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DadOfTwo
Topic Author
Posts: 18
Joined: Thu Feb 02, 2017 8:11 am

How to determine image is cached on OS?

Mon Dec 04, 2017 3:34 am

Hi all

Am looking at the way Brightscript auto caches images and if it's possible to determine programmatically if the image being loaded into a Roku native list (via itemComponentName) is loading from the server or loading via the OS cache. 

Observing the `loadStatus` on the Poster fires the exact same results.

We're taking a look at this cause we're seeing inconsistent behaviour with an Animation fade up on loaded images into a RowList. Images loaded via the server fade up as expected. Images loaded from the cache fade up a lot faster, visually around 4 times faster.
If we force the images to load via the server each time, via a cache buster, the images fade up as expected.

Here's an example of the code we're using for the itemComponentName:


<?xml version="1.0" encoding="utf-8" ?>

<component name="RowListItem" extends="Group" >

  <script type="text/brightscript" uri="pkg:/components/view/RowListItem.brs" />

  <interface >
    <field id="itemContent" type="node" onChange="showContent"/>
  </interface>

  <children>
    <Poster id="itemPoster" />
    <Animation id="fadeAnimation" duration="1.5" optional="true" repeat="false" easeFunction="linear" >
      <FloatFieldInterpolator id="fadeInterp" key="[ 0.0, 0.5, 1.0 ]"
          fieldToInterp="itemPoster.opacity" />
    </Animation>
  </children>

</component>



And the script:
sub init()
  m.top.findNode("itemPoster").translation = [10, 10]
end sub

function posterLoadedStateHandler (status) as Void
  if (status.getData() = "ready")
    fadeImageUp()
    m.top.findNode("itemPoster").unobserveField("loadStatus")
  end if
end function

function fadeImageUp () as Void
  m.top.findNode("itemPoster").opacity = 0
  m.top.FindNode("fadeInterp").keyValue = [0.0, 0.5, 1.0]
  m.top.FindNode("fadeAnimation").control = "START"
end function

sub showContent()
  if (m.top.height > 0 AND m.top.width > 0)
    m.top.findNode("itemPoster").observeField("loadStatus", "posterLoadedStateHandler")
    m.top.findNode("itemPoster").uri = m.top.itemcontent.HDPOSTERURL
    m.top.findNode("itemPoster").width  = m.top.width
    m.top.findNode("itemPoster").height = m.top.height
  end if
end sub
 
DadOfTwo
Topic Author
Posts: 18
Joined: Thu Feb 02, 2017 8:11 am

Re: How to determine image is cached on OS?

Fri Dec 08, 2017 2:32 am

Is the answer to this, No. There is no way with the current Roku OS to differentiate images loaded from the cache from images loading externally for the first time?

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