Android Camera之 --- Camera API说明(二)

最新推荐文章于 2024-01-29 11:04:15 发布

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最新推荐文章于 2024-01-29 11:04:15 发布 · 1.7k 阅读

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本文是Android Camera API系列的第二部分，主要讲解Camera API中的回调接口如ShutterCallback、ErrorCallback和FaceDetectionListener，以及辅助类Face、Size和Area的用法。Face用于存储人脸识别信息，Size表示分辨率，Area则在3A模式中定义矩形区域。所有的回调通过postEventFromNative方法由Handler处理。

Camera API 介绍系列文章：

Android Camera之 --- Camera API说明(一)

Android Camera之 --- Camera API说明(二)

Android Camera之 --- Camera API说明(三)

下面重点介绍Camera API内的回调函数和内部辅助类，以及msg的相应过程。

首先来认识以下Camera内部的回调接口，使用者必须实现器大部分很的回调接口以便更好的操作camera设备。

1. interface ShutterCallback

    // 回调接口，快门声
    // takePicture(ShutterCallback, PictureCallback, PictureCallback, PictureCallback)的第一个参数，被触发来播放一个快门声音
    @Deprecated
    public interface ShutterCallback
    {
        /**
         * Called as near as possible to the moment when a photo is captured
         * from the sensor.  This is a good opportunity to play a shutter sound
         * or give other feedback of camera operation.  This may be some time
         * after the photo was triggered, but some time before the actual data
         * is available.
         */
        void onShutter();
    }

2. interface PictureCallback

    // 回调接口， 提供拍照时的数据，数据类型有:Raw picture, posview picture, JPEG picture.
    // takePicture(ShutterCallback, PictureCallback, PictureCallback, PictureCallback)的后三个参数都为PictureCallback.
    // 分别为RawPictureCallback, PostViewPictureCallback, JPEGPictureCallback
    @Deprecated
    public interface PictureCallback {
        /**
         * Called when image data is available after a picture is taken.
         * The format of the data depends on the context of the callback
         * and {@link Camera.Parameters} settings.
         *
         * @param data   a byte array of the picture data
         * @param camera the Camera service object
         */
        void onPictureTaken(byte[] data, Camera camera);
    };

3. interface PreviewCallback

// 回调接口，用来获取YUV数据，格式必须支持NV21和YV12.
    // 想获取YV12,则必须调用Camera.Parameters。setPreviewFormat(int)进行设置，默认为NV21数据
    @Deprecated
    public interface PreviewCallback
    {
        /**
         * Called as preview frames are displayed.  This callback is invoked
         * on the event thread {@link #open(int)} was called from.
         *
         * <p>If using the {@link android.graphics.ImageFormat#YV12} format,
         * refer to the equations in {@link Camera.Parameters#setPreviewFormat}
         * for the arrangement of the pixel data in the preview cal