 @@ DocumentOrShadowRoot::GetFullscreenElement()
   return nullptr;
 }
 
+Element*
+DocumentOrShadowRoot::ElementFromPoint(float aX, float aY)
+{
+  return ElementFromPointHelper(aX, aY, false, true);
+}
+
+void
+DocumentOrShadowRoot::ElementsFromPoint(float aX, float aY,
+                                        nsTArray<RefPtr<Element>>& aElements)
+{
+  ElementsFromPointHelper(aX, aY, nsIDocument::FLUSH_LAYOUT, aElements);
+}
+
+Element*
+DocumentOrShadowRoot::ElementFromPointHelper(float aX, float aY,
+                                             bool aIgnoreRootScrollFrame,
+                                             bool aFlushLayout)
+{
+  AutoTArray<RefPtr<Element>, 1> elementArray;
+  ElementsFromPointHelper(aX, aY,
+                          ((aIgnoreRootScrollFrame ? nsIDocument::IGNORE_ROOT_SCROLL_FRAME : 0) |
+                           (aFlushLayout ? nsIDocument::FLUSH_LAYOUT : 0) |
+                           nsIDocument::IS_ELEMENT_FROM_POINT),
+                          elementArray);
+  if (elementArray.IsEmpty()) {
+    return nullptr;
+  }
+  return elementArray[0];
+}
+
+void
+DocumentOrShadowRoot::ElementsFromPointHelper(float aX, float aY,
+                                              uint32_t aFlags,
+                                              nsTArray<RefPtr<mozilla::dom::Element>>& aElements)
+{
+  // As per the the spec, we return null if either coord is negative
+  if (!(aFlags & nsIDocument::IGNORE_ROOT_SCROLL_FRAME) && (aX < 0 || aY < 0)) {
+    return;
+  }
+
+  nscoord x = nsPresContext::CSSPixelsToAppUnits(aX);
+  nscoord y = nsPresContext::CSSPixelsToAppUnits(aY);
+  nsPoint pt(x, y);
+
+  nsCOMPtr<nsIDocument> doc = AsNode().OwnerDoc();
+
+  // Make sure the layout information we get is up-to-date, and
+  // ensure we get a root frame (for everything but XUL)
+  if (aFlags & nsIDocument::FLUSH_LAYOUT) {
+    doc->FlushPendingNotifications(Flush_Layout);
+  }
+
+  nsIPresShell* ps = doc->GetShell();
+  if (!ps) {
+    return;
+  }
+  nsIFrame* rootFrame = ps->GetRootFrame();
+
+  // XUL docs, unlike HTML, have no frame tree until everything's done loading
+  if (!rootFrame) {
+    return; // return null to premature XUL callers as a reminder to wait
+  }
+
+  nsTArray<nsIFrame*> outFrames;
+  // Emulate what GetFrameAtPoint does, since we want all the frames under our
+  // point.
+  nsLayoutUtils::GetFramesForArea(rootFrame, nsRect(pt, nsSize(1, 1)), outFrames,
+    nsLayoutUtils::IGNORE_PAINT_SUPPRESSION | nsLayoutUtils::IGNORE_CROSS_DOC |
+    ((aFlags & nsIDocument::IGNORE_ROOT_SCROLL_FRAME) ? nsLayoutUtils::IGNORE_ROOT_SCROLL_FRAME : 0));
+
+  // Dunno when this would ever happen, as we should at least have a root frame under us?
+  if (outFrames.IsEmpty()) {
+    return;
+  }
+
+  // Used to filter out repeated elements in sequence.
+  nsIContent* lastAdded = nullptr;
+
+  for (uint32_t i = 0; i < outFrames.Length(); i++) {
+    nsIContent* node = doc->GetContentInThisDocument(outFrames[i]);
+
+    if (!node || !node->IsElement()) {
+      // If this helper is called via ElementsFromPoint, we need to make sure
+      // our frame is an element. Otherwise return whatever the top frame is
+      // even if it isn't the top-painted element.
+      // SVG 'text' element's SVGTextFrame doesn't respond to hit-testing, so
+      // if 'node' is a child of such an element then we need to manually defer
+      // to the parent here.
+      if (!(aFlags & nsIDocument::IS_ELEMENT_FROM_POINT) &&
+          !outFrames[i]->IsSVGText()) {
+        continue;
+      }
+      node = node->GetParent();
+      if (node) {
+        ShadowRoot* shadow = ShadowRoot::FromNode(node);
+        node = shadow->Host();
+      }
+    }
+
+    //XXXsmaug There is plenty of unspec'ed behavior here
+    //         https://github.com/w3c/webcomponents/issues/735
+    //         https://github.com/w3c/webcomponents/issues/736
+    node = Retarget(node);
+
+    if (node && node != lastAdded) {
+      aElements.AppendElement(node->AsElement());
+      lastAdded = node;
+      // If this helper is called via ElementFromPoint, just return the first
+      // element we find.
+      if (aFlags & nsIDocument::IS_ELEMENT_FROM_POINT) {
+        return;
+      }
+    }
+  }
+}
+
 }
 }
diff --git a/dom/base/DocumentOrShadowRoot.h b/dom/base/DocumentOrShadowRoot.h
index e056078275..962f7ac0b5 100644
--- a/dom/base/DocumentOrShadowRoot.h
+++ b/dom/base/DocumentOrShadowRoot.h
@@ -117,6 +117,29 @@ public:
   Element* GetPointerLockElement();
   Element* GetFullscreenElement();
 
+  Element* ElementFromPoint(float aX, float aY);
+  void ElementsFromPoint(float aX, float aY,
+                         nsTArray<RefPtr<mozilla::dom::Element>>& aElements);
+
+  /**
+   * Helper for nsIDOMDocument::elementFromPoint implementation that allows
+   * ignoring the scroll frame and/or avoiding layout flushes.
+   *
+   * @see nsIDOMWindowUtils::elementFromPoint
+   */
+  Element* ElementFromPointHelper(float aX, float aY,
+                                  bool aIgnoreRootScrollFrame,
+                                  bool aFlushLayout);
+  enum ElementsFromPointFlags
+  {
+    IGNORE_ROOT_SCROLL_FRAME = 1,
+    FLUSH_LAYOUT = 2,
+    IS_ELEMENT_FROM_POINT = 4
+  };
+
+  void ElementsFromPointHelper(float aX, float aY, uint32_t aFlags,
+                               nsTArray<RefPtr<mozilla::dom::Element>>& aElements);
+
 protected:
   nsIContent* Retarget(nsIContent* aContent) const;
 
diff --git a/dom/base/nsDocument.cpp b/dom/base/nsDocument.cpp
index 562d9e1735..cbb71feaed 100644
--- a/dom/base/nsDocument.cpp
+++ b/dom/base/nsDocument.cpp
@@ -3120,106 +3120,6 @@ nsDocument::ElementFromPoint(float aX, float aY, nsIDOMElement** aReturn)
   return NS_OK;
 }
 
-Element*
-nsIDocument::ElementFromPoint(float aX, float aY)
-{
-  return ElementFromPointHelper(aX, aY, false, true);
-}
-
-void
-nsIDocument::ElementsFromPoint(float aX, float aY,
-                               nsTArray<RefPtr<Element>>& aElements)
-{
-  ElementsFromPointHelper(aX, aY, nsIDocument::FLUSH_LAYOUT, aElements);
-}
-
-Element*
-nsDocument::ElementFromPointHelper(float aX, float aY,
-                                   bool aIgnoreRootScrollFrame,
-                                   bool aFlushLayout)
-{
-  AutoTArray<RefPtr<Element>, 1> elementArray;
-  ElementsFromPointHelper(aX, aY,
-                          ((aIgnoreRootScrollFrame ? nsIDocument::IGNORE_ROOT_SCROLL_FRAME : 0) |
-                           (aFlushLayout ? nsIDocument::FLUSH_LAYOUT : 0) |
-                           nsIDocument::IS_ELEMENT_FROM_POINT),
-                          elementArray);
-  if (elementArray.IsEmpty()) {
-    return nullptr;
-  }
-  return elementArray[0];
-}
-
-void
-nsDocument::ElementsFromPointHelper(float aX, float aY,
-                                    uint32_t aFlags,
-                                    nsTArray<RefPtr<mozilla::dom::Element>>& aElements)
-{
-  // As per the the spec, we return null if either coord is negative
-  if (!(aFlags & nsIDocument::IGNORE_ROOT_SCROLL_FRAME) && (aX < 0 || aY < 0)) {
-    return;
-  }
-
-  nscoord x = nsPresContext::CSSPixelsToAppUnits(aX);
-  nscoord y = nsPresContext::CSSPixelsToAppUnits(aY);
-  nsPoint pt(x, y);
-
-  // Make sure the layout information we get is up-to-date, and
-  // ensure we get a root frame (for everything but XUL)
-  if (aFlags & nsIDocument::FLUSH_LAYOUT) {
-    FlushPendingNotifications(Flush_Layout);
-  }
-
-  nsIPresShell *ps = GetShell();
-  if (!ps) {
-    return;
-  }
-  nsIFrame *rootFrame = ps->GetRootFrame();
-
-  // XUL docs, unlike HTML, have no frame tree until everything's done loading
-  if (!rootFrame) {
-    return; // return null to premature XUL callers as a reminder to wait
-  }
-
-  nsTArray<nsIFrame*> outFrames;
-  // Emulate what GetFrameAtPoint does, since we want all the frames under our
-  // point.
-  nsLayoutUtils::GetFramesForArea(rootFrame, nsRect(pt, nsSize(1, 1)), outFrames,
-    nsLayoutUtils::IGNORE_PAINT_SUPPRESSION | nsLayoutUtils::IGNORE_CROSS_DOC |
-    ((aFlags & nsIDocument::IGNORE_ROOT_SCROLL_FRAME) ? nsLayoutUtils::IGNORE_ROOT_SCROLL_FRAME : 0));
-
-  // Dunno when this would ever happen, as we should at least have a root frame under us?
-  if (outFrames.IsEmpty()) {
-    return;
-  }
-
-  // Used to filter out repeated elements in sequence.
-  nsIContent* lastAdded = nullptr;
-
-  for (uint32_t i = 0; i < outFrames.Length(); i++) {
-    nsIContent* node = GetContentInThisDocument(outFrames[i]);
-
-    if (!node || !node->IsElement()) {
-      // If this helper is called via ElementsFromPoint, we need to make sure
-      // our frame is an element. Otherwise return whatever the top frame is
-      // even if it isn't the top-painted element.
-      if (!(aFlags & nsIDocument::IS_ELEMENT_FROM_POINT)) {
-        continue;
-      }
-      node = node->GetParent();
-    }
-    if (node && node != lastAdded) {
-      aElements.AppendElement(node->AsElement());
-      lastAdded = node;
-      // If this helper is called via ElementFromPoint, just return the first
-      // element we find.
-      if (aFlags & nsIDocument::IS_ELEMENT_FROM_POINT) {
-        return;
-      }
-    }
-  }
-}
-
 nsresult
 nsDocument::NodesFromRectHelper(float aX, float aY,
                                 float aTopSize, float aRightSize,
@@ -8387,7 +8287,7 @@ nsDocument::DoUnblockOnload()
 }
 
 nsIContent*
-nsDocument::GetContentInThisDocument(nsIFrame* aFrame) const
+nsIDocument::GetContentInThisDocument(nsIFrame* aFrame) const
 {
   for (nsIFrame* f = aFrame; f;
        f = nsLayoutUtils::GetParentOrPlaceholderForCrossDoc(f)) {
diff --git a/dom/base/nsDocument.h b/dom/base/nsDocument.h
index 1c10d7b5c3..923fb49ae9 100644
--- a/dom/base/nsDocument.h
+++ b/dom/base/nsDocument.h
@@ -692,14 +692,6 @@ public:
                                    nsIAtom* aAttrName,
                                    const nsAString& aAttrValue) const override;
 
-  virtual Element* ElementFromPointHelper(float aX, float aY,
-                                          bool aIgnoreRootScrollFrame,
-                                          bool aFlushLayout) override;
-
-  virtual void ElementsFromPointHelper(float aX, float aY,
-                                       uint32_t aFlags,
-                                       nsTArray<RefPtr<mozilla::dom::Element>>& aElements) override;
-
   virtual nsresult NodesFromRectHelper(float aX, float aY,
                                                    float aTopSize, float aRightSize,
                                                    float aBottomSize, float aLeftSize,
@@ -1312,16 +1304,6 @@ private:
 
   nsresult InitCSP(nsIChannel* aChannel);
 
-  /**
-   * Find the (non-anonymous) content in this document for aFrame. It will
-   * be aFrame's content node if that content is in this document and not
-   * anonymous. Otherwise, when aFrame is in a subdocument, we use the frame
-   * element containing the subdocument containing aFrame, and/or find the
-   * nearest non-anonymous ancestor in this document.
-   * Returns null if there is no such element.
-   */
-  nsIContent* GetContentInThisDocument(nsIFrame* aFrame) const;
-
   // Just like EnableStyleSheetsForSet, but doesn't check whether
   // aSheetSet is null and allows the caller to control whether to set
   // aSheetSet as the preferred set in the CSSLoader.
diff --git a/dom/base/nsIDocument.h b/dom/base/nsIDocument.h
index dcaee4fabd..d64827aa6d 100644
--- a/dom/base/nsIDocument.h
+++ b/dom/base/nsIDocument.h
@@ -1811,26 +1811,6 @@ public:
                                    nsIAtom* aAttrName,
                                    const nsAString& aAttrValue) const = 0;
 
-  /**
-   * Helper for nsIDOMDocument::elementFromPoint implementation that allows
-   * ignoring the scroll frame and/or avoiding layout flushes.
-   *
-   * @see nsIDOMWindowUtils::elementFromPoint
-   */
-  virtual Element* ElementFromPointHelper(float aX, float aY,
-                                          bool aIgnoreRootScrollFrame,
-                                          bool aFlushLayout) = 0;
-
-  enum ElementsFromPointFlags {
-    IGNORE_ROOT_SCROLL_FRAME = 1,
-    FLUSH_LAYOUT = 2,
-    IS_ELEMENT_FROM_POINT = 4
-  };
-
-  virtual void ElementsFromPointHelper(float aX, float aY,
-                                       uint32_t aFlags,
-                                       nsTArray<RefPtr<mozilla::dom::Element>>& aElements) = 0;
-
   virtual nsresult NodesFromRectHelper(float aX, float aY,
                                        float aTopSize, float aRightSize,
                                        float aBottomSize, float aLeftSize,
@@ -2664,10 +2644,6 @@ public:
   void GetPreferredStyleSheetSet(nsAString& aSheetSet);
   virtual mozilla::dom::DOMStringList* StyleSheetSets() = 0;
   virtual void EnableStyleSheetsForSet(const nsAString& aSheetSet) = 0;
-  Element* ElementFromPoint(float aX, float aY);
-  void ElementsFromPoint(float aX,
-                         float aY,
-                         nsTArray<RefPtr<mozilla::dom::Element>>& aElements);
 
   /**
    * Retrieve the location of the caret position (DOM node and character
@@ -2835,6 +2811,16 @@ public:
 
   bool ModuleScriptsEnabled();
 
+  /**
+   * Find the (non-anonymous) content in this document for aFrame. It will
+   * be aFrame's content node if that content is in this document and not
+   * anonymous. Otherwise, when aFrame is in a subdocument, we use the frame
+   * element containing the subdocument containing aFrame, and/or find the
+   * nearest non-anonymous ancestor in this document.
+   * Returns null if there is no such element.
+   */
+  nsIContent* GetContentInThisDocument(nsIFrame* aFrame) const;
+
   virtual void AddResizeObserver(mozilla::dom::ResizeObserver* aResizeObserver) = 0;
 
   virtual void ScheduleResizeObserversNotification() const = 0;