Android实现拍照 并裁剪图片功能

实现拍照并裁剪图片功能需要以下步骤：

1. 添加权限

在AndroidManifest.xml文件中添加以下权限：

<uses-permission android:name="android.permission.CAMERA"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

2. 创建布局文件

创建一个布局文件camera_preview.xml，并添加一个SurfaceView和一个Button，用于显示和拍照。

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/camera_preview"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <SurfaceView
        android:id="@+id/surface_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

    <Button
        android:id="@+id/button_capture"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="拍照"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"/>

</RelativeLayout>

3. 实现拍照功能

在Activity中，获取Camera实例，并在SurfaceView上显示预览图像。当用户点击拍照按钮时，调用Camera.takePicture()方法拍照。拍照成功后，保存照片并显示裁剪界面。

public class CameraActivity extends Activity implements SurfaceHolder.Callback {

    private Camera mCamera;
    private SurfaceView mSurfaceView;
    private SurfaceHolder mSurfaceHolder;
    private Button mButtonCapture;

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

        // 获取SurfaceView和Button实例
        mSurfaceView = findViewById(R.id.surface_view);
        mButtonCapture = findViewById(R.id.button_capture);

        // 监听Button点击事件
        mButtonCapture.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // 拍照
                mCamera.takePicture(null, null, mPictureCallback);
            }
        });

        // 获取SurfaceHolder实例，并添加回调监听
        mSurfaceHolder = mSurfaceView.getHolder();
        mSurfaceHolder.addCallback(this);
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        // 打开摄像头并设置预览
        mCamera = Camera.open();
        try {
            mCamera.setPreviewDisplay(holder);
            mCamera.startPreview();
        } catch (IOException e) {
            Log.d("CameraTest", "Error setting camera preview: " + e.getMessage());
        }
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
        // 在SurfaceView上显示预览图像
        if (mSurfaceHolder.getSurface() == null) {
            return;
        }
        try {
            mCamera.stopPreview();
        } catch (Exception e) {
            Log.d("CameraTest", "Error stopping camera preview: " + e.getMessage());
        }
        try {
            mCamera.setPreviewDisplay(mSurfaceHolder);
            mCamera.startPreview();
        } catch (Exception e) {
            Log.d("CameraTest", "Error starting camera preview: " + e.getMessage());
        }
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        // 释放摄像头资源
        mCamera.stopPreview();
        mCamera.release();
        mCamera = null;
    }

    private Camera.PictureCallback mPictureCallback = new Camera.PictureCallback() {
        @Override
        public void onPictureTaken(byte[] data, Camera camera) {
            // 保存照片
            File pictureFile = getOutputMediaFile();
            if (pictureFile == null) {
                Log.d("CameraTest", "Error creating media file, check storage permissions");
                return;
            }
            try {
                FileOutputStream fos = new FileOutputStream(pictureFile);
                fos.write(data);
                fos.close();
            } catch (FileNotFoundException e) {
                Log.d("CameraTest", "File not found: " + e.getMessage());
            } catch (IOException e) {
                Log.d("CameraTest", "Error accessing file: " + e.getMessage());
            }

            // 显示裁剪界面
            Intent intent = new Intent(CameraActivity.this, CropActivity.class);
            intent.putExtra("image_path", pictureFile.getPath());
            startActivity(intent);
        }
    };

    private File getOutputMediaFile() {
        // 创建目录
        File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(
                Environment.DIRECTORY_PICTURES), "MyCameraApp");
        if (!mediaStorageDir.exists()) {
            if (!mediaStorageDir.mkdirs()) {
                Log.d("CameraTest", "failed to create directory");
                return null;
            }
        }

        // 创建文件
        String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
        File mediaFile = new File(mediaStorageDir.getPath() + File.separator +
                "IMG_" + timeStamp + ".jpg");
        return mediaFile;
    }
}

4. 实现裁剪功能

创建一个布局文件crop.xml，添加一个ImageView和一个Button，用于显示图片和保存裁剪后的图片。

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/crop_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ImageView
        android:id="@+id/image_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:scaleType="fitCenter"/>

    <Button
        android:id="@+id/button_save"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="保存"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"/>

</RelativeLayout>

在CropActivity中，获取传递过来的图片路径，并将图片显示在ImageView上。当用户点击保存按钮时，调用Bitmap.createBitmap()方法裁剪图片，并保存到相册。

public class CropActivity extends Activity {

    private ImageView mImageView;
    private Button mButtonSave;

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

        // 获取ImageView和Button实例
        mImageView = findViewById(R.id.image_view);
        mButtonSave = findViewById(R.id.button_save);

        // 获取传递过来的图片路径
        Intent intent = getIntent();
        String imagePath = intent.getStringExtra("image_path");

        // 将图片显示在ImageView上
        Bitmap bitmap = BitmapFactory.decodeFile(imagePath);
        mImageView.setImageBitmap(bitmap);

        // 监听Button点击事件
        mButtonSave.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // 裁剪并保存图片
                Bitmap croppedBitmap = getCroppedBitmap(bitmap);
                saveBitmapToGallery(croppedBitmap);
                Toast.makeText(getApplicationContext(), "保存成功", Toast.LENGTH_SHORT).show();
                finish();
            }
        });
    }

    private Bitmap getCroppedBitmap(Bitmap bitmap) {
        // 获取ImageView的尺寸
        int viewWidth = mImageView.getWidth();
        int viewHeight = mImageView.getHeight();

        // 获取图片的尺寸
        int imageWidth = bitmap.getWidth();
        int imageHeight = bitmap.getHeight();

        // 计算缩放比例
        float scale = Math.min((float) viewWidth / imageWidth, (float) viewHeight / imageHeight);

        // 计算裁剪区域
        int cropWidth = (int) (viewWidth / scale);
        int cropHeight = (int) (viewHeight / scale);
        int x = (imageWidth - cropWidth) / 2;
        int y = (imageHeight - cropHeight) / 2;

        // 裁剪图片
        Bitmap croppedBitmap = Bitmap.createBitmap(bitmap, x, y, cropWidth, cropHeight);
        return croppedBitmap;
    }

    private void saveBitmapToGallery(Bitmap bitmap) {
        // 创建目录
        File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(
                Environment.DIRECTORY_PICTURES), "MyCameraApp");
        if (!mediaStorageDir.exists()) {
            if (!mediaStorageDir.mkdirs()) {
                Log.d("CameraTest", "failed to create directory");
                return;
            }
        }

        // 保存图片
        String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
        String imagePath = mediaStorageDir.getPath() + File.separator +
                "IMG_" + timeStamp + ".jpg";
        File imageFile = new File(imagePath);
        try {
            FileOutputStream fos = new FileOutputStream(imageFile);
            bitmap.compress(Bitmap.CompressFormat.JPEG, 100, fos);
            fos.flush();
            fos.close();
        } catch (IOException e) {
            Log.d("CameraTest", "Error accessing file: " + e.getMessage());
        }

        // 通知相册更新
        MediaScannerConnection.scanFile(this, new String[]{imagePath}, null, null);
    }
}