压缩图像android

时间:2017-07-07 10:18:47

标签: android image scaling image-scaling image-compression


我有一个应用程序,您可以在其中拍照或从库中选择一个图像。 必须将拍摄/选择的照片上传到服务器。
我的问题是,由于有不同的设备具有不同的大小和分辨率,压缩的图像应该加载到服务器上的原始大小,还是应该按比例放大然后压缩?
为所有设备缩放图像的最佳方法是什么?

现在,当用户通过相机或图库拍摄照片时,我正在使用此算法

private void setPic() throws IOException {
        // First decode with inJustDecodeBounds=true to check dimensions
        final BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeFile(mCurrentPhotoPath, options);
        // Calculate inSampleSize
        int sampleSize = calculateInSampleSize(options, 720, 720);
        Log.d("UserPanel", "Samplesize: " + sampleSize);
        Log.d("SquareImage", ""+image.getWidth());
        options.inSampleSize = sampleSize;

        // Decode bitmap with inSampleSize set
        options.inJustDecodeBounds = false;
        options.inPreferredConfig= Bitmap.Config.ARGB_8888;
        Bitmap bitmap = BitmapFactory.decodeFile(mCurrentPhotoPath, options);
        Log.d("UserPanel", "Bytebitmap: " + bitmap.getByteCount());
        ExifInterface exif = new ExifInterface(mCurrentPhotoPath);
        String orientString = exif.getAttribute(ExifInterface.TAG_ORIENTATION);
        int orientation = orientString != null ? Integer.parseInt(orientString) : ExifInterface.ORIENTATION_NORMAL;

        int rotationAngle = 0;
        if (orientation == ExifInterface.ORIENTATION_ROTATE_90) rotationAngle = 90;
        if (orientation == ExifInterface.ORIENTATION_ROTATE_180) rotationAngle = 180;
        if (orientation == ExifInterface.ORIENTATION_ROTATE_270) rotationAngle = 270;

        Matrix matrix = new Matrix();
        matrix.setRotate(rotationAngle, (float) bitmap.getWidth() / 2, (float) bitmap.getHeight() / 2);
        Bitmap rotatedBitmap = Bitmap.createBitmap(bitmap, 0, 0, options.outWidth, options.outHeight, matrix, true);
        Log.d("UserPanel", "Bytebitmaprotate: " + rotatedBitmap.getByteCount());
        MediaStore.Images.Media.insertImage(getContentResolver(), rotatedBitmap, imageFileName, "");
        File fdelete = new File(mCurrentPhotoPath);
        if (fdelete.delete()) Log.d("UserPanel", "Delete");
        imageToServer = getStringImage(rotatedBitmap);
    }

这是calculateSampleSize

public static 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;
        Log.d("UserPanel", "Width: " + width + " height: " + height);
        int inSampleSize = 1;

        if (height > reqHeight || width > reqWidth) {

            final int halfHeight = height / 2;
            final int halfWidth = width / 2;

            // Calculate the largest inSampleSize value that is a power of 2 and keeps both
            // height and width larger than the requested height and width.
            while ((halfHeight / inSampleSize) >= reqHeight
                    && (halfWidth / inSampleSize) >= reqWidth) {
                inSampleSize *= 2;
            }
        }

        return inSampleSize;
    }

为了压缩图像,我修改了100KB的大小

private String getStringImage(Bitmap bmp) {
        int compressQuality = 100;
        int streamLength = 0;
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        do{
            ByteArrayOutputStream bmpStream = new ByteArrayOutputStream();
            Log.d("compressBitmap", "Quality: " + compressQuality);
            bmp.compress(Bitmap.CompressFormat.JPEG, compressQuality, bmpStream);
            byte[] bmpPicByteArray = bmpStream.toByteArray();
            streamLength = bmpPicByteArray.length;
            compressQuality -= 5;
            Log.d("compressBitmap", "Size: " + streamLength/1024+" kb");
        }while (streamLength >= 100000);
        bmp.compress(Bitmap.CompressFormat.JPEG, compressQuality, baos);
        byte[] imageBytes = baos.toByteArray();
        Log.d("UserPanel", "Bytebitmap compress: " + imageBytes.length);
        String encodedImage = Base64.encodeToString(imageBytes, Base64.DEFAULT);
        return encodedImage;
    }

1 个答案:

答案 0 :(得分:-1)

尝试使用此类压缩图像

import android.content.Context;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.media.ExifInterface;
import android.net.Uri;
import android.os.Environment;
import android.provider.MediaStore;
import android.util.Log;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;


public class CompressImage {

    Context mContext;

    public CompressImage(Context context) {
        this.mContext = context;
    }

    public String compressImage(String imageUri) throws IOException {

        String filePath = getRealPathFromURI(imageUri);
        if(filePath == null)
        {
            filePath = imageUri;
        }
        Bitmap scaledBitmap = null;

        BitmapFactory.Options options = new BitmapFactory.Options();

//      by setting this field as true, the actual bitmap pixels are not loaded in the memory. Just the bounds are loaded. If
//      you try the use the bitmap here, you will get null.
        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);

//      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 = 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);
            Log.d("EXIF", "Exif: " + orientation);
            Matrix matrix = new Matrix();
            if (orientation == 6) {
                matrix.postRotate(90);
                Log.d("EXIF", "Exif: " + orientation);
            } else if (orientation == 3) {
                matrix.postRotate(180);
                Log.d("EXIF", "Exif: " + orientation);
            } else if (orientation == 8) {
                matrix.postRotate(270);
                Log.d("EXIF", "Exif: " + orientation);
            }
            scaledBitmap = Bitmap.createBitmap(scaledBitmap, 0, 0,
                    scaledBitmap.getWidth(), scaledBitmap.getHeight(), matrix,
                    true);
        } catch (IOException e) {
            e.printStackTrace();
        }

        FileOutputStream out = null;
        String filename = imageUri;
        File oldfile = new File(imageUri);
        if (oldfile.exists()) {
            oldfile.delete();
        }
        try {
            out = new FileOutputStream(filename);

//          write the compressed bitmap at the destination specified by filename.
            scaledBitmap.compress(Bitmap.CompressFormat.JPEG, 80, out);

        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }

        return filename;

    }

    public String getFilename() throws IOException {
//        File file = new File(Environment.getExternalStorageDirectory().getPath(), "MyFolder/Images");
//        if (!file.exists()) {
//            file.mkdirs();
//        }
//        String uriSting = (file.getAbsolutePath() + "/" + System.currentTimeMillis() + ".jpg");

        String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss")
                .format(new Date());
        String imageFileName = "twice_" + timeStamp + "_";
        File storageDir = Environment
                .getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES);
        File image = File.createTempFile(imageFileName, /* prefix */
                ".jpg", /* suffix */
                storageDir /* directory */
        );

//        ChatRoomFragment.picturePath= image.getAbsolutePath();
        return image.getAbsolutePath();

    }

    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;
    }


}