许多应用程序允许共享从图库中挑选的图像。
他们上传原始图片文件吗？这是1-3 MB？或者他们处理？
在任何情况下，我如何从文件路径中获取图像，通过降低分辨率来减小其大小，并将其保存在其他地方并尝试上传？
我试过了：
Bitmap photo = decodeSampledBitmapFromFile(filePath, DESIRED_WIDTH,
DESIRED_HEIGHT);
FileOutputStream out = new FileOutputStream(filePath);
photo.compress(Bitmap.CompressFormat.JPEG, 100, out);
public static Bitmap decodeSampledBitmapFromFile(String path, int reqWidth,
int reqHeight) {
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeFile(path, options);
final int height = options.outHeight;
final int width = options.outWidth;
options.inPreferredConfig = Bitmap.Config.ARGB_8888;
int inSampleSize = 1;
if (height > reqHeight) {
inSampleSize = Math.round((float) height / (float) reqHeight);
}
int expectedWidth = width / inSampleSize;
if (expectedWidth > reqWidth) {
inSampleSize = Math.round((float) width / (float) reqWidth);
}
options.inSampleSize = inSampleSize;
options.inJustDecodeBounds = false;
return BitmapFactory.decodeFile(path, options);
}
但这是他们正确的方法吗？因为我看到了建议compression operation takes rather big amount of time here的答案
这很有效试试这个
private String decodeFile(String path,int DESIREDWIDTH, int DESIREDHEIGHT) {
String strMyImagePath = null;
Bitmap scaledBitmap = null;
try {
// Part 1: Decode image
Bitmap unscaledBitmap = ScalingUtilities.decodeFile(path, DESIREDWIDTH, DESIREDHEIGHT, ScalingLogic.FIT);
if (!(unscaledBitmap.getWidth() <= DESIREDWIDTH && unscaledBitmap.getHeight() <= DESIREDHEIGHT)) {
// Part 2: Scale image
scaledBitmap = ScalingUtilities.createScaledBitmap(unscaledBitmap, DESIREDWIDTH, DESIREDHEIGHT, ScalingLogic.FIT);
} else {
unscaledBitmap.recycle();
return path;
}
// Store to tmp file
String extr = Environment.getExternalStorageDirectory().toString();
File mFolder = new File(extr + "/TMMFOLDER");
if (!mFolder.exists()) {
mFolder.mkdir();
}
String s = "tmp.png";
File f = new File(mFolder.getAbsolutePath(), s);
strMyImagePath = f.getAbsolutePath();
FileOutputStream fos = null;
try {
fos = new FileOutputStream(f);
scaledBitmap.compress(Bitmap.CompressFormat.JPEG, 75, fos);
fos.flush();
fos.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
scaledBitmap.recycle();
} catch (Throwable e) {
}
if (strMyImagePath == null) {
return path;
}
return strMyImagePath;
}
scaling utilities.Java
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.graphics.BitmapFactory.Options;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Rect;
/**
* Class containing static utility methods for bitmap decoding and scaling
*
* @author
*/
public class ScalingUtilities {
/**
* Utility function for decoding an image resource. The decoded bitmap will
* be optimized for further scaling to the requested destination dimensions
* and scaling logic.
*
* @param res The resources object containing the image data
* @param resId The resource id of the image data
* @param dstWidth Width of destination area
* @param dstHeight Height of destination area
* @param scalingLogic Logic to use to avoid image stretching
* @return Decoded bitmap
*/
public static Bitmap decodeResource(Resources res, int resId, int dstWidth, int dstHeight,
ScalingLogic scalingLogic) {
Options options = new Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeResource(res, resId, options);
options.inJustDecodeBounds = false;
options.inSampleSize = calculateSampleSize(options.outWidth, options.outHeight, dstWidth,
dstHeight, scalingLogic);
Bitmap unscaledBitmap = BitmapFactory.decodeResource(res, resId, options);
return unscaledBitmap;
}
public static Bitmap decodeFile(String path, int dstWidth, int dstHeight,
ScalingLogic scalingLogic) {
Options options = new Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeFile(path, options);
options.inJustDecodeBounds = false;
options.inSampleSize = calculateSampleSize(options.outWidth, options.outHeight, dstWidth,
dstHeight, scalingLogic);
Bitmap unscaledBitmap = BitmapFactory.decodeFile(path, options);
return unscaledBitmap;
}
/**
* Utility function for creating a scaled version of an existing bitmap
*
* @param unscaledBitmap Bitmap to scale
* @param dstWidth Wanted width of destination bitmap
* @param dstHeight Wanted height of destination bitmap
* @param scalingLogic Logic to use to avoid image stretching
* @return New scaled bitmap object
*/
public static Bitmap createScaledBitmap(Bitmap unscaledBitmap, int dstWidth, int dstHeight,
ScalingLogic scalingLogic) {
Rect srcRect = calculateSrcRect(unscaledBitmap.getWidth(), unscaledBitmap.getHeight(),
dstWidth, dstHeight, scalingLogic);
Rect dstRect = calculateDstRect(unscaledBitmap.getWidth(), unscaledBitmap.getHeight(),
dstWidth, dstHeight, scalingLogic);
Bitmap scaledBitmap = Bitmap.createBitmap(dstRect.width(), dstRect.height(),
Config.ARGB_8888);
Canvas canvas = new Canvas(scaledBitmap);
canvas.drawBitmap(unscaledBitmap, srcRect, dstRect, new Paint(Paint.FILTER_BITMAP_FLAG));
return scaledBitmap;
}
/**
* ScalingLogic defines how scaling should be carried out if source and
* destination image has different aspect ratio.
*
* CROP: Scales the image the minimum amount while making sure that at least
* one of the two dimensions fit inside the requested destination area.
* Parts of the source image will be cropped to realize this.
*
* FIT: Scales the image the minimum amount while making sure both
* dimensions fit inside the requested destination area. The resulting
* destination dimensions might be adjusted to a smaller size than
* requested.
*/
public static enum ScalingLogic {
CROP, FIT
}
/**
* Calculate optimal down-sampling factor given the dimensions of a source
* image, the dimensions of a destination area and a scaling logic.
*
* @param srcWidth Width of source image
* @param srcHeight Height of source image
* @param dstWidth Width of destination area
* @param dstHeight Height of destination area
* @param scalingLogic Logic to use to avoid image stretching
* @return Optimal down scaling sample size for decoding
*/
public static int calculateSampleSize(int srcWidth, int srcHeight, int dstWidth, int dstHeight,
ScalingLogic scalingLogic) {
if (scalingLogic == ScalingLogic.FIT) {
final float srcAspect = (float)srcWidth / (float)srcHeight;
final float dstAspect = (float)dstWidth / (float)dstHeight;
if (srcAspect > dstAspect) {
return srcWidth / dstWidth;
} else {
return srcHeight / dstHeight;
}
} else {
final float srcAspect = (float)srcWidth / (float)srcHeight;
final float dstAspect = (float)dstWidth / (float)dstHeight;
if (srcAspect > dstAspect) {
return srcHeight / dstHeight;
} else {
return srcWidth / dstWidth;
}
}
}
/**
* Calculates source rectangle for scaling bitmap
*
* @param srcWidth Width of source image
* @param srcHeight Height of source image
* @param dstWidth Width of destination area
* @param dstHeight Height of destination area
* @param scalingLogic Logic to use to avoid image stretching
* @return Optimal source rectangle
*/
public static Rect calculateSrcRect(int srcWidth, int srcHeight, int dstWidth, int dstHeight,
ScalingLogic scalingLogic) {
if (scalingLogic == ScalingLogic.CROP) {
final float srcAspect = (float)srcWidth / (float)srcHeight;
final float dstAspect = (float)dstWidth / (float)dstHeight;
if (srcAspect > dstAspect) {
final int srcRectWidth = (int)(srcHeight * dstAspect);
final int srcRectLeft = (srcWidth - srcRectWidth) / 2;
return new Rect(srcRectLeft, 0, srcRectLeft + srcRectWidth, srcHeight);
} else {
final int srcRectHeight = (int)(srcWidth / dstAspect);
final int scrRectTop = (int)(srcHeight - srcRectHeight) / 2;
return new Rect(0, scrRectTop, srcWidth, scrRectTop + srcRectHeight);
}
} else {
return new Rect(0, 0, srcWidth, srcHeight);
}
}
/**
* Calculates destination rectangle for scaling bitmap
*
* @param srcWidth Width of source image
* @param srcHeight Height of source image
* @param dstWidth Width of destination area
* @param dstHeight Height of destination area
* @param scalingLogic Logic to use to avoid image stretching
* @return Optimal destination rectangle
*/
public static Rect calculateDstRect(int srcWidth, int srcHeight, int dstWidth, int dstHeight,
ScalingLogic scalingLogic) {
if (scalingLogic == ScalingLogic.FIT) {
final float srcAspect = (float)srcWidth / (float)srcHeight;
final float dstAspect = (float)dstWidth / (float)dstHeight;
if (srcAspect > dstAspect) {
return new Rect(0, 0, dstWidth, (int)(dstWidth / srcAspect));
} else {
return new Rect(0, 0, (int)(dstHeight * srcAspect), dstHeight);
}
} else {
return new Rect(0, 0, dstWidth, dstHeight);
}
}
}
我使用此功能在上传之前减小图像的大小，它将图像大小减小到接近200 KB并保持质量相对较好，您可以通过更改REQUIRED_SIZE和inSampleSize来修改它以实现您的目的：
public File saveBitmapToFile(File file){
try {
// BitmapFactory options to downsize the image
BitmapFactory.Options o = new BitmapFactory.Options();
o.inJustDecodeBounds = true;
o.inSampleSize = 6;
// factor of downsizing the image
FileInputStream inputStream = new FileInputStream(file);
//Bitmap selectedBitmap = null;
BitmapFactory.decodeStream(inputStream, null, o);
inputStream.close();
// The new size we want to scale to
final int REQUIRED_SIZE=75;
// Find the correct scale value. It should be the power of 2.
int scale = 1;
while(o.outWidth / scale / 2 >= REQUIRED_SIZE &&
o.outHeight / scale / 2 >= REQUIRED_SIZE) {
scale *= 2;
}
BitmapFactory.Options o2 = new BitmapFactory.Options();
o2.inSampleSize = scale;
inputStream = new FileInputStream(file);
Bitmap selectedBitmap = BitmapFactory.decodeStream(inputStream, null, o2);
inputStream.close();
// here i override the original image file
file.createNewFile();
FileOutputStream outputStream = new FileOutputStream(file);
selectedBitmap.compress(Bitmap.CompressFormat.JPEG, 100 , outputStream);
return file;
} catch (Exception e) {
return null;
}
}
注意：我在此函数中调整大小并覆盖原始文件图像，您也可以将其写入另一个文件。
我希望它可以帮助你。
这是我的解决方案
/*
* This procedure will replace the original image
* So you need to do a tmp copy to send before reduce
*/
public static boolean reduceImage(String path, long maxSize) {
File img = new File(path);
boolean result = false;
BitmapFactory.Options options = new BitmapFactory.Options();
Bitmap bitmap = null;
options.inSampleSize=1;
while (img.length()>maxSize) {
options.inSampleSize = options.inSampleSize+1;
bitmap = BitmapFactory.decodeFile(path, options);
img.delete();
try
{
FileOutputStream fos = new FileOutputStream(path);
img.compress(path.toLowerCase().endsWith("png")?
Bitmap.CompressFormat.PNG:
Bitmap.CompressFormat.JPEG, 100, fos);
fos.close();
result = true;
}catch (Exception errVar) {
errVar.printStackTrace();
}
};
return result;
}
编辑删除了其他程序调用
此代码缩小了图像大小
private Bitmap compressImage(Bitmap image) {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
image.compress(Bitmap.CompressFormat.JPEG, 100, baos);//Compression quality, here 100 means no compression, the storage of compressed data to baos
int options = 90;
while (baos.toByteArray().length / 1024 > 400) { //Loop if compressed picture is greater than 400kb, than to compression
baos.reset();//Reset baos is empty baos
image.compress(Bitmap.CompressFormat.JPEG, options, baos);//The compression options%, storing the compressed data to the baos
options -= 10;//Every time reduced by 10
}
ByteArrayInputStream isBm = new ByteArrayInputStream(baos.toByteArray());//The storage of compressed data in the baos to ByteArrayInputStream
Bitmap bitmap = BitmapFactory.decodeStream(isBm, null, null);//The ByteArrayInputStream data generation
return bitmap;
}
使用此方法返回压缩到大约200 KB的位图图像。您可以将其配置为获取所需大小的位图图像。
public static Bitmap scaleImage(Context context, Uri photoUri) throws IOException {
InputStream is = context.getContentResolver().openInputStream(photoUri);
BitmapFactory.Options dbo = new BitmapFactory.Options();
dbo.inJustDecodeBounds = true;
BitmapFactory.decodeStream(is, null, dbo);
is.close();
int rotatedWidth, rotatedHeight;
int orientation = getOrientation(context, photoUri);
if (orientation == 90 || orientation == 270) {
rotatedWidth = dbo.outHeight;
rotatedHeight = dbo.outWidth;
} else {
rotatedWidth = dbo.outWidth;
rotatedHeight = dbo.outHeight;
}
Bitmap srcBitmap;
is = context.getContentResolver().openInputStream(photoUri);
if (rotatedWidth > MAX_IMAGE_DIMENSION || rotatedHeight > MAX_IMAGE_DIMENSION) {
float widthRatio = ((float) rotatedWidth) / ((float) MAX_IMAGE_DIMENSION);
float heightRatio = ((float) rotatedHeight) / ((float) MAX_IMAGE_DIMENSION);
float maxRatio = Math.max(widthRatio, heightRatio);
// Create the bitmap from file
BitmapFactory.Options options = new BitmapFactory.Options();
options.inSampleSize = (int) maxRatio;
srcBitmap = BitmapFactory.decodeStream(is, null, options);
} else {
srcBitmap = BitmapFactory.decodeStream(is);
}
is.close();
/*
* if the orientation is not 0 (or -1, which means we don't know), we
* have to do a rotation.
*/
if (orientation > 0) {
Matrix matrix = new Matrix();
matrix.postRotate(orientation);
srcBitmap = Bitmap.createBitmap(srcBitmap, 0, 0, srcBitmap.getWidth(),
srcBitmap.getHeight(), matrix, true);
}
String type = context.getContentResolver().getType(photoUri);
ByteArrayOutputStream baos = new ByteArrayOutputStream();
if (type.equals("image/png")) {
srcBitmap.compress(Bitmap.CompressFormat.PNG, 100, baos);
} else if (type.equals("image/jpg") || type.equals("image/jpeg")) {
srcBitmap.compress(Bitmap.CompressFormat.JPEG, 100, baos);
}
byte[] bMapArray = baos.toByteArray();
baos.close();
return BitmapFactory.decodeByteArray(bMapArray, 0, bMapArray.length);
}