WPF开发随笔收录-WriteableBitmap绘制高性能曲线图

一、前言

之前分享过一期关于DrawingVisual来绘制高性能曲线的博客，今天再分享一篇通过另一种方式来绘制高性能曲线的方法，也就是通过WriteableBitmap的方式；具体的一些细节这里就不啰嗦了，同样是局部绘制的思想，滚动条拖动到哪里，就只绘制那一部分的曲线，直接贴代码；（该程序在英特尔11代CPU的电脑可能会遇到拖动滚动条曲线图卡住不动的情况，这个是显卡驱动的问题，官方已经修复了，遇到这问题的记得更新一下驱动）

二、正文

1、新建一个类，继承FrameworkElement，然后在里面实现一下绘图的逻辑；

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Text;
using System.IO;
using System.Windows;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Resources;
using _Font = System.Drawing.Font;
using GDI = System.Drawing;

namespace WriteableBitmapDemo.Controls
{
    public class CruveWriteableBitmap : FrameworkElement
    {
        private static PrivateFontCollection pfc = new PrivateFontCollection();
        private WriteableBitmap bitmap;

        private int bitmap_width = 0;
        private int bitmap_height = 0;

        private static _Font font = null;
        private static _Font time_font = null;

        private PointF[][] horizontals = null;
        private PointF[][] horizontals_thin = null;
        private PointF[][] verticals = null;
        private PointF[][] verticals_thin = null;

        private List top_points1;
        private List top_points2;
        private List top_points3;
        private List bottom_points;

        private List labelPosition_up;
        private List<string> labelText_up;
        private List labelPosition_down;
        private List<string> labelText_down;

        private List timePosition;
        private List<string> timeText;

        private GDI.Pen blackPen = new GDI.Pen(GDI.Color.Black, 1.5f);
        private GDI.Pen grayPen = new GDI.Pen(GDI.Color.Gray, 1f);

        private GDI.Pen top_pen1 = new GDI.Pen(GDI.Color.Black, 2);
        private GDI.Pen top_pen2 = new GDI.Pen(GDI.Color.Orange, 2);
        private GDI.Pen top_pen3 = new GDI.Pen(GDI.Color.Purple, 2);public float scaleX { get; set; } = 1f;
        private float _ScaleY { get; set; } = 1f;
        public float ScaleY
        {
            get { return _ScaleY; }
            set
            {
                _ScaleY = value;
            }
        }

        static CruveWriteableBitmap()
        {
            var appRootDataDir = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "msyh.ttf");
            if (!File.Exists(appRootDataDir))
            {
                var key = $"/CurveChartDemo;component/Fonts/msyh.ttf";
                StreamResourceInfo info = Application.GetResourceStream(new Uri(key, UriKind.Relative));
                using (var stream = info.Stream)
                {
                    byte[] bytes = new byte[stream.Length];
                    int len = stream.Read(bytes, 0, bytes.Length);
                    File.WriteAllBytes(appRootDataDir, bytes);
                }
            }
            pfc.AddFontFile(appRootDataDir);
        }

        public CruveWriteableBitmap()
        {
            time_font = new _Font(pfc.Families[0], 10);
            font = new _Font(pfc.Families[0], 8);
        }

        public void DrawPoints()
        {
            //InitBitmap();
            if (this.bitmap == null)
            {
                return;
            }

            this.bitmap.Lock();
            using (Bitmap backBufferBitmap = new Bitmap(this.bitmap_width, this.bitmap_height,
                this.bitmap.BackBufferStride, GDI.Imaging.PixelFormat.Format24bppRgb,
                this.bitmap.BackBuffer))
            {
                using (Graphics backBufferGraphics = Graphics.FromImage(backBufferBitmap))
                {
                    backBufferGraphics.SmoothingMode = SmoothingMode.AntiAlias;
                    backBufferGraphics.CompositingQuality = CompositingQuality.HighSpeed;

                    backBufferGraphics.Clear(GDI.Color.White);

                    //粗横线
                    if (this.horizontals != null)
                    {
                        foreach (var horizontal in this.horizontals)
                        {
                            backBufferGraphics.DrawLine(blackPen, horizontal[0], horizontal[1]);
                        }
                    }
                    //细横线
                    if (this.horizontals_thin != null)
                    {
                        foreach (var horizontal in this.horizontals_thin)
                        {
                            backBufferGraphics.DrawLine(grayPen, horizontal[0], horizontal[1]);
                        }
                    }
                    //粗竖线
                    if (this.verticals != null)
                    {
                        foreach (var vertical in this.verticals)
                        {
                            backBufferGraphics.DrawLine(blackPen, vertical[0], vertical[1]);
                        }
                    }
                    //细竖线
                    if (this.verticals_thin != null)
                    {
                        foreach (var vertical in this.verticals_thin)
                        {
                            backBufferGraphics.DrawLine(grayPen, vertical[0], vertical[1]);
                        }
                    }
                    //上图曲线1
                    if (this.top_points1 != null && this.top_points1.Count > 0)
                    {
                        backBufferGraphics.DrawLines(top_pen1, top_points1.ToArray());
                    }
                    //上图曲线2
                    if (this.top_points2 != null && this.top_points2.Count > 0)
                    {
                        backBufferGraphics.DrawLines(top_pen2, this.top_points2.ToArray());
                    }
                    //上图曲线3
                    if (this.top_points3 != null && this.top_points3.Count > 0)
                    {
                        backBufferGraphics.DrawLines(top_pen3, this.top_points3.ToArray());
                    }
                    //下图曲线
                    if (this.bottom_points != null && this.bottom_points.Count > 0)
                    {
                        backBufferGraphics.DrawLines(top_pen1, this.bottom_points.ToArray());
                    }

                    //文本
                    if (labelPosition_up != null && labelPosition_up.Count > 0)
                    {
                        SizeF fontSize = backBufferGraphics.MeasureString(labelText_up[0], font);
                        for (int i = 0; i < labelPosition_up.Count; ++i)
                        {
                            backBufferGraphics.DrawString(labelText_up[i], font, GDI.Brushes.Black, labelPosition_up[i].X, labelPosition_up[i].Y - fontSize.Height);
                        }
                    }
                    if (labelPosition_down != null && labelPosition_down.Count > 0)
                    {
                        for (int i = 0; i < labelPosition_down.Count; ++i)
                        {
                            backBufferGraphics.DrawString(labelText_down[i], font, GDI.Brushes.Black, labelPosition_down[i].X, labelPosition_down[i].Y);
                        }
                    }
                    if (timePosition != null && timePosition.Count > 0)
                    {
                        for (int i = 0; i < timePosition.Count; ++i)
                        {
                            if (i == 0)
                                backBufferGraphics.DrawString(timeText[i], time_font, GDI.Brushes.Black, timePosition[i].X, timePosition[i].Y);
                            else
                            {
                                SizeF fontSize = backBufferGraphics.MeasureString(timeText[i], time_font);
                                backBufferGraphics.DrawString(timeText[i], time_font, GDI.Brushes.Black, timePosition[i].X - fontSize.Width / 2, timePosition[i].Y);
                            }

                        }
                    }

                    backBufferGraphics.Flush();
                }
            }
            this.bitmap.AddDirtyRect(new Int32Rect(0, 0, this.bitmap_width, this.bitmap_height));
            this.bitmap.Unlock();
        }public void UpdateTimeLabel(List timePosition, List<string> timeText)
        {
            this.timePosition = timePosition;
            this.timeText = timeText;
        }
        public void UpdatePosition(List fhr1_points, List fhr2_points, List fhr3_points, List toco_points)
        {
            this.top_points1 = fhr1_points;
            this.top_points2 = fhr2_points;
            this.top_points3 = fhr3_points;
            this.bottom_points = toco_points;
        }

        public void UpdateLabelPosition(List labelPosition_up, List<string> labelText_up, List labelPosition_down, List<string> labelText_down)
        {
            this.labelPosition_up = labelPosition_up;
            this.labelText_up = labelText_up;
            this.labelPosition_down = labelPosition_down;
            this.labelText_down = labelText_down;
        }

        public void UpdateHorizontalLine(PointF[][] horizontals, PointF[][] horizontals_thin)
        {
            this.horizontals = horizontals;
            this.horizontals_thin = horizontals_thin;
        }

        public void UpdateVerticalLine(PointF[][] verticals, PointF[][] verticals_thin)
        {
            this.verticals = verticals;
            this.verticals_thin = verticals_thin;
        }

        protected override void OnRender(DrawingContext dc)
        {
            InitBitmap();
            if (this.bitmap != null)
            {
                dc.DrawImage(bitmap, new Rect(0, 0, RenderSize.Width, RenderSize.Height));
            }
            base.OnRender(dc);
        }

        private void InitBitmap()
        {
            if (bitmap == null || this.bitmap.Width != (int)this.ActualWidth || this.bitmap.Height != (int)this.ActualHeight)
            {
                if ((int)this.ActualWidth > 0 && (int)this.ActualHeight > 0)
                {
                    this.bitmap_width = (int)this.ActualWidth;
                    this.bitmap_height = (int)this.ActualHeight;
                    this.bitmap = new WriteableBitmap(bitmap_width, bitmap_height, 96, 96, PixelFormats.Bgr24, null);
                    this.bitmap.Lock();
                    using (Bitmap backBufferBitmap = new Bitmap(bitmap_width, bitmap_height,
                        this.bitmap.BackBufferStride, GDI.Imaging.PixelFormat.Format24bppRgb,
                        this.bitmap.BackBuffer))
                    {
                        using (Graphics backBufferGraphics = Graphics.FromImage(backBufferBitmap))
                        {
                            backBufferGraphics.SmoothingMode = SmoothingMode.HighSpeed;
                            backBufferGraphics.CompositingQuality = CompositingQuality.HighSpeed;
                            backBufferGraphics.Clear(GDI.Color.White);
                            backBufferGraphics.Flush();
                        }
                    }
                    this.bitmap.AddDirtyRect(new Int32Rect(0, 0, bitmap_width, bitmap_height));
                    this.bitmap.Unlock();
                }
            }
        }
    }
}

2、主窗口添加该控件，并添加滚动条那些

<Window
    x:Class="WriteableBitmapDemo.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:ct="clr-namespace:WriteableBitmapDemo.Controls"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:local="clr-namespace:WriteableBitmapDemo"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    Title="MainWindow"
    Width="1500"
    Height="450"
    Loaded="Window_Loaded"
    mc:Ignorable="d">
    <Grid>
        <ct:CruveWriteableBitmap x:Name="curve" Margin="0,0,0,20" />
        <ScrollViewer
            Name="scroll"
            HorizontalScrollBarVisibility="Auto"
            ScrollChanged="ScrollViewer_ScrollChanged"
            VerticalScrollBarVisibility="Disabled">
            <Canvas x:Name="canvas" Height="1" />
        ScrollViewer>
        <Canvas
            x:Name="CanvasPanel"
            Margin="0,0,0,20"
            Background="Transparent" />
    Grid>
Window>

3、主窗口后台添加曲线数值生成方法和更新视图数据方法

using System.Collections.Generic;
using System.Drawing;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;

namespace WriteableBitmapDemo
{
    /// 

    /// MainWindow.xaml 的交互逻辑
    /// 
    public partial class MainWindow : Window
    {
        private bool isAdd = true;

        private Dictionary<int, int> dicTopPoints = new Dictionary<int, int>();
        private Dictionary<int, int> dicBottomPoints = new Dictionary<int, int>();

        private float y_scale;

        private static int Top_Val_Max = 240;
        private static int Top_Val_Min = 30;
        private static int Top_X_Sex = 20;
        private static int Bottom = 100;
        private static int Center = 25;
        private static int BottomOffset = 0;

        private double offset = -1;

        public MainWindow()
        {
            InitializeComponent();

            CanvasPanel.MouseMove += delegate (object sender, MouseEventArgs e)
            {
                if (e.LeftButton == MouseButtonState.Pressed)
                {
                    if (Mouse.Captured == null) Mouse.Capture(CanvasPanel);

                    if (offset >= 0 && offset <= CanvasPanel.ActualWidth)
                    {
                        scroll.ScrollToHorizontalOffset(scroll.HorizontalOffset - (e.GetPosition(this).X - offset));
                    }
                    offset = e.GetPosition(this).X;
                }
                else
                {
                    offset = -1;
                    Mouse.Capture(null); // 释放鼠标捕获
                }
            };
        }

        private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            //生成曲线数据
            int temp = 50;
            for (int i = 0; i < 24 * 60 * 60 * 4; i++)
            {
                if (isAdd)
                {
                    dicTopPoints.Add(i, temp);
                    temp += 2;
                }
                else
                {
                    dicTopPoints.Add(i, temp);
                    temp -= 2;
                }

                if (temp == 210) isAdd = false;
                if (temp == 50) isAdd = true;
            }
            temp = 0;
            for (int i = 0; i < 24 * 60 * 60 * 4; i++)
            {
                if (isAdd)
                {
                    dicBottomPoints.Add(i, temp);
                    temp += 2;
                }
                else
                {
                    dicBottomPoints.Add(i, temp);
                    temp -= 2;
                }

                if (temp == 100) isAdd = false;
                if (temp == 0) isAdd = true;
            }
            //初始化滚动条和触发曲线绘制
            canvas.Width = dicTopPoints.Count;
            scroll.ScrollToLeftEnd();
        }

        private void ScrollViewer_ScrollChanged(object sender, ScrollChangedEventArgs e)
        {
            InitChartData((float)scroll.HorizontalOffset);
        }

        /// 

        /// 根据滚动条偏移量更新需要绘制的数据
        /// 
        /// 
        private void InitChartData(float offset)
        {
            y_scale = (float)((curve.ActualHeight - Center) / (Top_Val_Max - Top_Val_Min + Bottom));

            //上图横线
            List horizontalList = new List();
            List horizontalList_thin = new List();
            for (int y = 0; y <= Top_Val_Max - Top_Val_Min; y += 10)
            {
                float currentHeight = (float)(curve.ActualHeight - (y + Bottom) * y_scale - Center);
                PointF point1 = new PointF(0, currentHeight);
                PointF point2 = new PointF((float)curve.ActualWidth, currentHeight);
                if (y % 30 == 0)
                    horizontalList.Add(new PointF[] { point1, point2 });
                else
                    horizontalList_thin.Add(new PointF[] { point1, point2 });
            }
            for (int y = 0; y <= Bottom; y += 10)
            {
                float currentHeight = (float)(curve.ActualHeight - y * y_scale - BottomOffset);
                PointF point1 = new PointF(0, currentHeight);
                PointF point2 = new PointF((float)curve.ActualWidth, currentHeight);
                if (y % 20 == 0)
                    horizontalList.Add(new PointF[] { point1, point2 });
                else
                    horizontalList_thin.Add(new PointF[] { point1, point2 });
            }

            //竖线与文字
            List verticals = new List();
            List verticals_thin = new List();

            List timePosition = new List();
            List<string> timeText = new List<string>();

            List labelPosition_up = new List();
            List<string> labelText_up = new List<string>();

            List labelPosition_down = new List();
            List<string> labelText_down = new List<string>();

            for (int i = 0; i < offset + curve.ActualWidth; i += Top_X_Sex * 2)
            {
                if (i < offset) continue;
                //下竖线
                PointF point1 = new PointF(i - offset, (float)(curve.ActualHeight - BottomOffset));
                PointF point2 = new PointF(i - offset, (float)(curve.ActualHeight - Bottom * y_scale - BottomOffset));
                //上竖线
                PointF point3 = new PointF(i - offset, 0);
                PointF point4 = new PointF(i - offset, (float)(curve.ActualHeight - Bottom * y_scale - Center));

                if ((i + (60 * 2)) % (60 * 2) == 0)
                {
                    verticals.Add(new PointF[] { point1, point2 });
                    verticals.Add(new PointF[] { point3, point4 });
                }
                else
                {
                    verticals_thin.Add(new PointF[] { point1, point2 });
                    verticals_thin.Add(new PointF[] { point3, point4 });
                }

                if (i % 240 == 0)
                {
                    timeText.Add(i + "");
                    timePosition.Add(new PointF(i - offset, (float)(curve.ActualHeight - Bottom * y_scale - Center)));
                }

                if ((i + (60 * 2)) % (120 * 2) == 0)
                {
                    for (int y = Top_Val_Min; y <= Top_Val_Max; y += 10)
                    {
                        if (y % 30 == 0)
                        {
                            labelText_up.Add(y + "");
                            labelPosition_up.Add(new PointF(i - offset, (float)(curve.ActualHeight - (Bottom + y - Top_Val_Min) * y_scale - Center)));
                        }
                    }
                    for (int y = 20; y <= 100; y += 10)
                    {
                        if (y % 20 == 0)
                        {
                            labelText_down.Add(y + "");
                            labelPosition_down.Add(new PointF(i - offset, (float)(curve.ActualHeight - y * y_scale)));
                        }
                    }
                }
            }

            List top_points1 = new List();
            for (int i = (int)offset, j = 0; i < dicTopPoints.Count && j < curve.ActualWidth; i++, j++)
            {
                top_points1.Add(new PointF(j, (float)(curve.ActualHeight - (dicTopPoints[i] + 100 - Top_Val_Min) * y_scale) - Center));
            }

            List top_points2 = new List();
            for (int i = (int)offset, j = 0; i < dicTopPoints.Count && j < curve.ActualWidth; i++, j++)
            {
                top_points2.Add(new PointF(j, (float)(curve.ActualHeight - (dicTopPoints[i] + 20 + 100 - Top_Val_Min) * y_scale) - Center));
            }

            List top_points3 = new List();
            for (int i = (int)offset, j = 0; i < dicTopPoints.Count && j < curve.ActualWidth; i++, j++)
            {
                top_points3.Add(new PointF(j, (float)(curve.ActualHeight - (dicTopPoints[i] - 20 + 100 - Top_Val_Min) * y_scale) - Center));
            }

            List bottom_points = new List();
            for (int i = (int)offset, j = 0; i < dicBottomPoints.Count && j < curve.ActualWidth; i++, j++)
            {
                bottom_points.Add(new PointF(j, (float)(curve.ActualHeight - dicBottomPoints[i] * y_scale - BottomOffset)));
            }

            curve.UpdateHorizontalLine(horizontalList.ToArray(), horizontalList_thin.ToArray());
            curve.UpdateVerticalLine(verticals.ToArray(), verticals_thin.ToArray());
            curve.UpdatePosition(top_points1, top_points2, top_points3, bottom_points);
            curve.UpdateTimeLabel(timePosition, timeText);
            curve.UpdateLabelPosition(labelPosition_up, labelText_up, labelPosition_down, labelText_down);
            curve.DrawPoints();
        }
    }
}

4、运行效果如下，欢迎各位大佬指点