BitmapFactory.decodeResource() returns null for shape defined in xml drawable

问题

I looked through multiple similar questions, although I haven't found proper answer on my query.

I have a drawable, defined in shape.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle" >

    <solid android:color="@color/bg_color" />
</shape>

I want to convert it to Bitmap object in order to perform some operations, but BitmapFactory.decodeResource() returns null.

This is how I'm doing it:

Bitmap bmp = BitmapFactory.decodeResource(getResources(), R.drawable.shape);

What am I doing wrong? Is BitmapFactory.decodeResource() applicable for xml defined drawables?

回答1:

Since you want to load a Drawable, not a Bitmap, use this:

Drawable d = getResources().getDrawable(R.drawable.your_drawable, your_app_theme);

To turn it into a Bitmap:

public static Bitmap drawableToBitmap (Drawable drawable) {

    if (drawable instanceof BitmapDrawable) {
        return ((BitmapDrawable)drawable).getBitmap();
    }

    Bitmap bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight(), Config.ARGB_8888);
    Canvas canvas = new Canvas(bitmap); 
    drawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());
    drawable.draw(canvas);

    return bitmap;
}

Taken from: How to convert a Drawable to a Bitmap?

回答2:

public static Bitmap convertDrawableResToBitmap(@DrawableRes int drawableId, Integer width, Integer height) {
    Drawable d = getResources().getDrawable(drawableId);

    if (d instanceof BitmapDrawable) {
        return ((BitmapDrawable) d).getBitmap();
    }

    if (d instanceof GradientDrawable) {
        GradientDrawable g = (GradientDrawable) d;

        int w = d.getIntrinsicWidth() > 0 ? d.getIntrinsicWidth() : width;
        int h = d.getIntrinsicHeight() > 0 ? d.getIntrinsicHeight() : height;

        Bitmap bitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(bitmap);
        g.setBounds(0, 0, w, h);
        g.setStroke(1, Color.BLACK);
        g.setFilterBitmap(true);
        g.draw(canvas);
        return bitmap;
    }

    Bitmap bit = BitmapFactory.decodeResource(getResources(), drawableId);
    return bit.copy(Bitmap.Config.ARGB_8888, true);
}

//------------------------

Bitmap b = convertDrawableResToBitmap(R.drawable.myDraw , 50, 50);

回答3:

it is a drawable, not a bitmap. You should use getDrawable instead

回答4:

You may have put .xml into directory:.../drawable-24, and try to put it into .../drawable instead.

it works for me, hope this can help someone.

来源：https://stackoverflow.com/questions/24389043/bitmapfactory-decoderesource-returns-null-for-shape-defined-in-xml-drawable

标签

android

android-drawable

xml-drawable