Bug 50660 - Drag and drop for file upload form control r=jst,enndeakin

content/html/content/src/nsHTMLInputElement.cpp

@@ -1372,6 +1372,31 @@ nsHTMLInputElement::SetFiles(const nsCOMArray<nsIDOMFile>& aFiles,
   mFiles.Clear();
   mFiles.AppendObjects(aFiles);
 
+  AfterSetFiles(aSetValueChanged);
+}
+
+void
+nsHTMLInputElement::SetFiles(nsIDOMFileList* aFiles,
+                             bool aSetValueChanged)
+{
+  mFiles.Clear();
+
+  if (aFiles) {
+    PRUint32 listLength;
+    aFiles->GetLength(&listLength);
+    for (PRUint32 i = 0; i < listLength; i++) {
+      nsCOMPtr<nsIDOMFile> file;
+      aFiles->Item(i, getter_AddRefs(file));
+      mFiles.AppendObject(file);
+    }
+  }
+
+  AfterSetFiles(aSetValueChanged);
+}
+
+void
+nsHTMLInputElement::AfterSetFiles(bool aSetValueChanged)
+{
   // No need to flush here, if there's no frame at this point we
   // don't need to force creation of one just to tell it about this
   // new value.  We just want the display to update as needed.

content/html/content/src/nsHTMLInputElement.h

@@ -145,11 +145,11 @@ public:
   {
     return nsGenericHTMLElement::GetEditor(aEditor);
   }
-
-  // Forward nsIDOMHTMLElement
-  NS_FORWARD_NSIDOMHTMLELEMENT_NOFOCUSCLICK(nsGenericHTMLFormElement::)
-  NS_IMETHOD Focus();
-  NS_IMETHOD Click();
+
+  // Forward nsIDOMHTMLElement
+  NS_FORWARD_NSIDOMHTMLELEMENT_NOFOCUSCLICK(nsGenericHTMLFormElement::)
+  NS_IMETHOD Focus();
+  NS_IMETHOD Click();
 
   NS_IMETHOD SetUserInput(const nsAString& aInput);
 
@@ -218,6 +218,7 @@ public:
   void GetDisplayFileName(nsAString& aFileName) const;
   const nsCOMArray<nsIDOMFile>& GetFiles() const;
   void SetFiles(const nsCOMArray<nsIDOMFile>& aFiles, bool aSetValueChanged);
+  void SetFiles(nsIDOMFileList* aFiles, bool aSetValueChanged);
 
   void SetCheckedChangedInternal(PRBool aCheckedChanged);
   PRBool GetCheckedChanged() const {
@@ -457,6 +458,11 @@ protected:
    */
   nsresult UpdateFileList();
 
+  /**
+   * Called after calling one of the SetFiles() functions.
+   */
+  void AfterSetFiles(bool aSetValueChanged);
+
   /**
    * Determine whether the editor needs to be initialized explicitly for
    * a particular event.

layout/forms/nsFileControlFrame.cpp

@@ -93,6 +93,9 @@
 #include "nsDOMFile.h"
 #include "nsEventStates.h"
 
+#include "nsIDOMDOMStringList.h"
+#include "nsIDOMDragEvent.h"
+
 namespace dom = mozilla::dom;
 
 #define SYNC_TEXT 0x1
@@ -136,6 +139,15 @@ nsFileControlFrame::DestroyFrom(nsIFrame* aDestructRoot)
   mTextFrame = nsnull;
   ENSURE_TRUE(mContent);
 
+  // Remove the drag events
+  nsCOMPtr<nsIDOMEventTarget> dragTarget = do_QueryInterface(mContent);
+  if (dragTarget) {
+    dragTarget->RemoveEventListener(NS_LITERAL_STRING("drop"),
+                                    mMouseListener, PR_FALSE);
+    dragTarget->RemoveEventListener(NS_LITERAL_STRING("dragover"),
+                                    mMouseListener, PR_FALSE);
+  }
+
   // remove mMouseListener as a mouse event listener (bug 40533, bug 355931)
   NS_NAMED_LITERAL_STRING(click, "click");
 
@@ -258,6 +270,14 @@ nsFileControlFrame::CreateAnonymousContent(nsTArray<ContentInfo>& aElements)
   if (!aElements.AppendElement(mTextContent))
     return NS_ERROR_OUT_OF_MEMORY;
 
+  // Register the whole frame as an event listener of drag events
+  nsCOMPtr<nsIDOMEventTarget> dragTarget = do_QueryInterface(mContent);
+  NS_ENSURE_STATE(dragTarget);
+  dragTarget->AddEventListener(NS_LITERAL_STRING("drop"),
+                               mMouseListener, PR_FALSE);
+  dragTarget->AddEventListener(NS_LITERAL_STRING("dragover"),
+                               mMouseListener, PR_FALSE);
+
   NS_NAMED_LITERAL_STRING(click, "click");
   nsCOMPtr<nsIDOMEventGroup> systemGroup;
   mContent->GetSystemEventGroup(getter_AddRefs(systemGroup));
@@ -498,6 +518,74 @@ nsFileControlFrame::BrowseMouseListener::MouseClick(nsIDOMEvent* aMouseEvent)
   return input ? input->FireAsyncClickHandler() : NS_OK;
 }
 
+/**
+ * This is called when we receive any registered events on the control.
+ * We've only registered for drop, dragover and click events, and click events
+ * already call MouseClick() for us. Here, we handle file drops.
+ */
+NS_IMETHODIMP
+nsFileControlFrame::BrowseMouseListener::HandleEvent(nsIDOMEvent* aEvent)
+{
+  NS_ASSERTION(mFrame, "We should have been unregistered");
+  nsCOMPtr<nsIDOMNSUIEvent> uiEvent = do_QueryInterface(aEvent);
+  NS_ENSURE_STATE(uiEvent);
+  PRBool defaultPrevented = PR_FALSE;
+  uiEvent->GetPreventDefault(&defaultPrevented);
+  if (defaultPrevented) {
+    return NS_OK;
+  }
+  
+  nsCOMPtr<nsIDOMDragEvent> dragEvent = do_QueryInterface(aEvent);
+  if (!dragEvent || !IsValidDropData(dragEvent)) {
+    return NS_OK;
+  }
+
+  nsAutoString eventType;
+  aEvent->GetType(eventType);
+  if (eventType.EqualsLiteral("dragover")) {
+    // Prevent default if we can accept this drag data
+    aEvent->PreventDefault();
+    return NS_OK;
+  }
+
+  if (eventType.EqualsLiteral("drop")) {
+    aEvent->StopPropagation();
+    aEvent->PreventDefault();
+
+    nsIContent* content = mFrame->GetContent();
+    NS_ASSERTION(content, "The frame has no content???");
+
+    nsHTMLInputElement* inputElement = nsHTMLInputElement::FromContent(content);
+    NS_ASSERTION(inputElement, "No input element for this file upload control frame!");
+
+    nsCOMPtr<nsIDOMDataTransfer> dataTransfer;
+    dragEvent->GetDataTransfer(getter_AddRefs(dataTransfer));
+
+    nsCOMPtr<nsIDOMFileList> fileList;
+    dataTransfer->GetFiles(getter_AddRefs(fileList));
+    inputElement->SetFiles(fileList, true);
+  }
+
+  return NS_OK;
+}
+
+/* static */ PRBool
+nsFileControlFrame::BrowseMouseListener::IsValidDropData(nsIDOMDragEvent* aEvent)
+{
+  nsCOMPtr<nsIDOMDataTransfer> dataTransfer;
+  aEvent->GetDataTransfer(getter_AddRefs(dataTransfer));
+  NS_ENSURE_TRUE(dataTransfer, PR_FALSE);
+
+  nsCOMPtr<nsIDOMDOMStringList> types;
+  dataTransfer->GetTypes(getter_AddRefs(types));
+  NS_ENSURE_TRUE(types, PR_FALSE);
+
+  // We only support dropping files onto a file upload control
+  PRBool typeSupported;
+  types->Contains(NS_LITERAL_STRING("Files"), &typeSupported);
+  return typeSupported;
+}
+
 nscoord
 nsFileControlFrame::GetMinWidth(nsRenderingContext *aRenderingContext)
 {

layout/forms/nsFileControlFrame.h

@@ -48,6 +48,8 @@
 #include "nsTextControlFrame.h"
 typedef   nsTextControlFrame nsNewFrame;
 
+class nsIDOMDragEvent;
+
 class nsFileControlFrame : public nsBlockFrame,
                            public nsIFormControlFrame,
                            public nsIAnonymousContentCreator
@@ -169,6 +171,9 @@ protected:
   public:
     BrowseMouseListener(nsFileControlFrame* aFrame) : MouseListener(aFrame) {};
      NS_IMETHOD MouseClick(nsIDOMEvent* aMouseEvent);
+     NS_IMETHOD HandleEvent(nsIDOMEvent* aEvent);
+
+     static PRBool IsValidDropData(nsIDOMDragEvent* aEvent);
   };
 
   virtual PRBool IsFrameOfType(PRUint32 aFlags) const