关于android:Android-Camera开发系列调整Camera预览方向

 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

目前在深圳下班

欢送大家关注我的微信公众号“小驰笔记”

大家一起学习交换