有时候咱们想依据本人的须要调整下Camera的预览方向，那么是调用哪个API能够达到咱们的目标呢？
咱们看下下图拍的几张小可爱的照片，别离是失常方向、旋转180度、90度拍的照片。
一、Camera API
Camera1上，咱们能够通过setDisplayOrientation（int degress）；来设置camera预览的方向。
mCamera.setDisplayOrientation(Surface.ROTATION_180);这里也贴下源码外面对于setDisplayOrientaion接口的具体阐明。
/** * Set the clockwise rotation of preview display in degrees. This affects * the preview frames and the picture displayed after snapshot. This method * is useful for portrait mode applications. Note that preview display of * front-facing cameras is flipped horizontally before the rotation, that * is, the image is reflected along the central vertical axis of the camera * sensor. So the users can see themselves as looking into a mirror. * * <p>This does not affect the order of byte array passed in {@link * PreviewCallback#onPreviewFrame}, JPEG pictures, or recorded videos. This * method is not allowed to be called during preview. * * <p>If you want to make the camera image show in the same orientation as * the display, you can use the following code. * <pre> * public static void setCameraDisplayOrientation(Activity activity, * int cameraId, android.hardware.Camera camera) { * android.hardware.Camera.CameraInfo info = * new android.hardware.Camera.CameraInfo(); * android.hardware.Camera.getCameraInfo(cameraId, info); * int rotation = activity.getWindowManager().getDefaultDisplay() * .getRotation(); * int degrees = 0; * switch (rotation) { * case Surface.ROTATION_0: degrees = 0; break; * case Surface.ROTATION_90: degrees = 90; break; * case Surface.ROTATION_180: degrees = 180; break; * case Surface.ROTATION_270: degrees = 270; break; * } * * int result; * if (info.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) { * result = (info.orientation + degrees) % 360; * result = (360 - result) % 360; // compensate the mirror * } else { // back-facing * result = (info.orientation - degrees + 360) % 360; * } * camera.setDisplayOrientation(result); * } * </pre> * * <p>Starting from API level 14, this method can be called when preview is * active. * * <p><b>Note: </b>Before API level 24, the default value for orientation is 0\. Starting in * API level 24, the default orientation will be such that applications in forced-landscape mode * will have correct preview orientation, which may be either a default of 0 or * 180\. Applications that operate in portrait mode or allow for changing orientation must still * call this method after each orientation change to ensure correct preview display in all * cases.</p> * * @param degrees the angle that the picture will be rotated clockwise. * Valid values are 0, 90, 180, and 270. * @throws RuntimeException if setting orientation fails; usually this would * be because of a hardware or other low-level error, or because * release() has been called on this Camera instance. * @see #setPreviewDisplay(SurfaceHolder) */ public native final void setDisplayOrientation(int degrees);二、Camera2 API
Camera2的API上，找了一通，发现并没有像Camera1上，能够通过相似的接口来设置预览方向，不过能够通过TextureView.setTransform(matrix);来通过调整textureView的显示来达到目标。
public void openCamera(){ CameraManager manager = (CameraManager) mContext.getSystemService(Context.CAMERA_SERVICE); try { ......//调整预览画面显示方向configureTextureViewTransform(mTextureView.getWidth(),mTextureView.getHeight()); manager.openCamera(cameraId, mStateCallback, null); ...... }}private void configureTextureViewTransform(int viewWidth, int viewHeight) { if (null == mTextureView) { return; } int rotation = 0 ;/*activity.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); }自己从事Android Camera相干开发已有5年
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