summaryrefslogtreecommitdiffstats
path: root/dom/base/nsContentAreaDragDrop.cpp
blob: 1734ab378db9e03ccf60a5b7e078c264420ad1a7 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "nsReadableUtils.h"

// Local Includes
#include "nsContentAreaDragDrop.h"

// Helper Classes
#include "nsString.h"

// Interfaces needed to be included
#include "nsCopySupport.h"
#include "nsIDOMUIEvent.h"
#include "nsISelection.h"
#include "nsISelectionController.h"
#include "nsIDOMNode.h"
#include "nsIDOMNodeList.h"
#include "nsIDOMEvent.h"
#include "nsIDOMDragEvent.h"
#include "nsPIDOMWindow.h"
#include "nsIDOMRange.h"
#include "nsIFormControl.h"
#include "nsIDOMHTMLAreaElement.h"
#include "nsIDOMHTMLAnchorElement.h"
#include "nsITransferable.h"
#include "nsComponentManagerUtils.h"
#include "nsXPCOM.h"
#include "nsISupportsPrimitives.h"
#include "nsServiceManagerUtils.h"
#include "nsNetUtil.h"
#include "nsIFile.h"
#include "nsFrameLoader.h"
#include "nsIWebNavigation.h"
#include "nsIDocShell.h"
#include "nsIContent.h"
#include "nsIImageLoadingContent.h"
#include "nsITextControlElement.h"
#include "nsUnicharUtils.h"
#include "nsIURL.h"
#include "nsIDocument.h"
#include "nsIScriptSecurityManager.h"
#include "nsIPrincipal.h"
#include "nsIDocShellTreeItem.h"
#include "nsIWebBrowserPersist.h"
#include "nsEscape.h"
#include "nsContentUtils.h"
#include "nsIMIMEService.h"
#include "imgIContainer.h"
#include "imgIRequest.h"
#include "mozilla/dom/DataTransfer.h"
#include "nsIMIMEInfo.h"
#include "nsRange.h"
#include "TabParent.h"
#include "mozilla/dom/Element.h"
#include "mozilla/dom/HTMLAreaElement.h"
#include "nsVariant.h"

using namespace mozilla::dom;

class MOZ_STACK_CLASS DragDataProducer
{
public:
  DragDataProducer(nsPIDOMWindowOuter* aWindow,
                   nsIContent* aTarget,
                   nsIContent* aSelectionTargetNode,
                   bool aIsAltKeyPressed);
  nsresult Produce(DataTransfer* aDataTransfer,
                   bool* aCanDrag,
                   nsISelection** aSelection,
                   nsIContent** aDragNode);

private:
  void AddString(DataTransfer* aDataTransfer,
                 const nsAString& aFlavor,
                 const nsAString& aData,
                 nsIPrincipal* aPrincipal);
  nsresult AddStringsToDataTransfer(nsIContent* aDragNode,
                                    DataTransfer* aDataTransfer);
  static nsresult GetDraggableSelectionData(nsISelection* inSelection,
                                            nsIContent* inRealTargetNode,
                                            nsIContent **outImageOrLinkNode,
                                            bool* outDragSelectedText);
  static already_AddRefed<nsIContent> FindParentLinkNode(nsIContent* inNode);
  static MOZ_MUST_USE nsresult
  GetAnchorURL(nsIContent* inNode, nsAString& outURL);
  static void GetNodeString(nsIContent* inNode, nsAString & outNodeString);
  static void CreateLinkText(const nsAString& inURL, const nsAString & inText,
                              nsAString& outLinkText);

  nsCOMPtr<nsPIDOMWindowOuter> mWindow;
  nsCOMPtr<nsIContent> mTarget;
  nsCOMPtr<nsIContent> mSelectionTargetNode;
  bool mIsAltKeyPressed;

  nsString mUrlString;
  nsString mImageSourceString;
  nsString mImageDestFileName;
  nsString mTitleString;
  // will be filled automatically if you fill urlstring
  nsString mHtmlString;
  nsString mContextString;
  nsString mInfoString;

  bool mIsAnchor;
  nsCOMPtr<imgIContainer> mImage;
};


nsresult
nsContentAreaDragDrop::GetDragData(nsPIDOMWindowOuter* aWindow,
                                   nsIContent* aTarget,
                                   nsIContent* aSelectionTargetNode,
                                   bool aIsAltKeyPressed,
                                   DataTransfer* aDataTransfer,
                                   bool* aCanDrag,
                                   nsISelection** aSelection,
                                   nsIContent** aDragNode)
{
  NS_ENSURE_TRUE(aSelectionTargetNode, NS_ERROR_INVALID_ARG);

  *aCanDrag = true;

  DragDataProducer
    provider(aWindow, aTarget, aSelectionTargetNode, aIsAltKeyPressed);
  return provider.Produce(aDataTransfer, aCanDrag, aSelection, aDragNode);
}


NS_IMPL_ISUPPORTS(nsContentAreaDragDropDataProvider, nsIFlavorDataProvider)

// SaveURIToFile
// used on platforms where it's possible to drag items (e.g. images)
// into the file system
nsresult
nsContentAreaDragDropDataProvider::SaveURIToFile(nsAString& inSourceURIString,
                                                 nsIFile* inDestFile,
                                                 bool isPrivate)
{
  nsCOMPtr<nsIURI> sourceURI;
  nsresult rv = NS_NewURI(getter_AddRefs(sourceURI), inSourceURIString);
  if (NS_FAILED(rv)) {
    return NS_ERROR_FAILURE;
  }

  nsCOMPtr<nsIURL> sourceURL = do_QueryInterface(sourceURI);
  if (!sourceURL) {
    return NS_ERROR_NO_INTERFACE;
  }

  rv = inDestFile->CreateUnique(nsIFile::NORMAL_FILE_TYPE, 0600);
  NS_ENSURE_SUCCESS(rv, rv);

  // we rely on the fact that the WPB is refcounted by the channel etc,
  // so we don't keep a ref to it. It will die when finished.
  nsCOMPtr<nsIWebBrowserPersist> persist =
    do_CreateInstance("@mozilla.org/embedding/browser/nsWebBrowserPersist;1",
                      &rv);
  NS_ENSURE_SUCCESS(rv, rv);

  persist->SetPersistFlags(nsIWebBrowserPersist::PERSIST_FLAGS_AUTODETECT_APPLY_CONVERSION);

  // referrer policy can be anything since the referrer is nullptr
  return persist->SavePrivacyAwareURI(sourceURI, nullptr, nullptr,
                                      mozilla::net::RP_Default,
                                      nullptr, nullptr,
                                      inDestFile, isPrivate);
}

// This is our nsIFlavorDataProvider callback. There are several
// assumptions here that make this work:
//
// 1. Someone put a kFilePromiseURLMime flavor into the transferable
//    with the source URI of the file to save (as a string). We did
//    that in AddStringsToDataTransfer.
//
// 2. Someone put a kFilePromiseDirectoryMime flavor into the
//    transferable with an nsIFile for the directory we are to
//    save in. That has to be done by platform-specific code (in
//    widget), which gets the destination directory from
//    OS-specific drag information.
//
NS_IMETHODIMP
nsContentAreaDragDropDataProvider::GetFlavorData(nsITransferable *aTransferable,
                                                 const char *aFlavor,
                                                 nsISupports **aData,
                                                 uint32_t *aDataLen)
{
  NS_ENSURE_ARG_POINTER(aData && aDataLen);
  *aData = nullptr;
  *aDataLen = 0;

  nsresult rv = NS_ERROR_NOT_IMPLEMENTED;

  if (strcmp(aFlavor, kFilePromiseMime) == 0) {
    // get the URI from the kFilePromiseURLMime flavor
    NS_ENSURE_ARG(aTransferable);
    nsCOMPtr<nsISupports> tmp;
    uint32_t dataSize = 0;
    aTransferable->GetTransferData(kFilePromiseURLMime,
                                   getter_AddRefs(tmp), &dataSize);
    nsCOMPtr<nsISupportsString> supportsString =
      do_QueryInterface(tmp);
    if (!supportsString)
      return NS_ERROR_FAILURE;

    nsAutoString sourceURLString;
    supportsString->GetData(sourceURLString);
    if (sourceURLString.IsEmpty())
      return NS_ERROR_FAILURE;

    aTransferable->GetTransferData(kFilePromiseDestFilename,
                                   getter_AddRefs(tmp), &dataSize);
    supportsString = do_QueryInterface(tmp);
    if (!supportsString)
      return NS_ERROR_FAILURE;

    nsAutoString targetFilename;
    supportsString->GetData(targetFilename);
    if (targetFilename.IsEmpty())
      return NS_ERROR_FAILURE;

    // get the target directory from the kFilePromiseDirectoryMime
    // flavor
    nsCOMPtr<nsISupports> dirPrimitive;
    dataSize = 0;
    aTransferable->GetTransferData(kFilePromiseDirectoryMime,
                                   getter_AddRefs(dirPrimitive), &dataSize);
    nsCOMPtr<nsIFile> destDirectory = do_QueryInterface(dirPrimitive);
    if (!destDirectory)
      return NS_ERROR_FAILURE;

    nsCOMPtr<nsIFile> file;
    rv = destDirectory->Clone(getter_AddRefs(file));
    NS_ENSURE_SUCCESS(rv, rv);

    file->Append(targetFilename);

    bool isPrivate;
    aTransferable->GetIsPrivateData(&isPrivate);

    rv = SaveURIToFile(sourceURLString, file, isPrivate);
    // send back an nsIFile
    if (NS_SUCCEEDED(rv)) {
      CallQueryInterface(file, aData);
      *aDataLen = sizeof(nsIFile*);
    }
  }

  return rv;
}

DragDataProducer::DragDataProducer(nsPIDOMWindowOuter* aWindow,
                                   nsIContent* aTarget,
                                   nsIContent* aSelectionTargetNode,
                                   bool aIsAltKeyPressed)
  : mWindow(aWindow),
    mTarget(aTarget),
    mSelectionTargetNode(aSelectionTargetNode),
    mIsAltKeyPressed(aIsAltKeyPressed),
    mIsAnchor(false)
{
}


//
// FindParentLinkNode
//
// Finds the parent with the given link tag starting at |inNode|. If
// it gets up to the root without finding it, we stop looking and
// return null.
//
already_AddRefed<nsIContent>
DragDataProducer::FindParentLinkNode(nsIContent* inNode)
{
  nsIContent* content = inNode;
  if (!content) {
    // That must have been the document node; nothing else to do here;
    return nullptr;
  }

  for (; content; content = content->GetParent()) {
    if (nsContentUtils::IsDraggableLink(content)) {
      nsCOMPtr<nsIContent> ret = content;
      return ret.forget();
    }
  }

  return nullptr;
}


//
// GetAnchorURL
//
nsresult
DragDataProducer::GetAnchorURL(nsIContent* inNode, nsAString& outURL)
{
  nsCOMPtr<nsIURI> linkURI;
  if (!inNode || !inNode->IsLink(getter_AddRefs(linkURI))) {
    // Not a link
    outURL.Truncate();
    return NS_OK;
  }

  nsAutoCString spec;
  nsresult rv = linkURI->GetSpec(spec);
  NS_ENSURE_SUCCESS(rv, rv);
  CopyUTF8toUTF16(spec, outURL);
  return NS_OK;
}


//
// CreateLinkText
//
// Creates the html for an anchor in the form
//  <a href="inURL">inText</a>
//
void
DragDataProducer::CreateLinkText(const nsAString& inURL,
                                 const nsAString & inText,
                                 nsAString& outLinkText)
{
  // use a temp var in case |inText| is the same string as
  // |outLinkText| to avoid overwriting it while building up the
  // string in pieces.
  nsAutoString linkText(NS_LITERAL_STRING("<a href=\"") +
                        inURL +
                        NS_LITERAL_STRING("\">") +
                        inText +
                        NS_LITERAL_STRING("</a>") );

  outLinkText = linkText;
}


//
// GetNodeString
//
// Gets the text associated with a node
//
void
DragDataProducer::GetNodeString(nsIContent* inNode,
                                nsAString & outNodeString)
{
  nsCOMPtr<nsINode> node = inNode;

  outNodeString.Truncate();

  // use a range to get the text-equivalent of the node
  nsCOMPtr<nsIDocument> doc = node->OwnerDoc();
  mozilla::ErrorResult rv;
  RefPtr<nsRange> range = doc->CreateRange(rv);
  if (range) {
    range->SelectNode(*node, rv);
    range->ToString(outNodeString);
  }
}

nsresult
DragDataProducer::Produce(DataTransfer* aDataTransfer,
                          bool* aCanDrag,
                          nsISelection** aSelection,
                          nsIContent** aDragNode)
{
  NS_PRECONDITION(aCanDrag && aSelection && aDataTransfer && aDragNode,
                  "null pointer passed to Produce");
  NS_ASSERTION(mWindow, "window not set");
  NS_ASSERTION(mSelectionTargetNode, "selection target node should have been set");

  *aDragNode = nullptr;

  nsresult rv;
  nsIContent* dragNode = nullptr;
  *aSelection = nullptr;

  // Find the selection to see what we could be dragging and if what we're
  // dragging is in what is selected. If this is an editable textbox, use
  // the textbox's selection, otherwise use the window's selection.
  nsCOMPtr<nsISelection> selection;
  nsIContent* editingElement = mSelectionTargetNode->IsEditable() ?
                               mSelectionTargetNode->GetEditingHost() : nullptr;
  nsCOMPtr<nsITextControlElement> textControl =
    nsITextControlElement::GetTextControlElementFromEditingHost(editingElement);
  if (textControl) {
    nsISelectionController* selcon = textControl->GetSelectionController();
    if (selcon) {
      selcon->GetSelection(nsISelectionController::SELECTION_NORMAL, getter_AddRefs(selection));
    }

    if (!selection)
      return NS_OK;
  }
  else {
    selection = mWindow->GetSelection();
    if (!selection)
      return NS_OK;

    // Check if the node is inside a form control. Don't set aCanDrag to false
    //however, as we still want to allow the drag.
    nsCOMPtr<nsIContent> findFormNode = mSelectionTargetNode;
    nsIContent* findFormParent = findFormNode->GetParent();
    while (findFormParent) {
      nsCOMPtr<nsIFormControl> form(do_QueryInterface(findFormParent));
      if (form && !form->AllowDraggableChildren()) {
        return NS_OK;
      }
      findFormParent = findFormParent->GetParent();
    }
  }
    
  // if set, serialize the content under this node
  nsCOMPtr<nsIContent> nodeToSerialize;

  nsCOMPtr<nsIDocShellTreeItem> dsti = mWindow->GetDocShell();
  const bool isChromeShell =
    dsti && dsti->ItemType() == nsIDocShellTreeItem::typeChrome;

  // In chrome shells, only allow dragging inside editable areas.
  if (isChromeShell && !editingElement) {
    nsCOMPtr<nsIFrameLoaderOwner> flo = do_QueryInterface(mTarget);
    if (flo) {
      RefPtr<nsFrameLoader> fl = flo->GetFrameLoader();
      if (fl) {
        TabParent* tp = static_cast<TabParent*>(fl->GetRemoteBrowser());
        if (tp) {
          // We have a TabParent, so it may have data for dnd in case the child
          // process started a dnd session.
          tp->AddInitialDnDDataTo(aDataTransfer);
        }
      }
    }
    return NS_OK;
  }

  if (isChromeShell && textControl) {
    // Only use the selection if the target node is in the selection.
    bool selectionContainsTarget = false;
    nsCOMPtr<nsIDOMNode> targetNode = do_QueryInterface(mSelectionTargetNode);
    selection->ContainsNode(targetNode, false, &selectionContainsTarget);
    if (!selectionContainsTarget)
      return NS_OK;

    selection.swap(*aSelection);
  }
  else {
    // In content shells, a number of checks are made below to determine
    // whether an image or a link is being dragged. If so, add additional
    // data to the data transfer. This is also done for chrome shells, but
    // only when in a non-textbox editor.

    bool haveSelectedContent = false;

    // possible parent link node
    nsCOMPtr<nsIContent> parentLink;
    nsCOMPtr<nsIContent> draggedNode;

    {
      // only drag form elements by using the alt key,
      // otherwise buttons and select widgets are hard to use

      // Note that while <object> elements implement nsIFormControl, we should
      // really allow dragging them if they happen to be images.
      nsCOMPtr<nsIFormControl> form(do_QueryInterface(mTarget));
      if (form && !mIsAltKeyPressed && form->GetType() != NS_FORM_OBJECT) {
        *aCanDrag = false;
        return NS_OK;
      }

      draggedNode = mTarget;
    }

    nsCOMPtr<nsIDOMHTMLAreaElement>   area;   // client-side image map
    nsCOMPtr<nsIImageLoadingContent>  image;
    nsCOMPtr<nsIDOMHTMLAnchorElement> link;

    nsCOMPtr<nsIContent> selectedImageOrLinkNode;
    GetDraggableSelectionData(selection, mSelectionTargetNode,
                              getter_AddRefs(selectedImageOrLinkNode),
                              &haveSelectedContent);

    // either plain text or anchor text is selected
    if (haveSelectedContent) {
      selection.swap(*aSelection);
    } else if (selectedImageOrLinkNode) {
      // an image is selected
      image = do_QueryInterface(selectedImageOrLinkNode);
    } else {
      // nothing is selected -
      //
      // look for draggable elements under the mouse
      //
      // if the alt key is down, don't start a drag if we're in an
      // anchor because we want to do selection.
      parentLink = FindParentLinkNode(draggedNode);
      if (parentLink && mIsAltKeyPressed) {
        *aCanDrag = false;
        return NS_OK;
      }

      area  = do_QueryInterface(draggedNode);
      image = do_QueryInterface(draggedNode);
      link  = do_QueryInterface(draggedNode);
    }

    {
      // set for linked images, and links
      nsCOMPtr<nsIContent> linkNode;

      if (area) {
        // use the alt text (or, if missing, the href) as the title
        HTMLAreaElement* areaElem = static_cast<HTMLAreaElement*>(area.get());
        areaElem->GetAttribute(NS_LITERAL_STRING("alt"), mTitleString);
        if (mTitleString.IsEmpty()) {
          // this can be a relative link
          areaElem->GetAttribute(NS_LITERAL_STRING("href"), mTitleString);
        }

        // we'll generate HTML like <a href="absurl">alt text</a>
        mIsAnchor = true;

        // gives an absolute link
        nsresult rv = GetAnchorURL(draggedNode, mUrlString);
        NS_ENSURE_SUCCESS(rv, rv);

        mHtmlString.AssignLiteral("<a href=\"");
        mHtmlString.Append(mUrlString);
        mHtmlString.AppendLiteral("\">");
        mHtmlString.Append(mTitleString);
        mHtmlString.AppendLiteral("</a>");

        dragNode = draggedNode;
      } else if (image) {
        mIsAnchor = true;
        // grab the href as the url, use alt text as the title of the
        // area if it's there.  the drag data is the image tag and src
        // attribute.
        nsCOMPtr<nsIURI> imageURI;
        image->GetCurrentURI(getter_AddRefs(imageURI));
        if (imageURI) {
          nsAutoCString spec;
          rv = imageURI->GetSpec(spec);
          NS_ENSURE_SUCCESS(rv, rv);
          CopyUTF8toUTF16(spec, mUrlString);
        }

        nsCOMPtr<nsIDOMElement> imageElement(do_QueryInterface(image));
        // XXXbz Shouldn't we use the "title" attr for title?  Using
        // "alt" seems very wrong....
        if (imageElement) {
          imageElement->GetAttribute(NS_LITERAL_STRING("alt"), mTitleString);
        }

        if (mTitleString.IsEmpty()) {
          mTitleString = mUrlString;
        }

        nsCOMPtr<imgIRequest> imgRequest;

        // grab the image data, and its request.
        nsCOMPtr<imgIContainer> img =
          nsContentUtils::GetImageFromContent(image,
                                              getter_AddRefs(imgRequest));

        nsCOMPtr<nsIMIMEService> mimeService =
          do_GetService("@mozilla.org/mime;1");

        // Fix the file extension in the URL if necessary
        if (imgRequest && mimeService) {
          nsCOMPtr<nsIURI> imgUri;
          imgRequest->GetURI(getter_AddRefs(imgUri));

          nsCOMPtr<nsIURL> imgUrl(do_QueryInterface(imgUri));

          if (imgUrl) {
            nsAutoCString extension;
            imgUrl->GetFileExtension(extension);

            nsXPIDLCString mimeType;
            imgRequest->GetMimeType(getter_Copies(mimeType));

            nsCOMPtr<nsIMIMEInfo> mimeInfo;
            mimeService->GetFromTypeAndExtension(mimeType, EmptyCString(),
                                                 getter_AddRefs(mimeInfo));

            if (mimeInfo) {
              nsAutoCString spec;
              rv = imgUrl->GetSpec(spec);
              NS_ENSURE_SUCCESS(rv, rv);

              // pass out the image source string
              CopyUTF8toUTF16(spec, mImageSourceString);

              bool validExtension;
              if (extension.IsEmpty() || 
                  NS_FAILED(mimeInfo->ExtensionExists(extension,
                                                      &validExtension)) ||
                  !validExtension) {
                // Fix the file extension in the URL
                nsresult rv = imgUrl->Clone(getter_AddRefs(imgUri));
                NS_ENSURE_SUCCESS(rv, rv);

                imgUrl = do_QueryInterface(imgUri);

                nsAutoCString primaryExtension;
                mimeInfo->GetPrimaryExtension(primaryExtension);

                imgUrl->SetFileExtension(primaryExtension);
              }

              nsAutoCString fileName;
              imgUrl->GetFileName(fileName);

              NS_UnescapeURL(fileName);

              // make the filename safe for the filesystem
              fileName.ReplaceChar(FILE_PATH_SEPARATOR FILE_ILLEGAL_CHARACTERS,
                                   '-');

              CopyUTF8toUTF16(fileName, mImageDestFileName);

              // and the image object
              mImage = img;
            }
          }
        }

        if (parentLink) {
          // If we are dragging around an image in an anchor, then we
          // are dragging the entire anchor
          linkNode = parentLink;
          nodeToSerialize = linkNode;
        } else {
          nodeToSerialize = do_QueryInterface(draggedNode);
        }
        dragNode = nodeToSerialize;
      } else if (link) {
        // set linkNode. The code below will handle this
        linkNode = do_QueryInterface(link);    // XXX test this
        GetNodeString(draggedNode, mTitleString);
      } else if (parentLink) {
        // parentLink will always be null if there's selected content
        linkNode = parentLink;
        nodeToSerialize = linkNode;
      } else if (!haveSelectedContent) {
        // nothing draggable
        return NS_OK;
      }

      if (linkNode) {
        mIsAnchor = true;
        rv = GetAnchorURL(linkNode, mUrlString);
        NS_ENSURE_SUCCESS(rv, rv);
        dragNode = linkNode;
      }
    }
  }

  if (nodeToSerialize || *aSelection) {
    mHtmlString.Truncate();
    mContextString.Truncate();
    mInfoString.Truncate();
    mTitleString.Truncate();

    nsCOMPtr<nsIDocument> doc = mWindow->GetDoc();
    NS_ENSURE_TRUE(doc, NS_ERROR_FAILURE);

    // if we have selected text, use it in preference to the node
    nsCOMPtr<nsITransferable> transferable;
    if (*aSelection) {
      rv = nsCopySupport::GetTransferableForSelection(*aSelection, doc,
                                                      getter_AddRefs(transferable));
    }
    else {
      rv = nsCopySupport::GetTransferableForNode(nodeToSerialize, doc,
                                                 getter_AddRefs(transferable));
    }
    NS_ENSURE_SUCCESS(rv, rv);

    nsCOMPtr<nsISupports> supports;
    nsCOMPtr<nsISupportsString> data;
    uint32_t dataSize;
    rv = transferable->GetTransferData(kHTMLMime, getter_AddRefs(supports),
                                       &dataSize);
    data = do_QueryInterface(supports);
    if (NS_SUCCEEDED(rv)) {
      data->GetData(mHtmlString);
    }
    rv = transferable->GetTransferData(kHTMLContext, getter_AddRefs(supports),
                                       &dataSize);
    data = do_QueryInterface(supports);
    if (NS_SUCCEEDED(rv)) {
      data->GetData(mContextString);
    }
    rv = transferable->GetTransferData(kHTMLInfo, getter_AddRefs(supports),
                                       &dataSize);
    data = do_QueryInterface(supports);
    if (NS_SUCCEEDED(rv)) {
      data->GetData(mInfoString);
    }
    rv = transferable->GetTransferData(kUnicodeMime, getter_AddRefs(supports),
                                       &dataSize);
    data = do_QueryInterface(supports);
    NS_ENSURE_SUCCESS(rv, rv); // require plain text at a minimum
    data->GetData(mTitleString);
  }

  // default text value is the URL
  if (mTitleString.IsEmpty()) {
    mTitleString = mUrlString;
  }

  // if we haven't constructed a html version, make one now
  if (mHtmlString.IsEmpty() && !mUrlString.IsEmpty())
    CreateLinkText(mUrlString, mTitleString, mHtmlString);

  // if there is no drag node, which will be the case for a selection, just
  // use the selection target node.
  rv = AddStringsToDataTransfer(
         dragNode ? dragNode : mSelectionTargetNode.get(), aDataTransfer);
  NS_ENSURE_SUCCESS(rv, rv);

  NS_IF_ADDREF(*aDragNode = dragNode);
  return NS_OK;
}

void
DragDataProducer::AddString(DataTransfer* aDataTransfer,
                            const nsAString& aFlavor,
                            const nsAString& aData,
                            nsIPrincipal* aPrincipal)
{
  RefPtr<nsVariantCC> variant = new nsVariantCC();
  variant->SetAsAString(aData);
  aDataTransfer->SetDataWithPrincipal(aFlavor, variant, 0, aPrincipal);
}

nsresult
DragDataProducer::AddStringsToDataTransfer(nsIContent* aDragNode,
                                           DataTransfer* aDataTransfer)
{
  NS_ASSERTION(aDragNode, "adding strings for null node");

  // set all of the data to have the principal of the node where the data came from
  nsIPrincipal* principal = aDragNode->NodePrincipal();

  // add a special flavor if we're an anchor to indicate that we have
  // a URL in the drag data
  if (!mUrlString.IsEmpty() && mIsAnchor) {
    nsAutoString dragData(mUrlString);
    dragData.Append('\n');
    // Remove leading and trailing newlines in the title and replace them with
    // space in remaining positions - they confuse PlacesUtils::unwrapNodes
    // that expects url\ntitle formatted data for x-moz-url.
    nsAutoString title(mTitleString);
    title.Trim("\r\n");
    title.ReplaceChar("\r\n", ' ');
    dragData += title;

    AddString(aDataTransfer, NS_LITERAL_STRING(kURLMime), dragData, principal);
    AddString(aDataTransfer, NS_LITERAL_STRING(kURLDataMime), mUrlString, principal);
    AddString(aDataTransfer, NS_LITERAL_STRING(kURLDescriptionMime), mTitleString, principal);
    AddString(aDataTransfer, NS_LITERAL_STRING("text/uri-list"), mUrlString, principal);
  }

  // add a special flavor for the html context data
  if (!mContextString.IsEmpty())
    AddString(aDataTransfer, NS_LITERAL_STRING(kHTMLContext), mContextString, principal);

  // add a special flavor if we have html info data
  if (!mInfoString.IsEmpty())
    AddString(aDataTransfer, NS_LITERAL_STRING(kHTMLInfo), mInfoString, principal);

  // add the full html
  if (!mHtmlString.IsEmpty())
    AddString(aDataTransfer, NS_LITERAL_STRING(kHTMLMime), mHtmlString, principal);

  // add the plain text. we use the url for text/plain data if an anchor is
  // being dragged, rather than the title text of the link or the alt text for
  // an anchor image.
  AddString(aDataTransfer, NS_LITERAL_STRING(kTextMime),
            mIsAnchor ? mUrlString : mTitleString, principal);

  // add image data, if present. For now, all we're going to do with
  // this is turn it into a native data flavor, so indicate that with
  // a new flavor so as not to confuse anyone who is really registered
  // for image/gif or image/jpg.
  if (mImage) {
    RefPtr<nsVariantCC> variant = new nsVariantCC();
    variant->SetAsISupports(mImage);
    aDataTransfer->SetDataWithPrincipal(NS_LITERAL_STRING(kNativeImageMime),
                                        variant, 0, principal);

    // assume the image comes from a file, and add a file promise. We
    // register ourselves as a nsIFlavorDataProvider, and will use the
    // GetFlavorData callback to save the image to disk.

    nsCOMPtr<nsIFlavorDataProvider> dataProvider =
      new nsContentAreaDragDropDataProvider();
    if (dataProvider) {
      RefPtr<nsVariantCC> variant = new nsVariantCC();
      variant->SetAsISupports(dataProvider);
      aDataTransfer->SetDataWithPrincipal(NS_LITERAL_STRING(kFilePromiseMime),
                                          variant, 0, principal);
    }

    AddString(aDataTransfer, NS_LITERAL_STRING(kFilePromiseURLMime),
              mImageSourceString, principal);
    AddString(aDataTransfer, NS_LITERAL_STRING(kFilePromiseDestFilename),
              mImageDestFileName, principal);

    // if not an anchor, add the image url
    if (!mIsAnchor) {
      AddString(aDataTransfer, NS_LITERAL_STRING(kURLDataMime), mUrlString, principal);
      AddString(aDataTransfer, NS_LITERAL_STRING("text/uri-list"), mUrlString, principal);
    }
  }

  return NS_OK;
}

// note that this can return NS_OK, but a null out param (by design)
// static
nsresult
DragDataProducer::GetDraggableSelectionData(nsISelection* inSelection,
                                            nsIContent* inRealTargetNode,
                                            nsIContent **outImageOrLinkNode,
                                            bool* outDragSelectedText)
{
  NS_ENSURE_ARG(inSelection);
  NS_ENSURE_ARG(inRealTargetNode);
  NS_ENSURE_ARG_POINTER(outImageOrLinkNode);

  *outImageOrLinkNode = nullptr;
  *outDragSelectedText = false;

  bool selectionContainsTarget = false;

  bool isCollapsed = false;
  inSelection->GetIsCollapsed(&isCollapsed);
  if (!isCollapsed) {
    nsCOMPtr<nsIDOMNode> realTargetNode = do_QueryInterface(inRealTargetNode);
    inSelection->ContainsNode(realTargetNode, false,
                              &selectionContainsTarget);

    if (selectionContainsTarget) {
      // track down the anchor node, if any, for the url
      nsCOMPtr<nsIDOMNode> selectionStart;
      inSelection->GetAnchorNode(getter_AddRefs(selectionStart));

      nsCOMPtr<nsIDOMNode> selectionEnd;
      inSelection->GetFocusNode(getter_AddRefs(selectionEnd));

      // look for a selection around a single node, like an image.
      // in this case, drag the image, rather than a serialization of the HTML
      // XXX generalize this to other draggable element types?
      if (selectionStart == selectionEnd) {
        bool hasChildren;
        selectionStart->HasChildNodes(&hasChildren);
        if (hasChildren) {
          // see if just one node is selected
          int32_t anchorOffset, focusOffset;
          inSelection->GetAnchorOffset(&anchorOffset);
          inSelection->GetFocusOffset(&focusOffset);
          if (abs(anchorOffset - focusOffset) == 1) {
            nsCOMPtr<nsIContent> selStartContent =
              do_QueryInterface(selectionStart);

            if (selStartContent) {
              int32_t childOffset =
                (anchorOffset < focusOffset) ? anchorOffset : focusOffset;
              nsIContent *childContent =
                selStartContent->GetChildAt(childOffset);
              // if we find an image, we'll fall into the node-dragging code,
              // rather the the selection-dragging code
              if (nsContentUtils::IsDraggableImage(childContent)) {
                NS_ADDREF(*outImageOrLinkNode = childContent);
                return NS_OK;
              }
            }
          }
        }
      }

      // indicate that a link or text is selected
      *outDragSelectedText = true;
    }
  }

  return NS_OK;
}