Question

我必须将图像保存到sqlite db.It正在工作。例如我可以保存来自相机的照片。但是当我从照片库中选择一张照片（700kb或更多）时，它没有保存到DB中。所以我认为我可以制作这么大尺寸的照片。所以我在下面写了这些代码;

 protected void onActivityResult(int requestCode, int resultCode, Intent data) {
     if(requestCode == SELECT_PHOTO && resultCode == RESULT_OK){
        Uri selectedImage = data.getData();
        InputStream imageStream = null;
        try {
            imageStream = getContentResolver().openInputStream(selectedImage);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
        //Resmin boyutu küçültüldükten sonra DB'ye atılacak.102400,512000
        Bitmap yourSelectedImage = BitmapFactory.decodeStream(imageStream);
        cekilenFoto.setImageBitmap(yourSelectedImage);
        resimData = getBitmapAsByteArray(yourSelectedImage);
    }
}

这不是小事。它正在关闭设备上的应用程序。这里出了什么问题？

Answer 1

我认为重新调整图像的效果会减少图像的大小。

if ( yourSelectedImage!= null) {
        Bitmap resizedBitmap = Bitmap.createScaledBitmap(bit, width,
                height, true);
    cekilenFoto.setImageBitmap(resizedBitmap);
    resimData = getBitmapAsByteArray(resizedBitmap);
   }

你可以在int中给出的宽度和高度以及可变大小。恩。

int width=500;
int height=500;

Answer 2

虽然Sridhar的答案是有效的，但有一点要记住，它需要首先以完整大小解码InputStream，从而增加内存使用量。如果InputStream表示非常大的图像，这可能是一个问题，因为它可能导致OutOfMemoryExceptions。这是一个直接从InputStream到缩放位图的方法：

public static Bitmap scaledBitmapFromStream(Context context, InputStream tempIs) {
    // Buffer the InputStream so that it can be accessed twice.
    InputStream is = new BufferedInputStream(tempIs);

    // Find the dimensions of the input image, and calculate the sampleSize.
    BitmapFactory.Options options = new BitmapFactory.Options();
    options.inJustDecodeBounds = true;
    BitmapFactory.decodeStream(is, null, options);
    options.inJustDecodeBounds = false;

    // Calculate the inSampleSize. This is the factor that the image will be rescaled by.
    options.inSampleSize = calculateInSampleSize(context, options.outWidth, options.outHeight);

    // Reset the input stream, so it can be read again.
    try {
        is.reset();
    } catch (IOException e) {
        throw new RuntimeException("BufferedInputStream.reset() failed.", e);
    }

    // The 'options' parameter here tells the BitmapFactory to downscale.
    Bitmap output = BitmapFactory.decodeStream(is, null, options);

    // Close the input stream.
    try {
        is.close();
    } catch (IOException e) {
        e.printStackTrace();
    }

    return output;
}

/**
 * How much you want to downsample will vary based on your application, but this implementation
 * calculates a safe display size based on devices screen resolution and OpenGL MAX_TEXTURE_SIZE.
 */
public static int calculateInSampleSize(Context context, int inputWidth, int inputHeight) {
    DisplayMetrics displayMetrics = context.getResources().getDisplayMetrics();
    final int maxWidth = Math.min(displayMetrics.widthPixels, GLES20.GL_MAX_TEXTURE_SIZE);
    final int maxHeight = Math.min(displayMetrics.heightPixels, GLES20.GL_MAX_TEXTURE_SIZE);

    int inSampleSize = 1;
    if (inputWidth > maxWidth || inputHeight > maxHeight) {

        // Calculate ratios of height and width to requested height and width
        final int heightRatio = Math.round((float) inputHeight / (float) maxHeight);
        final int widthRatio = Math.round((float) inputWidth / (float) maxWidth);

        // Choose the smallest ratio as inSampleSize value, this will guarantee
        // a final image with both dimensions larger than or equal to the
        // requested height and width.
        inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
    }

    return inSampleSize;
}

有关inJustDecodeBounds和Bitmap sampling的更多信息，请参阅https://developer.android.com/training/displaying-bitmaps/load-bitmap.html。

如何缩小从图库中选择的照片的尺寸

2 个答案: