API proposal: drag view

[Scott Palmer]

I see.  I was thinking that the API was working with Nodes in the Scene to render the drag "view" anyway.  If it's going the other way around and needs an Image for the main operation then it makes more sense the way you have it, as it is the Node case that is special, not the Image case.

Scott

On 2013-01-14, at 10:13 AM, Pavel Safrata <pavel.safrata at oracle.com> wrote:

> Hi Scott,
> the problem with using an ImageView as you did is that we cannot render it to an image unless it is part of the scene. Including an ImageView that you don't want to have in scene only for using an image in an API that takes images sounds crazy.
> 
> I think of the image-accepting method as the main method of the API. The other method is a convenience method that removes the necessity to do the snapshot manually in the most common case.
> 
> Thanks,
> Pavel
> 
> On 14.1.2013 16:02, Scott Palmer wrote:
>> It is trivial to wrap an Image in an ImageView.  Is there really a need for two methods?
>> 
>> I assume setDragView(new ImageView(img), dx, dy) is equivalent to setDragView(img, dx, dy).
>> 
>> Other APIs don't special case Image like this. E.g. the constructor for Label (and other controls) is Label(String, Node) and it does not also have Label(String, Image).
>> 
>> Regards,
>> 
>> Scott
>> 
>> 
>> On Mon, Jan 14, 2013 at 2:59 AM, Pavel Safrata <pavel.safrata at oracle.com> wrote:
>> Hello,
>> this is a proposal of an API allowing to specify the image floating with mouse cursor during a drag&drop operation.
>> 
>> Jira: http://javafx-jira.kenai.com/browse/RT-14730
>> 
>> I propose to add two methods to DragBoard:
>> setDragView(Image image, double offsetX, double offsetY)
>> setDragView(Node node, double offsetX, double offsetY)
>> 
>> The first one simply uses the given image for the drag view with the offsetX and offsetY specifying cursor position over the image. The second one renders the given node to an image and uses the result (the coordinates being in the node's local space).
>> 
>> The typical usage will look like this:
>>         sourceNode.setOnDragDetected(new EventHandler<MouseEvent>() {
>>             public void handle(MouseEvent event) {
>>                 Dragboard db = source.startDragAndDrop(TransferMode.ANY);
>>                 ClipboardContent content = ...
>>                 db.setContent(content);
>>                 db.setDragView(sourceNode, event.getX(), event.getY()); // that's it
>>                 event.consume();
>>             }
>>         });
>> 
>> 
>> This API is meant for telling the operating system what visual cues to provide, I don't think it is useful (and I'm not sure it is even possible) to provide getters.
>> 
>> There is a possibility to provide default drag view - if none of those methods is called, the default drag view would be an image of the drag gesture source. This should work nice most of the times. However, it may cause inconveniences to some existing apps - for instance a text editor node which puts the selected text on the DragBoard - after updating FX the application starts to show the entire editor in the drag view. For this reason I think the default behavior should remain unchanged.
>> 
>> Thanks,
>> Pavel
>> 
>