[移动开发]Android GradientDrawable 转 Bitmap

需求：最新开发，有几个渐变色的背景，因为图片比较大，为减小应用体积，用drawable资源文件来加载，然后代码转为Bitmap在设置背景。

实现：
1、drawable文件(色值随意定的，只是demo)：

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
	<!--实现应用背景颜色渐变-->
	<gradient
        android:startColor="@color/colorAccent"
        android:endColor="@color/colorPrimaryDark"
        android:angle="270"/>
</shape>

2、代码中转Bitmap

private Bitmap getBitmapGradient(){
		Drawable drawable = mContext.getResources().getDrawable(R.drawable.background_gradient);
        GradientDrawable gradientDrawable = (GradientDrawable) drawable;
        //我这图片宽高是全局变量mWidth，mHeight
        bitmap = Bitmap.createBitmap(mWidth, mHeight, Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(bitmap);
        gradientDrawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());
        gradientDrawable.draw(canvas);
        return bitmap;
}		

参考链接：
Converting GradientDrawable to Bitmap

参考代码：

public static Bitmap drawableToBitmap(Context mContext, int drawableInt) {
    Bitmap bitmap;

    Drawable drawable = getDrawable(mContext, drawableInt);

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

        bitmap = Bitmap.createBitmap(140, 140, Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(bitmap);
        gradientDrawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());
        gradientDrawable.draw(canvas);
        return bitmap;
    }

    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;
}