Android的Camera比较难用,从一代到二代的API接口,对开发者都不友好,这两天正好做个项目,要实时获取到预览画面的图片,使用Camera2做,看了Google的Demo,只能拍照,没法有实时回调,类似于Camera1的OnPreviewCallBack,查阅得知,Camera2用ImageReader来实现,基于源码,自己封装了一个类,先看看分装后的写法
- public class MainActivity extends AppCompatActivity {
- private AutoFitTextureView mTextureView;
- private Camera2Helper helper;
- @Override
- protected void onCreate(Bundle savedInstanceState) {
- super.onCreate(savedInstanceState);
- setContentView(R.layout.activity_main);
- init();
- }
- @Override
- public void onResume() {
- super.onResume();
- helper.open(); //会动态请求权限,请重写 onRequestPermissionsResult
- }
- public void init() {
- mTextureView = findViewById(R.id.texture);
- helper = new Camera2Helper(this, mTextureView);
- helper.setOnImageAvailableListener(new Camera2Helper.OnPreviewCallbackListener() {
- @Override
- public void onImageAvailable(Image image) {
- Log.d("weijw1", "helper onImageAvailable");
- }
- });
- }
- @Override
- public void onPause() {
- helper.closeCamera();
- super.onPause();
- }
- @Override
- public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions,
- @NonNull int[] grantResults) {
- if (requestCode == helper.getCameraRequestCode()) {
- if (grantResults.length != 1 || grantResults[0] != PackageManager.PERMISSION_GRANTED) {
- Toast.makeText(getApplicationContext(), R.string.request_permission, Toast.LENGTH_SHORT).show();
- }
- } else {
- super.onRequestPermissionsResult(requestCode, permissions, grantResults);
- }
- }
- }
封装的类,交Camera2Helper,对外常用的接口,就只有 open,closeCamera,和一个setOnImageAvailableListener来接收回调
- public class Camera2Helper {
- private static final String TAG = "Camera2Helper";
- private Activity mActivity;
- private AutoFitTextureView mTextureView;
- private HandlerThread mBackgroundThread;
- private Handler mBackgroundHandler;
- private CaptureRequest.Builder mPreviewRequestBuilder;
- private CaptureRequest mPreviewRequest;
- private static final int REQUEST_CAMERA_PERMISSION = 1;
- private ImageReader mImageReader;
- private static final int STATE_PREVIEW = 0;
- private static final int STATE_WAITING_LOCK = 1;
- private static final int STATE_WAITING_PRECAPTURE = 2;
- private static final int STATE_WAITING_NON_PRECAPTURE = 3;
- private static final int STATE_PICTURE_TAKEN = 4;
- private static final int MAX_PREVIEW_WIDTH = 1920;
- private static final int MAX_PREVIEW_HEIGHT = 1080;
- private int mImageFormat = ImageFormat.YUV_420_888;
- private int mState = STATE_PREVIEW;
- private int mSensorOrientation; //Orientation of the camera sensor
- private String mCameraId;
- private Semaphore mCameraOpenCloseLock = new Semaphore(1);
- private CameraCaptureSession mCaptureSession;
- private CameraDevice mCameraDevice;
- private Size mPreviewSize;
- private OnOpenErrorListener mOpenErrorListener; //打开错误,不设置才用默认策略
- private OnPreviewCallbackListener mImageAvaiableListener; //摄像头画面可达的时候
- public Camera2Helper(@NonNull Activity activity, @NonNull AutoFitTextureView textureView) {
- this.mActivity = activity;
- this.mTextureView = textureView;
- }
- /**
- * {@link TextureView.SurfaceTextureListener} handles several lifecycle events on a
- * {@link TextureView}.
- */
- private final TextureView.SurfaceTextureListener mSurfaceTextureListener
- = new TextureView.SurfaceTextureListener() {
- @Override
- public void onSurfaceTextureAvailable(SurfaceTexture texture, int width, int height) {
- openCamera(width, height);
- }
- @Override
- public void onSurfaceTextureSizeChanged(SurfaceTexture texture, int width, int height) {
- configureTransform(width, height);
- }
- @Override
- public boolean onSurfaceTextureDestroyed(SurfaceTexture texture) {
- return true;
- }
- @Override
- public void onSurfaceTextureUpdated(SurfaceTexture texture) {
- }
- };
- /**
- * {@link CameraDevice.StateCallback} is called when {@link CameraDevice} changes its state.
- */
- private final CameraDevice.StateCallback mStateCallback = new CameraDevice.StateCallback() {
- @Override
- public void onOpened(@NonNull CameraDevice cameraDevice) {
- // This method is called when the camera is opened. We start camera preview here.
- mCameraOpenCloseLock.release();
- mCameraDevice = cameraDevice;
- createCameraPreviewSession();
- }
- @Override
- public void onDisconnected(@NonNull CameraDevice cameraDevice) {
- mCameraOpenCloseLock.release();
- cameraDevice.close();
- mCameraDevice = null;
- }
- @Override
- public void onError(@NonNull CameraDevice cameraDevice, int error) {
- mCameraOpenCloseLock.release();
- cameraDevice.close();
- mCameraDevice = null;
- if (mOpenErrorListener != null) {
- mOpenErrorListener.onOpenError();
- } else {
- mActivity.finish();
- }
- }
- };
- /**
- * A {@link CameraCaptureSession.CaptureCallback} that handles events related to JPEG capture.
- */
- private CameraCaptureSession.CaptureCallback mCaptureCallback
- = new CameraCaptureSession.CaptureCallback() {
- private void process(CaptureResult result) {
- switch (mState) {
- case STATE_PREVIEW: {
- // We have nothing to do when the camera preview is working normally.
- break;
- }
- case STATE_WAITING_LOCK: {
- Integer afState = result.get(CaptureResult.CONTROL_AF_STATE);
- if (afState == null) {
- } else if (CaptureResult.CONTROL_AF_STATE_FOCUSED_LOCKED == afState ||
- CaptureResult.CONTROL_AF_STATE_NOT_FOCUSED_LOCKED == afState) {
- // CONTROL_AE_STATE can be null on some devices
- Integer aeState = result.get(CaptureResult.CONTROL_AE_STATE);
- if (aeState == null ||
- aeState == CaptureResult.CONTROL_AE_STATE_CONVERGED) {
- mState = STATE_PICTURE_TAKEN;
- } else {
- runPrecaptureSequence();
- }
- }
- break;
- }
- case STATE_WAITING_PRECAPTURE: {
- // CONTROL_AE_STATE can be null on some devices
- Integer aeState = result.get(CaptureResult.CONTROL_AE_STATE);
- if (aeState == null ||
- aeState == CaptureResult.CONTROL_AE_STATE_PRECAPTURE ||
- aeState == CaptureRequest.CONTROL_AE_STATE_FLASH_REQUIRED) {
- mState = STATE_WAITING_NON_PRECAPTURE;
- }
- break;
- }
- case STATE_WAITING_NON_PRECAPTURE: {
- // CONTROL_AE_STATE can be null on some devices
- Integer aeState = result.get(CaptureResult.CONTROL_AE_STATE);
- if (aeState == null || aeState != CaptureResult.CONTROL_AE_STATE_PRECAPTURE) {
- mState = STATE_PICTURE_TAKEN;
- }
- break;
- }
- }
- }
- @Override
- public void onCaptureProgressed(@NonNull CameraCaptureSession session,
- @NonNull CaptureRequest request,
- @NonNull CaptureResult partialResult) {
- process(partialResult);
- }
- @Override
- public void onCaptureCompleted(@NonNull CameraCaptureSession session,
- @NonNull CaptureRequest request,
- @NonNull TotalCaptureResult result) {
- process(result);
- }
- };
- /**
- * Run the precapture sequence for capturing a still image. This method should be called when
- * we get a response in {@link #mCaptureCallback} from {}.
- */
- private void runPrecaptureSequence() {
- try {
- // This is how to tell the camera to trigger.
- mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AE_PRECAPTURE_TRIGGER,
- CaptureRequest.CONTROL_AE_PRECAPTURE_TRIGGER_START);
- // Tell #mCaptureCallback to wait for the precapture sequence to be set.
- mState = STATE_WAITING_PRECAPTURE;
- mCaptureSession.capture(mPreviewRequestBuilder.build(), mCaptureCallback,
- mBackgroundHandler);
- } catch (CameraAccessException e) {
- e.printStackTrace();
- }
- }
- /**
- * Creates a new {@link CameraCaptureSession} for camera preview.
- */
- private void createCameraPreviewSession() {
- try {
- SurfaceTexture texture = mTextureView.getSurfaceTexture();
- assert texture != null;
- // We configure the size of default buffer to be the size of camera preview we want.
- texture.setDefaultBufferSize(mPreviewSize.getWidth(), mPreviewSize.getHeight());
- // This is the output Surface we need to start preview.
- Surface surface = new Surface(texture);
- // We set up a CaptureRequest.Builder with the output Surface.
- mPreviewRequestBuilder
- = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
- mPreviewRequestBuilder.addTarget(surface);
- mPreviewRequestBuilder.addTarget(mImageReader.getSurface()); //不加这句话没有回调
- // Here, we create a CameraCaptureSession for camera preview.
- mCameraDevice.createCaptureSession(Arrays.asList(surface, mImageReader.getSurface()),
- new CameraCaptureSession.StateCallback() {
- @Override
- public void onConfigured(@NonNull CameraCaptureSession cameraCaptureSession) {
- // The camera is already closed
- if (null == mCameraDevice) {
- return;
- }
- // When the session is ready, we start displaying the preview.
- mCaptureSession = cameraCaptureSession;
- try {
- // Auto focus should be continuous for camera preview.
- mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE,
- CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
- // Flash is automatically enabled when necessary.
- // Finally, we start displaying the camera preview.
- mPreviewRequest = mPreviewRequestBuilder.build();
- mCaptureSession.setRepeatingRequest(mPreviewRequest,
- mCaptureCallback, mBackgroundHandler);
- } catch (CameraAccessException e) {
- e.printStackTrace();
- }
- }
- @Override
- public void onConfigureFailed(
- @NonNull CameraCaptureSession cameraCaptureSession) {
- Toast.makeText(mActivity, "Config Session Failed", Toast.LENGTH_SHORT).show();
- }
- }, null
- );
- } catch (CameraAccessException e) {
- e.printStackTrace();
- }
- }
- private void requestCameraPermission() {
- ActivityCompat.requestPermissions(mActivity, new String[]{
- Manifest.permission.CAMERA,
- }, REQUEST_CAMERA_PERMISSION);
- }
- public void open() {
- startBackgroundThread();
- // When the screen is turned off and turned back on, the SurfaceTexture is already
- // available, and "onSurfaceTextureAvailable" will not be called. In that case, we can open
- // a camera and start preview from here (otherwise, we wait until the surface is ready in
- // the SurfaceTextureListener).
- if (mTextureView.isAvailable()) {
- openCamera(mTextureView.getWidth(), mTextureView.getHeight());
- } else {
- mTextureView.setSurfaceTextureListener(mSurfaceTextureListener);
- }
- }
- /**
- * Opens the camera specified
- */
- private void openCamera(int width, int height) {
- if (ActivityCompat.checkSelfPermission(mActivity, Manifest.permission.CAMERA)
- != PackageManager.PERMISSION_GRANTED) {
- requestCameraPermission();
- return;
- }
- setUpCameraOutputs(width, height);
- configureTransform(width, height);
- CameraManager manager = (CameraManager) mActivity.getSystemService(Context.CAMERA_SERVICE);
- if (manager == null) {
- return;
- }
- try {
- if (!mCameraOpenCloseLock.tryAcquire(2500, TimeUnit.MILLISECONDS)) {
- throw new RuntimeException("Time out waiting to lock camera opening.");
- }
- manager.openCamera(mCameraId, mStateCallback, mBackgroundHandler);
- } catch (CameraAccessException e) {
- e.printStackTrace();
- } catch (InterruptedException e) {
- throw new RuntimeException("Interrupted while trying to lock camera opening.", e);
- }
- }
- /**
- * Sets up member variables related to camera.
- *
- * @param width The width of available size for camera preview
- * @param height The height of available size for camera preview
- */
- @SuppressWarnings("SuspiciousNameCombination")
- private void setUpCameraOutputs(int width, int height) {
- CameraManager manager = (CameraManager) mActivity.getSystemService(Context.CAMERA_SERVICE);
- if (manager == null) {
- return;
- }
- try {
- for (String cameraId : manager.getCameraIdList()) {
- CameraCharacteristics characteristics
- = manager.getCameraCharacteristics(cameraId);
- // We don't use a front facing camera in this sample.
- Integer facing = characteristics.get(CameraCharacteristics.LENS_FACING);
- if (facing != null && facing == CameraCharacteristics.LENS_FACING_FRONT) {
- continue;
- }
- StreamConfigurationMap map = characteristics.get(
- CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
- if (map == null) {
- continue;
- }
- // For still image captures, we use the largest availablIe size.
- Size largest = Collections.max(
- Arrays.asList(map.getOutputSizes(mImageFormat)),
- new CompareSizesByArea());
- mImageReader = ImageReader.newInstance(largest.getWidth(), largest.getHeight(),
- mImageFormat, /*maxImages*/2);
- mImageReader.setOnImageAvailableListener(
- mOnImageAvailableListener, mBackgroundHandler);
- // Find out if we need to swap dimension to get the preview size relative to sensor
- // coordinate.
- int displayRotation = mActivity.getWindowManager().getDefaultDisplay().getRotation();
- //noinspection ConstantConditions
- mSensorOrientation = characteristics.get(CameraCharacteristics.SENSOR_ORIENTATION);
- boolean swappedDimensions = false;
- switch (displayRotation) {
- case Surface.ROTATION_0:
- case Surface.ROTATION_180:
- if (mSensorOrientation == 90 || mSensorOrientation == 270) {
- swappedDimensions = true;
- }
- break;
- case Surface.ROTATION_90:
- case Surface.ROTATION_270:
- if (mSensorOrientation == 0 || mSensorOrientation == 180) {
- swappedDimensions = true;
- }
- break;
- default:
- Log.e(TAG, "Display rotation is invalid: " + displayRotation);
- }
- Point displaySize = new Point();
- mActivity.getWindowManager().getDefaultDisplay().getSize(displaySize);
- int rotatedPreviewWidth = width;
- int rotatedPreviewHeight = height;
- int maxPreviewWidth = displaySize.x;
- int maxPreviewHeight = displaySize.y;
- if (swappedDimensions) {
- rotatedPreviewWidth = height;
- rotatedPreviewHeight = width;
- maxPreviewWidth = displaySize.y;
- maxPreviewHeight = displaySize.x;
- }
- if (maxPreviewWidth > MAX_PREVIEW_WIDTH) {
- maxPreviewWidth = MAX_PREVIEW_WIDTH;
- }
- if (maxPreviewHeight > MAX_PREVIEW_HEIGHT) {
- maxPreviewHeight = MAX_PREVIEW_HEIGHT;
- }
- // Danger, W.R.! Attempting to use too large a preview size could exceed the camera
- // bus' bandwidth limitation, resulting in gorgeous previews but the storage of
- // garbage capture data.
- mPreviewSize = chooseOptimalSize(map.getOutputSizes(SurfaceTexture.class),
- rotatedPreviewWidth, rotatedPreviewHeight, maxPreviewWidth,
- maxPreviewHeight, largest);
- // We fit the aspect ratio of TextureView to the size of preview we picked.
- int orientation = mActivity.getResources().getConfiguration().orientation;
- if (orientation == Configuration.ORIENTATION_LANDSCAPE) {
- mTextureView.setAspectRatio(
- mPreviewSize.getWidth(), mPreviewSize.getHeight());
- } else {
- mTextureView.setAspectRatio(
- mPreviewSize.getHeight(), mPreviewSize.getWidth());
- }
- mCameraId = cameraId;
- return;
- }
- } catch (CameraAccessException e) {
- e.printStackTrace();
- } catch (NullPointerException e) {
- // Currently an NPE is thrown when the Camera2API is used but not supported on the
- // device this code runs.
- }
- }
- private void startBackgroundThread() {
- mBackgroundThread = new HandlerThread("imageAvailableListener");
- mBackgroundThread.start();
- mBackgroundHandler = new Handler(mBackgroundThread.getLooper());
- }
- /**
- * Configures the necessary {@link android.graphics.Matrix} transformation to `mTextureView`.
- * This method should be called after the camera preview size is determined in
- * setUpCameraOutputs and also the size of `mTextureView` is fixed.
- *
- * @param viewWidth The width of `mTextureView`
- * @param viewHeight The height of `mTextureView`
- */
- private void configureTransform(int viewWidth, int viewHeight) {
- if (null == mTextureView || null == mPreviewSize) {
- return;
- }
- int rotation = mActivity.getWindowManager().getDefaultDisplay().getRotation();
- Matrix matrix = new Matrix();
- RectF viewRect = new RectF(0, 0, viewWidth, viewHeight);
- RectF bufferRect = new RectF(0, 0, mPreviewSize.getHeight(), mPreviewSize.getWidth());
- float centerX = viewRect.centerX();
- float centerY = viewRect.centerY();
- if (Surface.ROTATION_90 == rotation || Surface.ROTATION_270 == rotation) {
- bufferRect.offset(centerX - bufferRect.centerX(), centerY - bufferRect.centerY());
- matrix.setRectToRect(viewRect, bufferRect, Matrix.ScaleToFit.FILL);
- float scale = Math.max(
- (float) viewHeight / mPreviewSize.getHeight(),
- (float) viewWidth / mPreviewSize.getWidth());
- matrix.postScale(scale, scale, centerX, centerY);
- matrix.postRotate(90 * (rotation - 2), centerX, centerY);
- } else if (Surface.ROTATION_180 == rotation) {
- matrix.postRotate(180, centerX, centerY);
- }
- mTextureView.setTransform(matrix);
- }
- /**
- * Closes the current {@link CameraDevice}.
- */
- public void closeCamera() {
- stopBackgroundThread();
- try {
- mCameraOpenCloseLock.acquire();
- if (null != mCaptureSession) {
- mCaptureSession.close();
- mCaptureSession = null;
- }
- if (null != mCameraDevice) {
- mCameraDevice.close();
- mCameraDevice = null;
- }
- if (null != mImageReader) {
- mImageReader.close();
- mImageReader = null;
- }
- } catch (InterruptedException e) {
- throw new RuntimeException("Interrupted while trying to lock camera closing.", e);
- } finally {
- mCameraOpenCloseLock.release();
- }
- }
- /**
- * Stops the background thread and its {@link Handler}.
- */
- private void stopBackgroundThread() {
- mBackgroundThread.quitSafely();
- try {
- mBackgroundThread.join();
- mBackgroundThread = null;
- mBackgroundHandler = null;
- } catch (InterruptedException e) {
- e.printStackTrace();
- }
- }
- /**
- * 返回摄像头权限的请求码
- *
- * @return 返回请求码
- */
- public int getCameraRequestCode() {
- return REQUEST_CAMERA_PERMISSION;
- }
- /**
- * Given {@code choices} of {@code Size}s supported by a camera, choose the smallest one that
- * is at least as large as the respective texture view size, and that is at most as large as the
- * respective max size, and whose aspect ratio matches with the specified value. If such size
- * doesn't exist, choose the largest one that is at most as large as the respective max size,
- * and whose aspect ratio matches with the specified value.
- *
- * @param choices The list of sizes that the camera supports for the intended output
- * class
- * @param textureViewWidth The width of the texture view relative to sensor coordinate
- * @param textureViewHeight The height of the texture view relative to sensor coordinate
- * @param maxWidth The maximum width that can be chosen
- * @param maxHeight The maximum height that can be chosen
- * @param aspectRatio The aspect ratio
- * @return The optimal {@code Size}, or an arbitrary one if none were big enough
- */
- private static Size chooseOptimalSize(Size[] choices, int textureViewWidth,
- int textureViewHeight, int maxWidth, int maxHeight, Size aspectRatio) {
- // Collect the supported resolutions that are at least as big as the preview Surface
- List<Size> bigEnough = new ArrayList<>();
- // Collect the supported resolutions that are smaller than the preview Surface
- List<Size> notBigEnough = new ArrayList<>();
- int w = aspectRatio.getWidth();
- int h = aspectRatio.getHeight();
- for (Size option : choices) {
- if (option.getWidth() <= maxWidth && option.getHeight() <= maxHeight &&
- option.getHeight() == option.getWidth() * h / w) {
- if (option.getWidth() >= textureViewWidth &&
- option.getHeight() >= textureViewHeight) {
- bigEnough.add(option);
- } else {
- notBigEnough.add(option);
- }
- }
- }
- // Pick the smallest of those big enough. If there is no one big enough, pick the
- // largest of those not big enough.
- if (bigEnough.size() > 0) {
- return Collections.min(bigEnough, new CompareSizesByArea());
- } else if (notBigEnough.size() > 0) {
- return Collections.max(notBigEnough, new CompareSizesByArea());
- } else {
- Log.e(TAG, "Couldn't find any suitable preview size");
- return choices[0];
- }
- }
- /**
- * Compares two {@code Size}s based on their areas.
- */
- static class CompareSizesByArea implements Comparator<Size> {
- @Override
- public int compare(Size lhs, Size rhs) {
- // We cast here to ensure the multiplications won't overflow
- return Long.signum((long) lhs.getWidth() * lhs.getHeight() -
- (long) rhs.getWidth() * rhs.getHeight());
- }
- }
- /**
- * This a callback object for the {@link ImageReader}. "onImageAvailable" will be called when a
- * still image is ready to be saved.
- */
- private final ImageReader.OnImageAvailableListener mOnImageAvailableListener
- = new ImageReader.OnImageAvailableListener() {
- @Override
- public void onImageAvailable(ImageReader reader) {
- Image image = reader.acquireNextImage();
- if (image == null) {
- Log.d(TAG, "onImageAvailable,image is null");
- return;
- }
- if (mImageAvaiableListener != null) {
- mImageAvaiableListener.onImageAvailable(image);
- }
- image.close(); //一定要关掉,否则回调和预览都会阻塞
- }
- };
- /**
- * 设置视频预览后的回调格式
- *
- * @param format 遵循ImageFormat格式
- */
- public Camera2Helper setImageFormat(int format) {
- mImageFormat = format;
- return this;
- }
- /**
- * 获取摄像头方向
- *
- * @return 方向,详见mSensorOrientation赋值 {@link Camera2Helper#setUpCameraOutputs}
- */
- public int getSensorOrientation() {
- return mSensorOrientation;
- }
- /**
- * 打开错误的回调,可以不设置,不设置采用默认策略
- *
- * @param listener 回调listener
- */
- public Camera2Helper setOnOpenErrorListener(OnOpenErrorListener listener) {
- mOpenErrorListener = listener;
- return this;
- }
- /**
- * 摄像头图像回调,类似于Camera1的PreviewCallback
- *
- * @param listener 回调listener
- */
- public Camera2Helper setOnImageAvailableListener(OnPreviewCallbackListener listener) {
- mImageAvaiableListener = listener;
- return this;
- }
- /**
- * 打开摄像头错误
- */
- interface OnOpenErrorListener {
- void onOpenError();
- }
- /**
- * 当摄像头数据回调可达的时候
- */
- interface OnPreviewCallbackListener {
- void onImageAvailable(Image image);
- }
- }
代码比较多,不多说了,都是Camera2的封装,主要是加了
mPreviewRequestBuilder.addTarget(mImageReader.getSurface()); //不加这句话没有回调
Camera2为了避免频繁回调,弱化了onPreviewCallback的接口,它可以根据自己添加的target去回调画面,因为有些人用的场景是拍照,有的人是为了实时画面比对一些东西
然后是AutoFitTextureView,这是GoogleDemo里写的可以自动调节大小的类,现在推荐用TextureView,而不是SurfaceView,前者特性更好点
- public class AutoFitTextureView extends TextureView {
- private int mRatioWidth = 0;
- private int mRatioHeight = 0;
- public AutoFitTextureView(Context context) {
- this(context, null);
- }
- public AutoFitTextureView(Context context, AttributeSet attrs) {
- this(context, attrs, 0);
- }
- public AutoFitTextureView(Context context, AttributeSet attrs, int defStyle) {
- super(context, attrs, defStyle);
- }
- /**
- * Sets the aspect ratio for this view. The size of the view will be measured based on the ratio
- * calculated from the parameters. Note that the actual sizes of parameters don't matter, that
- * is, calling setAspectRatio(2, 3) and setAspectRatio(4, 6) make the same result.
- *
- * @param width Relative horizontal size
- * @param height Relative vertical size
- */
- public void setAspectRatio(int width, int height) {
- if (width < 0 || height < 0) {
- throw new IllegalArgumentException("Size cannot be negative.");
- }
- mRatioWidth = width;
- mRatioHeight = height;
- requestLayout();
- }
- @Override
- protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
- super.onMeasure(widthMeasureSpec, heightMeasureSpec);
- int width = MeasureSpec.getSize(widthMeasureSpec);
- int height = MeasureSpec.getSize(heightMeasureSpec);
- if (0 == mRatioWidth || 0 == mRatioHeight) {
- setMeasuredDimension(width, height);
- } else {
- if (width < height * mRatioWidth / mRatioHeight) {
- setMeasuredDimension(width, width * mRatioHeight / mRatioWidth);
- } else {
- setMeasuredDimension(height * mRatioWidth / mRatioHeight, height);
- }
- }
- }
- }
总得来说,接口比一代好用,但是还是不够友好,期待三代的接口
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