Android:旋转并显示文件中的图像 [英] Android: Rotate and display image from file

问题描述

我有一个非常简单的ImageView布局.我的应用程序打开相机，保存图像，然后使用BitmapFactory.decodeFile在ImageView中显示图像.唯一的问题是它旋转了.我知道a)这是由于手机的摄像头默认设置为横向，所以这需要用代码处理，并且b)图像处理必须在与UI分开的线程中完成.

I have a very simple layout with an ImageView. My application opens the camera, saves an image, and then displays the image in the ImageView with BitmapFactory.decodeFile. The only issue is that it's rotated. I understand that a) this is due to the phone's camera defaulting to landscape, so this needs to be handled in code and b) image processing must be done in a separate thread from the UI.

Android培训文档似乎旨在从资源ID而不是文件路径加载图像.因为我可以完全按照教程进行操作，但是最终还是难以解决分歧.

The Android training documentation seems to be geared toward loading images from resource id's instead of file paths. This just throws a wrench in things as I'm able to follow the tutorials up to a point but ultimately have trouble reconciling the differences.

我当然是新来的，所以如果有人可以给我一个高水平的概述来完成此任务需要做什么，我将非常感激.以下代码是我当前将位图添加到ImageView的位置.我假设对单独线程的调用将在onCreate中进行?

I'm certainly new at this so if someone could just give me a high-level overview of what needs to be done to accomplish this, I'd really appreciate it. The following code is where I'm currently adding the bitmap to the ImageView. I assume that my call to the separate thread would go in onCreate?

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_display_image);

    Bitmap bm = BitmapFactory.decodeFile(MainActivity.image_path);

    displayImageView = (ImageView) findViewById(R.id.myImageView);

    displayImageView.setImageBitmap(bm);
}

推荐答案

使用 ExifInterface 旋转

picturePath = getIntent().getStringExtra("path");
Bitmap bitmap = BitmapFactory.decodeFile(picturePath);
ExifInterface exif = new ExifInterface(picturePath);
int orientation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION, ExifInterface.ORIENTATION_UNDEFINED);

Matrix matrix = new Matrix();
switch (orientation) {
case ExifInterface.ORIENTATION_ROTATE_90:
    matrix.postRotate(90);
    break;
case ExifInterface.ORIENTATION_ROTATE_180:
    matrix.postRotate(180);
    break;
case ExifInterface.ORIENTATION_ROTATE_270:
    matrix.postRotate(270);
    break;
default:
    break;
}

myImageView.setImageBitmap(bitmap);
bitmap.recycle();

注意::此处选择picturePath来自Gallery

• 教程

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