[Image] Add scale support for base64-encoded image

[cxfeng1-zz]

Now TabBar component support base64-encoded data-uris for the icon, but it has a image scale problem. If I use 3X image, it will become too large for the tab bar.

And if I use 1X image, it will become too fuzzy for the retina screen.

The correct way should be like this:

Maybe UIImage converter should support scale for base64-encoded image , let js tell the native what scale the image is, or just use 3X image and make the scale 3.0.

[vjeux]

Thanks for the very detailed issue! I think what needs to be done here is not to tell whether the image is 3x or 1x but what the scale independent size of the image should be.

[cxfeng1-zz]

Any news about this?

[crysfel]

Same problem here, any work around?

[brentvatne]

@cxfeng1 @crysfel - could either of you take a crack at this and submit a PR?

[cxfeng1-zz]

@vjeux Since RCTTabBarItem uses UITabBarItem which is not able to set custom UIImageView，I can not tell what size and content mode of the image should be. So the immediate solution may be to add scale support for base64-encoded image in case of similar situation that you can't change the size of view but just want the image to be scaled.

[cxfeng1-zz]

@frantic Thanks for the merging, this issue will be closed.