Enable dragging of images to desktop (Finder), Preview, etc. (on Mac).

This hooks up drag-and-drop of file promises, lazy writing to the drag
pasteboard, drag-sourcing of TIFF images (via Cocoa) and file contents.

Patch Set 5 improvements: Adds asynchronous writing of promised files.

Patch Set 4 improvements: Big refactoring -- drag source stuff is now
handled by the WebDragSource (Cocoa) object, with messages proxied
through the TabContentsViewCocoa object. The WebDragSource object
carries a weak reference to the TCVC, owns the WebDropData, and keeps
track of the drag pasteboard types/promises.

Patch Set 3 improvements over Patch Set 2: It shouldn't crash anymore. Made
drop_data_ reference counted, in anticipation of asynchronous file
writing.

TODO #1: Testing. Still need a unit test, maybe. Should make sure that
dragging by file contents actually works.

TODO #2 (in some other patch): Refactor some of the WebDropData
extraction code out, e.g., file name extraction should be made common
with other platforms.

TODO #3 (in some other patch): We really should make WebDropData cheaper
to copy around and retain. I'm not convinced it's a good idea to push
out the entire thing over IPC, especially since the data pushed could be
very big and may not even be used.

BUG=15640
TEST=drag images to various applications

Patch by viettrungluu@gmail.com


git-svn-id: svn://svn.chromium.org/chrome/trunk/src@22187 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 403 insertions, 0 deletions

diff --git a/chrome/browser/cocoa/web_drag_source.h b/chrome/browser/cocoa/web_drag_source.h
new file mode 100644
index 0000000..6532878
--- /dev/null
+++ b/chrome/browser/cocoa/web_drag_source.h
@@ -0,0 +1,57 @@
+// Copyright (c) 2009 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.
+
+#import <Cocoa/Cocoa.h>
+
+#include "base/scoped_nsobject.h"
+#include "base/scoped_ptr.h"
+
+struct WebDropData;
+@class TabContentsViewCocoa;
+
+// A class that handles tracking and event processing for a drag and drop
+// originating from the content area.
+@interface WebDragSource : NSObject {
+ @private
+  // Our tab. Weak reference (owns or co-owns us).
+  TabContentsViewCocoa* contentsView_;
+
+  // Our drop data. Should only be initialized once.
+  scoped_ptr<WebDropData> dropData_;
+
+  // Our pasteboard.
+  scoped_nsobject<NSPasteboard> pasteboard_;
+}
+
+// Initialize a WebDragSource object for a drag (originating on the given
+// contentsView and with the given dropData and pboard). Fill the pasteboard
+// with data types appropriate for dropData.
+- (id)initWithContentsView:(TabContentsViewCocoa*)contentsView
+                  dropData:(const WebDropData*)dropData
+                pasteboard:(NSPasteboard*)pboard;
+
+// Call when asked to do a lazy write to the pasteboard; hook up to
+// -pasteboard:provideDataForType: (on the contentsView).
+- (void)lazyWriteToPasteboard:(NSPasteboard*)pboard
+                      forType:(NSString*)type;
+
+// Start the drag (on the originally provided contentsView); can do this right
+// after -initWithContentsView:....
+- (void)startDrag;
+
+// End the drag and clear the pasteboard; hook up to
+// -draggedImage:endedAt:operation:.
+- (void)endDragAt:(NSPoint)screenPoint
+      isCancelled:(BOOL)cancelled;
+
+// Drag moved; hook up to -draggedImage:movedTo:.
+- (void)moveDragTo:(NSPoint)screenPoint;
+
+// Call to drag a promised file to the given path (should be called before
+// -endDragAt:...); hook up to -namesOfPromisedFilesDroppedAtDestination:.
+// Returns the file name (not including path) of the file deposited (or which
+// will be deposited).
+- (NSString*)dragPromisedFileTo:(NSString*)path;
+
+@end
diff --git a/chrome/browser/cocoa/web_drag_source.mm b/chrome/browser/cocoa/web_drag_source.mm
new file mode 100644
index 0000000..6fd44a7
--- /dev/null
+++ b/chrome/browser/cocoa/web_drag_source.mm
@@ -0,0 +1,346 @@
+// Copyright (c) 2009 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.
+
+#import "chrome/browser/cocoa/web_drag_source.h"
+
+#include "base/file_util.h"
+#include "base/string_util.h"
+#include "base/sys_string_conversions.h"
+#include "base/task.h"
+#include "base/thread.h"
+#include "chrome/browser/browser_process.h"
+#include "chrome/browser/cocoa/nsimage_cache.h"
+#include "chrome/browser/renderer_host/render_view_host.h"
+#include "chrome/browser/tab_contents/tab_contents.h"
+#include "chrome/browser/tab_contents/tab_contents_view_mac.h"
+#include "net/base/file_stream.h"
+#include "net/base/net_errors.h"
+#include "net/base/net_util.h"
+#import "third_party/mozilla/include/NSPasteboard+Utils.h"
+#include "webkit/glue/webdropdata.h"
+
+using base::SysNSStringToUTF8;
+using base::SysUTF8ToNSString;
+using base::SysUTF16ToNSString;
+using net::FileStream;
+
+
+namespace {
+
+// Make a drag image from the drop data.
+// TODO(viettrungluu@gmail.com): Move this somewhere more sensible.
+NSImage* MakeDragImage(const WebDropData* drop_data) {
+  // TODO(viettrungluu@gmail.com): Just a stub for now. Make it do something.
+
+  // Default to returning a generic image.
+  return nsimage_cache::ImageNamed(@"nav.pdf");
+}
+
+// Returns a filename appropriate for the drop data (of form "FILENAME-seq.EXT"
+// if seq > 0).
+// TODO(viettrungluu@gmail.com): Refactor to make it common across platforms,
+// and move it somewhere sensible.
+FilePath GetFileNameFromDragData(
+    const WebDropData& drop_data, unsigned seq) {
+  // Images without ALT text will only have a file extension so we need to
+  // synthesize one from the provided extension and URL.
+  FilePath file_name([SysUTF16ToNSString(drop_data.file_description_filename)
+          fileSystemRepresentation]);
+  file_name = file_name.BaseName().RemoveExtension();
+
+  if (file_name.empty()) {
+    // Retrieve the name from the URL.
+    file_name = FilePath::FromWStringHack(
+        net::GetSuggestedFilename(drop_data.url, "", "", L""));
+  }
+
+  file_name = file_name.ReplaceExtension([SysUTF16ToNSString(
+          drop_data.file_extension) fileSystemRepresentation]);
+
+  if (seq > 0) {
+    file_name =
+        file_name.InsertBeforeExtension(std::string("-")+UintToString(seq));
+  }
+
+  return file_name;
+}
+
+// This class's sole task is to write out data for a promised file; the caller
+// is responsible for opening the file.
+class PromiseWriterTask : public Task {
+ public:
+  // Assumes ownership of file_stream.
+  PromiseWriterTask(const WebDropData& drop_data,
+                    FileStream* file_stream);
+  virtual ~PromiseWriterTask();
+  virtual void Run();
+
+ private:
+  WebDropData drop_data_;
+
+  // This class takes ownership of file_stream_ and will close and delete it.
+  scoped_ptr<FileStream> file_stream_;
+};
+
+// Takes the drop data and an open file stream (which it takes ownership of and
+// will close and delete).
+PromiseWriterTask::PromiseWriterTask(const WebDropData& drop_data,
+                                     FileStream* file_stream) :
+    drop_data_(drop_data) {
+  file_stream_.reset(file_stream);
+  DCHECK(file_stream_.get());
+}
+
+PromiseWriterTask::~PromiseWriterTask() {
+  DCHECK(file_stream_.get());
+  if (file_stream_.get())
+    file_stream_->Close();
+}
+
+void PromiseWriterTask::Run() {
+  CHECK(file_stream_.get());
+  file_stream_->Write(drop_data_.file_contents.data(),
+                      drop_data_.file_contents.length(),
+                      NULL);
+
+  // Let our destructor take care of business.
+}
+
+}  // namespace
+
+
+@interface WebDragSource(Private)
+
+- (void)fillPasteboard;
+- (NSImage*)dragImage;
+
+@end  // @interface WebDragSource(Private)
+
+
+@implementation WebDragSource
+
+- (id)initWithContentsView:(TabContentsViewCocoa*)contentsView
+                  dropData:(const WebDropData*)dropData
+                pasteboard:(NSPasteboard*)pboard {
+  if ((self = [super init])) {
+    contentsView_ = contentsView;
+    DCHECK(contentsView_);
+
+    dropData_.reset(new WebDropData(*dropData));
+    DCHECK(dropData_.get());
+
+    pasteboard_.reset([pboard retain]);
+    DCHECK(pasteboard_.get());
+
+    [self fillPasteboard];
+  }
+
+  return self;
+}
+
+- (void)lazyWriteToPasteboard:(NSPasteboard*)pboard forType:(NSString*)type {
+  // Be extra paranoid; avoid crashing.
+  if (!dropData_.get()) {
+    NOTREACHED() << "No drag-and-drop data available for lazy write.";
+    return;
+  }
+
+  // HTML.
+  if ([type isEqualToString:NSHTMLPboardType]) {
+    DCHECK(!dropData_->text_html.empty());
+    [pboard setString:SysUTF16ToNSString(dropData_->text_html)
+              forType:NSHTMLPboardType];
+
+  // URL.
+  } else if ([type isEqualToString:NSURLPboardType]) {
+    DCHECK(dropData_->url.is_valid());
+    [pboard     setURLs:[NSArray
+        arrayWithObject:SysUTF8ToNSString(dropData_->url.spec())]
+             withTitles:[NSArray arrayWithObject:
+                            SysUTF16ToNSString(dropData_->url_title)]];
+
+  // File contents.
+  } else if ([type isEqualToString:NSFileContentsPboardType] ||
+      [type isEqualToString:NSCreateFileContentsPboardType(
+              SysUTF16ToNSString(dropData_->file_extension))]) {
+    // TODO(viettrungluu@gmail.com): find something which is known to accept
+    // NSFileContentsPboardType to check that this actually works!
+    scoped_nsobject<NSFileWrapper> file_wrapper(
+        [[NSFileWrapper alloc] initRegularFileWithContents:[NSData
+                dataWithBytes:dropData_->file_contents.data()
+                       length:dropData_->file_contents.length()]]);
+    [file_wrapper setPreferredFilename:SysUTF8ToNSString(
+            GetFileNameFromDragData(*dropData_, 0).value())];
+    [pboard writeFileWrapper:file_wrapper];
+
+  // TIFF.
+  } else if ([type isEqualToString:NSTIFFPboardType]) {
+    // FIXME(viettrungluu@gmail.com): This is a bit odd since we rely on Cocoa
+    // to render our image into a TIFF. This is also suboptimal since this is
+    // all done synchronously. I'm not sure there's much we can easily do about
+    // it.
+    scoped_nsobject<NSImage> image(
+        [[NSImage alloc] initWithData:[NSData
+                dataWithBytes:dropData_->file_contents.data()
+                       length:dropData_->file_contents.length()]]);
+    [pboard setData:[image TIFFRepresentation] forType:NSTIFFPboardType];
+
+  // Plain text.
+  } else if ([type isEqualToString:NSStringPboardType]) {
+    DCHECK(!dropData_->plain_text.empty());
+    [pboard setString:SysUTF16ToNSString(dropData_->plain_text)
+              forType:NSStringPboardType];
+
+  // Oops!
+  } else {
+    NOTREACHED() << "Asked for a drag pasteboard type we didn't offer.";
+  }
+}
+
+- (void)startDrag {
+  NSEvent* currentEvent = [NSApp currentEvent];
+  [contentsView_ dragImage:[self dragImage]
+                        at:[contentsView_
+                               convertPoint:[currentEvent locationInWindow]
+                                   fromView:nil]
+                    offset:NSZeroSize
+                     event:currentEvent
+                pasteboard:pasteboard_
+                    source:contentsView_
+                 slideBack:YES];
+}
+
+- (void)endDragAt:(NSPoint)screenPoint
+      isCancelled:(BOOL)cancelled {
+  RenderViewHost* rvh = [contentsView_ tabContents]->render_view_host();
+  if (rvh) {
+    rvh->DragSourceSystemDragEnded();
+
+    // Convert |screenPoint| to view coordinates and flip it.
+    NSPoint localPoint = [contentsView_ convertPointFromBase:screenPoint];
+    NSRect viewFrame = [contentsView_ frame];
+    localPoint.y = viewFrame.size.height - localPoint.y;
+    // Flip |screenPoint|.
+    NSRect screenFrame = [[[contentsView_ window] screen] frame];
+    screenPoint.y = screenFrame.size.height - screenPoint.y;
+
+    if (cancelled) {
+      rvh->DragSourceCancelledAt(localPoint.x, localPoint.y,
+                                 screenPoint.x, screenPoint.y);
+    } else {
+      rvh->DragSourceEndedAt(localPoint.x, localPoint.y,
+                             screenPoint.x, screenPoint.y);
+    }
+  }
+
+  // Make sure the pasteboard owner isn't us.
+  [pasteboard_ declareTypes:[NSArray array] owner:nil];
+}
+
+- (void)moveDragTo:(NSPoint)screenPoint {
+  RenderViewHost* rvh = [contentsView_ tabContents]->render_view_host();
+  if (rvh) {
+    // Convert |screenPoint| to view coordinates and flip it.
+    NSPoint localPoint = [contentsView_ convertPointFromBase:screenPoint];
+    NSRect viewFrame = [contentsView_ frame];
+    localPoint.y = viewFrame.size.height - localPoint.y;
+    // Flip |screenPoint|.
+    NSRect screenFrame = [[[contentsView_ window] screen] frame];
+    screenPoint.y = screenFrame.size.height - screenPoint.y;
+
+    rvh->DragSourceMovedTo(localPoint.x, localPoint.y,
+                           screenPoint.x, screenPoint.y);
+  }
+}
+
+- (NSString*)dragPromisedFileTo:(NSString*)path {
+  // Be extra paranoid; avoid crashing.
+  if (!dropData_.get()) {
+    NOTREACHED() << "No drag-and-drop data available for promised file.";
+    return nil;
+  }
+
+  FileStream* file_stream = new FileStream;
+  DCHECK(file_stream);
+  if (!file_stream)
+    return nil;
+
+  FilePath path_name(SysNSStringToUTF8(path));
+  FilePath file_name;
+  unsigned seq;
+  const unsigned k_max_seq = 99;
+  for (seq = 0; seq <= k_max_seq; seq++) {
+    file_name = GetFileNameFromDragData(*dropData_, seq);
+    FilePath file_path = path_name.Append(file_name);
+
+    // Explicitly (and redundantly check) for file -- despite the fact that our
+    // open won't overwrite -- just to avoid log spew.
+    if (!file_util::PathExists(file_path) &&
+        file_stream->Open(path_name.Append(file_name),
+            base::PLATFORM_FILE_CREATE | base::PLATFORM_FILE_WRITE) == net::OK)
+      break;
+  }
+  if (seq > k_max_seq) {
+    delete file_stream;
+    return nil;
+  }
+
+  // The writer will take care of closing and deletion.
+  g_browser_process->file_thread()->message_loop()->PostTask(FROM_HERE,
+      new PromiseWriterTask(*dropData_, file_stream));
+
+  // Once we've created the file, we should return the file name.
+  return SysUTF8ToNSString(file_name.value());
+}
+
+@end  // @implementation WebDragSource
+
+
+@implementation WebDragSource (Private)
+
+- (void)fillPasteboard {
+  DCHECK(pasteboard_.get());
+
+  [pasteboard_ declareTypes:[NSArray array] owner:contentsView_];
+
+  // HTML.
+  if (!dropData_->text_html.empty())
+    [pasteboard_ addTypes:[NSArray arrayWithObject:NSHTMLPboardType]
+                    owner:contentsView_];
+
+  // URL.
+  if (dropData_->url.is_valid())
+    [pasteboard_ addTypes:[NSArray arrayWithObject:NSURLPboardType]
+                    owner:contentsView_];
+
+  // File.
+  if (!dropData_->file_contents.empty()) {
+    NSString* file_ext = SysUTF16ToNSString(dropData_->file_extension);
+
+    // File contents (with and without specific type), file (HFS) promise, TIFF.
+    // TODO(viettrungluu@gmail.com): others?
+    [pasteboard_ addTypes:[NSArray arrayWithObjects:
+                                  NSFileContentsPboardType,
+                                  NSCreateFileContentsPboardType(file_ext),
+                                  NSFilesPromisePboardType,
+                                  NSTIFFPboardType,
+                                  nil]
+                    owner:contentsView_];
+
+    // For the file promise, we need to specify the extension.
+    [pasteboard_ setPropertyList:[NSArray arrayWithObject:file_ext]
+                         forType:NSFilesPromisePboardType];
+  }
+
+  // Plain text.
+  if (!dropData_->plain_text.empty())
+    [pasteboard_ addTypes:[NSArray arrayWithObject:NSStringPboardType]
+                    owner:contentsView_];
+}
+
+- (NSImage*)dragImage {
+  return MakeDragImage(dropData_.get());
+}
+
+@end  // @implementation WebDragSource (Private)