缩放图像而不会丢失图像质量不起作用

Question

有谁知道如何缩放位图图像而不会失去图像质量？目前我面临这个问题,所选图像的大小可能太大导致应用程序返回到另一个活动.

所以现在我尝试使用这种方法来缩放所选图像而不会降低其质量.我从这里得到了代码.

 protected void onActivityResult(int requestCode, int resultCode,
                                    Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        switch (requestCode) {
            case RESULT_LOAD_IMAGE:
                if (requestCode == RESULT_LOAD_IMAGE && resultCode == RESULT_OK & null != data) {
                    Uri selectedImage = data.getData();
                    String[] filePathColumn = {MediaStore.Images.Media.DATA};
                    Cursor cursor = getContentResolver()
                            .query(selectedImage, filePathColumn, null, null,
                                    null);
                    cursor.moveToFirst();
                    int columnIndex = cursor.getColumnIndex(filePathColumn[0]);
                    String picturePath = cursor.getString(columnIndex);
                    cursor.close();
                    Bitmap a = (BitmapFactory.decodeFile(picturePath));
                    photo = scaleBitmap(a, 200, 200);
                    imageView.setImageBitmap(photo);
                }
                break;
}

  public static Bitmap scaleBitmap(Bitmap bitmap, int newWidth, int newHeight) {
        Bitmap scaledBitmap = Bitmap.createBitmap(newWidth, newHeight, Bitmap.Config.ARGB_8888);

        float scaleX = newWidth / (float) bitmap.getWidth();
        float scaleY = newHeight / (float) bitmap.getHeight();
        float pivotX = 0;
        float pivotY = 0;

        Matrix scaleMatrix = new Matrix();
        scaleMatrix.setScale(scaleX, scaleY, pivotX, pivotY);

        Canvas canvas = new Canvas(scaledBitmap);
        canvas.setMatrix(scaleMatrix);
        canvas.drawBitmap(bitmap, 0, 0, new Paint(Paint.FILTER_BITMAP_FLAG));

        return scaledBitmap;
    }

答案似乎对大多数人有帮助,但为什么它对我不起作用？我错过了什么吗？

原始图像

在imageView上选择图像显示

Answer 1

请尝试这个

public Bitmap scaleBitmap(Bitmap bitmap,int newWidth,int newHeight) {    
    Bitmap scaledBitmap = Bitmap.createBitmap(newWidth, newHeight, Config.ARGB_8888);

    float ratioX = newWidth / (float) bitmap.getWidth();
    float ratioY = newHeight / (float) bitmap.getHeight();
    float middleX = newWidth / 2.0f;
    float middleY = newHeight / 2.0f;

    Matrix scaleMatrix = new Matrix();
    scaleMatrix.setScale(ratioX, ratioY, middleX, middleY);

    Canvas canvas = new Canvas(scaledBitmap);
    canvas.setMatrix(scaleMatrix);
    canvas.drawBitmap(bitmap, middleX - bitmap.getWidth() / 2, middleY - bitmap.getHeight() / 2, new Paint(Paint.FILTER_BITMAP_FLAG));

    return scaledBitmap;

    }