Loading a LONG list with images

[Tom Glod]

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.

This is the code from my dg column.

global PixabayResults


      if PixabayResults["cache"]["DL:" & PixabayResults["data"][the dgindex
of me]["previewURL"]] is empty then
         send "GetImageTrigger " & the dgindex of me & comma & quote &
PixabayResults["data"][the dgindex of me]["previewURL"] & quote & comma &
random(25500) to card "Search Pixabay"
         put image id 1410033 of card "Resources" into image 1 of me --
14110033 image id is the placeholder.
         set the visible of image 1 of me to true
         set the MyIndex of me to empty
         //set the visible of group "Image Tools" of me to false
      else
         put PixabayResults["cache"]["DL:" & PixabayResults["data"][the
dgindex of me]["previewURL"]] into image 1 of me
         set the visible of image 1 of me to true
         set the MyIndex of me to the dgIndex of me
         delete global PixabayResults["downloaded"][the dgIndex of me] --
delete the flag to update this row because its a visible row with newly
downloaded file
         //set the visible of group "Image Tools" of me to false
      end if


on GetImageTrigger ThisIndex,ThisURL,ThisRandom
   send "GetAndCachePreviewImage " & ThisIndex & comma & quote & ThisURL &
quote & comma & random(25500) to card "Search Pixabay" in 0 milliseconds
end GetImageTrigger

on GetAndCachePreviewImage ThisIndex,ThisURL,ThisRandomNumber
   Task_Scheduler_Add "Download File To Variable","DL:" &
ThisURL,ThisURL,"" -- this schedules TSNET request to download image then
waits for the image to download

   wait until AppStarterStackTaskScheduler["finished"]["DL:" & ThisURL] is
not empty with messages -- wait with messages until its finished

   if AppStarterStackTaskScheduler["finished"]["DL:" & ThisURL] is "error"
then
      throw "Thumbnail Download Failed:" & ThisURL
   else
      put AppStarterStackTaskScheduler["data"]["DL:" & ThisURL]["data"]
into PixabayResults["cache"]["DL:" & ThisURL]
      put 1 into PixabayResults["downloaded"][ThisIndex]
      delete variable AppStarterStackTaskScheduler["data"]["DL:" &
ThisURL]["data"]
   end if
end GetAndCachePreviewImage










On Mon, Feb 21, 2022 at 6:20 PM Tom Glod <tom at makeshyft.com> wrote:

> Dan can you check this video and the pixabay search example?
> https://youtu.be/jN2bQbhQ0L8?t=216
> Is this what you have in mind?
> These images are loaded as the row comes into view.
>
> On Mon, Feb 21, 2022 at 6:07 PM Dan Friedman via use-livecode <
> use-livecode at lists.runrev.com> wrote:
>
>> Richard,
>>
>> Probably not over a couple thousand.  The images are square -- they need
>> to be resized to the DG template image size, but not scaled (H vs W).
>>
>> -Dan
>>
>>
>> On 2/21/22, 12:14 PM, "use-livecode on behalf of Richard Gaskin via
>> use-livecode" <use-livecode-bounces at lists.runrev.com on behalf of
>> use-livecode at lists.runrev.com> wrote:
>>
>>     How many images?
>>
>>     I once made a solution for 3,000 images, but it may not scale well
>> above
>>     8,000 or so depending on memory and connection speed.
>>
>>     --
>>       Richard Gaskin
>>       Fourth World Systems
>>
>>
>>
>>
>>     Dan Friedman wrote:
>>
>>      > Does anyone have any answers to the issue of loading a long list
>> with
>>      > images so that it loads images "as needed" like a webpage does.
>>      >
>>      > I have a DataGrid with several hundred rows.  Each row has a
>> specific
>>      > image that is to be displayed with that row (like a list of songs).
>>      > The image is loaded from the web.   Is there a method to load the
>>      > DataGrid and only load the images for the rows that are shown?
>>  And,
>>      > when you scroll the grid, the images for the newly shown rows are
>> then
>>      > loaded.  The loading need to happen somehow without halting the
>>      > scrolling or making it stutter.
>>      >
>>      > I hope that makes sense!
>>      > -Dan
>>
>>
>>
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>