flutter开发实战-Camera自定义相机拍照功能实现
一、前言
在项目中使用image_picker插件时候，在android设备上使用无法默认设置前置摄像头（暂时不清楚什么原因），由于项目默认需要使用前置摄像头，所以最终采用自定义相机实现拍照功能。
二、Camera使用前设置
在工程的iOS的info.plist文件中添加相机、麦克风权限描述
<key>NSCameraUsageDescription</key>
<string>your usage description here</string>
<key>NSMicrophoneUsageDescription</key>
<string>your usage description here</string>
在工程的Android的gradle设置minSdkVersion
找到android/app/build.gradle文件
minSdkVersion 21
二、使用插件Camera插件
camera : 适用于iOS、Android和Web的Flutter插件，允许访问设备摄像头。
我们需要在工程中引入camera插件
pubspec.yaml中引入插件
# Camera相机拍照等
camera: ^0.10.5+5
处理相机访问权限
在初始化相机控制器时可能会引发权限错误，需要处理这些错误。
-
CameraAccessDenied：当用户拒绝相机访问权限时抛出。
-
CameraAccessDeniedWithoutPrompt：仅限iOS。当用户先前拒绝该权限时抛出。iOS不允许再次提示警报对话框。用户必须进入“设置”>“隐私”>“相机”才能访问相机。
-
CameraAccessRestricted:仅限iOS。当摄像头访问受到限制且用户无法授予权限（家长控制）时抛出。
-
AudioAccessDenied：当用户拒绝音频访问权限时抛出。
-
AudioAccessDeniedWithoutPrompt：目前仅限iOS。当用户先前拒绝该权限时抛出。iOS不允许再次提示警报对话框。用户必须转到“设置”>“隐私”>“麦克风”才能启用音频访问。
-
AudioAccessRestricted:目前仅限iOS。当音频访问受到限制并且用户无法授予权限（家长控制）时抛出。
2.1、camera功能设置
当使用camera时，我们需要设置一些camera的属性内容，比如切换前后摄像头、开启拍照、开启预览、停止预览等。
获取cameras
final cameras = await availableCameras();
camera中使用CameraController来控制相关功能。
设置缩放级别zoomLevel
Future<void> setZoomLevel(double scale) async {
await controller!.setZoomLevel(scale);
}
切换闪光灯模式
void onSetFlashModeButtonPressed(FlashMode mode) {
setFlashMode(mode).then((_) {
if (mounted) {
setState(() {});
}
showInSnackBar('Flash mode set to ${mode.toString().split('.').last}');
});
}
设置曝光模式
void onSetExposureModeButtonPressed(ExposureMode mode) {
setExposureMode(mode).then((_) {
if (mounted) {
setState(() {});
}
showInSnackBar('Exposure mode set to ${mode.toString().split('.').last}');
});
}
设置焦距模式
void onSetFocusModeButtonPressed(FocusMode mode) {
setFocusMode(mode).then((_) {
if (mounted) {
setState(() {});
}
showInSnackBar('Focus mode set to ${mode.toString().split('.').last}');
});
}
开启预览
Future<void> onResumePreview() async {
final CameraController? cameraController = controller;
if (cameraController == null || !cameraController.value.isInitialized) {
print('Error: select a camera first.');
return;
}
if (cameraController.value.isPreviewPaused) {
await cameraController.resumePreview();
}
}
暂停预览
Future<void> onPausePreview() async {
final CameraController? cameraController = controller;
if (cameraController == null || !cameraController.value.isInitialized) {
print('Error: select a camera first.');
return;
}
if (!cameraController.value.isPreviewPaused) {
await cameraController.pausePreview();
}
}
切换前后摄像头
void onViewFinderTap(TapDownDetails details, BoxConstraints constraints) {
if (controller == null) {
return;
}
final CameraController? cameraController = controller;
final Offset offset = Offset(
details.localPosition.dx / constraints.maxWidth,
details.localPosition.dy / constraints.maxHeight,
);
cameraController?.setExposurePoint(offset);
cameraController?.setFocusPoint(offset);
}
Future<void> onNewCameraSelected(CameraDescription cameraDescription) async {
final CameraController cameraController = CameraController(
cameraDescription,
ResolutionPreset.high,
enableAudio: enableAudio,
imageFormatGroup: ImageFormatGroup.jpeg,
);
controller = cameraController;
// If the controller is updated then update the UI.
cameraController.addListener(() {
if (mounted) {
setState(() {});
}
if (cameraController.value.hasError) {
print("Camera error ${cameraController.value.errorDescription}");
}
});
try {
await cameraController.initialize();
await Future.wait(<Future<Object>>[
// The exposure mode is currently not supported on the web.
cameraController
.getMaxZoomLevel()
.then((double value) => _maxAvailableZoom = value),
cameraController
.getMinZoomLevel()
.then((double value) => _minAvailableZoom = value),
]);
} on CameraException catch (e) {
// _showCameraException(e);
}
setState(() {
isCameraStarting = true;
});
controller!.initialize().then((_) {
if (!mounted) {
return;
}
setState(() {
isCameraStarting = false;
});
}).catchError((Object e) {
if (e is CameraException) {
switch (e.code) {
case 'CameraAccessDenied':
// Handle access errors here.
break;
default:
// Handle other errors here.
break;
}
}
});
if (mounted) {
setState(() {});
}
}
上面介绍了一些CameraController的常用设置，当然肯定不全，大致列了几条。
2.2、WidgetsBinding 生命周期改变相机设置
我们自定义Camera，需要在didChangeAppLifecycleState来处理相机。我们需要添加mixin WidgetsBindingObserver
在initState中添加WidgetsBinding.instance?.addObserver(this);
在dispose中移除WidgetsBinding.instance?.removeObserver(this);
这样我们就可以在app的生命周期状态改变时候，更新相机
@override
void didChangeAppLifecycleState(AppLifecycleState state) {
final CameraController? cameraController = controller;
// App state changed before we got the chance to initialize.
if (cameraController == null || !cameraController.value.isInitialized) {
return;
}
if (state == AppLifecycleState.inactive) {
cameraController.dispose();
} else if (state == AppLifecycleState.resumed) {
onNewCameraSelected(cameraController.description);
}
}
2.3、处理预览的画面出现变形的问题
在处理自定义相机功能，我们需要处理预览的画面出现变形的问题。这里我们需要使用CameraPreview。
我们需要使用Transform.scale来进行处理，处理预览的画面出现变形的问题的解决代码如下
Widget buildCameraPreviewWidget(BuildContext context) {
final Size size = MediaQuery.of(context).size;
final CameraController? cameraController = controller;
return Container(
width: size.width,
height: size.height,
child: Stack(
alignment: Alignment.center,
clipBehavior: Clip.hardEdge,
children: [
RepaintBoundary(
key: _cameraViewGlobalKey,
child: Transform.scale(
scale: 1.0,
// scale: controller!.value.aspectRatio / deviceRatio,
alignment: Alignment.center,
child: AspectRatio(
aspectRatio: size.aspectRatio,
child: OverflowBox(
alignment: Alignment.center,
child: FittedBox(
fit: BoxFit.fitHeight,
child: SizedBox(
width: size.width,
height: size.width * cameraController!.value.aspectRatio,
child: Stack(fit: StackFit.expand, children: <Widget>[
_cameraPreviewWidget(),
]),
),
),
),
),
),
),
],
),
);
}
/// Display the preview from the camera (or a message if the preview is not available).
Widget _cameraPreviewWidget() {
final CameraController? cameraController = controller;
if (cameraController == null || !cameraController.value.isInitialized) {
return const Text(
'cameraController未初始化完成',
style: TextStyle(
color: Colors.white,
fontSize: 24.0,
fontWeight: FontWeight.w900,
),
);
} else {
return Listener(
onPointerDown: (_) => _pointers++,
onPointerUp: (_) => _pointers--,
child: CameraPreview(
controller!,
child: LayoutBuilder(
builder: (BuildContext context, BoxConstraints constraints) {
return GestureDetector(
behavior: HitTestBehavior.opaque,
onScaleStart: _handleScaleStart,
onScaleUpdate: _handleScaleUpdate,
onTapDown: (TapDownDetails details) =>
onViewFinderTap(details, constraints),
);
}),
),
);
}
}
在代码中，我们使用Transform.scale设置为1.0，当设置AspectRatio来设置size.aspectRatio。
2.4、实现拍照功能
在我们代码中，我们使用takePicture来实现拍照，拍照代码如下
Future<void> onTakePicture() async {
setState(() {
isTaking = true;
});
takePicture().then((XFile? file) async {
if (mounted) {
onPausePreview();
if (file != null) {
// 保存到相册
// await SaveToAlbumUtil.saveLocalImage(file.path);
RenderBox renderBox = _cameraContainerGlobalKey.currentContext!
.findRenderObject() as RenderBox;
// offset.dx , offset.dy 就是控件的左上角坐标
Offset offset = renderBox.localToGlobal(Offset.zero);
//获取size
Size size = renderBox.size;
// 创建文件path
String imageDir = await PathUtil.createDirectory("local_images");
String imagePath = '$imageDir/${TimeUtil.currentTimeMillis()}.png';
// // 获取当前设备的像素比
double dpr = ui.window.devicePixelRatio;
print("devicePixelRatio:${dpr}");
print(
"offset:(${offset.dx},${offset.dy})--size:(${size.width},${size.height})");
File? targetFile = await ImageUtil.cropImage(
file.path,
imagePath,
x: (dpr * offset.dx).floor(),
y: (dpr * offset.dy).floor(),
width: (dpr * size.width).ceil(),
height: (dpr * size.height).ceil(),
flipHorizontal: isCameraFront,
);
print("cropImage targetFile:${targetFile}");
if (targetFile != null) {
selectedImagePath = targetFile.path;
// await SaveToAlbumUtil.saveLocalImage(targetFile.path);
}
setState(() {
isHasTakePhoto = true;
});
} else {
// 没有获得图片，重试
}
setState(() {
isTaking = false;
});
}
});
}
在裁剪图片中实现如下
import 'dart:io';
import 'dart:math';
import 'dart:ui' as ui;
import 'dart:math' as math;
import 'package:flutter/cupertino.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/rendering.dart';
import 'package:image/image.dart' as IMG;
class ImageUtil {
//拿到图片的字节数组
static Future<ui.Image> loadImageByFile(String path) async {
var list = await File(path).readAsBytes();
return ImageUtil.loadImageByUInt8List(list);
}
//通过[Uint8List]获取图片
static Future<ui.Image> loadImageByUInt8List(Uint8List list) async {
ui.Codec codec = await ui.instantiateImageCodec(list);
ui.FrameInfo frame = await codec.getNextFrame();
return frame.image;
}
// 根据GlobalKey来截图Widget
static Future<Uint8List?> makeImageUInt8List(GlobalKey globalKey) async {
RenderRepaintBoundary boundary =
globalKey.currentContext?.findRenderObject() as RenderRepaintBoundary;
// 这个可以获取当前设备的像素比
var dpr = ui.window.devicePixelRatio;
ui.Image image = await boundary.toImage(pixelRatio: dpr);
ByteData? byteData = await image.toByteData(format: ui.ImageByteFormat.png);
Uint8List? pngBytes = byteData?.buffer.asUint8List();
return pngBytes;
}
static Future<File?> cropSquare(
String srcFilePath, String destFilePath, bool flip) async {
var bytes = await File(srcFilePath).readAsBytes();
IMG.Image? src = IMG.decodeImage(bytes);
if (src != null) {
var cropSize = min(src.width, src.height);
int offsetX = (src.width - min(src.width, src.height)) ~/ 2;
int offsetY = (src.height - min(src.width, src.height)) ~/ 2;
// IMG.Image destImage = IMG.copyCrop(src, offsetX, offsetY, cropSize, cropSize);
IMG.Image destImage = IMG.copyCrop(src,
x: offsetX, y: offsetY, width: cropSize, height: cropSize);
if (flip) {
destImage = IMG.flipVertical(destImage);
}
var jpg = IMG.encodeJpg(destImage);
return await File(destFilePath).writeAsBytes(jpg);
} else {
throw StateError("cropSquare error");
}
}
static Future<File?> cropImage(
String srcFilePath,
String destFilePath, {
required int x,
required int y,
required int width,
required int height,
bool flipVertical = false,
bool flipHorizontal = false,
}) async {
var bytes = await File(srcFilePath).readAsBytes();
IMG.Image? src = IMG.decodeImage(bytes);
if (src != null) {
print("cropImage scr size:(${src.width},${src.height})");
IMG.Image destImage = IMG.copyCrop(src,
x: x, y: y, width: width, height: height);
if (flipVertical) {
destImage = IMG.flipVertical(destImage);
}
if (flipHorizontal) {
destImage = IMG.flipHorizontal(destImage);
}
var jpg = IMG.encodeJpg(destImage);
return await File(destFilePath).writeAsBytes(jpg);
} else {
throw StateError("cropSquare error");
}
}
}
2.5、拍照完重拍逻辑
当拍照后可能需要重新拍照，这时候我们需要重拍逻辑。
void onRetakeButtonPressed() {
setState(() {
isHasTakePhoto = false;
});
selectedImagePath = null;
onResumePreview();
}
Future<void> onResumePreview() async {
final CameraController? cameraController = controller;
if (cameraController == null || !cameraController.value.isInitialized) {
print('Error: select a camera first.');
return;
}
if (cameraController.value.isPreviewPaused) {
await cameraController.resumePreview();
}
}
三、实现自定义相机拍照的功能完整代码
我们实现了实现自定义相机拍照的功能完整代码如下
// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// ignore_for_file: public_member_api_docs
import 'dart:async';
import 'dart:io';
import 'package:camera/camera.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:flutter_app_demolab/image_util.dart';
import 'package:flutter_app_demolab/path_util.dart';
import 'dart:ui' as ui;
import 'package:flutter_app_demolab/tools/utils/color_util.dart';
import 'package:flutter_app_demolab/tools/utils/time_util.dart';
import 'package:flutter_screenutil/flutter_screenutil.dart';
class MyCameraPage extends StatefulWidget {
const MyCameraPage({
super.key,
required this.cameras,
required this.onSelectedImagePathPressed,
});
final List<CameraDescription> cameras;
final Function(String? selectedImagePath) onSelectedImagePathPressed;
@override
State<MyCameraPage> createState() => _MyCameraPageState();
}
class _MyCameraPageState extends State<MyCameraPage>
with WidgetsBindingObserver, TickerProviderStateMixin {
CameraController? controller;
GlobalKey _cameraViewGlobalKey = GlobalKey();
GlobalKey _cameraContainerGlobalKey = GlobalKey();
bool enableAudio = false;
// Counting pointers (number of user fingers on screen)
///以下是关于手指缩放画面的变量
int _pointers = 0;
double _minAvailableZoom = 1.0;
double _maxAvailableZoom = 1.0;
double _currentScale = 1.0;
double _baseScale = 1.0;
Size? mediaSize;
double? scale;
double? defaultZoomLevel;
bool isHasTakePhoto = false;
bool isCameraFront = true;
String? selectedImagePath;
bool isTaking = false;
bool isCameraStarting = false;
@override
void initState() {
super.initState();
// To display the current output from the Camera,
// create a CameraController.
if (widget.cameras.isNotEmpty && widget.cameras.length >= 2) {
controller = CameraController(
// Get a specific camera from the list of available cameras.
widget.cameras[1],
// Define the resolution to use.
ResolutionPreset.high,
);
// Next, initialize the controller. This returns a Future.
setState(() {
isCameraStarting = true;
});
controller!.initialize().then((_) {
if (!mounted) {
return;
}
setState(() {
isCameraStarting = false;
});
}).catchError((Object e) {
if (e is CameraException) {
switch (e.code) {
case 'CameraAccessDenied':
// Handle access errors here.
break;
default:
// Handle other errors here.
break;
}
}
});
}
WidgetsBinding.instance?.addObserver(this);
}
@override
void dispose() {
WidgetsBinding.instance?.removeObserver(this);
controller?.dispose();
super.dispose();
}
@override
void didChangeAppLifecycleState(AppLifecycleState state) {
final CameraController? cameraController = controller;
// App state changed before we got the chance to initialize.
if (cameraController == null || !cameraController.value.isInitialized) {
return;
}
if (state == AppLifecycleState.inactive) {
cameraController.dispose();
} else if (state == AppLifecycleState.resumed) {
onNewCameraSelected(cameraController.description);
}
}
final GlobalKey<ScaffoldState> _scaffoldKey = GlobalKey<ScaffoldState>();
@override
Widget build(BuildContext context) {
return Scaffold(
key: _scaffoldKey,
body: buildCameraContainer(context),
);
}
Widget buildCameraContainer(BuildContext context) {
final Size size = MediaQuery.of(context).size;
if (widget.cameras.isEmpty) {
return Container(
width: size.width,
height: size.height,
decoration: const BoxDecoration(
color: Colors.black,
),
child: Text(
"未获取到可用的相机，请退出重试。",
textAlign: TextAlign.center,
maxLines: 2,
overflow: TextOverflow.ellipsis,
softWrap: true,
style: TextStyle(
fontSize: 16,
fontWeight: FontWeight.w500,
fontStyle: FontStyle.normal,
color: ColorUtil.hexColor(0xffffff),
decoration: TextDecoration.none,
),
),
);
} else {
return Container(
key: _cameraContainerGlobalKey,
width: size.width,
height: size.height,
decoration: const BoxDecoration(
color: Colors.black,
),
child: Stack(
alignment: Alignment.center,
children: [
Column(
children: [
Expanded(
child: buildFutureBuilder(context),
)
],
),
buildStackBarWidget(context),
],
),
);
}
}
Widget buildFutureBuilder(BuildContext context) {
if (controller != null && controller!.value.isInitialized) {
///初始化完成以后，再获取可以缩放画面最大最小的参数
mediaSize = MediaQuery.of(context).size;
scale = 1 / (controller!.value.aspectRatio * mediaSize!.aspectRatio);
controller!
.getMaxZoomLevel()
.then((double value) => _maxAvailableZoom = value);
controller!
.getMinZoomLevel()
.then((double value) => _minAvailableZoom = value);
return buildCameraPreviewWidget(context);
}
return const Center(child: CircularProgressIndicator());
}
Widget buildStackBarWidget(BuildContext context) {
final Size size = MediaQuery.of(context).size;
double bottomBarHeight = 120;
double cameraHeight = size.height - bottomBarHeight;
EdgeInsets viewPadding = MediaQuery.of(context).viewPadding;
return Container(
child: Stack(
children: [
Positioned(
bottom: 0,
child: Container(
width: size.width,
height: bottomBarHeight,
color: Colors.transparent,
child: Stack(
alignment: Alignment.center,
children: [
Positioned(
left: 25,
child: buildCloseIcon(context),
),
buildTakePhotoButton(context),
Positioned(
right: 25,
child: buildRetakeButton(context),
),
],
),
),
),
Positioned(
top: viewPadding.top + 25,
right: 10,
child: buildExchangeButton(context),
),
],
),
);
}
Widget buildCameraPreviewWidget(BuildContext context) {
final Size size = MediaQuery.of(context).size;
final CameraController? cameraController = controller;
return Container(
width: size.width,
height: size.height,
child: Stack(
alignment: Alignment.center,
clipBehavior: Clip.hardEdge,
children: [
RepaintBoundary(
key: _cameraViewGlobalKey,
child: Transform.scale(
scale: 1.0,
// scale: controller!.value.aspectRatio / deviceRatio,
alignment: Alignment.center,
child: AspectRatio(
aspectRatio: size.aspectRatio,
child: OverflowBox(
alignment: Alignment.center,
child: FittedBox(
fit: BoxFit.fitHeight,
child: SizedBox(
width: size.width,
height: size.width * cameraController!.value.aspectRatio,
child: Stack(fit: StackFit.expand, children: <Widget>[
_cameraPreviewWidget(),
]),
),
),
),
),
),
),
],
),
);
}
/// Display the preview from the camera (or a message if the preview is not available).
Widget _cameraPreviewWidget() {
final CameraController? cameraController = controller;
if (cameraController == null || !cameraController.value.isInitialized) {
return const Text(
'cameraController未初始化完成',
style: TextStyle(
color: Colors.white,
fontSize: 24.0,
fontWeight: FontWeight.w900,
),
);
} else {
return Listener(
onPointerDown: (_) => _pointers++,
onPointerUp: (_) => _pointers--,
child: CameraPreview(
controller!,
child: LayoutBuilder(
builder: (BuildContext context, BoxConstraints constraints) {
return GestureDetector(
behavior: HitTestBehavior.opaque,
onScaleStart: _handleScaleStart,
onScaleUpdate: _handleScaleUpdate,
onTapDown: (TapDownDetails details) =>
onViewFinderTap(details, constraints),
);
}),
),
);
}
}
Widget buildCloseIcon(BuildContext context) {
return GestureDetector(
onTap: () {
Navigator.pop(context);
},
child: Container(
color: Colors.transparent,
child: Container(
width: 50,
height: 50,
decoration: BoxDecoration(
color: Colors.transparent,
border: Border.all(
color: Colors.transparent,
style: BorderStyle.solid,
width: 1,
),
borderRadius: BorderRadius.all(Radius.circular(20)),
),
child: Icon(
Icons.close,
size: 30,
color: Colors.white,
weight: 0.5,
),
),
),
);
}
Widget buildTakePhotoButton(BuildContext context) {
return GestureDetector(
onTap: () {
if (isTaking == false) {
if (isHasTakePhoto == true) {
widget.onSelectedImagePathPressed(selectedImagePath);
Navigator.pop(context);
} else {
onTakePicturePressed();
}
}
},
child: Container(
color: Colors.transparent,
child: Container(
width: 60,
height: 60,
decoration: const BoxDecoration(
color: Colors.transparent,
),
child: Stack(
alignment: Alignment.center,
children: [
Image.asset(
"assets/camera/my_take_photo.png",
width: 60.0,
height: 60.0,
fit: BoxFit.contain,
),
buildHasCheck(context),
],
),
),
),
);
}
Widget buildHasCheck(BuildContext context) {
if (isTaking == true) {
return buildLoading(context);
}
if (isHasTakePhoto) {
return Icon(
Icons.check,
size: 30,
color: Colors.black,
weight: 0.5,
);
}
return Container();
}
Widget buildExchangeButton(BuildContext context) {
if (isHasTakePhoto == true) {
return Container();
}
return GestureDetector(
onTap: () {
onExchangeCameraPressed();
},
child: Container(
color: Colors.transparent,
child: Container(
width: 50,
height: 50,
decoration: BoxDecoration(
color: Colors.transparent,
border: Border.all(
color: Colors.transparent,
style: BorderStyle.solid,
width: 2,
),
borderRadius: BorderRadius.all(Radius.circular(20)),
),
child: Container(
width: 40,
height: 40,
decoration: BoxDecoration(
color: Colors.transparent,
border: Border.all(
color: Colors.transparent,
style: BorderStyle.solid,
width: 5,
),
borderRadius: BorderRadius.all(Radius.circular(20)),
),
child: Image.asset(
"assets/camera/my_exchange_camera.png",
width: 50.0,
height: 50.0,
fit: BoxFit.contain,
),
),
),
),
);
}
Widget buildRetakeButton(BuildContext context) {
if (isHasTakePhoto == false) {
return Container();
}
return GestureDetector(
onTap: () {
onRetakeButtonPressed();
},
child: Container(
color: Colors.transparent,
child: Container(
width: 70,
height: 38,
alignment: Alignment.center,
decoration: BoxDecoration(
color: ColorUtil.hexColor(0x000000, alpha: 0.25),
border: Border.all(
color: Colors.transparent,
style: BorderStyle.solid,
width: 2,
),
borderRadius: BorderRadius.all(Radius.circular(5)),
),
child: Text(
"重拍",
textAlign: TextAlign.center,
maxLines: 2,
overflow: TextOverflow.ellipsis,
softWrap: true,
style: TextStyle(
fontSize: 16,
fontWeight: FontWeight.w500,
fontStyle: FontStyle.normal,
color: ColorUtil.hexColor(0xffffff),
decoration: TextDecoration.none,
),
),
),
),
);
}
Widget buildLoading(BuildContext context) {
return SizedBox(
height: 58,
width: 58,
child: CircularProgressIndicator(
backgroundColor: Colors.grey[200],
valueColor: AlwaysStoppedAnimation(Colors.blue),
),
);
}
void onRetakeButtonPressed() {
setState(() {
isHasTakePhoto = false;
});
selectedImagePath = null;
onResumePreview();
}
Future<void> onPausePreview() async {
final CameraController? cameraController = controller;
if (cameraController == null || !cameraController.value.isInitialized) {
print('Error: select a camera first.');
return;
}
if (!cameraController.value.isPreviewPaused) {
await cameraController.pausePreview();
}
}
Future<void> onResumePreview() async {
final CameraController? cameraController = controller;
if (cameraController == null || !cameraController.value.isInitialized) {
print('Error: select a camera first.');
return;
}
if (cameraController.value.isPreviewPaused) {
await cameraController.resumePreview();
}
}
Future<void> onExchangeCameraPressed() async {
setState(() {
isHasTakePhoto = false;
});
if (isCameraFront == true) {
if (widget.cameras.isNotEmpty && widget.cameras.length >= 2) {
onNewCameraSelected(widget.cameras[0]);
}
isCameraFront = false;
} else {
if (widget.cameras.isNotEmpty && widget.cameras.length >= 2) {
onNewCameraSelected(widget.cameras[1]);
}
isCameraFront = true;
}
}
void onTakePicturePressed() {
onTakePicture();
}
Future<void> onTakePicture() async {
setState(() {
isTaking = true;
});
takePicture().then((XFile? file) async {
if (mounted) {
onPausePreview();
if (file != null) {
// 保存到相册
// await SaveToAlbumUtil.saveLocalImage(file.path);
RenderBox renderBox = _cameraContainerGlobalKey.currentContext!
.findRenderObject() as RenderBox;
// offset.dx , offset.dy 就是控件的左上角坐标
Offset offset = renderBox.localToGlobal(Offset.zero);
//获取size
Size size = renderBox.size;
// 创建文件path
String imageDir = await PathUtil.createDirectory("local_images");
String imagePath = '$imageDir/${TimeUtil.currentTimeMillis()}.png';
// // 获取当前设备的像素比
double dpr = ui.window.devicePixelRatio;
print("devicePixelRatio:${dpr}");
print(
"offset:(${offset.dx},${offset.dy})--size:(${size.width},${size.height})");
File? targetFile = await ImageUtil.cropImage(
file.path,
imagePath,
x: (dpr * offset.dx).floor(),
y: (dpr * offset.dy).floor(),
width: (dpr * size.width).ceil(),
height: (dpr * size.height).ceil(),
flipHorizontal: isCameraFront,
);
print("cropImage targetFile:${targetFile}");
if (targetFile != null) {
selectedImagePath = targetFile.path;
// await SaveToAlbumUtil.saveLocalImage(targetFile.path);
}
setState(() {
isHasTakePhoto = true;
});
} else {
// 没有获得图片，重试
}
setState(() {
isTaking = false;
});
}
});
}
Future<void> _handleScaleStart(ScaleStartDetails details) async {
_baseScale = _currentScale;
await controller!.setZoomLevel(_minAvailableZoom);
}
Future<void> _handleScaleUpdate(ScaleUpdateDetails details) async {
// When there are not exactly two fingers on screen don't scale
if (controller == null || _pointers != 2) {
return;
}
_currentScale = (_baseScale * details.scale)
.clamp(_minAvailableZoom, _maxAvailableZoom);
await controller!.setZoomLevel(_currentScale);
}
void onViewFinderTap(TapDownDetails details, BoxConstraints constraints) {
if (controller == null) {
return;
}
final CameraController? cameraController = controller;
final Offset offset = Offset(
details.localPosition.dx / constraints.maxWidth,
details.localPosition.dy / constraints.maxHeight,
);
cameraController?.setExposurePoint(offset);
cameraController?.setFocusPoint(offset);
}
Future<void> onNewCameraSelected(CameraDescription cameraDescription) async {
final CameraController cameraController = CameraController(
cameraDescription,
ResolutionPreset.high,
enableAudio: enableAudio,
imageFormatGroup: ImageFormatGroup.jpeg,
);
controller = cameraController;
// If the controller is updated then update the UI.
cameraController.addListener(() {
if (mounted) {
setState(() {});
}
if (cameraController.value.hasError) {
print("Camera error ${cameraController.value.errorDescription}");
}
});
try {
await cameraController.initialize();
await Future.wait(<Future<Object>>[
// The exposure mode is currently not supported on the web.
cameraController
.getMaxZoomLevel()
.then((double value) => _maxAvailableZoom = value),
cameraController
.getMinZoomLevel()
.then((double value) => _minAvailableZoom = value),
]);
} on CameraException catch (e) {
// _showCameraException(e);
}
setState(() {
isCameraStarting = true;
});
controller!.initialize().then((_) {
if (!mounted) {
return;
}
setState(() {
isCameraStarting = false;
});
}).catchError((Object e) {
if (e is CameraException) {
switch (e.code) {
case 'CameraAccessDenied':
// Handle access errors here.
break;
default:
// Handle other errors here.
break;
}
}
});
if (mounted) {
setState(() {});
}
}
Future<XFile?> takePicture() async {
final CameraController? cameraController = controller;
if (cameraController == null || !cameraController.value.isInitialized) {
print("Error: select a camera first.");
return null;
}
if (cameraController.value.isTakingPicture) {
// A capture is already pending, do nothing.
return null;
}
try {
final XFile file = await cameraController.takePicture();
return file;
} on CameraException catch (e) {
print("takePicture CameraException e:${e.toString()}");
return null;
}
}
}
当需要拍照时候，我们调用showModalBottomSheet来打开camera
//显示底部弹窗
static void bottomSheetDialog(BuildContext context, Widget widget) {
showModalBottomSheet(
context: context,
isScrollControlled: true,
builder: (ctx) {
return widget;
},
);
}
//返回上一级
static void pop(BuildContext context) {
Navigator.pop(context);
}
打开自定义相机页面
Future<void> testCustomCamera(BuildContext context) async {
final cameras = await availableCameras();
DialogUtils.bottomSheetDialog(
context,
MyCameraPage(
cameras: cameras,
onSelectedImagePathPressed: (String? selectedImagePath) {
print("selectedImageFilePath:${selectedImagePath}");
if (selectedImagePath != null) {
// File imageFile = File(selectedImagePath!);
// if (callback != null) {
// callback(imageFile);
// }
}
},
),
);
}
https://brucegwo.blog.csdn.net/article/details/135997096
四、小结
flutter开发实战-Camera自定义相机拍照功能实现
学习记录，每天不停进步。
