Refactor Image Loading: Use Internal Storage with Content URI for Enhanced Security and Compatibility

[Scapesfear]

Purpose / Description

• Internalizing Shared Images: Temporarily storing shared images in the app's internal cache for secure handling.
• Using Content:// URIs: Leveraging FileProvider to generate secure, modern, and Android-compliant URIs instead of direct file paths.
• Secure WebView Loading: Loading images in WebView using content:// URIs with a controlled HTML structure, ensuring compatibility.

Fixes

Fixes #17776
Superseeds and closes #17778

Approach

Internalizing Shared Images:
The shared image is first internalized, ensuring it’s stored temporarily within AnkiDroid's private storage, making it accessible only to the app. This resolves any issues related to image accessibility or permission errors.

Using content:// URIs:
By utilizing Android's FileProvider to generate content:// URIs, the PR avoids direct file path access, which may fail on newer Android versions (Android 10 and above). The content:// URI provides a safe, standardized way to share and access files between apps, complying with Android’s modern file access restrictions.

WebView Compatibility:
The PR fixes the issue where images weren't displaying by using the content:// URI format in WebView. This ensures proper loading of images in the app without needing risky settings, which could expose sensitive data or create security vulnerabilities.

How Has This Been Tested?

Manual Testing on Samsung F23 5G

test_loadimage.mp4

Checklist

Please, go through these checks before submitting the PR.

• You have a descriptive commit message with a short title (first line, max 50 chars).
• You have commented your code, particularly in hard-to-understand areas
• You have performed a self-review of your own code
• UI changes: include screenshots of all affected screens (in particular showing any new or changed strings)
• UI Changes: You have tested your change using the Google Accessibility Scanner

[mikehardy]

Seems like it should work, and this will be a nice improvement, thank you

Left a style note about shifting to a quick-return vs deep if/else nesting

Left a note that's a must-change (but an easy one) about log levels

[mikehardy]

This works for me - it.exists() may not be strictly necessary but a little extra checking can't hurt here

Timber.w now - thank you, early returns so nesting is avoided but error conditions are cleanly dealt with one by one in an obvious way - thank you

Good call-out from David to indicate to the user something went wrong, that's a good addition

This will be a nice fix for the share case, and now in combination with the crop fix where png/webp go through, we should have a "really, it works!" feature for sharing images to ankidroid from the context menu.

That add image via share feature broke when we started using the WebView in order to add sharing an SVG as a feature - which is a lesson in unintended consequences! But now all working I think, jpg, svg, png, webp

[mikehardy]

Marked for high priority review so we can get this in (hopefully)

QA ✅ - I have pulled the PR locally and confirm that images shared (from, for instance, android files app or gallery) are now correctly displayed in the previewer when you use "AnkiDroid - Add Image" system share target, so this passes testing

Still doesn't preserve transparency on crop but that's separate of course - I'm surprised that #17840 isn't in yet! - will push on that one

[criticalAY]

LGTM then

[lukstbit]

LGTM, thanks!
Please squash the two commits.

[lukstbit]

Thanks!