API Review RT:17407 Canvas Node

Daniel Zwolenski zonski at googlemail.com
Mon Apr 23 15:27:53 PDT 2012

Sorry, I'm not following the problem. 

Wouldn't the height and width properties provide the callback to say 'I have been resized'? This would include the amount resized-by so the developer could just render the new area if they want (or redraw the whole scene, etc). If the developer chooses not to patch/repaint then that's their choice.

HTML has never had good layout manager concepts so for me it is not the best benchmark in this topic. 

What's the requirement to repaint on every frame? I don't follow that. 

On 24/04/2012, at 6:11 AM, Kevin Rushforth <kevin.rushforth at oracle.com> wrote:

> I wrote:
>> I can't think of any reason it should not be resizable. 
> Good think I'm not the only one thinking about it, then. :)
> Yes, this would be an issue. So unless/until we are ready to deal with this, my earlier suggestion of binding to the width/height property, and adding your own listeners is probably the way to go.
> -- Kevin
> Jim Graham wrote:
>> We would have to deal with damage repair.  Right now it is a persistent rendering, not an area to be "repainted" on every frame.
>> If we wanted it to be dynamically and asynchronously resizable we would have to switch to (or provide?) a call-back model of rendering and you would have to keep enough state to be able to render it again on every frame.  HTML5 Canvas demos are not rendered that way, though they can be at their own will - they simply clear the entire canvas and re-render on every pulse.  Or, they just render the new stuff.  Their call.  If they change size, like you can with Canvas, then they are responsible for changing the size and rendering the new stuff - just like if you manually modify the size of our Canvas.
>>            ...jim
>> On 4/23/12 5:36 AM, Kevin Rushforth wrote:
>>> If Canvas were a "Resizable" node then yes, it could do that. Off-hand,
>>> I can't think of any reason it should not be resizable.
>>> -- Kevin
>>> Daniel Zwolenski wrote:
>>>>> A Canvas node is a fixed size, so it only resizes when you tell it
>>>>> to. If you want it to track the size of the Scene (or similar), you
>>>>> could bind its width and height properties and react to change
>>>>> notifications.
>>>> Any reason why Canvas wouldn't just adhere to the Layout algorithm of
>>>> the Container it is in? Eg if in a BorderPane center then fill, if in
>>>> a GridPane take up that cell, etc. If we want to fix size then we
>>>> would use min/max constraints.
>>>> That would seem the most sensible and useful thing to me.

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