概述
相机几乎是每个APP都要用到的功能，万一老板让你定制相机方不方？反正我是有点方。关于相机的两天奋斗总结免费送给你。
Intent intent = new Intent(); intent.setAction(MediaStore.ACTION_IMAGE_CAPTURE); startActivity(intent);
或者指定返回图片的名称mCurrentPhotoFile。
Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE); intent.putExtra(MediaStore.EXTRA_OUTPUT,Uri.fromFile(mCurrentPhotoFile)); startActivityForResult(intent, CAMERA_WITH_DATA);
2.自定义启动相机。
今天以第二种为例。
自定义相机的一般步骤
创建显示相机画面的布局，
Android已经为我们选定好SurfaceView通过
SurfaceView#getHolder()获得链接Camera和SurfaceView的SurfaceHolderCamame.open()打开相机通过
SurfaceHolder链接Camera和urfaceView
一般步骤的代码演示
public class CameraSurfaceView extends SurfaceView implements SurfaceHolder.Callback, Camera.AutoFocusCallback {
private static final String TAG = "CameraSurfaceView"; private Context mContext; private SurfaceHolder holder; private Camera mCamera; private int mScreenWidth; private int mScreenHeight; public CameraSurfaceView(Context context) { this(context, null);
} public CameraSurfaceView(Context context, AttributeSet attrs) { this(context, attrs, 0);
} public CameraSurfaceView(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr);
mContext = context;
getScreenMetrix(context);
initView();
} private void getScreenMetrix(Context context) {
WindowManager WM = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
DisplayMetrics outMetrics = new DisplayMetrics();
WM.getDefaultDisplay().getMetrics(outMetrics);
mScreenWidth = outMetrics.widthPixels;
mScreenHeight = outMetrics.heightPixels;
} private void initView() {
holder = getHolder();//获得surfaceHolder引用
holder.addCallback(this);
holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);//设置类型
} @Override
public void surfaceCreated(SurfaceHolder holder) {
Log.i(TAG, "surfaceCreated"); if (mCamera == null) {
mCamera = Camera.open();//开启相机
try {
mCamera.setPreviewDisplay(holder);//摄像头画面显示在Surface上
} catch (IOException e) {
e.printStackTrace();
}
}
} @Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
Log.i(TAG, "surfaceChanged");
mCamera.startPreview();
} @Override
public void surfaceDestroyed(SurfaceHolder holder) {
Log.i(TAG, "surfaceDestroyed");
mCamera.stopPreview();//停止预览
mCamera.release();//释放相机资源
mCamera = null;
holder = null;
} @Override
public void onAutoFocus(boolean success, Camera Camera) { if (success) {
Log.i(TAG, "onAutoFocus success="+success);
}
}
}添加相机和自动聚焦限权
<uses-permission android:name="android.permission.CAMERA" /><uses-feature android:name="android.hardware.camera.autofocus" />
将CameraSurfaceView放在布局文件中，这里建议最外层为FrameLayout，后面会用到。如此，我们便有了一个没有照相功能的相机。初次之外，仔细观察相机显示画面，图片是不是变形严重？那是因为我们还没有为相机设置各种参数。在预览前要设置摄像头的分辨率、预览分辨率和图片分辨率的宽高比保持一致。这样图片才不会变形。这是个比较难以理解的部分，想深刻理解还需读者自己动手去实践。
private void setCameraParams(Camera camera, int width, int height) {
Log.i(TAG,"setCameraParams width="+width+" height="+height);
Camera.Parameters parameters = mCamera.getParameters();
// 获取摄像头支持的PictureSize列表
List<Camera.Size> pictureSizeList = parameters.getSupportedPictureSizes();
for (Camera.Size size : pictureSizeList) {
Log.i(TAG, "pictureSizeList size.width=" + size.width + " size.height=" + size.height);
} /**从列表中选取合适的分辨率*/
Camera.Size picSize = getProperSize(pictureSizeList, ((float) height / width));
if (null == picSize) {
Log.i(TAG, "null == picSize");
picSize = parameters.getPictureSize();
}
Log.i(TAG, "picSize.width=" + picSize.width + " picSize.height=" + picSize.height);
// 根据选出的PictureSize重新设置SurfaceView大小
float w = picSize.width;
float h = picSize.height;
parameters.setPictureSize(picSize.width,picSize.height);
this.setLayoutParams(new FrameLayout.LayoutParams((int) (height*(h/w)), height));
// 获取摄像头支持的PreviewSize列表
List<Camera.Size> previewSizeList = parameters.getSupportedPreviewSizes();
for (Camera.Size size : previewSizeList) {
Log.i(TAG, "previewSizeList size.width=" + size.width + " size.height=" + size.height);
}
Camera.Size preSize = getProperSize(previewSizeList, ((float) height) / width);
if (null != preSize) {
Log.i(TAG, "preSize.width=" + preSize.width + " preSize.height=" + preSize.height);
parameters.setPreviewSize(preSize.width, preSize.height);
}
parameters.setJpegQuality(100); // 设置照片质量
if (parameters.getSupportedFocusModes().contains(android.hardware.Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE)) {
parameters.setFocusMode(android.hardware.Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);// 连续对焦模式
}
mCamera.cancelAutoFocus();//自动对焦。
// 设置PreviewDisplay的方向，效果就是将捕获的画面旋转多少度显示
// TODO 这里直接设置90°不严谨，具体见https://developer.android.com/reference/android/hardware/Camera.html#setPreviewDisplay%28android.view.SurfaceHolder%29
mCamera.setDisplayOrientation(90);
mCamera.setParameters(parameters);
} /**
* 从列表中选取合适的分辨率
* 默认w:h = 4:3
* <p>tip：这里的w对应屏幕的height
* h对应屏幕的width<p/>
*/
private Camera.Size getProperSize(List<Camera.Size> pictureSizeList, float screenRatio) {
Log.i(TAG, "screenRatio=" + screenRatio);
Camera.Size result = null;
for (Camera.Size size : pictureSizeList) {
float currentRatio = ((float) size.width) / size.height;
if (currentRatio - screenRatio == 0) {
result = size;
break;
}
}
if (null == result) {
for (Camera.Size size : pictureSizeList) {
float curRatio = ((float) size.width) / size.height;
if (curRatio == 4f / 3) {// 默认w:h = 4:3
result = size;
break;
}
}
}
return result;
}进去的是屏幕宽高，出来的是调整好了的参数。在surfaceChanged方法中执行mCamera.startPreview(); 前调用setCameraParams(mCamera, mScreenWidth, mScreenHeight); 就可以了。最后要在AndroidManifest.xml里设置activity的方向android:screenOrientation="portrait"代码里有很多注释，其中也有我自己调试时候的Log，大家可以自己调试下，看看不同参数的效果。昨天调参数搞到一点多，都在折腾这个函数。唉，一把辛酸泪。
身为一个相机，居然不能照相？真是太丢脸了！下面给我们的相机添加上照相的功能。照相核心代码就一句：mCamera.takePicture(null, null, jpeg);
可以看到takePicture方法有三个参数，分别是ShutterCallback、PictureCallback和PictureCallback。这里我们只用了PictureCallback
// 拍照瞬间调用
private Camera.ShutterCallback shutter = new Camera.ShutterCallback() { @Override
public void onShutter() {
Log.i(TAG,"shutter");
}
}; // 获得没有压缩过的图片数据
private Camera.PictureCallback raw = new Camera.PictureCallback() { @Override
public void onPictureTaken(byte[] data, Camera Camera) {
Log.i(TAG, "raw");
}
}; //创建jpeg图片回调数据对象
private Camera.PictureCallback jpeg = new Camera.PictureCallback() { @Override
public void onPictureTaken(byte[] data, Camera Camera) {
BufferedOutputStream bos = null;
Bitmap bm = null; try { // 获得图片
bm = BitmapFactory.decodeByteArray(data, 0, data.length); if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
Log.i(TAG, "Environment.getExternalStorageDirectory()="+Environment.getExternalStorageDirectory());
String filePath = "/sdcard/dyk"+System.currentTimeMillis()+".jpg";//照片保存路径
File file = new File(filePath); if (!file.exists()){
file.createNewFile();
}
bos = new BufferedOutputStream(new FileOutputStream(file));
bm.compress(Bitmap.CompressFormat.JPEG, 100, bos);//将图片压缩到流中
}else{
Toast.makeText(mContext,"没有检测到内存卡", Toast.LENGTH_SHORT).show();
}
} catch (Exception e) {
e.printStackTrace();
} finally { try {
bos.flush();//输出
bos.close();//关闭
bm.recycle();// 回收bitmap空间
mCamera.stopPreview();// 关闭预览
mCamera.startPreview();// 开启预览
} catch (IOException e) {
e.printStackTrace();
}
}
}
};在jpeg#onPictureTaken()里。我们将存储照片信息的byte[] data解析成bitmap，然后转换成JPG格式的图片保存在SD卡中。注意finally中最后两句mCamera.stopPreview();// 关闭预览 mCamera.startPreview();// 开启预览 上文也提到：当调用camera.takePiture()方法后，camera关闭了预览，这时需要调用startPreview()来重新开启预览。如果不再次开启预览，则会一直停留在拍摄照片画面。为了方便外部调用拍照。这里我暴露了一个方法供外部拍照。
public void takePicture(){ //设置参数,并拍照
setCameraParams(mCamera, mScreenWidth, mScreenHeight); // 当调用camera.takePiture方法后，camera关闭了预览，这时需要调用startPreview()来重新开启预览
mCamera.takePicture(null, null, jpeg);
}在布局文件中添加一个Button，点击Button执行takePicture()方法。不要忘了添加写SD卡限权
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
至此，一个具有照相并保存拍摄图片功能的相机就做出来了。But，我们就此满足了吗？要是为了这些简单的功能我也不会写这篇博客。这只是个开始
真正的开始
别人APP在照相的时候，屏幕上居然可以显示像效果图那样的框框啦、辅助点啦、图片bulabulabula~。在网上搜索一番实现方式，再加上一些自己的理解，构成了这篇博客。
上文布局文件一直没有贴，现在贴出来大家先扫一眼，有些控件会在接下来展示
<?xml version="1.0" encoding="utf-8"?><FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent"> <com.dyk.cameratest.view.CameraSurfaceView android:id="@+id/cameraSurfaceView" android:layout_width="match_parent" android:layout_height="match_parent" /> <com.dyk.cameratest.view.RectOnCamera android:layout_width="match_parent" android:layout_height="match_parent" /> <RelativeLayout android:layout_width="match_parent" android:layout_height="match_parent"> <Button android:layout_alignParentBottom="true" android:layout_centerHorizontal="true" android:layout_marginBottom="20dp" android:id="@+id/takePic" android:layout_width="80dp" android:layout_height="50dp" android:background="#88427ac7" android:text="拍照" android:textColor="#aaa" /> </RelativeLayout></FrameLayout>
布局文件的最外层是个FrameLayout，我们知道FrameLayout是自带覆盖效果的。由来这个思路接下来就很简单了。编程重要的是思想，思想有了，其余的就剩具体的实现细节。
自定义边边框框
为了和CameraSurfaceView区分开，再自定义一个RectOnCamera专门用来画边边框框这些东西。这样做还一个好处是方便维护，不至于将所有东西都放在一个View中。
RectOnCamera
package com.dyk.cameratest.view;
.../**
* Created by 一口仨馍 on 2016/4/7.
*/public class RectOnCamera extends View {
private static final String TAG = "CameraSurfaceView"; private int mScreenWidth; private int mScreenHeight; private Paint mPaint; private RectF mRectF; // 圆
private Point centerPoint; private int radio; public RectOnCamera(Context context) { this(context, null);
} public RectOnCamera(Context context, AttributeSet attrs) { this(context, attrs, 0);
} public RectOnCamera(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr);
getScreenMetrix(context);
initView(context);
} private void getScreenMetrix(Context context) {
WindowManager WM = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
DisplayMetrics outMetrics = new DisplayMetrics();
WM.getDefaultDisplay().getMetrics(outMetrics);
mScreenWidth = outMetrics.widthPixels;
mScreenHeight = outMetrics.heightPixels;
} private void initView(Context context) {
mPaint = new Paint();
mPaint.setAntiAlias(true);// 抗锯齿
mPaint.setDither(true);// 防抖动
mPaint.setColor(Color.RED);
mPaint.setStrokeWidth(5);
mPaint.setStyle(Paint.Style.STROKE);// 空心
int marginLeft = (int) (mScreenWidth*0.15); int marginTop = (int) (mScreenHeight * 0.25);
mRectF = new RectF(marginLeft, marginTop, mScreenWidth - marginLeft, mScreenHeight - marginTop);
centerPoint = new Point(mScreenWidth/2, mScreenHeight/2);
radio = (int) (mScreenWidth*0.1);
} @Override
protected void onDraw(Canvas canvas) { super.onDraw(canvas);
mPaint.setColor(Color.RED);
canvas.drawRect(mRectF, mPaint);
mPaint.setColor(Color.WHITE);
Log.i(TAG, "onDraw");
canvas.drawCircle(centerPoint.x,centerPoint.y, radio,mPaint);// 外圆
canvas.drawCircle(centerPoint.x,centerPoint.y, radio - 20,mPaint); // 内圆
}
}这里简单的画了一个类似二维码扫描的框框，还有一个类似聚焦的内外圆。那么问题来了，聚焦的内外圆要随着手指滑而改变位置，而且要有聚焦的效果。可又和具有聚焦功能的CameraSurfaceView不是同一个类，不仅如此聚焦内外圆还完全覆盖了CameraSurfaceView。要处理这种问题，需要接口回调。这就是思想下面的细节。现在虽然确定接口回调，但还有一个问题，CameraSurfaceView类和RectOnCamera类中都没有对方的对象或者引用。没错，通过共同持有RectOnCamera和CameraSurfaceView的Activity可以实现此功能。下面是具体的实现方法
动起来
首先，想要随着手指的滑动而改变RectOnCamera的位置肯定是要复写onTouchEvent()方法
@Override public boolean onTouchEvent(MotionEvent event) { switch (event.getAction()){ case MotionEvent.ACTION_DOWN: case MotionEvent.ACTION_MOVE: case MotionEvent.ACTION_UP: int x = (int) event.getX(); int y = (int) event.getY();
centerPoint = new Point(x, y);
invalidate(); return true;
} return true;
}其次，定义回调接口
private IAutoFocus mIAutoFocus; /** 聚焦的回调接口 */
public interface IAutoFocus{
void autoFocus();
} public void setIAutoFocus(IAutoFocus mIAutoFocus) { this.mIAutoFocus = mIAutoFocus;
}在onTouchEvent()中return前加入
if (mIAutoFocus != null){
mIAutoFocus.autoFocus();
}至此我们的回调接口已经定义好了，此时还需要CameraSurfaceView暴露一个聚焦方法，以便Activity调用
public void setAutoFocus(){
mCamera.autoFocus(this);
}准备工作已经全部完成，下面请看Activity的具体实现：
public class MainActivity extends Activity implements View.OnClickListener,RectOnCamera.IAutoFocus{
private CameraSurfaceView mCameraSurfaceView; private RectOnCamera mRectOnCamera; private Button takePicBtn; private boolean isClicked; @Override
protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE); // 全屏显示
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.activity_main);
mCameraSurfaceView = (CameraSurfaceView) findViewById(R.id.cameraSurfaceView);
mRectOnCamera = (RectOnCamera) findViewById(R.id.rectOnCamera);
takePicBtn= (Button) findViewById(R.id.takePic);
mRectOnCamera.setIAutoFocus(this);
takePicBtn.setOnClickListener(this);
} @Override
public void onClick(View v) { switch (v.getId()){ case R.id.takePic:
mCameraSurfaceView.takePicture(); break; default: break;
}
} @Override
public void autoFocus() {
mCameraSurfaceView.setAutoFocus();
}
}可以看到，MainActivity实现了IAutoFocus接口，并且在复写的IAutoFocus#autoFocus()方法中，调用了CameraSurfaceView暴露出来的方法setAutoFocus()。至此，在RectOnCamera每次的滑动过程中都会改变聚焦内外圆的位置，还会增加聚焦功能。一心二用甚至一心多用岂不是更好。