我正在尝试缩小位图.简而言之,图像最初来自宽度为4016的ByteArray.在使用工厂选项缩小图像后,它仍会报告宽度为4016的图像.
以下是我的代码的两个片段：
Bitmap myBitmap = null;
@Override
protected byte[] doInBackground(Object... params) {
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
if (options.outHeight > options.outWidth) {
options.inSampleSize = calculateInSampleSize(options,640,960);
} else {
options.inSampleSize = calculateInSampleSize(options,960,640);
}
options.inJustDecodeBounds = false;
//myImageByteArray is 4016 wide
myBitmap = BitmapFactory.decodeByteArray(myImageByteArray,myImageByteArray.length,options);
//This log statement outputs 4016!!! Shouldn't it be smaller since I just decoded the byteArray with options?
Log.d("bitmap",myBitmap.getWidth()+"");
}
public int calculateInSampleSize(BitmapFactory.Options options,int reqWidth,int reqHeight) {
// Raw height and width of image
final int height = options.outHeight;
final int width = options.outWidth;
int inSampleSize = 1;
if (height > reqHeight || width > reqWidth) {
// Calculate ratios of height and width to requested height and
// width
final int heightRatio = Math.round((float) height / (float) reqHeight);
final int widthRatio = Math.round((float) width / (float) reqWidth);
// Choose the smallest ratio as inSampleSize value,this will
// guarantee
// a final image with both dimensions larger than or equal to
// the
// requested height and width.
inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
}
return inSampleSize;
}
更新：
以下是我的代码的两个片段：
Bitmap myBitmap = null;
@Override
protected byte[] doInBackground(Object... params) {
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
//myImageByteArray is 4016 wide
myBitmap = BitmapFactory.decodeByteArray(myImageByteArray,options);
if (options.outHeight > options.outWidth) {
options.inSampleSize = calculateInSampleSize(options,options);
//This log statement outputs around 1000 now.
Log.d("bitmap",this will
// guarantee
// a final image with both dimensions larger than or equal to
// the
// requested height and width.
inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
}
return inSampleSize;
}
解决方法
你需要两次调用.decodeByteArray(..)！一旦获得宽度和高度,.inJustDecodeBounds设置为true,然后再使用.inSampleSize获取实际缩放的Bitmap,代码中的options.outHeight和options.outWidth可能为零.
调用BitmapFactory.decodeByteArray(myImageByteArray,options);在检查出高度和宽度之前.
编辑
从Google’s Android Dev site看一下这个例子：
BitmapFactory.Options options = new BitmapFactory.Options(); options.inJustDecodeBounds = true; BitmapFactory.decodeResource(getResources(),R.id.myimage,options); int imageHeight = options.outHeight; int imageWidth = options.outWidth;