Loading a LONG list with images

[Dan Friedman]

Mark,

>> i.e. make sure the datagrid is only creating rows on demand, rather than 
>> up front, and then requesting images and updating them when they arrive

How do you do that?  What property do I set, or method is used to only load the displayed rows?

Tom's code snippet is a WONDERFUL start and I get the concept, but there are a bunch of missing parts that I'm not sure how (or where) to code.   Also, I don't know if it really matters or not, but Tom sent the code from his dg column, I am using a form DG.

-Dan
 

On 2/22/22, 12:51 AM, "use-livecode on behalf of Mark Waddingham via use-livecode" <use-livecode-bounces at lists.runrev.com on behalf of use-livecode at lists.runrev.com> wrote:

    On 2022-02-21 23:47, Tom Glod via use-livecode wrote:
    > This is how i did it .....  I hope this helps.
    > 
    > First to use the "numberofrecords" way of setting the datagrid data.
    > This is key, that way you only ever trigger loading of visible rows.

    So I've not got much to add to Tom's method

    i.e. make sure the datagrid is only creating rows on demand, rather than 
    up front, and then requesting images and updating them when they arrive

    Beyond a suggestion to ensure the images which are being downloaded are 
    already suitably sized/thumbnailed for display.

    Decompressing images is a relatively expensive operation - decompressing 
    and then downsizing them (thumbnailing) even more so.

    So, if you control the webservice that is providing the images it would 
    probably be worth making it so that the server can send you images at 
    the size needed and do the thumbnailing on the server (caching the 
    results alongside the original image on the server).

    For maximum fidelity you want the width/height * the device pixel scale 
    (which can vary from 1 to 3 these days).

    Warmest Regards,

    Mark.

    -- 
    Mark Waddingham ~ mark at livecode.com ~ http://www.livecode.com/
    LiveCode: Everyone can create apps

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