Maui Blazor 使用摄像头实现代码

/**
 * 设置元素的src
 * @param {any} canvasId canvasId的dom id
 * @param {any} videoId video的dom id
 * @param {any} srcId img的dom id
 * @param {any} widht 设置截图宽度
 * @param {any} height 设置截图高度
 */
function setImgSrc(dest,videoId, srcId, widht, height) {
    let video = document.getElementById(videoId);
    let canvas = document.getElementById(canvasId);
    console.log(video.clientHeight, video.clientWidth);
   
    canvas.getContext('2d').drawImage(video, 0, 0, widht, height);

    canvas.toBlob(function (blob) {
        var src = document.getElementById(srcId);
        src.setAttribute("height", height)
        src.setAttribute("width", widht);
        src.setAttribute("src", URL.createObjectURL(blob))
    }, "image/jpeg", 0.95);
}
/**
 * 初始化摄像头
 * @param {any} src 
 */
function startVideo(src) {
    if (navigator.mediaDevices && navigator.mediaDevices.getUserMedia) {
        navigator.mediaDevices.getUserMedia({ video: true }).then(function (stream) {
            let video = document.getElementById(src);
            if ("srcObject" in video) {
                video.srcObject = stream;
            } else {
                video.src = window.URL.createObjectURL(stream);
            }
            video.onloadedmetadata = function (e) {
                video.play();
            };
            //mirror image
            video.style.webkitTransform = "scaleX(-1)";
            video.style.transform = "scaleX(-1)";
        });
    }
}

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android">
	<application android:allowBackup="true" android:supportsRtl="true"></application>
	<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
	<uses-permission android:name="android.permission.INTERNET" />
	<!--相机权限-->
	<uses-permission android:name="android.permission.CAMERA" android:required="false"/>
	<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
	<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
	<!--相机功能-->
	<uses-feature android:name="android.hardware.camera" />
	<!--音频录制权限-->
	<uses-permission android:name="android.permission.RECORD_AUDIO" />
	<!--位置权限-->
	<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
	
	<!-- Needed only if your app targets Android 5.0 (API level 21) or higher. -->
	<uses-feature android:name="android.hardware.location.gps" />

	<queries>
		<intent>
			<action android:name="android.intent.action.VIEW" />
			<data android:scheme="http"/>
		</intent>
		<intent>
			<action android:name="android.intent.action.VIEW" />
			<data android:scheme="https"/>
		</intent>
	</queries>
</manifest>

[Activity(Theme = "@style/Maui.SplashTheme", MainLauncher = true, ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation | ConfigChanges.UiMode | ConfigChanges.ScreenLayout | ConfigChanges.SmallestScreenSize | ConfigChanges.Density)]
public class MainActivity : MauiAppCompatActivity
{
    protected override void OnCreate(Bundle savedInstanceState)
    {
        base.OnCreate(savedInstanceState);
        Platform.Init(this, savedInstanceState);
        // 申请所需权限 也可以再使用的时候去申请
        ActivityCompat.RequestPermissions(this, new[] { Manifest.Permission.Camera, Manifest.Permission.RecordAudio, Manifest.Permission.ModifyAudioSettings }, 0);
    }
}

#if ANDROID
using Android.Webkit;
using Microsoft.AspNetCore.Components.WebView.Maui;

namespace MainSample;

public class MauiWebChromeClient : WebChromeClient
{
    public override void OnPermissionRequest(PermissionRequest request)
    {
        request.Grant(request.GetResources());
    }
}

public class MauiBlazorWebViewHandler : BlazorWebViewHandler
{
    protected override void ConnectHandler(Android.Webkit.WebView platformView)
    {
        platformView.SetWebChromeClient(new MauiWebChromeClient());
        base.ConnectHandler(platformView);
    }
}

#endif

#if ANDROID
        builder.ConfigureMauiHandlers(handlers =>
        {
            handlers.AddHandler<IBlazorWebView, MauiBlazorWebViewHandler>();
        });
#endif

@page "/" @*界面路由*@

@inject IJSRuntime JSRuntime @*注入jsRuntime*@

@if(OpenCameraStatus) @*在摄像头没有被打开的情况不显示video*@
{
    <video id="@VideoId" width="@widht" height="@height" />
    <canvas class="d-none" id="@CanvasId" width="@widht" height="@height" />
}
<button @onclick="" style="margin:8px">打开摄像头</button> 
@*因为摄像头必须是用户手动触发如果界面是滑动进入无法直接调用方法打开摄像头所以添加按钮触发*@
<button style="margin:8px">截图</button> @*对视频流截取一张图*@

<img id="@ImgId" />

@code{
    private string CanvasId;
    private string ImgId;
    private string VideoId;
    private bool OpenCameraStatus;
    private int widht = 320;
    private int height = 500;

    private async Task OpenCamera()
    {
        if (!OpenCameraStatus)
        {
            // 由于打开摄像头的条件必须是用户手动触发如果滑动切换到界面是无法触发的
            await JSRuntime.InvokeVoidAsync("startVideo", "videoFeed");
            OpenCameraStatus = true;
            StateHasChanged();
        }
    }

    protected override async Task OnInitializedAsync()
    {
        // 初始化id
        ImgId = Guid.NewGuid().ToString("N");
        CanvasId = Guid.NewGuid().ToString("N");
        VideoId = Guid.NewGuid().ToString("N");
        await base.OnInitializedAsync();
    }

    private async Task Screenshot()
    {
        await JSRuntime.InvokeAsync<String>("setImgSrc", CanvasId,VideoId, ImgId, widht, height);
    }
}