[OpenLayers-Users] First try with html5 canvas for layers

[Adam Ratcliffe]

OK, that makes sense.  Will be interesting to hear more of how this  
works out with a browser-based database.

Cheers
Adam

On 23/11/2009, at 8:43 AM, Kris Geusebroek wrote:

> Hi Adam,
>
> As Chris rightly point out there is already a canvas implementation  
> of the OpenLayers.Renderer which can be used instead of VML or SVG  
> renderer.
> My changes for using canvas in OpenLayers are currently  
> concentrating on the other layer types like WMS or Grid layers.
>
> Cheers Kris
>
>
>
>
> -----Original Message-----
> From: adam.ratcliffe at gmail.com [mailto:adam.ratcliffe at gmail.com] On  
> Behalf Of Adam Ratcliffe
> Sent: Saturday, November 21, 2009 1:54 AM
> To: Kris Geusebroek
> Cc: users at openlayers.org
> Subject: Re: [OpenLayers-Users] First try with html5 canvas for layers
>
> Hi Kris,
>
> I'm fairly new to OpenLayers and assumed that when creating a vector
> layer for use with wfs-t that the layer features would be rendered
> using either SVG or VML, thus allowing for the full range of mouse
> interactions that other DOM elements support (click, mouseover,
> mouseout etc).
>
> With the canvas implementation how do you support edting of a polygon
> for instance?
>
> Cheers
> Adam
>
> On Sat, Nov 21, 2009 at 1:32 PM, Kris Geusebroek <kgeusebroek at xebia.com 
> > wrote:
>> Hi Adam,
>>
>> I think it doesn't make a difference in the current way OpenLayers  
>> works
>> other then replacing a lot of div's by a single canvas. Nothing to do
>> with interactivity I guess.
>>
>> The current div based vector layer can be used together with wfs-t or
>> getfeatureinfo request to make it interactive.
>>
>> And together with the refresh strategy (in trunk) you can make it  
>> look
>> like you are following the changes in data near real time.
>>
>>
>> Perhaps I misunderstood your remark. If so feel free to contact me
>>
>> Cheers Kris
>>
>> -----Original Message-----
>> From: users-bounces at openlayers.org [mailto:users-bounces at openlayers.org 
>> ]
>> On Behalf Of Adam Ratcliffe
>> Sent: Saturday, November 21, 2009 12:45 AM
>> To: users at openlayers.org
>> Subject: Re: [OpenLayers-Users] First try with html5 canvas for  
>> layers
>>
>> Hi Kris,
>>
>> Am I correct in thinking this technique would be useful for  
>> displaying
>> read-only vector data only?  Or are you considering an approach such
>> as overlaying a transparent image map to allow interactivity?
>>
>> Cheers
>> Adam
>>
>> On Thu, Nov 19, 2009 at 8:58 PM, Kris Geusebroek <kgeusebroek at xebia.com 
>> >
>> wrote:
>>> Hi Eric,
>>>
>>> Indeed it's cool, thanks.
>>> My goal was to write an application with open source technologies to
>>> track cars driving around.
>>> I wrote a prototype with geoserver and openlayers and this was
>>> succesfull. The big problem was the memory consumption (especially  
>>> in
>>> IE) because of the large amount of DOM manipulation that is done  
>>> when
>>> panning and zooming and drawing vector's (the cars, with fills,
>> stroke,
>>> label etc.)
>>>
>>> Since using a plugin is out of the question here I began  
>>> investigating
>>> the html5 canvas.
>>> I know it's not supported in IE, but for me that was a good thing
>>> because it gave me the opportunity to have the client choose a
>> different
>>> browser then IE.
>>>
>>> My plans for the future of the app is to also use workers and the
>>> browser database (to be able to store historical responses  
>>> clientside
>> to
>>> draw a route the car has followed for the last 10 minutes or so)
>>>
>>> Also I think the canvas gives us the opportunity to create a print
>>> control or a save map as, because in the end it's just an image.  
>>> (have
>>> to combine the layer specific canvasses into one but that's  
>>> easy ;-))
>>>
>>> If you have any other ideas or see different opportunities let me
>> know,
>>> my client is fundning me to experiment with html5 so I might be able
>> to
>>> spent some time on other's feature requests ;-)
>>>
>>> Cheers Kris
>>>
>>>
>>> -----Original Message-----
>>> From: Eric Lemoine [mailto:eric.lemoine at camptocamp.com]
>>> Sent: Thursday, November 19, 2009 6:53 AM
>>> To: Kris Geusebroek
>>> Cc: OpenLayers Users
>>> Subject: Re: [OpenLayers-Users] First try with html5 canvas for  
>>> layers
>>>
>>> On Wednesday, November 18, 2009, Kris Geusebroek
>> <kgeusebroek at xebia.com>
>>> wrote:
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> Hi All,
>>>>
>>>>
>>>>
>>>> I'm currently investigating the
>>>> possibilities of integrating html5 functionality into openlayers.
>>>>
>>>> My first try is using canvas for a layer
>>>> instead of div's
>>>>
>>>>
>>>>
>>>> I've setup a sandbox which you can
>>>> use to have a look:
>>>
>> http://dev.openlayers.org/sandbox/krisgeus/openlayers/examples/tilecache
>>> Canvas.html
>>>>
>>>>
>>>>
>>>> This is the first example to show it's
>>>> possible ;-). Only features now are zoom and pan without the resize
>>> transition effect.
>>>>
>>>> If anyone has remarks, ideas, feature
>>>> requests, help offerings etc. Feel free to contact me.
>>>
>>> This is cool!
>>>
>>> May I ask what's your goal with displaying tiles using canvas? Is it
>>> performance? I have never played with canvas so I'm interested to  
>>> know
>>> and talk about what it can bring to OpenLayers.
>>>
>>> Thanks Kris,
>>>
>>> --
>>> Eric Lemoine
>>>
>>> Camptocamp France SAS
>>> Savoie Technolac, BP 352
>>> 73377 Le Bourget du Lac, Cedex
>>>
>>> Tel : 00 33 4 79 44 44 96
>>> Mail : eric.lemoine at camptocamp.com
>>> http://www.camptocamp.com
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