[移动开发]SurfaceView之Android Camera预览

目录

前言

正文

SurfaceView类的创建。

预览的activity

前言

最近在研究OpenGL ES,发现关于Camera的基础部分还没理清楚，于是抱着打地基的态度先来弄下Camera以SurfaceView为载体的预览。这里只讲使用，原来比较复杂，后续有机会再补充。废话不多说马上进入正文。

正文

SurfaceView类的创建。

package com.example.mytest.camera

import android.content.Context
import android.graphics.ImageFormat
import android.hardware.Camera
import android.util.AttributeSet
import android.util.Log
import android.view.SurfaceHolder
import android.view.SurfaceView

class MySurfaceView(context: Context) : SurfaceView(context), SurfaceHolder.Callback {

    private val mCameraIndex: Int = Camera.CameraInfo.CAMERA_FACING_BACK
    //定义摄像机
    private var camera: Camera? = null
    //定义Camera的回调方法
    private val previewCallback: Camera.PreviewCallback = object : Camera.PreviewCallback {
        override fun onPreviewFrame(bytes: ByteArray, camera: Camera) {
//          TODO
        }
    }

    init {
        //加入SurfaceHolder.Callback在类中implements
        holder.addCallback(this);
        holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
        //保持屏幕常亮
        holder.setKeepScreenOn(true);

    }
    override fun surfaceCreated(holder: SurfaceHolder) {
        startCamera(mCameraIndex)
    }

    override fun surfaceChanged(holder: SurfaceHolder, format: Int, width: Int, height: Int) {}

    override fun surfaceDestroyed(holder: SurfaceHolder) {
        stopCamera()
    }

    //开启摄像机
    private fun startCamera(mCameraIndex: Int) {
        // 初始化并打开摄像头
//        if (camera == null) {
        try {
            camera = Camera.open(mCameraIndex)
        } catch (e: Exception) {
            return
        }
        //获取Camera参数
        val params: Camera.Parameters = camera!!.getParameters()
        if (params.getSupportedFocusModes()
                .contains(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE)
        ) {
            // 自动对焦
            params.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE)
        }
        params.setPreviewFormat(ImageFormat.NV21) // 设置预览图片格式
        params.setPictureFormat(ImageFormat.JPEG) // 设置拍照图片格式
        camera!!.setParameters(params)
        try {
            camera?.setPreviewCallback(previewCallback)
            camera?.setPreviewDisplay(holder)
            //旋转90度
            camera?.setDisplayOrientation(90)
            camera?.startPreview()
        } catch (ex: Exception) {
            ex.printStackTrace()
            camera?.release()
            camera = null
        }
//        }
    }
    //关闭摄像机
    private fun stopCamera() {
        camera?.setPreviewCallback(null)
        camera?.stopPreview()
        camera?.release()
        camera = null
    }

}

预览的activity

import android.Manifest
import android.content.pm.PackageManager
import android.os.Bundle
import android.widget.FrameLayout
import androidx.appcompat.app.AppCompatActivity
import androidx.core.app.ActivityCompat
import androidx.core.content.ContextCompat
import com.example.mytest.R

class MyCameraActivity : AppCompatActivity() {
    lateinit var mSurfaceView: MySurfaceView
    lateinit var mFrameLayout: FrameLayout

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_my_camera)
        mFrameLayout = findViewById(R.id.m_frameL)

        mSurfaceView = MySurfaceView(this)
        mFrameLayout.addView(mSurfaceView)

    }

    override fun onResume() {
        super.onResume()
       
    }

    override fun onDestroy() {
       requestPermission()
    }

    fun requestPermission() {
        val REQUEST_CODE = 1
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA) !== PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(this, arrayOf<String>(Manifest.permission.CAMERA, Manifest.permission.WRITE_EXTERNAL_STORAGE),
                REQUEST_CODE
            )
        }
    }
}

activity_my_camera.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".camera.MyCameraActivity">
    <FrameLayout
        android:id="@+id/m_frameL"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</androidx.constraintlayout.widget.ConstraintLayout>

当然这里使用到了拍照了 ，需要在manifest中注册权限并动态申请。

<uses-permission android:name="android.permission.CAMERA" />

<uses-feature android:name="android.hardware.camera" />
<uses-feature android:name="android.hardware.camera.autofocus" />