#HarmonyOS NEXT体验官#鸿蒙原生应用开发项目实战: 相机应用原创

鱼弦CTO

发布于 2024-8-27 09:46

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鸿蒙原生应用开发项目实战: 相机应用

介绍

本项目演示如何在鸿蒙操作系统上开发一个相机应用，它能够调用系统相机进行拍照和录像，并提供简单的图片编辑功能，如裁剪和滤镜效果。我们将使用CameraX库进行相机操作，并通过Bitmap API实现图像处理。

应用使用场景

日常拍摄：用户可以使用该应用随时拍摄照片和录制视频。
图片编辑：用户拍摄完毕后，可以对图片进行简单编辑，提高照片的观赏性。
社交分享：处理完的图片可以方便地分享到各大社交平台上。

原理解释

相机操作

CameraX是谷歌推出的现代化相机库，旨在简化相机相关的开发工作。它基于生命周期管理，使得相机的使用更加直观和可靠。

图像处理

通过Bitmap类，Android提供了强大的图像操作API。我们可以很方便地裁剪、旋转、调整颜色等。

算法原理流程图

+------------------+
| 启动应用         |
+--------+---------+
         |
         v
+--------+---------+
| 打开相机界面     |
+--------+---------+
         |
         v
+--------+---------+
| 用户选择拍照或录像|
+--------+---------+
         |
         v
+------------------+<---+
| 拍摄或录制视频   |    |
+--------+---------+    |
         |              |
         v              |
+--------+---------+----+
| 显示拍摄结果     |
+--------+---------+
         |
         v
+--------+---------+
| 用户选择编辑或保存|
+--------+---------+
         |
         v
+------------------+
| 裁剪/应用滤镜    |
+--------+---------+
         |
         v
+------------------+
| 保存并分享       |
+--------+---------+

实际应用代码示例实现

CameraX 初始化

public class MainActivity extends AppCompatActivity {

    private PreviewView previewView;

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

        previewView = findViewById(R.id.previewView);
        startCamera();
    }

    private void startCamera() {
        ListenableFuture<ProcessCameraProvider> cameraProviderFuture =
            ProcessCameraProvider.getInstance(this);

        cameraProviderFuture.addListener(() -> {
            try {
                ProcessCameraProvider cameraProvider = cameraProviderFuture.get();
                
                Preview preview = new Preview.Builder().build();
                CameraSelector cameraSelector = new CameraSelector.Builder()
                    .requireLensFacing(CameraSelector.LENS_FACING_BACK)
                    .build();

                preview.setSufaceProvider(previewView.getSufaceProvider());
                Camera camera = cameraProvider.bindToLifecycle((LifecycleOwner) this, cameraSelector, preview);

            } catch (Exception e) {
                Log.e(TAG, "Use case binding failed", e);
            }
        }, ContextCompat.getMainExecutor(this));
    }
}

拍照功能实现

private void takePhoto() {
    ImageCapture imageCapture = new ImageCapture.Builder().build();
    
    File photoFile = new File(getOutputDirectory(), 
        new SimpleDateFormat("yyyyMMdd_HHmmss", Locale.US).format(new Date()) + ".jpg");

    ImageCapture.OutputFileOptions outputOptions = 
        new ImageCapture.OutputFileOptions.Builder(photoFile).build();

    imageCapture.takePicture(outputOptions, ContextCompat.getMainExecutor(this), 
        new ImageCapture.OnImageSavedCallback() {
            @Override
            public void onImageSaved(@NonNull ImageCapture.OutputFileResults outputFileResults) {
                String msg = "Photo capture succeeded: " + photoFile.getAbsolutePath();
                Toast.makeText(getBaseContext(), msg, Toast.LENGTH_SHORT).show();
            }

            @Override
            public void onError(@NonNull ImageCaptureException exception) {
                String msg = "Photo capture failed: " + exception.getMessage();
                Toast.makeText(getBaseContext(), msg, Toast.LENGTH_SHORT).show();
            }
        });
}

简单图片编辑（裁剪）

public Bitmap cropBitmap(Bitmap source, int x, int y, int width, int height) {
    return Bitmap.createBitmap(source, x, y, width, height);
}

添加滤镜效果

public Bitmap applyFilter(Bitmap source) {
    Bitmap result = Bitmap.createBitmap(source.getWidth(), source.getHeight(), source.getConfig());
    for (int x = 0; x < source.getWidth(); x++) {
        for (int y = 0; y < source.getHeight(); y++) {
            int pixel = source.getPixel(x, y);
            int red = Color.red(pixel);
            int green = Color.green(pixel);
            int blue = Color.blue(pixel);
            int alpha = Color.alpha(pixel);

            int newRed = (red + 50) > 255 ? 255 : (red + 50);
            int newGreen = (green + 50) > 255 ? 255 : (green + 50);
            int newBlue = (blue + 50) > 255 ? 255 : (blue + 50);

            int newPixel = Color.argb(alpha, newRed, newGreen, newBlue);
            result.setPixel(x, y, newPixel);
        }
    }
    return result;
}

测试代码

public class CameraAppTest {

    @Test
    public void testCropBitmap() {
        Bitmap source = BitmapFactory.decodeResource(getResources(), R.drawable.sample);
        Bitmap cropped = cropBitmap(source, 10, 10, 100, 100);
        assertEquals(100, cropped.getWidth());
        assertEquals(100, cropped.getHeight());
    }

    @Test
    public void testApplyFilter() {
        Bitmap source = BitmapFactory.decodeResource(getResources(), R.drawable.sample);
        Bitmap filtered = applyFilter(source);
        // Add assertions to check the correctness of the applied filter.
    }
}