Question

我正在尝试减少用户从Gallery中选择的图像的大小，然后再将其传递给另一个intent。

我目前正在使用以下代码，但它似乎无法正常工作：

private Bitmap decodeFile(File f) throws IOException {
    Bitmap b = null;

    //Decode image size
    BitmapFactory.Options o = new BitmapFactory.Options();
    o.inJustDecodeBounds = true;

    FileInputStream fis = null;
    fis = new FileInputStream(f);

    BitmapFactory.decodeStream(fis, null, o);
    fis.close();

    int scale = 1;
    if (o.outHeight > IMAGE_MAX_SIZE || o.outWidth > IMAGE_MAX_SIZE) {
        scale = (int)Math.pow(2, (int) Math.ceil(Math.log(IMAGE_MAX_SIZE / 
           (double) Math.max(o.outHeight, o.outWidth)) / Math.log(0.5)));
    }

    //Decode with inSampleSize
    BitmapFactory.Options o2 = new BitmapFactory.Options();
    o2.inSampleSize = scale;
    fis = new FileInputStream(f);
    b = BitmapFactory.decodeStream(fis, null, o2);
    fis.close();

    return b;
}

Answer 1

最好的方法是通过意图传递图像路径，然后从那里降低图像质量。您无需降低当前活动中的图像质量并传递降级后的图像。

按照此处降低图像质量read here。那里使用inSampleSize可以降低图像质量。 inSampleSize越高，图像尺寸越小。

Answer 2

要压缩图像，您可以在代码下方使用。

import android.graphics.Bitmap;
import android.graphics.Bitmap.CompressFormat;
import android.graphics.BitmapFactory;
import android.graphics.Matrix;
import android.media.ExifInterface;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

public class ImageResizer {

    public static String getCompressImageFile(File original, int width, int height, String filePath) {
        Bitmap sampledSrcBitmap = decodeFile(original, width, height);

        if(sampledSrcBitmap == null) {
            return null;
        }
        Bitmap bitmap = getRotatedImage(sampledSrcBitmap,original.getPath());

        int bitmap_width = bitmap.getWidth();
        int bitmap_height = bitmap.getHeight();

        boolean success;
        if(bitmap_width<width && bitmap_height <height){
            success = writeToFile(bitmap, new File(filePath),100);
        }else{
            bitmap = resize(bitmap, width, height);
            success = writeToFile(bitmap, new File(filePath),80);
        }
        bitmap.recycle();
        if(success){
            return filePath;
        }else{
            return null;
        }
    }

    private static Bitmap getRotatedImage(Bitmap sampledSrcBitmap,String path){
        ExifInterface exif;
        Matrix matrix = new Matrix();
        Bitmap bitmap=null;
        try {
            exif = new ExifInterface(path);
            int orientation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION, 0);
            if (orientation == 6) {
                matrix.postRotate(90);
            } else if (orientation == 3) {
                matrix.postRotate(180);
            } else if (orientation == 8) {
                matrix.postRotate(270);
            }
            bitmap  = Bitmap.createBitmap(sampledSrcBitmap, 0, 0, sampledSrcBitmap.getWidth(), sampledSrcBitmap.getHeight(), matrix, true);
        } catch (IOException e) {
            e.printStackTrace();
        }
        return bitmap;
    }

    public static Bitmap resize(Bitmap sampledSrcBitmap, int width, int height) {
        int sourceWidth = sampledSrcBitmap.getWidth();
        int sourceHeight = sampledSrcBitmap.getHeight();
        height = calculateHeight(sourceWidth, sourceHeight, width);
        return Bitmap.createScaledBitmap(sampledSrcBitmap, width, height, true);
    }

    private static int calculateWidth(int originalWidth, int originalHeight, int height) {
        return (int) Math.ceil(originalWidth / ((double) originalHeight/height));
    }

    private static int calculateHeight(int originalWidth, int originalHeight, int width) {
        return (int) Math.ceil(originalHeight / ((double) originalWidth/width));
    }

    public static Bitmap decodeFile(File bitmapFile, int reqWidth, int reqHeight){
        BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeFile(bitmapFile.getAbsolutePath(), options);

        options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);
        options.inJustDecodeBounds = false;
        options.inDither = false;
        options.inPurgeable = true;
        options.inInputShareable = true;
        options.inPreferQualityOverSpeed = true;

        return BitmapFactory.decodeFile(bitmapFile.getAbsolutePath(), options);
    }

    public static int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) {
        if(reqWidth == -1) {
            reqWidth = options.outWidth;
        }

        if(reqHeight == -1) {
            reqHeight = options.outHeight;
        }

        // Raw height and width of image
        final int height = options.outHeight;
        final int width = options.outWidth;
        int inSampleSize = 1;

        if (height > reqHeight || width > reqWidth) {
            if (width > height) {
                inSampleSize = Math.round((float) height / (float) reqHeight);
            } else {
                inSampleSize = Math.round((float) width / (float) reqWidth);
            }
        }

        return inSampleSize;
    }

    public static boolean writeToFile(Bitmap image, File file, int quality) {
        ByteArrayOutputStream bytes = new ByteArrayOutputStream();
        image.compress(CompressFormat.JPEG, quality, bytes);

        try {

            FileOutputStream fos = new FileOutputStream(file);
            fos.write(bytes.toByteArray());
            fos.close();

        } catch (FileNotFoundException e) {
            e.printStackTrace();
            return false;
        } catch (IOException e) {
            e.printStackTrace();
            return false;
        }

        return true;
    }

}

要获取压缩图像路径调用getComressImagePath方法并为压缩选择图库图像路径。将压缩映像路径传递给下一个活动，您可以使用它上传到服务器。

   public static String getComressImagePath(String picturePath){
         //Here 720 is max width and 1280 is max height. you can set this as per your need. Lower the resolution smaller the image size.
        return ImageResize.getCompressFile(new File(picturePath), 720, 1280, getTempImagePath());
   }

   public static String getTempImagePath(){
        File root = new File(Environment.getExternalStorageDirectory() + File.separator + "IMAGES");

        if (!root.exists()) {
            root.mkdirs();
        }

        File image = null;  
        image = new File(root+File.separator+"fileName");
        try {
           image.createNewFile();
           return image.getAbsolutePath();      
       } catch (IOException e) {
           e.printStackTrace();
       }

       return null;
   }

Answer 3

您可以使用此代码......

public static Bitmap getThumbnailBitmap(final String path,
        final int thumbnailSize) {
    Bitmap bitmap;
    BitmapFactory.Options bounds = new BitmapFactory.Options();
    bounds.inJustDecodeBounds = true;
    BitmapFactory.decodeFile(path, bounds);
    if ((bounds.outWidth == -1) || (bounds.outHeight == -1)) {
        bitmap = null;
    }
    int originalSize = (bounds.outHeight > bounds.outWidth) ? bounds.outHeight
            : bounds.outWidth;
    BitmapFactory.Options opts = new BitmapFactory.Options();
    if (thumbnailSize > 0) {
        opts.inSampleSize = originalSize / thumbnailSize;
    } else {
        opts.inSampleSize = originalSize;
    }
    try {
        bitmap = BitmapFactory.decodeFile(path, opts);

    } catch (Exception ex) {
        return null;
    }
    return bitmap;
}

缩小图像尺寸

3 个答案: