[HOLD for payment 2023-10-09] [$500] Chat - Loader is shown on top of image even after image is loaded in attachment carousel

[lanitochka17]

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Action Performed:

1. Open a report
2. Send 3-4 images/pdf's
3. Scroll through carousel multiple times

Expected Result:

The loader should not appear on top of the image if the image is already loaded

Actual Result:

The loader appears on top of the image even if the image is already loaded

Workaround:

Unknown

Platforms:

Which of our officially supported platforms is this issue occurring on?

• Android / native
• Android / Chrome
• iOS / native
• iOS / Safari
• MacOS / Chrome / Safari
• MacOS / Desktop

Version Number: 1.3.57-5

Reproducible in staging?: Yes

Reproducible in production?: Yes

If this was caught during regression testing, add the test name, ID and link from TestRail:

Email or phone of affected tester (no customers):

Logs: https://stackoverflow.com/c/expensify/questions/4856

Notes/Photos/Videos: Any additional supporting documentation

WhatsApp.Video.2023-08-19.at.16.46.18.mp4

Record_2023-08-27-22-02-15_4f9154176b47c00da84e32064abf1c48.mp4

Expensify/Expensify Issue URL:

Issue reported by: @Krishna2323

Slack conversation: https://expensify.slack.com/archives/C049HHMV9SM/p1692443921240289

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• Krishna2323 | Contributor | 26743909
• krishna2323 | Reporter | 26743910

[melvin-bot]

Triggered auto assignment to @sakluger (Bug), see https://stackoverflow.com/c/expensify/questions/14418 for more details.

[melvin-bot]

Bug0 Triage Checklist (Main S/O)

• This "bug" occurs on a supported platform (ensure Platforms in OP are ✅)
• This bug is not a duplicate report (check E/App issues and #expensify-bugs)
  • If it is, comment with a link to the original report, close the issue and add any novel details to the original issue instead
• This bug is reproducible using the reproduction steps in the OP. S/O
  • If the reproduction steps are clear and you're unable to reproduce the bug, check with the reporter and QA first, then close the issue.
  • If the reproduction steps aren't clear and you determine the correct steps, please update the OP.
• This issue is filled out as thoroughly and clearly as possible
  • Pay special attention to the title, results, platforms where the bug occurs, and if the bug happens on staging/production.
• I have reviewed and subscribed to the linked Slack conversation to ensure Slack/Github stay in sync

[pradeepmdk]

Proposal

Please re-state the problem that we are trying to solve in this issue.

Chat - Loader is shown on top of image even after image is loaded in attachment carousel

What is the root cause of that problem?

from this PR https://github.com/Expensify/App/pull/20798/files#diff-d0e9c4b27eeb3cf558959584e3c3ea569b9a70c4fa1334846ac028a504cf035d introduced ImageTransformer so every time isActive image will transform

App/src/components/Attachments/AttachmentCarousel/Pager/AttachmentCarouselPage.js

Lines 76 to 77 in d09a1b6

	onLoadStart={() => setIsImageLoading(true)}
	onLoadEnd={() => setIsImageLoading(false)}

so that flickering will occur every time load an image and transform

What changes do you think we should make in order to solve the problem?

we should check image is already Transformed or not. This AttachmentCarouselPage is loaded from Flatlist so we need to declare one more state

    const [isImageTransformered, setIsImageTransformered] = useState(false);

and here

App/src/components/Attachments/AttachmentCarousel/Pager/AttachmentCarouselPage.js

Line 102 in d09a1b6

if (initialActivePageLoad) {

we need declare setIsImageTransformered(true);
and on onLoadEnd as well.
and

App/src/components/Attachments/AttachmentCarousel/Pager/AttachmentCarouselPage.js

Line 118 in d09a1b6

onLoadStart={() => setIsImageLoading(true)}

add onLoadEnd={() => setIsImageTransformered(true)}

the loader should show if the image is not Transforming only isActive && !isImageTransformered

Result

Screen.Recording.2023-09-15.at.6.51.36.AM.mov

[Krishna2323]

Proposal

Please re-state the problem that we are trying to solve in this issue.

Chat - Loader is shown on top of image even after image is loaded in attachment carousel

What is the root cause of that problem?

Our loader is configured to show as soon as the loading process began, without distinguishing between images loaded from the cache and those fetched from the internet. This meant that even if an image was instantly available in the cache and displayed immediately, our loader logic would still interpret this as a loading sequence. As a result, the isLoading state would momentarily set to true, only to revert back to false instantly, causing the loading indicator to flash or flicker briefly.

I already fixed similar issue few weeks ago: PR

What changes do you think we should make in order to solve the problem?

To address the flickering loader issue, we should introduce a slight delay before showing the loader, allowing cached images to display without triggering the loading indicator. Simultaneously, we need to enhance our mechanism for tracking image load status, ensuring that once an image is loaded, its status is remembered, preventing unnecessary loader displays for cached images. Synchronizing the fallback display with the image's actual load status will further mitigate the flash of the loader. Lastly, optimizing the caching of image dimensions will expedite image rendering, contributing to a smoother user experience.

Imports:

• Imported useRef and _ from 'underscore' in the new code.

State Variables:

• Added a new state variable isImageCached which is used to determine if the image is being loaded from the cache or the internet.
• Initialized isImageLoading state to false instead of true.
• Initialized showFallback state to true instead of isImageLoading.

    const [isImageLoading, setIsImageLoading] = useState(false);
    const [showFallback, setShowFallback] = useState(true);
    const [isImageCached, setIsImageCached] = useState(true);

Refs:

• Introduced a new ref isLoadedRef which seems to act as a flag to track if the image has been loaded at least once.

const isLoadedRef = useRef(null);

Effects:

• In the new code, there's an added effect that checks if the image is being loaded from cache or the internet. It introduces a delay using _.delay() from the underscore library to decide whether to update isImageCached.

    useEffect(() => {
        if (isLoadedRef.current || !isImageLoading) {
            return;
        }
        const timeout = _.delay(() => {
            if (!isImageLoading || isLoadedRef.current) {
                return;
            }
            setIsImageCached(false);
        }, 200);
        return () => clearTimeout(timeout);
    }, [isImageLoading]);

Image Component:

• The callback for the onLoadStart event of the inside the ImageTransformer was removed in the new code.
• The onLoadStart and onLoadEnd events of the inside the ImageWrapper were modified. The new onLoadStart checks the isLoadedRef and isImageLoading before setting isImageLoading to true. The onLoadEnd now sets both isImageLoading to false and isLoadedRef.current to true.

     onLoadStart={() => {
        if (isLoadedRef.current || isImageLoading) {
              return;
        }
        setIsImageLoading(true);
      }}

ActivityIndicator:

• The condition to show the ActivityIndicator is now (isActive && isImageLoading && !isImageCached). This means the loading spinner will only be shown if the page is active, the image is still loading, and the image is not cached.

    {isActive && isImageLoading && !isImageCached && (
        <ActivityIndicator
            size="large"
            style={StyleSheet.absoluteFill}
        />
    )}

Result

fix_demo.mp4

[melvin-bot]

@sakluger Uh oh! This issue is overdue by 2 days. Don't forget to update your issues!

[sakluger]

We're discussing moving the shortcuts modal to the RHN, so I'm going to close this issue.

[sakluger]

I'm sorry, I closed the wrong issue.

[Krishna2323]

@sakluger, that's what I was thinking 😂