mahara-contributors team mailing list archive

[Aaron Wells <1419532@xxxxxxxxxxxxxxxxxx>]

Hm, one thing that does work, in my testing, is if I use an embedded
(base64-encoded) image as the src, and then I add an "onload" command
that loads the real image.

For testing the principle, I just manually generated an empty png file
of the correct size, but in practice we'd have to generate one on the
fly. So it would look like this:

1. Generate an empty png file of the same image dimensions as the actual
image file. Compress this PNG file as much as possible.

2. Base64-encode the placeholder PNG file.

3. Use this for the HTML in the block:

<img src="data:image/png;base64,iVBORw0KGgoAAAANS..."
onload="this.src='{$src}';" alt="{$description}" itemprop="contentURL">

But, I have no idea whether the act of generating, compressing, and
encoding the placeholder PNG file, might actually take so long that it
slows down pageload itself. I guess it would be a tradeoff. Generating a
placeholder PNG to embed into the HTML extends the time for the web
server to generate the HTML of the page itself; but it decreases the
time for the browser to determine the final page layout geometry.

Well, it's something to think about for 15.10 maybe.

** Changed in: mahara
    Milestone: 15.04.0 => None

** Changed in: mahara
    Milestone: None => 15.10.0

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https://bugs.launchpad.net/bugs/1419532

Title:
  Add "width" and "Height" attributes to <img> tag in image blocks so
  they'll flow to the right size immediately

Status in Mahara ePortfolio:
  Won't Fix

Bug description:
  We should add "width" and "Height" attributes to the <img> tags
  generated by image blocks, so that the browser will render the image
  placeholder as the correct size even before the image finishes
  loading. This should help the page to feel like it's loading up more
  quickly.

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