我有一个应用程序，允许用户将其个人资料图像更改为存储在其设备上的另一个图像。为此，应用程序将选定的图像发送到远程服务器。所有这些工作都很好，所以我不要放置该部分的代码，以免使问题复杂化。我的问题是我希望减小发送到服务器的位图的大小，以防止例如5到6兆字节的大文件，这会使应用程序变慢。但这并不能很好地结束。
这是我的代码：
if (requestCode == 1 && resultCode == RESULT_OK) {
Uri selectedImageUri = data.getData();
imagepath = getPath(selectedImageUri);
Bitmap bitmap=BitmapFactory.decodeFile(imagepath);
ByteArrayOutputStream bytearrayoutputstream = new ByteArrayOutputStream();
//Resize the bitmap
Bitmap resizedBitmap = Bitmap.createScaledBitmap(bitmap, 150, 150, false);
resizedBitmap.compress(Bitmap.CompressFormat.JPEG,50,bytearrayoutputstream);
//Round the image
int min = Math.min(resizedBitmap.getWidth(), resizedBitmap.getHeight());
Bitmap bitmapRounded = Bitmap.createBitmap(min, min, resizedBitmap.getConfig());
Canvas canvas = new Canvas(bitmapRounded);
Paint paint = new Paint();
paint.setAntiAlias(true);
paint.setShader(new BitmapShader(resizedBitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP));
canvas.drawRoundRect((new RectF(0.0f, 0.0f, min, min)), min / 2, min / 2, paint);
//bitmap to imageView
avatar.setImageBitmap(bitmapRounded);
}
我试图缩小尺寸（不起作用），然后在将图像调整为相应的ImageView之前将图像取整（效果很好）。
我唯一无法使它正常工作的是减小位图的大小。
答案 0 :(得分：1)
我正在使用它来减小位图的大小，而且效果还不错：-
ByteArrayOutputStream baos = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.JPEG, 40, baos);
答案 1 :(得分：0)
如果要缩小图像，需要首先获取位图的高度和宽度，计算比例，然后创建缩放的位图。
int width = image.getWidth();
int height = image.getHeight();
您必须计算图像大小并返回缩放的位图。
在此处找到类似的问题：Reduce the size of a bitmap to a specified size in Android
希望您会得到确切的解决方案。
答案 2 :(得分：0)
尝试一下：
ByteArrayOutputStream ostream = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.PNG, 80, ostream);
答案 3 :(得分：0)
我正在使用此帮助程序类。
public class ScaleFile {
private Context mContext;
public ScaleFile(Context context) {
this.mContext = context;
}
public Bitmap scaleFile(String imageUri) {
String filePath = getRealPathFromURI(imageUri);
Bitmap scaledBitmap = null;
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
Bitmap bmp = BitmapFactory.decodeFile(filePath, options);
int actualHeight = options.outHeight;
int actualWidth = options.outWidth;
//max Height and width values of the compressed image is taken as 816x612
float maxHeight = 816.0f;
float maxWidth = 612.0f;
float imgRatio = actualWidth / actualHeight;
float maxRatio = maxWidth / maxHeight;
//width and height values are set maintaining the aspect ratio of the image
if (actualHeight > maxHeight || actualWidth > maxWidth) {
if (imgRatio < maxRatio) {
imgRatio = maxHeight / actualHeight;
actualWidth = (int) (imgRatio * actualWidth);
actualHeight = (int) maxHeight;
} else if (imgRatio > maxRatio) {
imgRatio = maxWidth / actualWidth;
actualHeight = (int) (imgRatio * actualHeight);
actualWidth = (int) maxWidth;
} else {
actualHeight = (int) maxHeight;
actualWidth = (int) maxWidth;
}
}
//setting inSampleSize value allows to load a scaled down version of the original image
options.inSampleSize = calculateInSampleSize(options, actualWidth, actualHeight);
options.inPurgeable = true;
options.inInputShareable = true;
options.inTempStorage = new byte[16 * 1024];
try {
//load the bitmap from its path
bmp = BitmapFactory.decodeFile(filePath, options);
} catch (OutOfMemoryError exception) {
exception.printStackTrace();
}
try {
scaledBitmap = Bitmap.createBitmap(actualWidth, actualHeight, Bitmap.Config.ARGB_8888);
} catch (OutOfMemoryError exception) {
exception.printStackTrace();
}
float ratioX = actualWidth / (float) options.outWidth;
float ratioY = actualHeight / (float) options.outHeight;
float middleX = actualWidth / 2.0f;
float middleY = actualHeight / 2.0f;
Matrix scaleMatrix = new Matrix();
scaleMatrix.setScale(ratioX, ratioY, middleX, middleY);
Canvas canvas = new Canvas(scaledBitmap);
canvas.setMatrix(scaleMatrix);
canvas.drawBitmap(bmp, middleX - bmp.getWidth() / 2, middleY - bmp.getHeight() / 2, new Paint(Paint.FILTER_BITMAP_FLAG));
// check the rotation of the image and display it properly
ExifInterface exif;
try {
exif = new ExifInterface(filePath);
int orientation = exif.getAttributeInt(
ExifInterface.TAG_ORIENTATION, 0);
Matrix matrix = new Matrix();
if (orientation == 6) {
matrix.postRotate(90);
} else if (orientation == 3) {
matrix.postRotate(180);
} else if (orientation == 8) {
matrix.postRotate(270);
}
scaledBitmap = Bitmap.createBitmap(scaledBitmap, 0, 0, scaledBitmap.getWidth(),
scaledBitmap.getHeight(), matrix, true);
} catch (IOException e) {
e.printStackTrace();
}
return scaledBitmap;
}
private String getRealPathFromURI(String contentURI) {
Uri contentUri = Uri.parse(contentURI);
Cursor cursor = mContext.getContentResolver().query(contentUri, null, null, null, null);
if (cursor == null) {
return contentUri.getPath();
} else {
cursor.moveToFirst();
int index = cursor.getColumnIndex(MediaStore.Images.ImageColumns.DATA);
return cursor.getString(index);
}
}
public int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) {
final int height = options.outHeight;
final int width = options.outWidth;
int inSampleSize = 1;
if (height > reqHeight || width > reqWidth) {
final int heightRatio = Math.round((float) height / (float) reqHeight);
final int widthRatio = Math.round((float) width / (float) reqWidth);
inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
}
final float totalPixels = width * height;
final float totalReqPixelsCap = reqWidth * reqHeight * 2;
while (totalPixels / (inSampleSize * inSampleSize) > totalReqPixelsCap) {
inSampleSize++;
}
return inSampleSize;
}
}