Question

我正在处理两个问题，试图在我的Android应用程序中显示图库中的照片。我想做的很简单：从图库中获取一张照片并将其放入我的MainActivity中的ImageView（100dp * 100dp）中。

第一个问题是，在某些手机上，例如Sony Xperia，照片在ImageView上设置时会旋转。为了解决这个问题，我在SO中找到了这段代码：

public Bitmap decodeFile(String path) 
{
    int orientation;

    try {
        if (path == null) {
            return null;
        }
        // decode image size
        BitmapFactory.Options o = new BitmapFactory.Options();
        o.inJustDecodeBounds = true;
        // Find the correct scale value. It should be the power of 2.
        final int REQUIRED_SIZE = 70;
        int width_tmp = o.outWidth, height_tmp = o.outHeight;
        int scale = 0;

        while (true) {
            if (width_tmp / 2 < REQUIRED_SIZE
                    || height_tmp / 2 < REQUIRED_SIZE)
                break;
            width_tmp /= 2;
            height_tmp /= 2;
            scale++;
        }
        // decode with inSampleSize
        BitmapFactory.Options o2 = new BitmapFactory.Options();
        o2.inSampleSize = scale;
        Bitmap bm = BitmapFactory.decodeFile(path, o2);
        Bitmap bitmap = bm;

        ExifInterface exif = new ExifInterface(path);

        orientation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION, 1);

        Log.e("ExifInteface .........", "rotation =" + orientation);

        // exif.setAttribute(ExifInterface.ORIENTATION_ROTATE_90, 90);

        Log.e("orientation", "" + orientation);
        Matrix m = new Matrix();

        if ((orientation == ExifInterface.ORIENTATION_ROTATE_180)) {
            m.postRotate(180);
            // m.postScale((float) bm.getWidth(), (float) bm.getHeight());
            // if(m.preRotate(90)){
            Log.e("in orientation", "" + orientation);
            bitmap = Bitmap.createBitmap(bm, 0, 0, bm.getWidth(),
                    bm.getHeight(), m, true);
            return bitmap;
        } else if (orientation == ExifInterface.ORIENTATION_ROTATE_90) {
            m.postRotate(90);
            Log.e("in orientation", "" + orientation);
            bitmap = Bitmap.createBitmap(bm, 0, 0, bm.getWidth(),
                    bm.getHeight(), m, true);
            return bitmap;
        } else if (orientation == ExifInterface.ORIENTATION_ROTATE_270) {
            m.postRotate(270);
            Log.e("in orientation", "" + orientation);
            bitmap = Bitmap.createBitmap(bm, 0, 0, bm.getWidth(),
                    bm.getHeight(), m, true);
            return bitmap;
        }
        return bitmap;
    } catch (Exception e) {
        return null;
    }
}

效果很好，但我也希望图像是正方形，现在情况并非如此。

为此，在我使用位图上的第一个方法后，我也称之为：

public static Bitmap cropToSquare(Bitmap bitmap)
{
    int width  = bitmap.getWidth();
    int height = bitmap.getHeight();
    int newWidth = (height > width) ? width : height;
    int newHeight = (height > width)? height - ( height - width) : height;
    int crop = (width - height) / 2;
    crop = (crop < 0)? 0: crop;
    Bitmap cropImg = Bitmap.createBitmap(bitmap, crop, 0, newWidth, newHeight);

    return cropImg;
}

它确实将位图变成了正方形，但问题是它会切割照片而不是重新缩放它。（基本上丢失了一半图像）

我很确定我想做的很简单，我该怎么做？

Answer 1

而不是使用，

Bitmap.createBitmap(bitmap, crop, 0, newWidth, newHeight);

使用以下行，

Bitmap.createScaledBitmap(bitmap, newWidth, newHeight, false);

Answer 2

无论如何，官方文件是最好的老师，请查看here

如何正确显示位图？

2 个答案: