关于android:Android-Camera开发系列设置对焦模式模式

你对 android camera 的对焦模式相熟吗？

晓得什么场景下该设置哪种对焦模式吗？

本文针对上面 2 点开展介绍，和大家一起学习~

 一、有哪几种对焦模式？二、如何应用各种对焦模式？

一、有哪几种对焦模式？

1）获取设施反对的对焦模式

Google 为咱们提供了查问以后设施反对的对焦模式的接口~

Camera1 获取对焦模式接口：

----- Camera.java

        public String getFocusMode() {return get(KEY_FOCUS_MODE);
        }

Camera2 获取对焦模式接口：

----- CameraCharacteristics.java

    @PublicKey
    public static final Key<int[]> CONTROL_AF_AVAILABLE_MODES =
            new Key<int[]>("android.control.afAvailableModes", int[].class);

2）各种对焦模式的介绍

这里只介绍罕用的几种对焦模式，详解的介绍，能够查看文末附的源码内容。
咱们罕用的也就上面 4 种对焦模式。

    public static final String FOCUS_MODE_AUTO = "auto";
    public static final String FOCUS_MODE_FIXED = "fixed";
    public static final String FOCUS_MODE_CONTINUOUS_VIDEO = "continuous-video";
    public static final String FOCUS_MODE_CONTINUOUS_PICTURE = "continuous-picture";

   FOCUS_MODE_AUTO：主动对焦，这个只会触发一次对焦，并且是须要在预览开启后，调用 autoFocus 接口后才会触发，像触点对焦、和拍照对焦都能够用到该模式；FOCUS_MODE_FIXED：定焦，有些摄像头自身不反对对焦；FOCUS_MODE_CONTINUOUS_VIDEO：录像的时候，能够采纳该模式，会继续对焦，设置 parameter 参数后就会失效；FOCUS_MODE_CONTINUOUS_PICTURE：拍照的时候，能够采纳该模式，会继续对焦，设置 parameter 参数后就会失效，对焦速度绝对 
   FOCUS_MODE_CONTINUOUS_VIDEO 会快点；

三、如何应用各种对焦模式？

下面第二点针对 4 种常见的对焦模式，做了简略的介绍，咱们也晓得，除了 auto 模式，像 FOCUS_MODE_CONTINUOUS_VIDEO、FOCUS_MODE_CONTINUOUS_PICTURE 模式，是在设置 camera parameter 参数后就失效。

上面来看下 google 给咱们提供了哪些调用接口：

1）Camera1

      public final void autoFocus(AutoFocusCallback cb)
      {...}

      public void setFocusMode(String value) {...}

      public void setParameters(Parameters params) {...}

      public final void cancelAutoFocus()
      {...}

2）Camera2

request.set(CaptureRequest.CONTROL_AF_MODE, int focusMode);

附 ：

各种对焦模式的介绍？（贴的 Android 源码外面的介绍，写的够具体）

       /**
         * Auto-focus mode. Applications should call {@link
         * #autoFocus(AutoFocusCallback)} to start the focus in this mode.
         */
        public static final String FOCUS_MODE_AUTO = "auto";

        /**
         * Focus is set at infinity. Applications should not call
         * {@link #autoFocus(AutoFocusCallback)} in this mode.
         */
        public static final String FOCUS_MODE_INFINITY = "infinity";

        /**
         * Macro (close-up) focus mode. Applications should call
         * {@link #autoFocus(AutoFocusCallback)} to start the focus in this
         * mode.
         */
        public static final String FOCUS_MODE_MACRO = "macro";

        /**
         * Focus is fixed. The camera is always in this mode if the focus is not
         * adjustable. If the camera has auto-focus, this mode can fix the
         * focus, which is usually at hyperfocal distance. Applications should
         * not call {@link #autoFocus(AutoFocusCallback)} in this mode.
         */
        public static final String FOCUS_MODE_FIXED = "fixed";

        /** @hide
         * Normal focus mode. Applications should call
         * {@link #autoFocus(AutoFocusCallback)} to start the focus in this
         * mode.
         */
        public static final String FOCUS_MODE_NORMAL = "normal";

        /**
         * Extended depth of field (EDOF). Focusing is done digitally and
         * continuously. Applications should not call {@link
         * #autoFocus(AutoFocusCallback)} in this mode.
         */
        public static final String FOCUS_MODE_EDOF = "edof";

        /**
         * Continuous auto focus mode intended for video recording. The camera
         * continuously tries to focus. This is the best choice for video
         * recording because the focus changes smoothly . Applications still can
         * call {@link #takePicture(Camera.ShutterCallback,
         * Camera.PictureCallback, Camera.PictureCallback)} in this mode but the
         * subject may not be in focus. Auto focus starts when the parameter is
         * set.
         *
         * <p>Since API level 14, applications can call {@link
         * #autoFocus(AutoFocusCallback)} in this mode. The focus callback will
         * immediately return with a boolean that indicates whether the focus is
         * sharp or not. The focus position is locked after autoFocus call. If
         * applications want to resume the continuous focus, cancelAutoFocus
         * must be called. Restarting the preview will not resume the continuous
         * autofocus. To stop continuous focus, applications should change the
         * focus mode to other modes.
         *
         * @see #FOCUS_MODE_CONTINUOUS_PICTURE
         */
        public static final String FOCUS_MODE_CONTINUOUS_VIDEO = "continuous-video";

        /**
         * Continuous auto focus mode intended for taking pictures. The camera
         * continuously tries to focus. The speed of focus change is more
         * aggressive than {@link #FOCUS_MODE_CONTINUOUS_VIDEO}. Auto focus
         * starts when the parameter is set.
         *
         * <p>Applications can call {@link #autoFocus(AutoFocusCallback)} in
         * this mode. If the autofocus is in the middle of scanning, the focus
         * callback will return when it completes. If the autofocus is not
         * scanning, the focus callback will immediately return with a boolean
         * that indicates whether the focus is sharp or not. The apps can then
         * decide if they want to take a picture immediately or to change the
         * focus mode to auto, and run a full autofocus cycle. The focus
         * position is locked after autoFocus call. If applications want to
         * resume the continuous focus, cancelAutoFocus must be called.
         * Restarting the preview will not resume the continuous autofocus. To
         * stop continuous focus, applications should change the focus mode to
         * other modes.
         *
         * @see #FOCUS_MODE_CONTINUOUS_VIDEO
         */
        public static final String FOCUS_MODE_CONTINUOUS_PICTURE = "continuous-picture";

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—- 2020.01.04 深圳