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Maui Blazor 使用攝像頭實(shí)現(xiàn)代碼

更新時(shí)間：2023年01月12日 10:20:53 作者：dotnet-simple

由于Maui Blazor中界面是由WebView渲染，所以再使用Android的攝像頭時(shí)無法去獲取，因?yàn)樵臄z像頭需要綁定界面組件，這篇文章主要介紹了Maui Blazor 使用攝像頭實(shí)現(xiàn),需要的朋友可以參考下

由于Maui Blazor中界面是由WebView渲染，所以再使用Android的攝像頭時(shí)無法去獲取，因?yàn)樵臄z像頭需要綁定界面組件
所以我找到了其他的實(shí)現(xiàn)方式，通過WebView使用js調(diào)用設(shè)備攝像頭支持多平臺(tái)兼容目前測試了Android 和PC 由于沒有ioc和mac無法測試大概率是兼容可能需要?jiǎng)討B(tài)申請權(quán)限

1. 添加js方法

我們再wwwroot中創(chuàng)建一個(gè)helper.js的文件并且添加以下倆個(gè)js函數(shù)
再index.html中添加<script src="helper.js"></script>引入js

/**
 * 設(shè)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 設(shè)置截圖寬度
 * @param {any} height 設(shè)置截圖高度
 */
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);
}
/**
 * 初始化攝像頭
 * @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)";
        });
    }
}

然后各個(gè)平臺(tái)的兼容

android：

Platforms/Android/AndroidManifest.xml文件內(nèi)容

<?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" />
	<!--相機(jī)權(quán)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" />
	<!--相機(jī)功能-->
	<uses-feature android:name="android.hardware.camera" />
	<!--音頻錄制權(quán)限-->
	<uses-permission android:name="android.permission.RECORD_AUDIO" />
	<!--位置權(quán)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>

Platforms/Android/MainActivity.cs文件內(nèi)容

[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);
        // 申請所需權(quán)限 也可以再使用的時(shí)候去申請
        ActivityCompat.RequestPermissions(this, new[] { Manifest.Permission.Camera, Manifest.Permission.RecordAudio, Manifest.Permission.ModifyAudioSettings }, 0);
    }
}

MauiWebChromeClient.cs文件內(nèi)容

#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

在MauiProgram.cs中添加以下代碼；如果沒有下面代碼會(huì)出現(xiàn)沒有攝像頭權(quán)限
具體在這個(gè) issue體現(xiàn)

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

以上是android的適配代碼 pc不需要設(shè)置額外代碼 ios和mac不清楚

然后編寫界面

@page "/" @*界面路由*@

@inject IJSRuntime JSRuntime @*注入jsRuntime*@

@if(OpenCameraStatus) @*在攝像頭沒有被打開的情況不顯示video*@
{
    <video id="@VideoId" width="@widht" height="@height" />
    <canvas class="d-none" id="@CanvasId" width="@widht" height="@height" />
}
<button @onclick="" style="margin:8px">打開攝像頭</button> 
@*因?yàn)閿z像頭必須是用戶手動(dòng)觸發(fā)如果界面是滑動(dòng)進(jìn)入無法直接調(diào)用方法打開攝像頭所以添加按鈕觸發(fā)*@
<button style="margin:8px">截圖</button> @*對視頻流截取一張圖*@

<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)
        {
            // 由于打開攝像頭的條件必須是用戶手動(dòng)觸發(fā)如果滑動(dòng)切換到界面是無法觸發(fā)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);
    }
}

然后可以運(yùn)行程序就可以看到我們的效果了

示例代碼：gitee github

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