Android相机Camera基础知识

一、概述
本章节主要讲述的Android相机Camera的相关知识点，主要包含三个方面，Android启动系统相机生成缩略图、Android启动系统相机生成原图以及Android自定义相机等。

二、Android启动系统相机

核心代码：

package com.czhappy.camerademo.activity;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.ImageView;
import com.czhappy.camerademo.R;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
public class MainActivity extends AppCompatActivity {
  private static int REQ_1 = 1;
  private static int REQ_2 = 2;
  private ImageView image_iv;
  private String mFilePath;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    image_iv = (ImageView) findViewById(R.id.image_iv);
    mFilePath = Environment.getExternalStorageDirectory().getPath();
    mFilePath = mFilePath +"/" + System.currentTimeMillis()+".jpg";
  }
  public void startCamera1(View view){
    //隐式Intent调用
    Intent it = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
    startActivityForResult(it, REQ_1);
  }
  public void startCamera2(View view){
    //隐式Intent调用
    Intent it = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
    Uri photoUri = Uri.fromFile(new File(mFilePath));
    it.putExtra(MediaStore.EXTRA_OUTPUT, photoUri);
    startActivityForResult(it, REQ_2);
  }
  public void customCamera(View view){
    Intent it = new Intent(MainActivity.this, CustomCameraActivity.class);
    startActivity(it);
  }
  
  @Override
  protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if(resultCode == RESULT_OK){
      if(requestCode == REQ_1){//缩略图
        Bundle bundle = data.getExtras();
        Bitmap bmp = (Bitmap) bundle.get("data");
        image_iv.setImageBitmap(bmp);
      }else if(requestCode == REQ_2){//原图
        FileInputStream fis = null;
        try {
          fis = new FileInputStream(mFilePath);
          Bitmap bitmap = BitmapFactory.decodeStream(fis);
          image_iv.setImageBitmap(bitmap);
        } catch (FileNotFoundException e) {
          e.printStackTrace();
        }finally {
          try {
            fis.close();
          } catch (IOException e) {
            e.printStackTrace();
          }
        }
      }
    }
  }
}

三、Android自定义相机

1.自定义相机步骤：

创建相机
创建SurfaceView
关联相机与SurfaceView
调整相机显示效果
自定义相机预览界面

2.核心代码：
自定义相机CustomCameraActivity.java

package com.czhappy.camerademo.activity;
import android.content.Intent;
import android.graphics.ImageFormat;
import android.hardware.Camera;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import com.czhappy.camerademo.R;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

public class CustomCameraActivity extends AppCompatActivity implements SurfaceHolder.Callback{
  private SurfaceView mPreview;
  private Camera mCamera;
  private SurfaceHolder mHolder;
  private Camera.PictureCallback mPictureCallback = new Camera.PictureCallback() {
    @Override
    public void onPictureTaken(byte[] data, Camera camera) {
      File tempFile = new File("/sdcard/temp.png");
      try {
        FileOutputStream fos = new FileOutputStream(tempFile);
        fos.write(data);
        fos.close();
        Intent it = new Intent(CustomCameraActivity.this, CaptureResultActivity.class);
        it.putExtra("picPath", tempFile.getAbsolutePath());
        startActivity(it);
        finish();
      } catch (FileNotFoundException e) {
        e.printStackTrace();
      } catch (IOException e) {
        e.printStackTrace();
      }
    }
  };
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_custom_camera);
    mPreview = (SurfaceView) this.findViewById(R.id.preview);
    mHolder = mPreview.getHolder();
    mHolder.addCallback(this);
    //点击自动对焦
    mPreview.setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View v) {
        mCamera.autoFocus(null);;
      }
    });
  }
  
  public void capture(View view){
    Camera.Parameters parameters = mCamera.getParameters();
    parameters.setPictureFormat(ImageFormat.JPEG);
    parameters.setPictureSize(800,400);
    parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO);//自动对焦
    mCamera.autoFocus(new Camera.AutoFocusCallback() {
      @Override
      public void onAutoFocus(boolean success, Camera camera) {
        //对焦准确拍摄照片
        if(success){
          mCamera.takePicture(null, null, mPictureCallback);
        }
      }
    });
  }
  
  private Camera getCamera(){
    mCamera = Camera.open();
    return mCamera;
  }
  
  private void setStartPreview(Camera camera, SurfaceHolder holder){
    try {
      camera.setPreviewDisplay(holder);
      camera.setDisplayOrientation(90);//设置相机预览为竖屏90度
      camera.startPreview();
    } catch (IOException e) {
      e.printStackTrace();
    }
  }
  
  private void releaseCamera(){
    if(mCamera!=null){
      mCamera.setPreviewCallback(null);
      mCamera.stopPreview();
      mCamera.release();
      mCamera = null;
    }
  }
  @Override
  protected void onResume() {
    super.onResume();
    if (mCamera==null){
      mCamera = getCamera();
      if(mHolder!=null){
        setStartPreview(mCamera, mHolder);
      }
    }
  }
  @Override
  protected void onPause() {
    super.onPause();
    releaseCamera();
  }
  @Override
  public void surfaceCreated(SurfaceHolder holder) {
    setStartPreview(mCamera, mHolder);
  }
  @Override
  public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
    mCamera.stopPreview();
    setStartPreview(mCamera, mHolder);
  }
  @Override
  public void surfaceDestroyed(SurfaceHolder holder) {
    releaseCamera();
  }
}

生成图片结果页面CaptureResultActivity.java

package com.czhappy.camerademo.activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Matrix;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.ImageView;
import com.czhappy.camerademo.R;
import java.io.FileInputStream;
import java.io.FileNotFoundException;

public class CaptureResultActivity extends AppCompatActivity {
  private String picPath;
  private ImageView result_iv;
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_capture_result);
    picPath = getIntent().getStringExtra("picPath");
    result_iv = (ImageView) findViewById(R.id.result_iv);
    try {
      FileInputStream fis = new FileInputStream(picPath);
      Bitmap bitmap = BitmapFactory.decodeStream(fis);
      Matrix matrix = new Matrix();
      matrix.setRotate(90);//旋转90度矩阵
      bitmap = Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight(), matrix, true);
      result_iv.setImageBitmap(bitmap);
    } catch (FileNotFoundException e) {
      e.printStackTrace();
    }
  }
}

四、项目源代码下载

http://xiazai.jb51.net/201701/yuanma/AndroidCamera(jb51.net).rar

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