Question

我正在以全屏模式显示图像，但每当要显示大图像时，图像视图中都不会显示任何内容。下面的代码尝试调整位图大小但得到相同的结果空白imageview。

public static Bitmap getResizedBitmap(Bitmap bm, int newHeight, int newWidth) {
        int width = bm.getWidth();
        int height = bm.getHeight();
        float scaleWidth = ((float) newWidth) / width;
        float scaleHeight = ((float) newHeight) / height;
        Matrix matrix = new Matrix();
        // RESIZE THE BIT MAP
        matrix.postScale(scaleWidth, scaleHeight);
        // RECREATE THE NEW BITMAP
        Bitmap resizedBitmap = Bitmap.createBitmap(bm, 0, 0, width, height,
                matrix, false);
        return resizedBitmap;
    }

Answer 1

你可以从两个方面解决问题 方法1

调用此方法（函数）

public Bitmap decodeImage(int resourceId) {
        try {
            // Decode image size
            BitmapFactory.Options o = new BitmapFactory.Options();
            o.inJustDecodeBounds = true;
            BitmapFactory.decodeResource(getResources(), resourceId, o);
            // The new size we want to scale to
            final int REQUIRED_SIZE = 100; // you are free to modify size as your requirement

            // 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;

            // Decode with inSampleSize
            BitmapFactory.Options o2 = new BitmapFactory.Options();
            o2.inSampleSize = scale;
            return BitmapFactory.decodeResource(getResources(), resourceId, o2);
        } catch (Throwable e) {
            e.printStackTrace();
        }
        return null;

    }

在适配器之前添加此内容

picture.setImageBitmap((decodeImage(item.drawableId));

而不是

 picture.setImageResource(item.drawableId);

Mehtod 2

您需要调整图像大小。更好的方法是将图像解码为位图，并将位图设置为ImageView。例如：

BitmapFactory.Options opts = new BitmapFactory.Options();
opts.inSampleSize = 4;
Bitmap bitmap = BitmapFactory.decodeResource(getResources(), item.drawableId, opts);
picture.setImageBitmap (bitmap);

Answer 2

我遇到了同样的问题。通过以下代码解决了。向方法提供filepath，desired width和desired height。有关更多参考see here

public static Bitmap decodeScaledBitmapFromSdCard(String filePath,
    int reqWidth, int reqHeight) {

    // First decode with inJustDecodeBounds=true to check dimensions
    final BitmapFactory.Options options = new BitmapFactory.Options();
    options.inJustDecodeBounds = true;
    BitmapFactory.decodeFile(filePath, options);

// Calculate inSampleSize
   options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);

// Decode bitmap with inSampleSize set
    options.inJustDecodeBounds = false;
    return BitmapFactory.decodeFile(filePath, options);
}

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;
    int inSampleSize = 1;

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

    // Calculate ratios of height and width to requested height and width
      final int heightRatio = Math.round((float) height / (float) reqHeight);
      final int widthRatio = Math.round((float) width / (float) reqWidth);

    // 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;
}

Answer 3

可能图像尺寸太大，系统无法分配足够的内存来加载它。

您可以尝试使用 BitmapFactory.Options sampleSize

对其进行缩放后加载图片

查看此链接以获取更多信息 http://developer.android.com/training/displaying-bitmaps/load-bitmap.html

Answer 4

可能会对你有用

   public static Bitmap decodeSampledBitmapFromResource(String pathName,
        int reqWidth, int reqHeight) {

    // First decode with inJustDecodeBounds=true to check dimensions
    final BitmapFactory.Options options = new BitmapFactory.Options();
    options.inJustDecodeBounds = true;
    BitmapFactory.decodeFile(pathName, options);

    // Calculate inSampleSize
    options.inSampleSize = calculateInSampleSize(options, reqWidth,
            reqHeight);

    // Decode bitmap with inSampleSize set
    options.inJustDecodeBounds = false;
    return BitmapFactory.decodeFile(pathName, options);
}

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;
    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;
}

Answer 5

您可以在Fragment中解决问题在适配器中添加方法

 public Bitmap decodeImage(int gridViewImageId) {
    try {
        // Decode image size
        BitmapFactory.Options o = new BitmapFactory.Options();
        o.inJustDecodeBounds = true;
        BitmapFactory.decodeResource(mContext.getResources(), gridViewImageId, o);
        // The new size we want to scale to
        final int REQUIRED_SIZE = 100; // you are free to modify size as your requirement

        // 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;

        // Decode with inSampleSize
        BitmapFactory.Options o2 = new BitmapFactory.Options();
        o2.inSampleSize = scale;
        return BitmapFactory.decodeResource(mContext.getResources(), gridViewImageId, o2);
    } catch (Throwable e) {
        e.printStackTrace();
    }
    return null;

}

并添加此行

imageViewAndroid.setImageBitmap(decodeImage(gridViewImageId[i]));

ImageView Android中无法显示高分辨率图像

5 个答案: