Bitmap加载方式
- BitmapFactory.decodeByteArray() 字节数组
- BitmapFactory.decodeFile() 文件路径
- BitmapFactory.decodeResource() 资源ID
- BitmapFactory.decodeStream() 流
如何高效加载Bitmap
- 理论依据：BitmapFactory.Options这个类为我们高效加载提供了可能。
- BitmapFactory.Options有以下几个重要属性：
- inJustDecodeBounds
- outWidth&outHeight
- inSampleSize
代码
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
public class BitmapUtil {
public static Bitmap ratio(String filePath,int pixelW,int pixelH){
BitmapFactory.Options newOptions = new BitmapFactory.Options();
newOptions.inJustDecodeBounds = true;
newOptions.inPreferredConfig = Bitmap.Config.RGB_565;
//预加载
BitmapFactory.decodeFile(filePath,newOptions);
int originalW = newOptions.outWidth;
int originalH = newOptions.outHeight;
newOptions.inSampleSize = getSimpleSize(originalW,
originalH,pixelW,pixelH);
newOptions.inJustDecodeBounds = false;
return BitmapFactory.decodeFile(filePath,newOptions);
}
private static int getSimpleSize(int originalW, int originalH, int pixelW, int pixelH) {
int simpleSize = 1;
if (originalW > pixelW || originalH > pixelH) {
//计算出实际宽高和目标宽高的比率
final int widthRatio = Math.round((float) originalW / (float) pixelW);
final int heightRatio = Math.round((float) originalH / (float) pixelH);
/*选择宽和高中最小的比率作为inSampleSize的值，这样可以保证最终图片的宽和高
一定都会大于等于目标的宽和高。*/
simpleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
}
return simpleSize;
}
}
