Get the ID of a drawable in ImageView
I think if I understand correctly this is what you are doing.
ImageView view = (ImageView) findViewById(R.id.someImage);
view.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View view) {
ImageView imageView = (ImageView) view;
assert(R.id.someImage == imageView.getId());
switch(getDrawableId(imageView)) {
case R.drawable.foo:
imageView.setDrawableResource(R.drawable.bar);
break;
case R.drawable.bar:
default:
imageView.setDrawableResource(R.drawable.foo);
break;
}
});
Right? So that function getDrawableId()
doesn't exist. You can't get a the id that a drawable was instantiated from because the id is just a reference to the location of data on the device on how to construct a drawable. Once the drawable is constructed it doesn't have a way to get back the resourceId that was used to create it. But you could make it work something like this using tags
ImageView view = (ImageView) findViewById(R.id.someImage);
view.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View view) {
ImageView imageView = (ImageView) view;
assert(R.id.someImage == imageView.getId());
// See here
Integer integer = (Integer) imageView.getTag();
integer = integer == null ? 0 : integer;
switch(integer) {
case R.drawable.foo:
imageView.setDrawableResource(R.drawable.bar);
imageView.setTag(R.drawable.bar);
break;
case R.drawable.bar:
default:
imageView.setDrawableResource(R.drawable.foo);
imageView.setTag(R.drawable.foo);
break;
}
});
I answered something like this in another question already, but will change it just a little for this one.
Unfortunately, there is no getImageResource()
or getDrawableId()
. But, I created a simple workaround by using the ImageView tags.
In onCreate():
imageView0 = (ImageView) findViewById(R.id.imageView0);
imageView1 = (ImageView) findViewById(R.id.imageView1);
imageView2 = (ImageView) findViewById(R.id.imageView2);
imageView0.setTag(R.drawable.apple);
imageView1.setTag(R.drawable.banana);
imageView2.setTag(R.drawable.cereal);
Then, if you like, you can create a simple function to get the drawable id:
private int getDrawableId(ImageView iv) {
return (Integer) iv.getTag();
}
Too easy.
Digging StackOverflow for answers on the similar issue I found people usually suggesting 2 approaches:
- Load a drawable into memory and compare ConstantState or bitmap itself to other one.
- Set a tag with drawable id into a view and compare tags when you need that.
Personally, I like the second approach for performance reason but tagging bunch of views with appropriate tags is painful and time consuming. This could be very frustrating in a big project. In my case I need to write a lot of Espresso tests which require comparing TextView
drawables, ImageView
resources, View
background and foreground. A lot of work.
So I eventually came up with a solution to delegate a 'dirty' work to the custom inflater. In every inflated view I search for a specific attributes and and set a tag to the view with a resource id if any is found. This approach is pretty much the same guys from Calligraphy used. I wrote a simple library for that: TagView
If you use it, you can retrieve any of predefined tags, containing drawable resource id that was set in xml layout file:
TagViewUtils.getTag(view, ViewTag.IMAGEVIEW_SRC.id)
TagViewUtils.getTag(view, ViewTag.TEXTVIEW_DRAWABLE_LEFT.id)
TagViewUtils.getTag(view, ViewTag.TEXTVIEW_DRAWABLE_TOP.id)
TagViewUtils.getTag(view, ViewTag.TEXTVIEW_DRAWABLE_RIGHT.id)
TagViewUtils.getTag(view, ViewTag.TEXTVIEW_DRAWABLE_BOTTOM.id)
TagViewUtils.getTag(view, ViewTag.VIEW_BACKGROUND.id)
TagViewUtils.getTag(view, ViewTag.VIEW_FOREGROUND.id)
The library supports any attribute, actually. You can add them manually, just look into the Custom attributes section on Github. If you set a drawable in runtime you can use convenient library methods:
setImageViewResource(ImageView view, int id)
In this case tagging is done for you internally. If you use Kotlin you can write a handy extensions to call view itself. Something like this:
fun ImageView.setImageResourceWithTag(@DrawableRes int id) {
TagViewUtils.setImageViewResource(this, id)
}
You can find additional info in Tagging in runtime
As of today, there is no support on this function. However, I found a little hack on this one.
imageView.setImageResource(R.drawable.ic_star_black_48dp);
imageView.setTag(R.drawable.ic_star_black_48dp);
So if you want to get the ID of the view, just get it's tag.
if (imageView.getTag() != null) {
int resourceID = (int) imageView.getTag();
//
// drawable id.
//
}