[Laszlo-dev] Dealing with unsupported HTML/CSS features in DHTML

[Raju Bitter]

Right, I forgot about that!

But what I mean, is more a standardized way of doing that. There's  
already a lot of complexity in OpenLaszlo for app deployment and  
runtime-specific features - with much of that not well documented. A  
standardized way of telling an app "I need features x,y and z in my  
app, and please call a method if some of those features is not  
supported."

The problem I see is that the knowledge about which browser currently  
supports a certain feature requires a lot of research - feels a bit  
like the early DHTML times. In the end it all comes down to how easy  
it is to use new features in the DHTML runtime. If two different  
versions of the an app (SWF and DHTML) are available, the developer  
still has to figure out which browser should get the SWF version, and  
which one the DHTML version.

But maybe you think there's no use case for that.

On Sep 2, 2009, at 12:43 PM, P T Withington wrote:

> There is (perhaps not documented?) canvas.capabilities, which is  
> intended to cover this.  It's initialized from  
> LzSprite.capabilities, which is initialized on a per-browser basis.   
> So, I think you just need to add to that.
>
> On 2009-09-02, at 06:20, Raju Bitter wrote:
>
>> I got a good comment on my last blog post showing the CSS text- 
>> shadow features.
>> http://openfuture.rajubitter.com/2009/08/25/openlaszlo-dhtml-css-3-demo-to-flash-or-not-to-flash-is-no-question/
>>
>> A guy called Mike said: "Also, I’ve rarely encountered a cross- 
>> platform issue with the Flash Player, which is one of the many  
>> reasons that developers use it. The DHTML/CSS version above doesn’t  
>> display for me in IE7 (I just get the spinning “Powered by…”) but  
>> the Flash below it does."
>>
>> I thought about that and came to the conclusion - that even for  
>> demos showing the features of HTML 5 and newer CSS standards - I  
>> don't want IE users to only see the spinning "Powered by...".
>>
>> I added some code to the demo I built, and now - based on the  
>> browser version - you'll see the following message if you access  
>> the application with an old browser or IE:
>> <OpenLaszlo-CSS-BrowserCheckWarning.png>
>>
>>
>> That's a much more positive way of informing the user that his  
>> current browser doesn't support the features required for this app.  
>> But I'd be interested in your oppionion, how should we handle  
>> unsupported browsers for DHTML demo apps, especially in future  
>> releases of OpenLaszlo? I thought of a class where you can register  
>> which capabilities your application needs for the full user  
>> experience, with a rating for importance: some features could be  
>> left out, and the application doesn't look as good. Some other  
>> features might be required, and then the user will have to access  
>> the app with a different browser.
>>
>> For technically interested folks we could have an info button on  
>> the warning message, giving more information about what feature is  
>> not supported in the current browser.
>>
>> Of course, all of this is not for consumer facing applications in  
>> production, more for the OpenLaszlo demos and docs. In production,  
>> I'd just check the browser and capabilities, and then deliver an  
>> SWF version for the older browsers.
>