MacViews: Implemented Drag & Drop

ui/views/cocoa/drag_drop_client_mac.mm

+// Copyright 2016 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 "ui/views/cocoa/drag_drop_client_mac.h"
+
+#include "base/mac/mac_util.h"
+#include "base/strings/sys_string_conversions.h"
+#include "ui/base/dragdrop/os_exchange_data.h"
+#import "ui/base/dragdrop/os_exchange_data_provider_mac.h"
+#include "ui/gfx/image/image_skia_util_mac.h"
+#include "ui/views/drag_utils.h"
+#import "ui/views/cocoa/bridged_content_view.h"
+#import "ui/views/cocoa/bridged_native_widget.h"
+#include "ui/views/widget/drop_helper.h"
+#include "ui/views/widget/native_widget_mac.h"
+
+@interface CocoaDragDropDataProvider () {
+  std::unique_ptr<ui::OSExchangeData> data_;

[tapted, 2016/05/31 11:49:58]

ah, so I think this can actually go to the @implementation - that's the more
common approach. However, we should still keep the private category to define
the `private` API: the stuff that not on the public @interface, and not on any
inherited methods, so here w should list

@interface CocoaDragDropDataProvider ()
- (id)initWithPasteboard:(NSPasteboard*)pasteboard;
- (ui::OSExchangeData*)data;
@end

[spqchan, 2016/05/31 23:06:12]

Done.

+}
+
+@end
+
+@implementation CocoaDragDropDataProvider
+
+- (id)initWithData:(const ui::OSExchangeData&)data {
+  if ((self = [super init])) {
+    data_.reset(new OSExchangeData(data.provider().Clone()));
+  }
+  return self;
+}
+
+- (id)initWithPasteboard:(NSPasteboard*)pasteboard {
+  if ((self = [super init])) {
+    data_ = ui::OSExchangeDataProviderMac::CreateDataFromPasteboard(pasteboard);
+  }
+  return self;
+}
+
+- (ui::OSExchangeData*)data {
+  return data_.get();
+}
+
+// NSPasteboardItemDataProvider protocol implementation.
+
+- (void)pasteboard:(NSPasteboard*)sender
+                  item:(NSPasteboardItem*)item
+    provideDataForType:(NSString*)type {
+  const ui::OSExchangeDataProviderMac* provider =

[tapted, 2016/05/31 11:49:58]

nit: 

const ui::OSExchangeDataProviderMac& provider (i.e cast the reference type
instead of the pointer type)

[spqchan, 2016/05/31 23:06:13]

Done.

+      static_cast<const ui::OSExchangeDataProviderMac*>(&data_->provider());
+  NSData* ns_data = provider->GetNSDataForType(type);
+  [sender setData:ns_data forType:type];
+}
+
+@end
+
+namespace views {
+
+DragDropClientMac::DragDropClientMac(BridgedNativeWidget* bridge)
+    : operation_(0), bridge_(bridge) {

[tapted, 2016/05/31 11:49:58]

add (if we keep it): view_(nullptr)

[spqchan, 2016/05/31 23:06:13]

Done.

+  DCHECK(bridge);
+  drop_helper_.reset(new DropHelper([bridge->ns_view() hostedView]));
+}
+
+DragDropClientMac::~DragDropClientMac() {}
+
+void DragDropClientMac::StartDragAndDrop(
+    View* view,
+    const ui::OSExchangeData& data,
+    const gfx::Point& location,

[tapted, 2016/05/31 11:49:58]

We're not using |location| here...We should probably prefer it over [window
mouseLocationOutsideOfEventStream]; since it's possible for the event queue to
lag behind. But we need to convert it into AppKit coordinates. But also that's
more complicated and maybe we actually don't need it :).

But we shouldn't pass in |location| if we don't use it. I think
StartDragAndDrop(..) just needs to take |data|, |operation| and |source|

[spqchan, 2016/05/31 23:06:13]

Done.

+    int operation,
+    ui::DragDropTypes::DragEventSource source) {
+  data_source_.reset([[CocoaDragDropDataProvider alloc] initWithData:data]);
+  view_ = view;
+  operation_ = operation;
+
+  const ui::OSExchangeDataProviderMac& provider =
+      static_cast<const ui::OSExchangeDataProviderMac&>(data.provider());
+
+  // Synthesize an event for dragging, since we can't be sure that
+  // [NSApp currentEvent] will return a valid dragging event.
+  NSWindow* window = bridge_->ns_window();
+  NSPoint position = [window mouseLocationOutsideOfEventStream];
+  NSTimeInterval event_time = [[NSApp currentEvent] timestamp];
+  NSEvent* event = [NSEvent mouseEventWithType:NSLeftMouseDragged
+                                      location:position
+                                 modifierFlags:NSLeftMouseDraggedMask
+                                     timestamp:event_time
+                                  windowNumber:[window windowNumber]
+                                       context:nil
+                                   eventNumber:0
+                                    clickCount:1
+                                      pressure:1.0];
+
+  NSImage* image = gfx::NSImageFromImageSkiaWithColorSpace(
+      provider.GetDragImage(), base::mac::GetSRGBColorSpace());
+
+  base::scoped_nsobject<NSPasteboardItem> item([[NSPasteboardItem alloc] init]);
+  [item setDataProvider:data_source_.get()
+               forTypes:ui::OSExchangeDataProviderMac::
+                            SupportedPasteboardTypes()];
+
+  base::scoped_nsobject<NSDraggingItem> dragItem(

[tapted, 2016/05/31 11:49:58]

nit: dragItem -> drag_item since we're in a C++ fn

[spqchan, 2016/05/31 23:06:13]

Done.

+      [[NSDraggingItem alloc] initWithPasteboardWriter:item.get()]);
+  NSRect draggingFrame =

[tapted, 2016/05/31 11:49:58]

Maybe
  NSRect dragging_frame = { [event locationInWindow], [image size] };
  dragging_frame.origin.y -= dragging_frame.size.height;

But also it's not immediately obvious why we need to subtract the height -
comment?

[spqchan, 2016/05/31 23:06:13]

Done.

+      NSMakeRect([event locationInWindow].x,
+                 [event locationInWindow].y - [image size].height,
+                 [image size].width, [image size].height);
+  [dragItem setDraggingFrame:draggingFrame contents:image];
+
+  [bridge_->ns_view() beginDraggingSessionWithItems:@[ dragItem.get() ]
+                                              event:event
+                                             source:bridge_->ns_view()];
+
+  while (data_source_.get()) {
+    [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode

[tapted, 2016/05/31 11:49:58]

We should use the run loop stuff in base (what you have is close to
MessagePumpNSRunLoop::DoRun() but there is some other important goo that happens
either side).

Here, we would do:

base::RunLoop run_loop;
quit_closure_ = run_loop.QuitClosure();
run_loop.Run();

and at the end of EndDrag(), we do

quit_closure_.Run();


(and declare quit_closure_ as a data member)

[spqchan, 2016/05/31 23:06:13]

Done.

+                             beforeDate:[NSDate distantFuture]];
+  }
+}
+
+NSDragOperation DragDropClientMac::DragUpdate(id<NSDraggingInfo> sender) {
+  int drag_operation = ui::DragDropTypes::DRAG_NONE;
+
+  // Since dragging from non MacView sources does not generate OSExchangeData,
+  // we need to generate one based on the provided pasteboard.
+  if (!data_source_.get()) {
+    data_source_.reset([[CocoaDragDropDataProvider alloc]
+        initWithPasteboard:[sender draggingPasteboard]]);
+  }
+
+  drag_operation = drop_helper_->OnDragOver(
+      *[data_source_ data], LocationInView([sender draggingLocation]),
+      operation_);
+  return ui::DragDropTypes::DragOperationToNSDragOperation(drag_operation);
+}
+
+NSDragOperation DragDropClientMac::Drop(id<NSDraggingInfo> sender) {
+  int drag_operation = drop_helper_->OnDrop(
+      *[data_source_ data], LocationInView([sender draggingLocation]),
+      operation_);
+  return ui::DragDropTypes::DragOperationToNSDragOperation(drag_operation);
+}
+
+void DragDropClientMac::EndDrag() {
+  view_ = nullptr;
+  data_source_.reset();
+}
+
+void DragDropClientMac::SetRootView(View* view) {
+  drop_helper_.reset(new DropHelper(view));
+}
+
+gfx::Point DragDropClientMac::LocationInView(NSPoint point) const {
+  return gfx::Point(point.x, NSHeight([bridge_->ns_window() frame]) - point.y);
+}
+
+}  // namespace views