RippleDrawableCompat.java

public class RippleDrawableCompat {

    public static class Builder {
        int normalColor = Color.TRANSPARENT;
        int pressColor = Color.TRANSPARENT;
        int strokeColor = Color.TRANSPARENT;
        int strokeWidth = 0;
        float radius = 0.0f;

        public Builder() {
        }

        public Builder normalColor(int normalColor) {
            this.normalColor = normalColor;
            return this;
        }

        public Builder pressColor(int pressColor) {
            this.pressColor = pressColor;
            return this;
        }

        public Builder strokeColor(int strokeColor) {
            this.strokeColor = strokeColor;
            return this;
        }

        public Builder strokeWidth(int strokeWidth) {
            this.strokeWidth = strokeWidth;
            return this;
        }

        public Builder radius(float radius) {
            this.radius = radius;
            return this;
        }

        public Drawable build() {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
                return createRippleDrawable(normalColor, pressColor, strokeColor, strokeWidth, radius);
            } else {
                return createStateListDrawable(normalColor, pressColor, strokeColor, strokeWidth, radius);
            }
        }
    }

    @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
    private static Drawable createRippleDrawable(@ColorInt int normalColor, @ColorInt int pressColor, @ColorInt int strokeColor, int strokeWidth, float radius) {
        Drawable content = createGradientDrawable(normalColor, strokeColor, strokeWidth, radius);
        Drawable mask = createShapeDrawable(radius);
        return new RippleDrawable(ColorStateList.valueOf(pressColor), content, mask);
    }

    private static Drawable createStateListDrawable(@ColorInt int normalColor, @ColorInt int pressColor, @ColorInt int strokeColor, int strokeWidth, float radius) {
        Drawable normal = createGradientDrawable(normalColor, strokeColor, strokeWidth, radius);
        Drawable press = createGradientDrawable(pressColor, strokeColor, strokeWidth, radius);

        StateListDrawable drawable = new StateListDrawable();
        drawable.addState(new int[]{android.R.attr.state_pressed}, press);
        drawable.addState(new int[]{}, normal);
        return drawable;
    }

    private static Drawable createGradientDrawable(@ColorInt int solidColor, @ColorInt int strokeColor, int strokeWidth, float radius) {
        GradientDrawable drawable = new GradientDrawable();
        drawable.setColor(solidColor);
        drawable.setStroke(strokeWidth, strokeColor);
        drawable.setCornerRadius(radius);
        return drawable;
    }

    private static Drawable createShapeDrawable(float radius) {
        float[] outerRadii = new float[8];
        Arrays.fill(outerRadii, radius);
        RoundRectShape roundRectShape = new RoundRectShape(outerRadii, null, null);
        return new ShapeDrawable(roundRectShape);
    }
}