How to set the size of vector drawable inside of a button in Android?

Question

The Android Studio Vector Assets tools convert vector drawable to PNG-s for devices pre-Lollipop but I get really bad quality PNG-s as you can see here:

What's more is that the button's background solid color is supposed to be this light green that you see on the left but the drawable overwrite it:

<item android:state_checked="true"
    android:drawable="@drawable/show">
    <shape android:shape="rectangle">
        <corners android:bottomRightRadius="8dp"/>
        <solid android:color="@color/waveComponentGreen"/>
    </shape>
</item>

<item android:state_checked="false"
    android:drawable="@drawable/hide">
    <shape android:shape="rectangle">
        <corners android:bottomRightRadius="8dp"/>
        <solid android:color="@color/waveComponentGreen"/>
    </shape>
</item>

The xml for the drawable is (the default from the material icons):

<vector xmlns:android="http://schemas.android.com/apk/res/android"
    android:width="24dp"
    android:height="24dp"
    android:viewportWidth="24.0"
    android:viewportHeight="24.0">
<path
    android:fillColor="#FF000000"
    android:pathData="M8.59,16.34l4.58,-4.59 -4.58,-4.59L10,5.75l6,6 -6,6z"/>

I wanted also to make the icon appear a bit smaller by tweaking the values and I noticed increasing the viewport dimensions decreases the icon but I'm not sure I understand why.

So: How do I make the icon and the generated PNG appear smaller, less blurry and with the background colour set in the resource file? Thank you.

EDIT: I managed to get the solid colour background with the icon by combining them in a separate xml file with layer-lists:

<layer-list
xmlns:android="http://schemas.android.com/apk/res/android" >
<item>
    <shape android:shape="rectangle">
        <corners android:bottomRightRadius="10dp"/>
        <solid android:color="@color/waveComponentGreen"/>
    </shape>
</item>
<item android:drawable="@drawable/show"
    android:top="10dp"
    android:bottom="10dp"
    android:left="10dp"
    android:right="10dp"
    />

The result is:

I managed to reduce the blurring by increasing the width and height of the vector drawable. However without the android:top|bottom|left|right tags, the drawable is stretched across the whole area of the button. The second button doesn't need to have a background solid color so I'm not using the layer-list tags => no way to set a top|bottom|left|right margin for the drawable.
If I reduce the button size what I'm doing is reducing the clickable area of the button.

My updated question is how to set the size of the vector drawable inside a button/toggle button/radio button without reducing the size of the button itself?

UPDATE
I couldn't find a way to resize the vector drawable on pre-API 21 devices. So instead I made the buttons themselves smaller and increased the touch area of each button.

Answer 1

The correct approach to scale any drawable would be to use vectorDrawable.setBounds(left,top,right,bottom) , but unfortunately that does not work for vector drawables (why Google ?).

So as a workaround I load my vector drawables , convert them to bitmap drawable and that will allow us to use the setBounds method on the bitmap drawable. Note that you are scaling bitmaps here , so you can lose some sharpness of the image. I mainly use those methods when I need to use my drawable as a compound drawable of a text view or a button for example.

I ended up writing a helper class that will load a vector drawable set a tint to it and return a bitmap drawable that you can actually scale and tint as you wish. I've tested it for API levels 19 up to 23 , and it works.

Don't forget to use vectorDrawables.useSupportLibrary = true in your build.gradle.

public class VectorDrawableUtils {

/**
 * Gets a Bitmap from provided Vector Drawable image
 *
 * @param vd VectorDrawable
 * @return Bitmap
 */
public static Optional<Bitmap> createBitmapFromVectorDrawable(final @NonNull Drawable vd) {
    try {
        Bitmap bitmap;
        bitmap = Bitmap.createBitmap(vd.getIntrinsicWidth(), vd.getIntrinsicHeight(), Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(bitmap);
        vd.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());
        vd.draw(canvas);
        return Optional.of(bitmap);
    } catch (OutOfMemoryError e) {
        Injector.getDependency(getContext(), IEventTracker.class).logHandledException(e);
        return Optional.empty();
    }
}

/**
 * Loads vector drawable and apply tint color on it.
 */
public static Drawable loadVectorDrawableWithTintColor(final @DrawableRes int vdRes,
                                                       final @ColorRes int clrRes,final Context context) {
    Drawable drawable = ContextCompat.getDrawable(context, vdRes);
    DrawableCompat.setTint(drawable, getContext().getResources().getColor(clrRes));
    return drawable;
}

/**
 * Converts given vector drawable to Bitmap drawable
 */
public static BitmapDrawable convertVectorDrawableToBitmapDrawable(final @NonNull Drawable vd) {
    //it is safe to create empty bitmap drawable from null source
    return new BitmapDrawable(createBitmapFromVectorDrawable(vd).get());
}

/**
 * Loads vector drawable , aplys tint on it and returns a wrapped bitmap drawable.
 * Bitmap drawable can be resized using setBounds method (unlike the VectorDrawable)
 * @param context Requires view context !
 */
public static Drawable loadVectorDrawableWithTint(
        final @DrawableRes int vectorDrawableRes, final @ColorRes int colorRes,final Context context) {
    Drawable vd = VectorDrawableUtils.loadVectorDrawableWithTintColor(vectorDrawableRes,
            colorRes, context);
    final BitmapDrawable bitmapDrawable = VectorDrawableUtils.convertVectorDrawableToBitmapDrawable(vd);
    ColorStateList tint = ContextCompat.getColorStateList(context,colorRes);
    final Drawable wrappedDrawable = DrawableCompat.wrap(bitmapDrawable);
    DrawableCompat.setTintList(wrappedDrawable,tint);
    return wrappedDrawable;
    }
}

Now I would use this helper class like this :

    Drawable bd = VectorDrawableUtils.loadVectorDrawableWithTint(
                R.drawable.ic_dropdown, R.color.black,getContext());
        bd.setBounds(0, 0, textView.getMeasuredHeight(), textView.getMeasuredHeight());
        textView.setCompoundDrawablesWithIntrinsicBounds(null, null, bd, null);

It is important to use a Context of a View or Activity, not the Application context! Hope it will solve your problem, or help someone else. And if someone has a better and cleaner solution, I am interested to know as well.