Images are sometimes skipped via iOS

[getCryptoAddress]

Expected Behavior

Images always render

Current Behavior

Images are sometimes skipped via iOS

For example: The background appeared only for the 3rd time

Possible Solution

Steps To Reproduce

1. Open https://getcryptoaddress.github.io/paper-wallets
2. Fill the form with random data
3. Click "Get Paper Wallets"
4. Click "Download"

Error Message & Stack Trace

no errors

Additional Context

Code:

1. https://github.com/getCryptoAddress/getCryptoAddress.github.io/blob/master/src/features/DownloadPaperWallet/ui/DownloadPaperWallet.vue#L47
2. https://github.com/getCryptoAddress/getCryptoAddress.github.io/blob/master/src/entities/PaperWallets/lib/download/downloadPaperWallet.ts#L10
3. https://github.com/getCryptoAddress/getCryptoAddress.github.io/blob/master/src/entities/PaperWallets/lib/download/downloadHtmlAsPng.ts#L8

Your Environment

• html-to-image: ^1.11.11
• iOS: iOS 16

[vivcat[bot]]

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[morlimoore]

Hi @getCryptoAddress, have you been able to move past this yet? I am using the html-to-image V1.11.11 and I experience the same issue as you. The image is only visible on the third download, and I don't know the cause of that.

[it4need]

Having the same issues here... I can reproduce this issue even on v1.11.0

[jonathanrstern]

Same here

[riccardoperra]

This is an iOS issue unfortunately https://bugs.webkit.org/show_bug.cgi?id=219770

I partially resolved this adding a delay of 250ms after the creation of the svg and before drawing to the canvas. 250 is just a magic number that I know in most of times image has been loaded. For images of high size and if you haven’t loaded it into the dom probably it’s not enough

toCanvas()

• call toSvg
• call createImage(svg)
• add delay
• draw canvas

[CheckCoder]

Same here

[jonathanrstern]

Finally found a reliable solution: the modern-screenshot library (a fork of html-to-image). Completely fixed the problem for me!

H/t @qq15725

https://github.com/qq15725/modern-screenshot

[riccardoperra]

beware that this solution seems still clone image like everyone else (https://github.com/qq15725/modern-screenshot/blob/main/src/clone-image.ts), so probably it is fixed by implicitly being asynchronous and adding some delays, since it uses worker (I don't know if it's a good idea, since the major computation only concerns the dom which is not available in the worker side)

default drawImageInterval is 100 https://github.com/qq15725/modern-screenshot/blob/0973c6c302e91b3d49921876f5c021b5ddda833a/src/create-context.ts#L53

[jonathanrstern]

He explained the difference here:

https://github.com/bubkoo/html-to-image/issues/361#issuecomment-1413526381

What do you think?

[riccardoperra]

Delaying the final canvas rendering by a fixed timeout can be the solution for most of cases.

It’s valid in my opinion since there isn’t any way to know if safari will render the image.

What I don’t like it’s this magic number which doesn’t guarantee it works every time 😅, but probably it’s the best it can be done at the moment.

Anyway this solution seems delaying n seconds for each image present in the html structure, so if you have like 10 images, it will be delayed for 1000ms~ (10 * 100ms) 🤔 but I don’t have the full understand of the code so I may be wrong.

Another important thing: what’s the device we are using to render that image, and how much mb is it?

Assuming we are trying to render an image around 0-1mb, most of iOS and macOS device can render it with a timeout of 100. If the image gets bigger, we surely need to increment this timeout. But I think there are others factors like device speed (what if energy save mode is on?)

currently I think the most safest way of rendering an image without having issues is using puppeteer/playwright with chrome under the hood 🤷🏻‍♂️ doing this will also allows to export the same image for all sort of devices (e.g. safari still can’t handle box-shadow), but it may be expensive

[qq15725]

10 image ref = 10 (canvasContext2d.drawImage('data:image/svg+xml,html-to-svg-data') and await 100ms)

I don't know how it works, but it works 😄

[jonathanrstern]

Can confirm that it's working beautifully! Thanks again @qq15725 :)

(For me, it's working on photos >5MB... will post an update if it stops working but for now I think we're good to go)

[CheckCoder]

10 image ref = 10 (canvasContext2d.drawImage('data:image/svg+xml,html-to-svg-data') and await 100ms)

I don't know how it works, but it works 😄

Thanks, work for me too.

[getCryptoAddress]

https://github.com/bubkoo/html-to-image/blob/master/src/index.ts#L58 if add

await new Promise((resolve) => setTimeout(resolve, 1));

Safari will render always

UPDATED ok, I created PR https://github.com/bubkoo/html-to-image/pull/423

UPDATED I'm wrong. I reproduced bug again. Not 8 times from 10, but 3 times from 10. It is better, but not solution

[getCryptoAddress]

Vue code example

<script lang="ts" setup>
     // ....

     // get svg from "html-to-image" for html
     canvasSvgElement.value = decodeURIComponent(await toSvg(targetElement));

    // wait vue render
    await nextTick();

    // get images into svg
    const images = canvasImageWrapperElement.value?.querySelectorAll("img");

    // wait all images
    if (images) {
      await Promise.all(
        [...images].map((img) => {
          return new Promise((resolve, reject) => {
            if (img.complete) {
              resolve(null);
            } else {
              img.onload = resolve;
              img.onerror = reject;
            }
          });
        })
      );

      console.log("images loaded"); // <--- it's true for safari

How I understand, safari needs time to render, not just load https://github.com/bubkoo/html-to-image/blob/master/src/embed-images.ts#L57 This is just a hypothesis, anyway the code above works in safari