How to Convert a Bitmap to Drawable in Android

How to convert a Bitmap to Drawable in android?

Sounds like you want to use BitmapDrawable

From the documentation:

A Drawable that wraps a bitmap and can
be tiled, stretched, or aligned. You
can create a BitmapDrawable from a
file path, an input stream, through
XML inflation, or from a Bitmap
object.

How to convert a Drawable to a Bitmap?

This converts a BitmapDrawable to a Bitmap.

Drawable d = ImagesArrayList.get(0);  
Bitmap bitmap = ((BitmapDrawable)d).getBitmap();

How to create Bitmap form Drawable object

You can convert your Drawable to Bitmap like this (for resource):

Bitmap icon = BitmapFactory.decodeResource(context.getResources(),
                                       R.drawable.drawable_source);

OR

If you've it stored in a variable, you can use this :

public static Bitmap drawableToBitmap (Drawable drawable) {
    Bitmap bitmap = null;

    if (drawable instanceof BitmapDrawable) {
        BitmapDrawable bitmapDrawable = (BitmapDrawable) drawable;
        if(bitmapDrawable.getBitmap() != null) {
            return bitmapDrawable.getBitmap();
        }
    }

    if(drawable.getIntrinsicWidth() <= 0 || drawable.getIntrinsicHeight() <= 0) {
        bitmap = Bitmap.createBitmap(1, 1, Bitmap.Config.ARGB_8888); // Single color bitmap will be created of 1x1 pixel
    } else {
        bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight(), Bitmap.Config.ARGB_8888);
    }

    Canvas canvas = new Canvas(bitmap);
    drawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());
    drawable.draw(canvas);
    return bitmap;
}

More details

converting drawable resource image into bitmap

You probably mean Notification.Builder.setLargeIcon(Bitmap), right? :)

Bitmap largeIcon = BitmapFactory.decodeResource(getResources(), R.drawable.large_icon);
notBuilder.setLargeIcon(largeIcon);

This is a great method of converting resource images into Android Bitmaps.

How to load an image from drawable and convert to a bitmap

The following method should work fine:

public static Bitmap getBitmapFromVectorDrawable(Context context, int drawableId) {
    Drawable drawable = ContextCompat.getDrawable(context, drawableId);
    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP) {
        drawable = (DrawableCompat.wrap(drawable)).mutate();
    }
    Bitmap bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(),
            drawable.getIntrinsicHeight(), Bitmap.Config.ARGB_8888);
    Canvas canvas = new Canvas(bitmap);
    drawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());
    drawable.draw(canvas);
    return bitmap;
}

build.gradle (project-level)

dependencies {
        classpath 'com.android.tools.build:gradle:2.2.0-alpha5'
    }

build.gradle (app-level)

android {
    compileSdkVersion 23
    buildToolsVersion '23.0.3'
    defaultConfig {
        minSdkVersion 16
        targetSdkVersion 23
        vectorDrawables.useSupportLibrary = true
    }
    ...
}
...

Or, you can use android-ktx in Kotlin too like this which works for any subclass of Drawable:

build.gradle

dependencies {
    implementation 'androidx.core:core-ktx:1.0.0-alpha1'
}

Then use Drawable#toBitmap() like this:

val bitmap = AppCompatResources.getDrawable(requireContext(), drawableId).toBitmap() 

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