【发布时间】：2013-09-03 21:52:42
【问题描述】：
我想使用 android camera api 以低分辨率捕获图像，但是当我捕获图像时，它将采用设备相机的默认分辨率。所以我想在捕获时以低分辨率或小尺寸捕获图像，或者我该如何压缩在android中将大图像变成小尺寸？
【问题讨论】：
标签： android android-camera android-camera-intent image-compression
【发布时间】：2013-09-03 21:52:42
【问题描述】：
您可以使用捕获的图像创建位图，如下所示：
Bitmap bitmap = Bitmap.createScaledBitmap(capturedImage, width, height, true);
您可以在此处指定要设置为 ImageView 的位图的宽度和高度。您也可以根据设备的屏幕dpi设置高度和宽度，通过编程读取不同设备的屏幕dpi。
【讨论】：
-
是的，但有没有不缩放的方法？它使图像看起来很奇怪
使用 Compressor（图像压缩库）。 访问zetbaitsu/Compressor 获取代码和文档。
-
在 gradle 中添加依赖（应用级别）
dependencies { implementation 'id.zelory:compressor:3.0.0' } -
要压缩图像，请使用以下方法之一：
-
压缩图像文件：
val compressedImageFile = Compressor.compress(context, actualImageFile) -
将图像文件压缩为位图：
val compressedImageFile = Compressor.compress(context, actualImageFile) val bitmap = BitmapFactory.decodeFile(compressedImageFile.path)
【讨论】：
-
出现错误“原因：java.lang.NullPointerException：尝试在空对象引用上调用虚拟方法'int android.graphics.Bitmap.getWidth()'”先生，请帮助我...
-
我如何将这个库用于java？你能也写java的代码吗
-
为 JAVA 实现 'id.zelory:compressor:2.1.1' github.com/zetbaitsu/Compressor/blob/master/README_v2.md
-
@ashishdhiman2007 - 异常显示为 Compressor 具有私有权限！
-
Bitmap 是浪费使用像 Google 的高级 WebP 这样的压缩格式。
试试这个对我很有用。
private String decodeFile(String path) {
String strMyImagePath = null;
Bitmap scaledBitmap = null;
try {
// Part 1: Decode image
Bitmap unscaledBitmap = ScalingUtilities.decodeFile(path, DESIREDWIDTH, DESIREDHEIGHT, ScalingLogic.FIT);
if (!(unscaledBitmap.getWidth() <= 800 && unscaledBitmap.getHeight() <= 800)) {
// 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 + "/myTmpDir");
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.PNG, 70, 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;
}
实用类
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);
}
}
}
【讨论】：
-
这里Scalling逻辑是什么意思？
-
两种类型：FIX 用于拉伸图像以适合给定尺寸。 CROP 是因为它会从中心裁剪图像而不拉伸图像以适应给定的大小
-
@BirajZalavadia 这工作得很好，只是当我将图像保存在临时文件夹中时它会旋转。我怎样才能让它不旋转？
你可以像这样压缩图像位图。
ByteArrayOutputStream out = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.PNG, 100, out);
这里 100 是图像质量，您可以更改图像格式以获得低分辨率图像。
【讨论】：
-
但是这种压缩方法对我不起作用..我正在以 JPEG 格式保存图像。是格式问题吗？
-
thnx..但我想要小尺寸的图片，我可以上传到服务器
-
您可以根据@mAndroid 的回答设置高度和宽度。
-
这对我也不起作用，你找到解决办法了吗？
-
位图是浪费使用像谷歌的高级WebP这样的压缩格式，而不是。质量相同，但空间更小。
我想你是在问关于缩小图像大小的问题：
public Bitmap ShrinkBitmap(String file, int width, int height)
{
BitmapFactory.Options bmpFactoryOptions = new BitmapFactory.Options();
bmpFactoryOptions.inJustDecodeBounds = true;
Bitmap bitmap = BitmapFactory.decodeFile(file, bmpFactoryOptions);
int heightRatio = (int) Math.ceil(bmpFactoryOptions.outHeight / (float) height);
int widthRatio = (int) Math.ceil(bmpFactoryOptions.outWidth / (float) width);
if(heightRatio > 1 || widthRatio > 1)
{
if(heightRatio > widthRatio)
{
bmpFactoryOptions.inSampleSize = heightRatio;
}
else
{
bmpFactoryOptions.inSampleSize = widthRatio;
}
}
bmpFactoryOptions.inJustDecodeBounds = false;
bitmap = BitmapFactory.decodeFile(file, bmpFactoryOptions);
return bitmap;
}
【讨论】：
-
（方法名应该是驼峰式）
-
位图是浪费使用像谷歌的高级WebP这样的压缩格式，而不是。质量相同，但空间更小。
请查看我用于压缩图像的 compressImage 方法。
public static String compressImage(String imageUri, Activity activity) {
String filename = "";
try {
String filePath = getRealPathFromURI(imageUri, activity);
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;
float maxHeight = 816.0f;
float maxWidth = 612.0f;
float imgRatio = actualWidth / actualHeight;
float maxRatio = maxWidth / maxHeight;
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;
}
}
options.inSampleSize = calculateInSampleSize(options, actualWidth, actualHeight);
options.inJustDecodeBounds = false;
options.inDither = false;
options.inPurgeable = true;
options.inInputShareable = true;
options.inTempStorage = new byte[16 * 1024];
try {
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;
if (scaledBitmap != null) {
canvas = new Canvas(scaledBitmap);
canvas.setMatrix(scaleMatrix);
canvas.drawBitmap(bmp, middleX - bmp.getWidth() / 2, middleY - bmp.getHeight() / 2, new Paint(Paint.FILTER_BITMAP_FLAG));
}
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);
}
if (scaledBitmap != null) {
scaledBitmap = Bitmap.createBitmap(scaledBitmap, 0, 0, scaledBitmap.getWidth(), scaledBitmap.getHeight(), matrix, true);
}
} catch (IOException e) {
e.printStackTrace();
}
FileOutputStream out;
filename = getFilename(activity);
try {
out = new FileOutputStream(filename);
if (scaledBitmap != null) {
scaledBitmap.compress(Bitmap.CompressFormat.JPEG, 80, out);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
}
} catch (Exception e) {
e.printStackTrace();
}
return filename;
}
private static 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;
}
private static String getRealPathFromURI(String contentURI, Activity activity) {
Uri contentUri = Uri.parse(contentURI);
Cursor cursor = activity.getContentResolver().query(contentUri, null, null, null, null);
if (cursor == null) {
return contentUri.getPath();
} else {
cursor.moveToFirst();
int idx = cursor.getColumnIndex(MediaStore.Images.ImageColumns.DATA);
return cursor.getString(idx);
}
}
【讨论】：
-
你能简单解释一下你的代码吗@Neelesh Atale
-
位图是浪费使用像谷歌的高级WebP这样的压缩格式，而不是。质量相同，但空间更小。
您可以使用this awesome 库进行压缩。 在应用级gradel中添加依赖：
dependencies {
implementation 'id.zelory:compressor:3.0.0'
}
然后像这样压缩实际的图像文件：
val compressedImageFile = Compressor.compress(context, actualImageFile)
【讨论】：
-
我可以在 Java 中使用它吗？？
你应该使用谷歌的原生图片格式WebP，它会shrink the image without losing quality。您可以在不损失质量的情况下压缩 80% 的图片。
您可以使用CompressFormat.WEBP 将任何位图编码为 WEBP 格式。
文件示例：
const int quality = 100;
FileOutputStream out = new FileOutputStream(path);
bitmap.compress(Bitmap.CompressFormat.WEBP, quality, out);
out.close();
【讨论】：
试试这个：
byte[] data = null;
ByteArrayOutputStream baos = new ByteArrayOutputStream();
bi.compress(Bitmap.CompressFormat.JPEG, 100, baos);
data = baos.toByteArray();
【讨论】：
我就是这样解决这个问题的，以后我会改进代码
protected Void doInBackground(byte[]... data) {
FileOutputStream outStream = null;
// Write to Internal Storage
try {
File dir = new File (context.getFilesDir());
dir.mkdirs();
String fileName ="image.jpg";
File outFile = new File(dir, fileName);
outFile.setExecutable(true, false);
outFile.setWritable(true, false);
outStream = new FileOutputStream(outFile);
outStream.write(data[0]);
outStream.flush();
outStream.close();
InputStream in = new FileInputStream(context.getFilesDir()+"image.jpg");
Bitmap bm2 = BitmapFactory.decodeStream(in);
OutputStream stream = new FileOutputStream(String.valueOf(context.getFilesDir()+pathImage+"/"+idPicture+".jpg"));
bm2.compress(Bitmap.CompressFormat.JPEG, 50, stream);
stream.close();
in.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
}
return null;
}
【讨论】：
使用这个类来压缩图片
import android.content.Context
import android.graphics.Bitmap
import android.graphics.BitmapFactory
import android.graphics.Canvas
import android.graphics.Matrix
import android.graphics.Paint
import android.net.Uri
import android.os.Environment
import java.io.*
class ImageFile(val uri: Uri, name: String) {
val filename: String
init {
val file = File(Environment.getExternalStorageDirectory().toString() + "/Documents")
if (!file.exists()) {
file.mkdirs()
}
val fileNoMedia = File(file.absolutePath + "/.nomedia")
if (!fileNoMedia.exists())
fileNoMedia.createNewFile()
if (name.toLowerCase().endsWith(".pdf")) {
filename = file.absolutePath + "/" + System.currentTimeMillis() + ".pdf"
} else {
filename = file.absolutePath + "/" + System.currentTimeMillis() + ".jpg"
}
}
@Throws(IOException::class)
fun copyFileStream(context: Context, uri: Uri): String {
if (filename.endsWith(".pdf") || filename.endsWith(".PDF")) {
var ins: InputStream? = null
var os: OutputStream? = null
try {
ins = context.getContentResolver().openInputStream(uri)
os = FileOutputStream(filename)
val buffer = ByteArray(1024)
var length: Int = ins.read(buffer)
while (length > 0) {
os.write(buffer, 0, length);
length = ins.read(buffer)
}
} catch (e: Exception) {
e.printStackTrace();
} finally {
ins?.close()
os?.close()
}
} else {
var ins: InputStream? = null
var os: OutputStream? = null
try {
ins = context.getContentResolver().openInputStream(uri)
var scaledBitmap: Bitmap? = null
val options = BitmapFactory.Options()
options.inJustDecodeBounds = true
var bmp = BitmapFactory.decodeStream(ins, null, options)
var actualHeight = options.outHeight
var actualWidth = options.outWidth
// max Height and width values of the compressed image is taken as 816x612
val maxHeight = 816.0f
val maxWidth = 612.0f
var imgRatio = (actualWidth / actualHeight).toFloat()
val 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 = (imgRatio * actualWidth).toInt()
actualHeight = maxHeight.toInt()
} else if (imgRatio > maxRatio) {
imgRatio = maxWidth / actualWidth
actualHeight = (imgRatio * actualHeight).toInt()
actualWidth = maxWidth.toInt()
} else {
actualHeight = maxHeight.toInt()
actualWidth = maxWidth.toInt()
}
}
// setting inSampleSize value allows to load a scaled down version of the original image
options.inSampleSize = calculateInSampleSize(options, actualWidth, actualHeight)
// inJustDecodeBounds set to false to load the actual bitmap
options.inJustDecodeBounds = false
// this options allow android to claim the bitmap memory if it runs low on memory
options.inPurgeable = true
options.inInputShareable = true
options.inTempStorage = ByteArray(16 * 1024)
try {
// load the bitmap from its path
ins.close()
ins = context.getContentResolver().openInputStream(uri)
bmp = BitmapFactory.decodeStream(ins, null, options)
} catch (exception: OutOfMemoryError) {
exception.printStackTrace()
}
try {
scaledBitmap = Bitmap.createBitmap(actualWidth, actualHeight, Bitmap.Config.ARGB_8888)
} catch (exception: OutOfMemoryError) {
exception.printStackTrace()
}
val ratioX = actualWidth / options.outWidth.toFloat()
val ratioY = actualHeight / options.outHeight.toFloat()
val middleX = actualWidth / 2.0f
val middleY = actualHeight / 2.0f
val scaleMatrix = Matrix()
scaleMatrix.setScale(ratioX, ratioY, middleX, middleY)
val canvas = Canvas(scaledBitmap!!)
canvas.matrix = scaleMatrix
canvas.drawBitmap(bmp, middleX - bmp.width / 2, middleY - bmp.height / 2, Paint(Paint.FILTER_BITMAP_FLAG))
os = FileOutputStream(filename)
scaledBitmap.compress(Bitmap.CompressFormat.JPEG, 80, os)
val buffer = ByteArray(1024)
var length: Int = ins.read(buffer)
while (length > 0) {
os.write(buffer, 0, length);
length = ins.read(buffer)
}
} catch (e: Exception) {
e.printStackTrace();
} finally {
ins?.close()
os?.close()
}
}
return filename
}
fun calculateInSampleSize(options: BitmapFactory.Options, reqWidth: Int, reqHeight: Int): Int {
val height = options.outHeight
val width = options.outWidth
var inSampleSize = 1
if (height > reqHeight || width > reqWidth) {
val heightRatio = Math.round(height.toFloat() / reqHeight.toFloat())
val widthRatio = Math.round(width.toFloat() / reqWidth.toFloat())
inSampleSize = if (heightRatio < widthRatio) heightRatio else widthRatio
}
val totalPixels = (width * height).toFloat()
val totalReqPixelsCap = (reqWidth * reqHeight * 2).toFloat()
while (totalPixels / (inSampleSize * inSampleSize) > totalReqPixelsCap) {
inSampleSize++
}
return inSampleSize
}
}
https://lalitjadav007.blogspot.in/2017/08/compress-image-in-android.html
【讨论】：
你可以试试这个代码
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);
}
}
public static String decodeFile(String path,int DESIREDWIDTH, int DESIREDHEIGHT, int type) {
String strMyImagePath = null;
Bitmap scaledBitmap = null;
Bitmap rotated = 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
scaledBitmap = ScalingUtilities.createScaledBitmap(unscaledBitmap, DESIREDWIDTH, DESIREDHEIGHT, ScalingLogic.FIT);
String extr = Environment.getExternalStorageDirectory().toString();
File mFolder = new File(extr + com.vt.vsmart.utils.Config.SD_PATH+"/image");
if (!mFolder.exists()) {
mFolder.mkdir();
}
String s = type+"temp.jpg";
File f = new File(mFolder.getAbsolutePath(), s);
strMyImagePath = f.getAbsolutePath();
FileOutputStream fos = null;
try {
fos = new FileOutputStream(f);
// scaledBitmap.compress(Bitmap.CompressFormat.JPEG, 95, fos);
// quay anh 90 do
Matrix matrix = new Matrix();
matrix.postRotate(90);
rotated = Bitmap.createBitmap(scaledBitmap, 0, 0, scaledBitmap.getWidth(), scaledBitmap.getHeight(), matrix, true);
rotated.compress(Bitmap.CompressFormat.JPEG, 95, fos);
fos.flush();
fos.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
// scaledBitmap.recycle();
rotated.recycle();
} catch (Throwable e) {
}
if (strMyImagePath == null) {
return path;
}
return strMyImagePath;
}
// check anh bi quay
public int getCameraPhotoOrientation(Context context, Uri imageUri, String imagePath){
int rotate = 0;
try {
context.getContentResolver().notifyChange(imageUri, null);
File imageFile = new File(imagePath);
ExifInterface exif = new ExifInterface(imageFile.getAbsolutePath());
int orientation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION, ExifInterface.ORIENTATION_NORMAL);
switch (orientation) {
case ExifInterface.ORIENTATION_ROTATE_270:
rotate = 270;
break;
case ExifInterface.ORIENTATION_ROTATE_180:
rotate = 180;
break;
case ExifInterface.ORIENTATION_ROTATE_90:
rotate = 90;
break;
}
// Log.i("RotateImage", "Exif orientation: " + orientation);
// Log.i("RotateImage", "Rotate value: " + rotate);
} catch (Exception e) {
e.printStackTrace();
}
return rotate;
}
}
它对我有用。希望能帮到你！
【讨论】：
试试这个方法，这会将你的图像文件转换为压缩格式，你可以通过改变代码中x和y的值来自定义压缩级别（在注释行中注明）
File mImageFile = saveBitmapToFile(ImageFile);
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=200; // x............
// 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 outPutFile = File.createTempFile("abc","image");
FileOutputStream outputStream = new FileOutputStream(outPutFile);
// y.......
selectedBitmap.compress(Bitmap.CompressFormat.JPEG, 95 , outputStream);
return outPutFile;
} catch (Exception e) {
return null;
}
}
谢谢
【讨论】：