C# winform中，如何获得一个treeview中所有选中的checkbox的文本值？

Posted 2023-05-06

rt，比如一个treeview中的一些checkbox项是选了的，怎么遍历整个treeview呢？

参考技术A void GetSelectedTreeNode(TreeNodeCollection nodes,List<TreeNode> selectedNodes)

foreach(TreeNode node in nodes)

if(node.Checked)

selectedNodes.Add(node);

GetSelectedTreeNode(node,selectedNodes);



最后在selectedNodes中是所有选中的TreeNode，如有别的需求，改一下代码就行了本回答被提问者采纳 参考技术B 循环他的treeview
CheckBox ck=(CheckBox)dli.FindControl("CheckBox1"); 参考技术C 用递归循环数节点

C# SkiaSharp OpenTK Winform - 如何从后台线程中绘制？

【中文标题】C# SkiaSharp OpenTK Winform - 如何从后台线程中绘制？

【英文标题】：C# SkiaSharp OpenTK Winform - How to draw from a background thread?

【发布时间】：2021-02-20 13:04:35

【问题描述】：

我正在尝试将 GDI+ 替换为 SkiaSharp，以获得数据可视化框架，该框架使用实时不断变化的工程数据呈现多层可平移-可缩放图。

在 GDI+ 中，应用程序执行以下操作：

创建了一组具有透明背景的绘图层，通常是一个网格层、一个或多个数据层，以及一个用于光标信息和突出显示的覆盖层，每个层都有一个单独的位图支持。 在渲染循环后台线程中，仅使用 GDI+ 重绘了每个渲染循环需要更新的层（位图）。这可能需要数千条计算和转换的线、矩形和文本来创建热图、波形、直方图、数据标签等。 堆栈中的每个绘图层随后将由后台线程 BitBlt'd 到复合位图 最终的复合位图随后会以最高 30 fps 的速度绘制到 GUI 线程中的 WinForm PictureBox。

直到最终图像呈现的所有工作都在一个或多个后台线程中完成。 GUI 线程仅参与将完成的图像绘制到 PictureBox。这很重要，因为还有许多其他 GUI 控件需要保持响应。这很好用，除了它都是基于 CPU 的。小窗口没有问题，但在 4K 屏幕上最大化会减慢渲染速度，足以使程序几乎无法使用。

我想用 GPU 加速的 SkiaSharp 重新创建这个概念。

我尝试创建了几十个不同的测试程序，但我不断遇到跨线程访问冲突，或者屏幕上没有显示，或者硬崩溃。让我问一些基本问题，而不是发布代码：

问题：

您将如何创建此框架？ SkiaSharp 甚至可以做到这一点吗？ 我的每个图层类都应该维护一个 SKSurface、SKCanvas、SKImage 或 SKBitmap 吗？ - 同样，如果在当前循环中不需要重新绘制图层，则该图层需要保留之前绘制的内容以用于下一个合成图像。 GUI 线程上需要一个 GLControl 和 GRContext 来显示最终的合成图像，但是否应该有另一个单独的 GRContext 供后台渲染线程使用？ - 如何使用 GPU 加速进行创作？ 是否有人可以指出类似概念的任何工作示例？ （GPU 加速从后台线程到 GLControl 的渲染） 我应该只使用隐藏在背景中的 SkiaSharp，并使用带有 PictureBox 的 GDI+ BitBlt 在屏幕上显示合成图像吗？ - 这会解决一些线程问题吗？

任何帮助定义方法和注意事项将不胜感激！

【参考方案1】：

我想出了如何使用 SKPicture 对象使用后台渲染线程记录每个图层的绘制命令，然后使用 GUI 线程将它们绘制回 SKGLControl 来使其工作。这满足了我的所有要求：它允许多个绘图层，使用后台线程进行渲染，仅渲染需要更新的层，使用 GPU 加速进行绘图，并且对于最大化的 4K 窗口非常快。

经验教训

我在此过程中学到的一些教训给我带来了很多困惑......

网上有使用带有 GPU 加速的 OpenTK.GLControl 的示例，也有使用内置 GPU 加速的 SkiaSharp.Views.Desktop.SKGLControl 的示例。 SKGLControl 绝对是此任务的正确控件。由于 FramebufferBinding 和 StencilBits 的问题，GLControl 正在为 DrawCircle 创建正方形并拒绝渲染任何曲线？！？ - 我放弃了。对于 SKPicture 对象，它也比 SKGLControl 慢。

SKGLControl 不需要也不喜欢使用 GLControl 所需的 SwapBuffers 或 Canvas.Flush。这导致了 SKGLControl 绘图的频闪和故障，这就是为什么我在与 GLControl 的杂草中奋战的原因。当我使用 SKGLControl 重建项目并摆脱 SwapBuffers 和 Canvas.Flush 时，一切都开始正常运行了。

对 Surfaces 和 Canvases 的引用不应超过一个 PaintSurface 周期。 SKPicture 是一个神奇的对象，它可以让您存储每个图层的绘图命令并一次又一次地播放它们。这与生成像素栅格而不是仅记录 Draw 命令的 SKBitmap 或 SKImage 不同。我无法让 SKBitmap 或 SKImage 在多线程环境中运行，并且仍然可以进行 GPU 加速。 SKPicture 非常适合这一点。

SKGLControl 的 Paint 事件和 PaintSurface 事件之间存在差异。 PaintSurface 事件是应该使用的，默认情况下是 GPU 加速的。

---

工作示例代码

以下是多层、多线程、GPU 加速的 SkiaSharp 绘图的全功能演示

这个例子创建了 4 个绘图层：

背景层 网格层 数据层 叠加层

图层使用后台线程绘制（渲染），然后使用 GUI 线程绘制到 SKGLControl。每个图层仅在需要时渲染，但所有图层都使用每个 PaintSurface 事件进行绘制。

试用代码：

在 Visual Studio 中创建一个新的 C# WinForms 项目。 添加 NuGet 包：“SkiaSharp.Views.WindowsForms”。这将自动添加“SkiaSharp”和“SkiaSharp.Views.Desktop.Common”。 将 SkiaSharp.Views.Desktop.SKGLControl 添加到 Form1。将其命名为“skglControl1” 将 skglControl1 的 Dock 设置为“填充”，以便填充 Form1。 将以下代码复制到Form1：

    using System;
    using System.Collections.Generic;
    using System.ComponentModel;
    using System.Drawing;
    using System.Threading;
    using System.Windows.Forms;
    using SkiaSharp;
    using SkiaSharp.Views.Desktop;
    
    namespace SkiaSharp_Multi_Layer_GPU
    
        // ---------------------------------------------------------------------
        // ---------------------------------------------------------------------
        // -------                                                       -------
        // -------                   WinForm - Form 1                    -------
        // -------                                                       -------
        // ---------------------------------------------------------------------
        // ---------------------------------------------------------------------

        public partial class Form1 : Form
        
            private Thread m_RenderThread = null;
            private AutoResetEvent m_ThreadGate = null;
            private List<Layer> m_Layers = null;
            private Layer m_Layer_Background = null;
            private Layer m_Layer_Grid = null;
            private Layer m_Layer_Data = null;
            private Layer m_Layer_Overlay = null;
            private bool m_KeepSwimming = true;
            private SKPoint m_MousePos = new SKPoint();
            private bool m_ShowGrid = true;
            private Point m_PrevMouseLoc = new Point();
    
    
            // ---------------------------
            // --- Form1 - Constructor ---
            // ---------------------------
    
            public Form1()
            
                InitializeComponent();
            
    
    
            // ------------------------------
            // --- Event - Form1 - OnLoad ---
            // ------------------------------
    
            protected override void OnLoad(EventArgs e)
            
                base.OnLoad(e);
    
                // Set the title of the Form
                this.Text = "SkiaSharp Demo - Multi-Layer, Multi-Threaded, GPU Accelerated";
    
                // Create layers to draw on, each with a dedicated SKPicture
                m_Layer_Background = new Layer("Background Layer");
                m_Layer_Grid = new Layer("Grid Layer");
                m_Layer_Data = new Layer("Data Layer");
                m_Layer_Overlay = new Layer("Overlay Layer");
    
                // Create a collection for the drawing layers
                m_Layers = new List<Layer>();
                m_Layers.Add(m_Layer_Background);
                m_Layers.Add(m_Layer_Grid);
                m_Layers.Add(m_Layer_Data);
                m_Layers.Add(m_Layer_Overlay);
    
                // Subscribe to the Draw Events for each layer
                m_Layer_Background.Draw += Layer_Background_Draw;
                m_Layer_Grid.Draw += Layer_Grid_Draw;
                m_Layer_Data.Draw += Layer_Data_Draw;
                m_Layer_Overlay.Draw += Layer_Overlay_Draw;
    
                // Subscribe to the SKGLControl events
                skglControl1.PaintSurface += SkglControl1_PaintSurface;
                skglControl1.Resize += SkglControl1_Resize;
                skglControl1.MouseMove += SkglControl1_MouseMove;
                skglControl1.MouseDoubleClick += SkglControl1_MouseDoubleClick;
                
                // Create a background rendering thread
                m_RenderThread = new Thread(RenderLoopMethod);
                m_ThreadGate = new AutoResetEvent(false);
    
                // Start the rendering thread
                m_RenderThread.Start();
            
    
    
            // ---------------------------------
            // --- Event - Form1 - OnClosing ---
            // ---------------------------------
    
            protected override void OnClosing(CancelEventArgs e)
            
                // Let the rendering thread terminate
                m_KeepSwimming = false;
                m_ThreadGate.Set();
    
                base.OnClosing(e);
            
    
    
            // --------------------------------------------
            // --- Event - SkglControl1 - Paint Surface ---
            // --------------------------------------------
    
            private void SkglControl1_PaintSurface(object sender, SkiaSharp.Views.Desktop.SKPaintGLSurfaceEventArgs e)
            
                // Clear the Canvas
                e.Surface.Canvas.Clear(SKColors.Black);
    
                // Paint each pre-rendered layer onto the Canvas using this GUI thread
                foreach (var layer in m_Layers)
                
                    layer.Paint(e.Surface.Canvas);
                
    
    
                using (var paint = new SKPaint())
                
                    paint.Color = SKColors.LimeGreen;
    
                    for (int i = 0; i < m_Layers.Count; i++)
                    
                        var layer = m_Layers[i];
                        var text = $"layer.Title - Renders = layer.RenderCount, Paints = layer.PaintCount";
                        var textLoc = new SKPoint(10, 10 + (i * 15));
    
                        e.Surface.Canvas.DrawText(text, textLoc, paint);
                    
    
    
                    paint.Color = SKColors.Cyan;
    
                    e.Surface.Canvas.DrawText("Click-Drag to update bars.", new SKPoint(10, 80), paint);
                    e.Surface.Canvas.DrawText("Double-Click to show / hide grid.", new SKPoint(10, 95), paint);
                    e.Surface.Canvas.DrawText("Resize to update all.", new SKPoint(10, 110), paint);
                
            
    
    
            // -------------------------------------
            // --- Event - SkglControl1 - Resize ---
            // -------------------------------------
    
            private void SkglControl1_Resize(object sender, EventArgs e)
            
                // Invalidate all of the Layers
                foreach (var layer in m_Layers)
                
                    layer.Invalidate();
                
    
                // Start a new rendering cycle to redraw all of the layers.
                UpdateDrawing();
            
    
    
            // -----------------------------------------
            // --- Event - SkglControl1 - Mouse Move ---
            // -----------------------------------------
    
            private void SkglControl1_MouseMove(object sender, MouseEventArgs e)
            
                // Save the mouse position
                m_MousePos = e.Location.ToSKPoint();
    
                // If Left-Click Drag, draw new bars
                if (e.Button == MouseButtons.Left)
                
                    // Invalidate the Data Layer to draw a new random set of bars
                    m_Layer_Data.Invalidate();
                
    
                // If Mouse Move, draw new mouse coordinates
                if (e.Location != m_PrevMouseLoc)
                
                    // Remember the previous mouse location
                    m_PrevMouseLoc = e.Location;
    
                    // Invalidate the Overlay Layer to show the new mouse coordinates
                    m_Layer_Overlay.Invalidate();
                
    
                // Start a new rendering cycle to redraw any invalidated layers.
                UpdateDrawing();
            
    
    
            // -------------------------------------------------
            // --- Event - SkglControl1 - Mouse Double Click ---
            // -------------------------------------------------
    
            private void SkglControl1_MouseDoubleClick(object sender, MouseEventArgs e)
            
                // Toggle the grid visibility
                m_ShowGrid = !m_ShowGrid;
    
                // Invalidate only the Grid Layer.  
                m_Layer_Grid.Invalidate();
    
                // Start a new rendering cycle to redraw any invalidated layers.
                UpdateDrawing();
            
    
    
            // ----------------------
            // --- Update Drawing ---
            // ----------------------
    
            public void UpdateDrawing()
            
                // Unblock the rendering thread to begin a render cycle.  Only the invalidated
                // Layers will be re-rendered, but all will be repainted onto the SKGLControl.
                m_ThreadGate.Set();
            
    
    
            // --------------------------
            // --- Render Loop Method ---
            // --------------------------
    
            private void RenderLoopMethod()
            
                while (m_KeepSwimming)
                
                    // Draw any invalidated layers using this Render thread
                    DrawLayers();
    
                    // Invalidate the SKGLControl to run the PaintSurface event on the GUI thread
                    // The PaintSurface event will Paint the layer stack to the SKGLControl
                    skglControl1.Invalidate();
    
                    // DoEvents to ensure that the GUI has time to process
                    Application.DoEvents();
    
                    // Block and wait for the next rendering cycle
                    m_ThreadGate.WaitOne();
                
            
    
    
            // -------------------
            // --- Draw Layers ---
            // -------------------
    
            private void DrawLayers()
            
                // Iterate through the collection of layers and raise the Draw event for each layer that is
                // invalidated.  Each event handler will receive a Canvas to draw on along with the Bounds for 
                // the Canvas, and can then draw the contents of that layer. The Draw commands are recorded and  
                // stored in an SKPicture for later playback to the SKGLControl.  This method can be called from
                // any thread.
    
                var clippingBounds = skglControl1.ClientRectangle.ToSKRect();
    
                foreach (var layer in m_Layers)
                
                    layer.Render(clippingBounds);
                
            
    
    
            // -----------------------------------------
            // --- Event - Layer - Background - Draw ---
            // -----------------------------------------
    
            private void Layer_Background_Draw(object sender, EventArgs_Draw e)
            
                // Create a diagonal gradient fill from Blue to Black to use as the background
                var topLeft = new SKPoint(e.Bounds.Left, e.Bounds.Top);
                var bottomRight = new SKPoint(e.Bounds.Right, e.Bounds.Bottom);
                var gradColors = new SKColor[2]  SKColors.DarkBlue, SKColors.Black ;
    
                using (var paint = new SKPaint())
                using (var shader = SKShader.CreateLinearGradient(topLeft, bottomRight, gradColors, SKShaderTileMode.Clamp))
                
                    paint.Shader = shader;
                    paint.Style = SKPaintStyle.Fill;
                    e.Canvas.DrawRect(e.Bounds, paint);
                
            
    
    
            // -----------------------------------
            // --- Event - Layer - Grid - Draw ---
            // -----------------------------------
    
            private void Layer_Grid_Draw(object sender, EventArgs_Draw e)
            
                if (m_ShowGrid)
                
                    // Draw a 25x25 grid of gray lines
    
                    using (var paint = new SKPaint())
                    
                        paint.Color = new SKColor(64, 64, 64); // Very dark gray
                        paint.Style = SKPaintStyle.Stroke;
                        paint.StrokeWidth = 1;
    
                        // Draw the Horizontal Grid Lines
                        for (int i = 0; i < 50; i++)
                        
                            var y = e.Bounds.Height * (i / 25f);
                            var leftPoint = new SKPoint(e.Bounds.Left, y);
                            var rightPoint = new SKPoint(e.Bounds.Right, y);
    
                            e.Canvas.DrawLine(leftPoint, rightPoint, paint);
                        
    
                        // Draw the Vertical Grid Lines
                        for (int i = 0; i < 50; i++)
                        
                            var x = e.Bounds.Width * (i / 25f);
                            var topPoint = new SKPoint(x, e.Bounds.Top);
                            var bottomPoint = new SKPoint(x, e.Bounds.Bottom);
    
                            e.Canvas.DrawLine(topPoint, bottomPoint, paint);
                        
                    
                
            
    
    
            // -----------------------------------
            // --- Event - Layer - Date - Draw ---
            // -----------------------------------
    
            private void Layer_Data_Draw(object sender, EventArgs_Draw e)
            
                // Draw a simple bar graph
    
                // Flip the Y-Axis so that zero is on the bottom
                e.Canvas.Scale(1, -1);
                e.Canvas.Translate(0, -e.Bounds.Height);
    
                var rand = new Random();
    
                // Create 25 red / yellow gradient bars of random length
                for (int i = 0; i < 25; i++)
                
                    var barWidth = e.Bounds.Width / 25f;
                    var barHeight = rand.Next((int)(e.Bounds.Height * 0.65d));
                    var barLeft = (i + 0) * barWidth;
                    var barRight = (i + 1) * barWidth;
                    var barTop = barHeight;
                    var barBottom = 0;
                    var topLeft = new SKPoint(barLeft, barTop);
                    var bottomRight = new SKPoint(barRight, barBottom);
                    var gradColors = new SKColor[2]  SKColors.Yellow, SKColors.Red ;
    
                    // Draw each bar with a gradient fill
                    using (var paint = new SKPaint())
                    using (var shader = SKShader.CreateLinearGradient(topLeft, bottomRight, gradColors, SKShaderTileMode.Clamp))
                    
                        paint.Style = SKPaintStyle.Fill;
                        paint.StrokeWidth = 1;
                        paint.Shader = shader;
    
                        e.Canvas.DrawRect(barLeft, barBottom, barWidth, barHeight, paint);
                    
    
                    // Draw the border of each bar
                    using (var paint = new SKPaint())
                    
                        paint.Color = SKColors.Blue;
                        paint.Style = SKPaintStyle.Stroke;
                        paint.StrokeWidth = 1;
    
                        e.Canvas.DrawRect(barLeft, barBottom, barWidth, barHeight, paint);
                    
                
            
    
    
            // --------------------------------------
            // --- Event - Layer - Overlay - Draw ---
            // --------------------------------------
    
            private void Layer_Overlay_Draw(object sender, EventArgs_Draw e)
            
                // Draw the mouse coordinate text next to the cursor
    
                using (var paint = new SKPaint())
                
                    // Configure the Paint to draw a black rectangle behind the text
                    paint.Color = SKColors.Black;
                    paint.Style = SKPaintStyle.Fill;
    
                    // Measure the bounds of the text
                    var text = m_MousePos.ToString();
                    SKRect textBounds = new SKRect();
                    paint.MeasureText(text, ref textBounds);
    
                    // Fix the inverted height value from the MeaureText
                    textBounds = textBounds.Standardized;
                    textBounds.Location = new SKPoint(m_MousePos.X, m_MousePos.Y - textBounds.Height);
    
                    // Draw the black filled rectangle where the text will go
                    e.Canvas.DrawRect(textBounds, paint);
    
                    // Change the Paint to yellow
                    paint.Color = SKColors.Yellow;
    
                    // Draw the mouse coordinates text
                    e.Canvas.DrawText(m_MousePos.ToString(), m_MousePos, paint);
                
            
        
    
    
    
        // ---------------------------------------------------------------------
        // ---------------------------------------------------------------------
        // -------                                                       -------
        // -------                     Class - Layer                     -------
        // -------                                                       -------
        // ---------------------------------------------------------------------
        // ---------------------------------------------------------------------
    
        public class Layer
        
            // The Draw event that the background rendering thread will use to draw on the SKPicture Canvas.  
            public event EventHandler<EventArgs_Draw> Draw;
    
            // The finished recording - Used to play back the Draw commands to the SKGLControl from the GUI thread
            private SKPicture m_Picture = null;
    
            // A flag that indicates if the Layer is valid, or needs to be redrawn.
            private bool m_IsValid = false;
    
    
            // ---------------------------
            // --- Layer - Constructor ---
            // ---------------------------
    
            public Layer(string title)
            
                this.Title = title;
            
    
    
            // -------------
            // --- Title ---
            // -------------
    
            public string Title  get; set; 
    
    
            // --------------
            // --- Render ---
            // --------------
    
     
            // Raises the Draw event and records any drawing commands to an SKPicture for later playback.  
            // This can be called from any thread.
      
    
            public void Render(SKRect clippingBounds)
            
                // Only redraw the Layer if it has been invalidated
                if (!m_IsValid)
                
                    // Create an SKPictureRecorder to record the Canvas Draw commands to an SKPicture
                    using (var recorder = new SKPictureRecorder())
                    
                        // Start recording 
                        recorder.BeginRecording(clippingBounds);
    
                        // Raise the Draw event.  The subscriber can then draw on the Canvas provided in the event
                        // and the commands will be recorded for later playback.
                        Draw?.Invoke(this, new EventArgs_Draw(recorder.RecordingCanvas, clippingBounds));
    
                        // Dispose of any previous Pictures
                        m_Picture?.Dispose();
    
                        // Create a new SKPicture with recorded Draw commands 
                        m_Picture = recorder.EndRecording();
    
                        this.RenderCount++;
    
                        m_IsValid = true;
                    
                
            
    
    
            // --------------------
            // --- Render Count ---
            // --------------------
    
            // Gets the number of times that this Layer has been rendered
    
            public int RenderCount  get; private set; 
    
    
            // -------------
            // --- Paint ---
            // -------------
    
            // Paints the previously recorded SKPicture to the provided skglControlCanvas.  This basically plays 
            // back the draw commands from the last Render.  This should be called from the SKGLControl.PaintSurface
            // event using the GUI thread.
    
            public void Paint(SKCanvas skglControlCanvas)
            
                if (m_Picture != null)
                
                    // Play back the previously recorded Draw commands to the skglControlCanvas using the GUI thread
                    skglControlCanvas.DrawPicture(m_Picture);
    
                    this.PaintCount++;
                
            
    
    
            // --------------------
            // --- Render Count ---
            // --------------------
    
            // Gets the number of times that this Layer has been painted
    
            public int PaintCount  get; private set; 
    
    
            // ------------------
            // --- Invalidate ---
            // ------------------
    
            // Forces the Layer to be redrawn with the next rendering cycle
    
            public void Invalidate()
            
                m_IsValid = false;
            
        
    
    
        // ---------------------------------------------------------------------
        // ---------------------------------------------------------------------
        // -------                                                       -------
        // -------                    EventArgs - Draw                   -------
        // -------                                                       -------
        // ---------------------------------------------------------------------
        // ---------------------------------------------------------------------
    
    
        public class EventArgs_Draw : EventArgs
        
            public SKRect Bounds  get; set; 
            public SKCanvas Canvas  get; set; 
    
            public EventArgs_Draw(SKCanvas canvas, SKRect bounds)
            
                this.Canvas = canvas;
                this.Bounds = bounds;