DrawableUtils.java 文件源码

/**
 * Some drawable implementations have problems with mutation. This method returns false if
 * there is a known issue in the given drawable's implementation.
 */
public static boolean canSafelyMutateDrawable(@NonNull Drawable drawable) {
    if (Build.VERSION.SDK_INT < 15 && drawable instanceof InsetDrawable) {
        return false;
    }  else if (Build.VERSION.SDK_INT < 15 && drawable instanceof GradientDrawable) {
        // GradientDrawable has a bug pre-ICS which results in mutate() resulting
        // in loss of color
        return false;
    } else if (Build.VERSION.SDK_INT < 17 && drawable instanceof LayerDrawable) {
        return false;
    }

    if (drawable instanceof DrawableContainer) {
        // If we have a DrawableContainer, let's traverse its child array
        final Drawable.ConstantState state = drawable.getConstantState();
        if (state instanceof DrawableContainer.DrawableContainerState) {
            final DrawableContainer.DrawableContainerState containerState =
                    (DrawableContainer.DrawableContainerState) state;
            for (final Drawable child : containerState.getChildren()) {
                if (!canSafelyMutateDrawable(child)) {
                    return false;
                }
            }
        }
    } else if (drawable instanceof android.support.v4.graphics.drawable.DrawableWrapper) {
        return canSafelyMutateDrawable(
                ((android.support.v4.graphics.drawable.DrawableWrapper) drawable)
                        .getWrappedDrawable());
    } /*else if (drawable instanceof android.support.v7.graphics.drawable.DrawableWrapper) {
        return canSafelyMutateDrawable(
                ((android.support.v7.graphics.drawable.DrawableWrapper) drawable)
                        .getWrappedDrawable());
    }*/ else if (drawable instanceof ScaleDrawable) {
        return canSafelyMutateDrawable(((ScaleDrawable) drawable).getDrawable());
    }

    return true;
}