Question

我尝试了其他帖子中的许多建议，但没有任何帮助。我对 .asp.net Web 应用程序还很陌生。我相信闪烁是由 HttpClient->PostAsync 调用引起的，因为当我增加 Thread.Sleep(100) 时，它似乎不太经常发生。此外，当我启动另一个网页（即在同一个 TCP 端口上创建一个 HttpClient）时，它似乎更频繁地发生。我将所有内容都放在更新面板中，并包含一个计时器作为 asyncpostbacktrigger，以便在每次回发时使用新图像数据更新此图像。我想我在下面包含了所有相关代码：

CSS/HTML：

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
    <style type="text/css">
        body {
            background-color: black;
            margin: 0;
            padding: 0;
        }
        #Image1 {
            position: fixed;
            width: 100%;
            height: 90.0vh;
            left: 0px;
            right: 0px;
            top: 5.0vh;
            bottom: 0px;
            object-fit: contain;
            z-index: -1;
        }  
    </style>
</head>
 
<body onload="'">
    <form id="form1" runat="server">
        <asp:ScriptManager ID="ScriptManager1" runat="server" EnablePageMethods="True" />
        <asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional">
            <Triggers>
                <asp:AsyncPostBackTrigger ControlID="Timer1" EventName="Tick" />
            </Triggers>
            <ContentTemplate>          
                <asp:Image ID="Image1" runat="server" />
            </ContentTemplate>
        </asp:UpdatePanel>
        <asp:Timer ID="Timer1" OnTick="Timer_tick" Interval="100" runat="server">
        </asp:Timer>
    </form>
</body>
</html>

C# 后端：

[StructLayout(LayoutKind.Sequential, Pack = 1)]
        public struct IMAGE_TYPE
        {
            public int count; //Running counter.
            public int dim; //The dimension of x and y (square).
            public int bufsize; //The number of bytes used for RGB data in data_image.
            double angle;
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 5000)]
            public byte[] future_unused;
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 2048*2048)]
            public byte[] data_image;
        }

private static int _tcpPort = 44338;
private static readonly HttpClient _client = new HttpClient();
private static readonly Bitmap _image = new Bitmap(2048, 2048, PixelFormat.Format32bppRgb);

protected void Page_Load(object sender, EventArgs e)
        {
            if (!Page.IsPostBack)
            {
                if (!_isPageLoaded)
                {
                    //No need to process this code besides from the initial loading of the webpage.
                    //This code will be ignored when webpage is refreshed or accessed by more than one user.
                    _isPageLoaded = true;

                    LocalImageBuf = new IMAGE_TYPE
                    {
                        data_image = new byte[2048*2048],
                        future_unused = new byte[5000],
                    };

                    string baseAddress = string.Format("http://localhost:{0}/", _tcpPort);
                    _client.BaseAddress = new Uri(baseAddress);

                    Thread getImageThread = new Thread(GetImage);
                    getImageThread.Start();
                }
            }
        }

private async void GetImage()
            {
                while (true)
                {
                    try
                    {
                        string img = "$IMG,0";
                        byte[] data = Encoding.ASCII.GetBytes(img);
                        ByteArrayContent array = new ByteArrayContent(data);
                        array.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");
                        using (HttpResponseMessage response = await _client.PostAsync("Image", array))
                        {
                            using (HttpContent content = response.Content)
                            {
                                byte[] imageData = await content.ReadAsByteArrayAsync();
                                //Image data is at index 5020 of the returned struct.
                                Array.Copy(imageData, 5020, LocalImageBuf, 0, LocalImageBuf.Length);
                            }
                        }
    
                        PrepareData();
    
                        //Sleep for 100ms.
                        Thread.Sleep(100);
                    }
                    catch (Exception e)
                    {
                        System.Diagnostics.Debug.WriteLine(e.Message);
    
                        //Sleep for 1s.
                        Thread.Sleep(1000);
                    }
                }
            }

private void PrepareData()
        {
            lock (LockClass.DrawLock)
            {
                Rectangle rect = new Rectangle(0, 0, _image.Width, _image.Height);
                BitmapData bitmapData = _image.LockBits(rect, ImageLockMode.ReadWrite, PixelFormat.Format32bppArgb);
                IntPtr pixels1 = bitmapData.Scan0;
                int stride = bitmapData.Stride;

                unsafe
                {
                    int* pt1 = (int*)pixels1.ToPointer();

                    //Begin at the first byte of the output buffer.
                    fixed (byte* img1 = &LocalImageBuf.data_image[0])
                    {
                        byte* ppt1 = img1;
                        for (int y = 0; y < _image.Height; y++)
                        {
                            for (int x = 0; x < _image.Width; x++, pt1++, ppt1++)
                            {
                                *pt1 = *ppt1;
                            }
                        }
                    }
                }

                _image.UnlockBits(bitmapData);
            }
        }

protected void Timer_tick(object sender, EventArgs e)
        {
            //Causes a postback trigger for our echo buffer to be saved to the client image.
            lock (LockClass.DrawLock)
            {
                using (var ms = new MemoryStream())
                {
                    _image.Save(ms, ImageFormat.Png);
                    Image1.ImageUrl = "data:image;base64," + Convert.ToBase64String(ms.ToArray());
                }
            }
        }

public static class LockClass
    {
        public static object DrawLock = new object();
    }

这是正在发生的事情的一个例子。我希望黄色圆圈始终显示（对于此示例，始终通过 PostAsync 返回相同的数据）。但它一直闪烁到数据空白的地方，可能每隔 0.5-3 秒（非常随机）。

.asp 图像随机闪烁

0 个答案: