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androidで画質を損なうことなく画像サイズを縮小します

Androidで画質を損なうことなく画像サイズを縮小する方法。
プロジェクトにImageViewがあります。その中に大きなサイズの画像を配置する必要があります。
Androidは初めてです。
助けてください。

androidimagebitmap
39
Mainak Mukherjee

以下のコードは、アスペクト比としてスケール画像を処理しています：

Bitmap bitmapImage = BitmapFactory.decodeFile("Your path");
int nh = (int) ( bitmapImage.getHeight() * (512.0 / bitmapImage.getWidth()) );
Bitmap scaled = Bitmap.createScaledBitmap(bitmapImage, 512, nh, true);
your_imageview.setImageBitmap(scaled);

Whatsappのような品質を失うことなく画像を圧縮する

public String compressImage(String imageUri) {

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

    }

    private String getRealPathFromURI(String contentURI) {
        Uri contentUri = Uri.parse(contentURI);
        Cursor cursor = 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;
    }
78
Jitty Aandyan

このコードを使用して、ビットマップをより小さなサイズで圧縮します。

BitmapFactory.Options Options = new BitmapFactory.Options();
Options.inSampleSize = 4;
Options.inJustDecodeBounds = false;
action_bitmap = BitmapFactory.decodeFile(Glob.savedImage, Options);

Glob.savedImageは、画像の文字列パスです。

1
Thoriya Prahalad

CompressFileイメージのクラスを作成

public class CompressFile {
    public static File getCompressedImageFile(File file, Context mContext) {
        try {
            BitmapFactory.Options o = new BitmapFactory.Options();
            o.inJustDecodeBounds = true;

            if (getFileExt(file.getName()).equals("png") || getFileExt(file.getName()).equals("PNG")) {
                o.inSampleSize = 6;
            } else {
                o.inSampleSize = 6;
            }

            FileInputStream inputStream = new FileInputStream(file);
            BitmapFactory.decodeStream(inputStream, null, o);
            inputStream.close();

            // The new size we want to scale to
            final int REQUIRED_SIZE = 100;

            // 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);

            ExifInterface ei = new ExifInterface(file.getAbsolutePath());
            int orientation = ei.getAttributeInt(ExifInterface.TAG_ORIENTATION,
                    ExifInterface.ORIENTATION_UNDEFINED);

            switch (orientation) {

                case ExifInterface.ORIENTATION_ROTATE_90:
                    rotateImage(selectedBitmap, 90);
                    break;

                case ExifInterface.ORIENTATION_ROTATE_180:
                    rotateImage(selectedBitmap, 180);
                    break;

                case ExifInterface.ORIENTATION_ROTATE_270:
                    rotateImage(selectedBitmap, 270);
                    break;

                case ExifInterface.ORIENTATION_NORMAL:

                default:
                    break;
            }
            inputStream.close();


            // here i override the original image file
            File folder = new File(Environment.getExternalStorageDirectory() + "/FolderName");
            boolean success = true;
            if (!folder.exists()) {
                success = folder.mkdir();
            }
            if (success) {
                File newFile = new File(new File(folder.getAbsolutePath()), file.getName());
                if (newFile.exists()) {
                    newFile.delete();
                }
                FileOutputStream outputStream = new FileOutputStream(newFile);

                if (getFileExt(file.getName()).equals("png") || getFileExt(file.getName()).equals("PNG")) {
                    selectedBitmap.compress(Bitmap.CompressFormat.PNG, 100, outputStream);
                } else {
                    selectedBitmap.compress(Bitmap.CompressFormat.JPEG, 100, outputStream);
                }

                return newFile;
            } else {
                return null;
            }
        } catch (Exception e) {
            return null;
        }
    }

    public static String getFileExt(String fileName) {
        return fileName.substring(fileName.lastIndexOf(".") + 1, fileName.length());
    }

    public static Bitmap rotateImage(Bitmap source, float angle) {
        Matrix matrix = new Matrix();
        matrix.postRotate(angle);
        return Bitmap.createBitmap(source, 0, 0, source.getWidth(), source.getHeight(),
                matrix, true);
    }
}
0
Mohsinali

ギャラリーから画像を取得する場合、受け入れられた回答は正常に機能しますが、ファイルマネージャから画像を取得しようとすると失敗します。その理由は、Uriの形式が異なるため、getRealPathFromURI(imageUri)は実際のパスを取得できません。

この問題を解決するには、ファイルマネージャーとギャラリーから取得した両方の画像をサポートするように調整されたcopressImage()とgetRealPathFromURI()を除いて、受け入れられた回答と同じ方法を使用します。

public static String compressImage(Context context, Uri uri) {

    String filePath = getRealPathFromURI(context, uri);
    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 = getFilename();
    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 static String getRealPathFromURI(Context context, Uri uri) {
    Uri queryUri = MediaStore.Files.getContentUri("external");
    String columnData = MediaStore.Files.FileColumns.DATA;
    String columnSize = MediaStore.Files.FileColumns.SIZE;

    String[] projectionData = {MediaStore.Files.FileColumns.DATA};


    String name = null;
    String size = null;

    Cursor cursor = context.getContentResolver().query(uri, null, null, null, null);
    if ((cursor != null) && (cursor.getCount() > 0)) {
        int nameIndex = cursor.getColumnIndex(OpenableColumns.DISPLAY_NAME);
        int sizeIndex = cursor.getColumnIndex(OpenableColumns.SIZE);

        cursor.moveToFirst();

        name = cursor.getString(nameIndex);
        size = cursor.getString(sizeIndex);

        cursor.close();
    }

    String imagePath = "";
    if ((name != null) && (size != null)) {
        String selectionNS = columnData + " LIKE '%" + name + "' AND " + columnSize + "='" + size + "'";

        Cursor cursorLike = context.getContentResolver().query(queryUri, projectionData, selectionNS, null, null);

        if ((cursorLike != null) && (cursorLike.getCount() > 0)) {
            cursorLike.moveToFirst();
            int indexData = cursorLike.getColumnIndex(columnData);
            if (cursorLike.getString(indexData) != null) {
                imagePath = cursorLike.getString(indexData);
            }
            cursorLike.close();
        }
    }

    return imagePath;
}
0
Zain