[webkit-qt] Image capture of the contents of a QML WebView

[Olivier Tilloy]

On 2013-05-23, Jocelyn Turcotte <jocelyn.turcotte at digia.com> wrote:
> Hello,
>
> if you want a QImage you should have a look at QQuickWindow::grabWindow().
> It only works on the whole scene, so currently you would have to cut the part that interests you out of the QImage.

Thanks for the pointer. The documentation for this method says "Warning: 
Calling this function will cause performance problems". Not very 
reassuring… And having to extract a part of the image is not a fun 
prospect either.


> On Thu, May 23, 2013 at 09:20:18AM +0200, Martin Leutelt wrote:
>> I guess that what you want to do could be achieved in several ways, depending on
>> which version of Qt/QML you're using.
>> Assuming you're using QtQuick1:

I’m using Qt5 and QtQuick2.

>> If you're using QtQuick2:
>> - also use ShaderEffectSource
>> - write a QML-plugin again, grab the whole screen of your application an cut out
>> the area of the item you're interested in by using the coordinates that you
>> passed to the plugin
>>
>> I think that the solution using shaders would fit your purpose fine, unless you
>> really need to have the 'screenshots' as real files. Hope that helps.

Yeah, I actually need to cache the image to a file. I’ve looked a bit 
into the ShaderEffect idea, and I think if I write a custom one, I 
should be able to render the node to a FBO and save it to a file. I have 
yet to give it a shot. When that happens, I’ll keep you posted with the 
results.

Thanks,

  Olivier