前言
Camera1 在 API 21 的时候已经被弃用了,虽然现在google 都推荐 使用 Camerax 来实现相机的一些功能,但这不妨碍我们学习 Camera1 和 Camera2,对此有基础了解,为后续学习 Camera2 和 Camerax 做铺垫
本篇文章,你将学习到:
- 实现相机的开启与预览
- 调整预览方向
- 切换摄像头
- 拍照及调整图片方向
一、实现相机的开启与预览
1. 效果图
2. 在清单文件中申请权限
<uses-permission android:name="android.permission.CAMERA" />
<!-- 支持相机才能运行 -->
<uses-feature
android:name="android.hardware.camera"
android:required="true" />
3. 在 Java 代码中添加运行时权限授权,在 Activity 的 onCreate 函数中添加如下代码:
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (checkSelfPermission(Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
requestPermissions(new String[] {Manifest.permission.CAMERA}, 1);
}
}
4. 布局文件
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<com.hjq.bar.TitleBar
android:id="@+id/title_bar"
android:layout_width="match_parent"
android:background="@color/teal_200"
android:layout_height="?android:attr/actionBarSize"
app:title="Camera1 使用"
app:titleStyle="bold"
app:titleSize="18sp"
app:backButton="false"
app:titleColor="@color/white"/>
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<SurfaceView
android:id="@+id/surface"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintDimensionRatio="H,3:4"/>
<Button
android:id="@+id/btn_trans"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintTop_toBottomOf="@id/surface"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintStart_toStartOf="parent"
android:layout_margin="10dp"
android:text="切换摄像头"/>
<Button
android:id="@+id/btn_takePhoto"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintTop_toBottomOf="@id/surface"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
android:text="拍照"/>
</androidx.constraintlayout.widget.ConstraintLayout>
</LinearLayout>
5. 获取相机个数
一般手机中,都有前置摄像头和后置摄像头,我们可以根据 Camera 的 getNumberOfCameras() 方法,来获取这些信息。比如:
/**
* 初始化相机
*/
private void initCamera() {
//获取相机个数
int numberOfCameras = Camera.getNumberOfCameras();
for (int i = 0; i < numberOfCameras; i++) {
Camera.CameraInfo info = new Camera.CameraInfo();
//获取相机信息
Camera.getCameraInfo(i, info);
//前置摄像头
if (Camera.CameraInfo.CAMERA_FACING_FRONT == info.facing) {
mFrontCameraId = i;
mFrontCameraInfo = info;
} else if (Camera.CameraInfo.CAMERA_FACING_BACK == info.facing) {
mBackCameraId = i;
mBackCameraInfo = info;
}
}
}
通过 Camera.getCameraInfo(i, info)
就可以拿到当前的 CameraInfo
的信息,里面有个参数我们需要注意一下,就是 facing
,它表示当前摄像机面对的方向,理解为前置和后置,然后我们把这些信息也保存起来。
6. 打开摄像头
使用 Camera.open(cameraid) 去打开摄像头
//根据 cameraId 打开不同摄像头,注意,Camera1只有打开摄像头之后,才能拿到那些配置数据
mCamera = Camera.open(cameraId);
7. 配置摄像头属性
在开启相机预览之前,我们需要对相机进行一些参数配置,比如聚焦,预览尺寸等;这里我使用的是 SurfaceView,所以等 SurfaceView 创建好之后,可以对它进行一些参数的设置:
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
startPreview(width, height);
}
...
/**
* 开始显示
*/
private void startPreview(int width, int height) {
initPreviewParams(width, height);
//设置预览 SurfaceHolder
Camera camera = mCamera;
if (camera != null) {
try {
camera.setPreviewDisplay(mSurfaceView.getHolder());
} catch (IOException e) {
e.printStackTrace();
}
}
//开始显示
camera.startPreview();
}
在 Camera中,我们可以通过 camera.getParameters() 拿到相机默认的参数,如果要配置自己的参数,可以使用 camera.setParameters(parameters) 去设置,不过这个比较比较好使,所以相机的配置开启这些,可以使用 HandlerThread 去开启,这里就不增加多余代码了。
initPreviewParams 的完整代码如下:
/**
* 设置预览参数,需要制定尺寸才行
* 在相机中,width > height 的,而我们的UI是3:4,所以这里也要做换算
*
* @param shortSize
* @param longSize
*/
private void initPreviewParams(int shortSize, int longSize) {
Camera camera = mCamera;
if (camera != null) {
Camera.Parameters parameters = camera.getParameters();
//获取手机支持的尺寸
List<Camera.Size> sizes = parameters.getSupportedPreviewSizes();
Camera.Size bestSize = getBestSize(shortSize, longSize, sizes);
//设置预览大小
parameters.setPreviewSize(bestSize.width, bestSize.height);
//设置图片大小,拍照
parameters.setPictureSize(bestSize.width, bestSize.height);
//设置格式
parameters.setPreviewFormat(ImageFormat.NV21);
//设置自动聚焦
List<String> modes = parameters.getSupportedFocusModes();
//查看支持的聚焦模式
for (String mode : modes) {
//默认图片聚焦模式
if (mode.contains(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE)){
parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);
break;
}
}
camera.setParameters(parameters);
}
}
8. 相机预览大小
首先,应该根据自己UI的大小去设置相机预览的大小,如果你的控件为 200x200,但相机的数据为 1920x1080 ,这样填充过去,画面肯定是会被拉伸的。
List<Camera.Size> sizes = parameters.getSupportedPreviewSizes()
注意相机的 width > height,所以获取一个最佳的预览尺寸可以这样写:
/**
* 获取预览最后尺寸
*
* @param shortSize
* @param longSize
* @param sizes
* @return
*/
private Camera.Size getBestSize(int shortSize, int longSize, List<Camera.Size> sizes) {
Camera.Size bestSize = null;
float uiRatio = (float) longSize / shortSize;
float minRatio = uiRatio;
for (Camera.Size previewSize : sizes) {
float cameraRatio = (float) previewSize.width / previewSize.height;
//如果找不到比例相同的,找一个最近的,防止预览变形
float offset = Math.abs(cameraRatio - minRatio);
if (offset < minRatio) {
minRatio = offset;
bestSize = previewSize;
}
//比例相同
if (uiRatio == cameraRatio) {
bestSize = previewSize;
break;
}
}
return bestSize;
}
二、调整预览方向
在调整预览方向前,我们需要先了解一些知识。
- 屏幕坐标: Android 坐标系中,在 (0,0) 坐标那,向右为 x 轴,向下为 y 轴。
- 自然方向: 设置的自然方向,比如手机默认就是竖直是自然方向,平板的话,横向就是自然方向
- 图片传感器方向: 手机的图片数据都来自摄像头硬件传感器,这个传感器有个默认的方向,一般是手机是横向的,这就跟手机的自然方向成 90° 关系了。
方向调整代码可以这样写:
/**
* 矫正相机预览画面
*
* @param info
*/
private void adjustCameraOrientation(Camera.CameraInfo info) {
//判断当前的横竖屏
int rotation = getWindowManager().getDefaultDisplay().getRotation();
int degress = 0;
//获取手机的方向
switch (rotation) {
case Surface.ROTATION_0:
degress = 0;
break;
case Surface.ROTATION_90:
degress = 90;
break;
case Surface.ROTATION_180:
degress = 180;
break;
case Surface.ROTATION_270:
degress = 270;
break;
}
int result = 0;
//后置摄像头
if (info.facing == Camera.CameraInfo.CAMERA_FACING_BACK) {
result = (info.orientation - degress + 360) % 360;
} else if (info.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) {
//先镜像
result = (info.orientation + degress) % 360;
result = (360 - result) % 360;
}
mCamera.setDisplayOrientation(result);
}
三、切换摄像头
现在用到的都是后置摄像头,切换也比较简单,首先先释放相机支援,然后再从配置参数,预览再来一遍即可:
//关闭摄像头
closeCamera();
mCameraID = mCameraID == mFrontCameraId ? mBackCameraId : mFrontCameraId;
//打开相机
openCamera(mCameraID);
//开启预览
startPreview(mSurfaceView.getWidth(), mSurfaceView.getHeight());
...
/**
* 关闭摄像头
*/
private void closeCamera() {
//停止预览
if (mCamera != null) {
mCamera.stopPreview();
mCamera.release();
mCamera = null;
}
}
四、拍照及调整图片方向
Camera
的拍照也比较简单,使用 takePicture(ShutterCallback shutter, PictureCallback raw, PictureCallback jpeg)
方法即可,它的三个参数如下:
-
ShutterCallback
:拍照瞬间调用,如果空回调,则由声音,传 null ,则没效果 -
PictureCallback
:图片的原始数据,即没处理过的 -
PictureCallback
: 图片的 JPEG 数据
拿到 byte 数据后,转换成 bitmap 即可,如下:
Camera camera = mCamera;
camera.takePicture(new Camera.ShutterCallback() {
@Override
public void onShutter() {
}
}, null, new Camera.PictureCallback() {
@Override
public void onPictureTaken(byte[] data, Camera camera) {
new SavePicAsyncTask(data).executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
}
});
这里的图片保存,用一个 AsyncTask 来保存:
/**
* 保存图片
*/
class SavePicAsyncTask extends AsyncTask<Void, Void, File> {
byte[] data;
File file;
public SavePicAsyncTask(byte[] data) {
this.data = data;
File dir = new File(GlobalConfig.PATH);
if (!dir.exists()) {
dir.mkdirs();
}
String name = "test.jpg";
file = new File(dir, name);
}
@Override
protected File doInBackground(Void... voids) {
Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);
if (bitmap == null) {
return null;
}
FileOutputStream fos = null;
try {
fos = new FileOutputStream(file);
//保存之前先调整方向
Camera.CameraInfo info = mCameraID == mFrontCameraId ? mFrontCameraInfo : mBackCameraInfo;
if (info.facing == Camera.CameraInfo.CAMERA_FACING_BACK) {
bitmap = BitmapUtils.rotate(bitmap, 90);
} else {
bitmap = BitmapUtils.rotate(bitmap, 270);
bitmap = BitmapUtils.mirror(bitmap);
}
bitmap.compress(Bitmap.CompressFormat.JPEG, 100, fos);
} catch (FileNotFoundException e) {
e.printStackTrace();
} finally {
CloseUtils.close(fos);
}
return file;
}
@Override
protected void onPostExecute(File file) {
super.onPostExecute(file);
if (file != null) {
Toast.makeText(MainActivity.this, "图片保存成功", Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(MainActivity.this, "图片保存失败", Toast.LENGTH_SHORT).show();
}
}
}
注意:保持路径代码。
public static final String PATH = Environment.getExternalStorageDirectory().getAbsolutePath() + "/CameraDemo";
五、完整代码
- CloseUtils.java
public class CloseUtils {
public static void close(Closeable... closeables){
if (closeables != null) {
for (Closeable closeable : closeables) {
if (closeable != null) {
try {
closeable.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
}
- BitmapUtils.java
public class BitmapUtils {
/**
* 镜像
* @param bitmap
* @return
*/
public static Bitmap mirror(Bitmap bitmap){
Matrix matrix = new Matrix();
matrix.postScale(-1f,1f);
return Bitmap.createBitmap(bitmap,0,0,bitmap.getWidth(),bitmap.getHeight(),matrix,true);
}
/**
* 旋转图片
* @param bitmap
* @param degress
* @return
*/
public static Bitmap rotate(Bitmap bitmap,float degress){
Matrix matrix = new Matrix();
matrix.postRotate(degress);
return Bitmap.createBitmap(bitmap,0,0,bitmap.getWidth(),bitmap.getHeight(),matrix,true);
}
}
- MainActivity.java
public class MainActivity extends BaseActivity {
@BindView(R.id.surface)
SurfaceView mSurfaceView;
private int mFrontCameraId;
private int mBackCameraId;
private Camera.CameraInfo mFrontCameraInfo;
private Camera.CameraInfo mBackCameraInfo;
private Camera mCamera;
private int mCameraID;
@Override
protected int getLayoutId() {
return R.layout.activity_main;
}
@Override
protected void initView() {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (checkSelfPermission(Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
requestPermissions(new String[] {Manifest.permission.CAMERA}, 1);
}
}
initCamera();
//打开摄像头
openCamera(mBackCameraId);
}
/**
* 初始化相机
*/
private void initCamera() {
//获取相机个数
int numberOfCameras = Camera.getNumberOfCameras();
for (int i = 0; i < numberOfCameras; i++) {
Camera.CameraInfo info = new Camera.CameraInfo();
//获取相机信息
Camera.getCameraInfo(i, info);
//前置摄像头
if (Camera.CameraInfo.CAMERA_FACING_FRONT == info.facing) {
mFrontCameraId = i;
mFrontCameraInfo = info;
} else if (Camera.CameraInfo.CAMERA_FACING_BACK == info.facing) {
mBackCameraId = i;
mBackCameraInfo = info;
}
}
}
@Override
protected void onResume() {
super.onResume();
if (mSurfaceView != null && mSurfaceView.getWidth() != 0){
openCamera(mCameraID);
startPreview(mSurfaceView.getWidth(),mSurfaceView.getHeight());
}else{
mSurfaceView.getHolder().addCallback(new PreviewCallback());
}
}
/**
* 开始显示
*/
private void startPreview(int width, int height) {
initPreviewParams(width, height);
//设置预览 SurfaceHolder
Camera camera = mCamera;
if (camera != null) {
try {
camera.setPreviewDisplay(mSurfaceView.getHolder());
} catch (IOException e) {
e.printStackTrace();
}
}
//开始显示
camera.startPreview();
}
/**
* 打开摄像头
*
* @param cameraId
*/
private void openCamera(int cameraId) {
//根据 cameraId 打开不同摄像头,注意,Camera1只有打开摄像头之后,才能拿到那些配置数据
mCamera = Camera.open(cameraId);
mCameraID = cameraId;
Camera.CameraInfo info = cameraId == mFrontCameraId ? mFrontCameraInfo : mBackCameraInfo;
adjustCameraOrientation(info);
}
/**
* 矫正相机预览画面
*
* @param info
*/
private void adjustCameraOrientation(Camera.CameraInfo info) {
//判断当前的横竖屏
int rotation = getWindowManager().getDefaultDisplay().getRotation();
int degress = 0;
//获取手机的方向
switch (rotation) {
case Surface.ROTATION_0:
degress = 0;
break;
case Surface.ROTATION_90:
degress = 90;
break;
case Surface.ROTATION_180:
degress = 180;
break;
case Surface.ROTATION_270:
degress = 270;
break;
}
int result = 0;
//后置摄像头
if (info.facing == Camera.CameraInfo.CAMERA_FACING_BACK) {
result = (info.orientation - degress + 360) % 360;
} else if (info.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) {
//先镜像
result = (info.orientation + degress) % 360;
result = (360 - result) % 360;
}
mCamera.setDisplayOrientation(result);
}
/**
* 设置预览参数,需要制定尺寸才行
* 在相机中,width > height 的,而我们的UI是3:4,所以这里也要做换算
*
* @param shortSize
* @param longSize
*/
private void initPreviewParams(int shortSize, int longSize) {
Camera camera = mCamera;
if (camera != null) {
Camera.Parameters parameters = camera.getParameters();
//获取手机支持的尺寸
List<Camera.Size> sizes = parameters.getSupportedPreviewSizes();
Camera.Size bestSize = getBestSize(shortSize, longSize, sizes);
//设置预览大小
parameters.setPreviewSize(bestSize.width, bestSize.height);
//设置图片大小,拍照
parameters.setPictureSize(bestSize.width, bestSize.height);
//设置格式
parameters.setPreviewFormat(ImageFormat.NV21);
//设置自动聚焦
List<String> modes = parameters.getSupportedFocusModes();
//查看支持的聚焦模式
for (String mode : modes) {
//默认图片聚焦模式
if (mode.contains(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE)){
parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);
break;
}
}
camera.setParameters(parameters);
}
}
/**
* 获取预览最后尺寸
*
* @param shortSize
* @param longSize
* @param sizes
* @return
*/
private Camera.Size getBestSize(int shortSize, int longSize, List<Camera.Size> sizes) {
Camera.Size bestSize = null;
float uiRatio = (float) longSize / shortSize;
float minRatio = uiRatio;
for (Camera.Size previewSize : sizes) {
float cameraRatio = (float) previewSize.width / previewSize.height;
//如果找不到比例相同的,找一个最近的,防止预览变形
float offset = Math.abs(cameraRatio - minRatio);
if (offset < minRatio) {
minRatio = offset;
bestSize = previewSize;
}
//比例相同
if (uiRatio == cameraRatio) {
bestSize = previewSize;
break;
}
}
return bestSize;
}
@Override
protected void onPause() {
super.onPause();
closeCamera();
}
@OnClick({R.id.btn_trans,R.id.btn_takePhoto})
public void clicked(View view) {
switch (view.getId()) {
case R.id.btn_trans:
//关闭摄像头
closeCamera();
mCameraID = mCameraID == mFrontCameraId ? mBackCameraId : mFrontCameraId;
//打开相机
openCamera(mCameraID);
//开启预览
startPreview(mSurfaceView.getWidth(), mSurfaceView.getHeight());
break;
case R.id.btn_takePhoto:
Camera camera = mCamera;
camera.takePicture(new Camera.ShutterCallback() {
@Override
public void onShutter() {
}
}, null, new Camera.PictureCallback() {
@Override
public void onPictureTaken(byte[] data, Camera camera) {
new SavePicAsyncTask(data).executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
}
});
break;
}
}
/**
* 保存图片
*/
class SavePicAsyncTask extends AsyncTask<Void, Void, File> {
byte[] data;
File file;
public SavePicAsyncTask(byte[] data) {
this.data = data;
File dir = new File(GlobalConfig.PATH);
if (!dir.exists()) {
dir.mkdirs();
}
String name = "test.jpg";
file = new File(dir, name);
}
@Override
protected File doInBackground(Void... voids) {
Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);
if (bitmap == null) {
return null;
}
FileOutputStream fos = null;
try {
fos = new FileOutputStream(file);
//保存之前先调整方向
Camera.CameraInfo info = mCameraID == mFrontCameraId ? mFrontCameraInfo : mBackCameraInfo;
if (info.facing == Camera.CameraInfo.CAMERA_FACING_BACK) {
bitmap = BitmapUtils.rotate(bitmap, 90);
} else {
bitmap = BitmapUtils.rotate(bitmap, 270);
bitmap = BitmapUtils.mirror(bitmap);
}
bitmap.compress(Bitmap.CompressFormat.JPEG, 100, fos);
} catch (FileNotFoundException e) {
e.printStackTrace();
} finally {
CloseUtils.close(fos);
}
return file;
}
@Override
protected void onPostExecute(File file) {
super.onPostExecute(file);
if (file != null) {
Toast.makeText(MainActivity.this, "图片保存成功", Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(MainActivity.this, "图片保存失败", Toast.LENGTH_SHORT).show();
}
}
}
/**
* 关闭摄像头
*/
private void closeCamera() {
//停止预览
if (mCamera != null) {
mCamera.stopPreview();
mCamera.release();
mCamera = null;
}
}
class PreviewCallback implements SurfaceHolder.Callback {
@Override
public void surfaceCreated(SurfaceHolder holder) {
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
startPreview(width, height);
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
}
}
@Override
protected void onDestroy() {
super.onDestroy();
closeCamera();
}
}