API REVIEW request for RT-17398: snapshot (aka render to image)

[Alexander Kouznetsov]

Hi Kevin,

The proposal looks very reasonable.

I want to clarify a few points:

 1. Does it allow to render nodes that are not part of any Scene? Looks
    like that.
 2. Can params be null? Meaning that for the nodes added to scene, its
    depthbuffer and camera parameters are used to render? It looks like
    boundsInLocal seems to be a good candidate for the view port in this
    case. Transform the identity and Fill is TRANSPARENT?

Best regards,
Alexander Kouznetsov


On 12.05.2012 5:03, Kevin Rushforth wrote:
> JIRA:  http://javafx-jira.kenai.com/browse/RT-17398
>
> This feature request will add public API to support taking a snapshot 
> of a Scene or Node and rendering it into an Image.
>
> To address this feature, I propose to add the following methods on the 
> existing Node and Scene class, along with two new classes to hold the 
> parameters and the result, respectively.
>
> Scene:
>    public Image snapshot(Image image)
>    public void snapshot(Callback<SnapshotResult,Void> callback, Image 
> image)
>
> Node:
>    public Image snapshot(SnapshotParameters params, Image image)
>    public void snapshot(Callback<SnapshotResult,Void> callback, 
> SnapshotParameters params, Image image)
>
> // Data container class with the following attributes
> SnapshotParameters:
>    get/setDepthBuffer(boolean)
>    get/setCamera(Camera)
>    get/setTransform(Transform);
>    get/setFill(Paint);
>    get/setViewport(Rectangle2D)
>
> // Data container class to return the result of an async snapshot, 
> currently immutable
> SnapshotResult:
>    Image image
>    Object source
>    SnapshotParameters params
>
>
> Here is the preliminary Javadoc for the four snapshot methods:
>
> -------------------------------------------------------------------
>
> Scene:
>    public Image snapshot(Image image)
>
> Takes a snapshot of this scene and returns the rendered image when it 
> is ready. CSS and layout processing will be done for the scene prior 
> to rendering it.
>
>    image - the image that will be used to hold the rendered scene. It 
> may be null in which case a new Image will be constructed. If the 
> image is non-null, the scene will be rendered into the existing image. 
> If the image is larger than the scene, the area outside the bounds of 
> the scene will be filled with the Scene fill color. If the image is 
> smaller than the scene, the rendered image will be clipped.
>
> -------------------------------------------------------------------
>
> Scene:
>    public void snapshot(Callback<SnapshotResult,Void> callback, Image 
> image)
>
> Takes a snapshot of this scene at the next frame and calls the 
> specified callback method when the image is ready. CSS and layout 
> processing will be done for the scene prior to rendering it. This is 
> an asynchronous call, which means that other events or animation might 
> be processed before the scene is rendered. If any such events modify a 
> node in the scene that modification will be reflected in the rendered 
> image (as it will also be reflected in the frame rendered to the Stage).
>
>    callback - a class whose call method will be called when the image 
> is ready. The SnapshotResult that is passed into the call method of 
> the callback will contain the rendered image and the source scene that 
> was rendered.
>
>    image - the image that will be used to hold the rendered scene. It 
> may be null in which case a new Image will be constructed. If the 
> image is non-null, the scene will be rendered into the existing image. 
> If the image is larger than the scene, the area outside the bounds of 
> the scene will be filled with the Scene fill color. If the image is 
> smaller than the scene, the rendered image will be clipped.
>
> -------------------------------------------------------------------
>
> Node:
>    public Image snapshot(SnapshotParameters params, Image image)
>
> Takes a snapshot of this node and returns the rendered image when it 
> is ready. CSS and layout processing will be done for the node, and any 
> of its children, prior to rendering it.
>
> Parameters:
>    params - the snapshot parameters containing attributes that will 
> control the rendering.
>
>    image - the image that will be used to hold the rendered node. It 
> may be null in which case a new Image will be constructed. If the 
> image is non-null, the node will be rendered into the existing image. 
> If the image is larger than the bounds of the node, the area outside 
> the bounds will be filled with the fill color specified in the 
> snapshot parameters. If the image is smaller than the bounds, the 
> rendered image will be clipped.
>
> -------------------------------------------------------------------
>
> Node:
>    public void snapshot(Callback<SnapshotResult,Void> callback, 
> SnapshotParameters params, Image image)
>
> Takes a snapshot of this node at the next frame and calls the 
> specified callback method when the image is ready. CSS and layout 
> processing will be done for the node, and any of its children, prior 
> to rendering it. This is an asynchronous call, which means that other 
> events or animation might be processed before the node is rendered. If 
> any such events modify the node, or any of its children, that 
> modification will be reflected in the rendered image (just like it 
> will also be reflected in the frame rendered to the Stage, if this 
> node is part of a live scene graph).
>
>    callback - a class whose call method will be called when the image 
> is ready. The SnapshotResult that is passed into the call method of 
> the callback will contain the rendered image, the source node that was 
> rendered, and a copy of the SnapshotParameters.
>
>    params - the snapshot parameters containing attributes that will 
> control the rendering.
>
>    image - the image that will be used to hold the rendered node. It 
> may be null in which case a new Image will be constructed. If the 
> image is non-null, the node will be rendered into the existing image. 
> If the image is larger than the bounds of the node, the area outside 
> the bounds will be filled with the fill color specified in the 
> snapshot parameters. If the image is smaller than the bounds, the 
> rendered image will be clipped.
>