B4A Library Webview - Right click to save image

Full-blown browsers enjoy a context menu, activated with a right click of the mouse. Among other tasks, you can select and download images appearing on the page.

Attached below you will find Contextual (.jar and .xml), a library which allows you to download and save images from a webview. Unzip to your Addlibs folder.

Use:
1) Include Contextual in your project. Check Contextual in the libraries tab.
2) Declare some variable as Contextual
3) Declare and add your webview as usual
4) Initialize your Contextual variable. You can use an empty string as the only parameter.
5) Call Contextual's addContextMenu() method, passing your declared webview as the only parameter.
6) At some point, you'll want to load a url in your webview. Nothing much happens in a blank webview.

When you find an image of interest that you wish to download, tap and hold it (aka, long click or long press). The context menu should appear, offering you 3 choices: Save to the pictures gallery, Save to SafeDirDefaultExternal, Cancel.

If you choose to save the image, the system sends you a notification indicating success or failure. In my tests, it appeared at the top of the device like any other notification, almost immediately.

Webview uses the system's download manager. In theory, it wants to use the download folder, but it can use the pictures folder (or gallery), and it seems happy to store images in your app's so-called SafeDirDefaultExternal folder. What it doesn't do, apparently, is store to your File.DirInternal folder.

Some servers go out of their way to obfuscate image url's. I have no control over that. Webview is trained to recognize if you've long-pressed an image. That image's url may not be accessible using normal methods.

I've tested the library on devices running os 8.1, 9 and 11. I don't know what happened to 10. A device running it presumably got upgraded. I've tested with apps compiled with SDK targets 28 and 29 with B4A 10.2.

Runtime Permissions:
Unless you're running Android 11 and SDK 29, you'll need external write permission in your manifest to save to the pictures folder. To save to SafeDirDefaultExternal, you need a runtime permission, but there is no request/check needed. In other words, when I test the app on an 8.1 or 9 device, I need request/check permission for the pictures folder. When I run an app on my Pixel3a, I don't seem to need any permissions. It just works somehow... If you're running on an older device, I have no idea what will happen. There was a time when you could store stuff where you wanted on your device. No more.

If you're running on a recent vintage device and you plug in the library, and the context menu appears, but nothing is downloaded, I'd say it was due to runtime permissions.

edit: I've updated the library (now V.92). It adds the external write permission to the manifest, and it warns you if permission to use it has been granted (should that be necessary). It also catches a crash relating to that permission. Downloading to SafeDirDefaultExternal doesn't require granting permission. If there is a problem downloading to the pictures folder, try saving the image to SafeDirDefaultExternal.

edit 2: I have another update (V.93), which I've not uploaded. In addition to downloading to the abovementioned folders, V .93 will save to File.DirInternal. While this may seem to conform with what we're supposed to do, it strikes me as the least useful of the choices (depending on what your app does). Images in the pictures and SafeDirDefaultExternal folders can be seen outside of your app. Certainly, images in the pictures folder are readily visible. But images saved to File.DirInternal cannot be seen outside of your app. You would have to devise a routine, eg, to put them into the pictures folder or to share them. In addition, yet another choice in the context menu, makes the menu itself fill the entire screen. And shrinking the menu makes accurate tapping problematic. For anyone wishing to have this additional option, the library is available.

 

[max123]

Attached below you will find Contextual (.jar and .xml), a library which allows you to download and save images from a webview. Unzip to your Addlibs folder.

Where is the library ?
I do not see any attached zip file.
Or maybe I missed something ?

 

[drgottjr]

wow! that was some post; you'd think i'd discovered the cure for covid.
unfortunately, there was no interest 2 years ago in the library, so i
discontinued development and put it away. i think some things would
have to be changed to keep it viable today. best not to have old libraries
floating around. i should have deleted the post too, but the ministry of
truth and virtue might come for me.

google's support for context menu in a webview is somewhat limited;
resources that look like they could be downloaded can't. and javascript's
domination of webpage creation makes some things difficult. maybe the
ultimatewebview library offers this functionality.

 

[max123]

Hi, thanks for the reply, actually I was looking on the forum how to download files from the webview for my project that I posted here:
https://www.b4x.com/android/forum/threads/download-files-from-webview-local-storage.141068/

While I was looking, I came across your post, I saw some likes but there was no zip file to download, it seemed strange to me.

I ask you please if you had developed this library using Java or B4A, maybe you could help me understand how to do it, I have this problem and I can no longer continue my project.

For me if file is saved on Downloads is not a problem, the problem is that theejs library exporter want export in the HTML folder I save inside DirRootExternal, I , but not sure for this, because threejs works on browser If you want to help me this is the same exact javascript code online, if here we press buttons (links) to export, it save the box.stl in Downloads, so probably the default file manager you used in your library can work fine for me. The problem maybe still on newers SDK 26+ where maybe have different policies.
https://threejs.org/examples/misc_exporter_stl.html

In my case in Android I open this link I posted, it download to Downloads folder, then because I've a STL viewer I just click "Open" and the viewer show the cube exported.

On PC I cannot try because I only have pretty olds pc and any my graphic card do not support WebGL, forced Firefox in settings, but the problem still in the GPU too old.

I wrote on the forum and nobody replies, at this moment my post have 116 views but no replies... the impression I have is that since B4A is free the forum is dead, apart from here 4-5 experts who have been using it for years, I see a lot of people reading, but no one responding, most of these people are novices and non-experts. In my opinion B4A becoming free has lost much of its value where many people used it for work, now they only use it to play, so much is it free. A great pity it ended this way, I'm very unhappy.?

Many thanks if you can help me

 

[drgottjr]

almost anything involving webview as browser is a mistake.

i found the .jar, i'm uploading it as is. i don't even remember
what you have to do to initialize it. maybe it's in my original
post. but you can look at the code and see what all is
involved. there are comments. i don't know what your project
involves, so i don't know if the library or its code can help you.

 

[max123]

Thanks, so no B4A code, only Java ?

 

[drgottjr]

although it is possible to do, i've never seen a b4a library.