Export snapshot - is it usable on LiveCode web apps?

[Andreas Bergendal]

That’s good to know! Then it must have been something else I was struggling
with - perhaps it had to do with getting a snapshot of the content of a
browser widget…? That would still present problems in certain (all?)
platforms, right?

tors 8 aug. 2024 kl. 14:39 skrev Mark Waddingham via use-livecode <
use-livecode at lists.runrev.com>:

> On 2024-08-08 10:22, Jimmieson, Phil via use-livecode wrote:
> > Hi folks,
> > I’m experimenting with converting one of my LiveCode iPad Apps into a
> > web version, to see how well it works, but there’s an issue that seems
> > to be a deal-breaker. My iPad app takes a screenshot of the LiveCode
> > stack when the user navigates away from the main card, so that the
> > image can be used elsewhere in the app. This works fine on iPad, but I
> > noticed that the web version of the app generates a javascript
> > exception when I try to leave the main card. On checking the
> > dictionary, I noticed that the export snapshot command is not listed as
> > being supported on web. Is this correct? If so, is there an alternative
> > that will work for web?
>
> So 'export snapshot from screen' is not supported - this is the form
> which takes the pixel data from the actual (composited) screen buffer.
>
> However, there is an alternate form which is entirely internal to the
> engine:
>
>     export snapshot from [ rect <rect> of ] <object>
>
> To use the internal form for a card you can do:
>
>     export snapshot from this card
>
> Or if you want a portion of the card:
>
>     export snapshot from rect 0,0,100,100 of this card
>
> Further there is an `at size <width>,<height>` clause which allows you
> to specify the size you want the resulting image.
>
> The difference here is that the internal form replicates the same
> process that the engine uses to render objects to a window - it renders
> the given rectangle of the object into a rect of the specified size (or
> the size of the rect/object if 'at size' is not specified).
>
> In contrast, the 'external' form has to ask the OS for the given
> rectangle of the actual screen's framebuffer.
>
> Hope this helps,
>
> Mark.
>
> --
> Mark Waddingham ~ mark at livecode.com ~ http://www.livecode.com/
> LiveCode: Build Amazing Things