关于WPF画图性能问题_wpf stroke 太多卡顿

作者：很楠不爱3 | 2024-03-05 13:36:09

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wpf stroke 太多卡顿

最近用wpf画心电图，尝试了wpf所有的方法，性能依然不能满足要求，后来发现舍本逐末了，现在记录下来，以免以后再走弯路。

首先要明白wpf管理的机制，如果你往canvas画一条线，一般就是 new Line() 然后添加到canvas里面，这样做的话就算你用轻量级的Polyline，或者使用DrawingVisual的方法。对于高频数据来说（比如心电波形）都会很卡，这里面使用inkcanvas添加stroke的方法效果最好。但是如果你过多执行strokes的clear()和Add，时间一长，内存就会爆掉，InkCanvas 只能胜任轻量级的工作，WPF 会管理 InkCanvas 中的所有元素，例如位置和尺寸，所以它会消耗大量的内存和 CPU处理时间。InkCanvas 会渲染所有的stroke 在其装饰器层(Adorner Layer)。

可能我对wpf的认识还不足，硬生的把wpf和GDI+隔离开来看了，后来在Just Wang的热心帮助下，终于找到了方法，看他的代码：


public class WriteableBitmapTrendLine : FrameworkElement
    {
        #region DependencyProperties
 
        public static readonly DependencyProperty LatestQuoteProperty =
            DependencyProperty.Register("LatestQuote", typeof(MinuteQuoteViewModel), typeof(WriteableBitmapTrendLine),
            new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.None, OnLatestQuotePropertyChanged));
 
        private static void OnLatestQuotePropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            WriteableBitmapTrendLine trendLine = (WriteableBitmapTrendLine)d;
            MinuteQuoteViewModel latestQuote = (MinuteQuoteViewModel)e.NewValue;
            if (latestQuote != null)
            {
                trendLine.DrawTrendLine(latestQuote.Ordinal, (float)latestQuote.LastPx);
            }
        }
 
        public MinuteQuoteViewModel LatestQuote
        {
            get { return (MinuteQuoteViewModel)GetValue(LatestQuoteProperty); }
            set { SetValue(LatestQuoteProperty, value); }
        }
 
        #endregion
 
        private const int COLS = 723;
        private const int ROWS = 41;
 
        private WriteableBitmap bitmap;
        private float maxPrice = 0.0F;
        private static int dx = 3;
        private float[] prices = new float[COLS / dx];
 
        public WriteableBitmapTrendLine()
        {
            this.bitmap = new WriteableBitmap(COLS, ROWS, 96, 96, PixelFormats.Rgb24, null);
 
            this.bitmap.Lock();
 
            using (Bitmap backBufferBitmap = new Bitmap(COLS, ROWS,
               this.bitmap.BackBufferStride, System.Drawing.Imaging.PixelFormat.Format24bppRgb,
               this.bitmap.BackBuffer))
            {
                using (Graphics backBufferGraphics = Graphics.FromImage(backBufferBitmap))
                {
                    backBufferGraphics.Clear(System.Drawing.Color.WhiteSmoke);
                    backBufferGraphics.Flush();
                }
            }
 
            this.bitmap.AddDirtyRect(new Int32Rect(0, 0, COLS, ROWS));
            this.bitmap.Unlock();
        }
 
        private void DrawTrendLine(int ordinal, float latestPrice)
        {
            if (double.IsNaN(latestPrice))
                return;
 
            this.prices[ordinal] = latestPrice;
            bool redraw = false;
            if (ordinal == 0)
            {
                this.maxPrice = latestPrice;
            }
            else
            {
                if (latestPrice > this.maxPrice)
                {
                    this.maxPrice = latestPrice;
                    redraw = true;
                }
            }
 
            if (ordinal == 0)
            {
                int width = this.bitmap.PixelWidth;
                int height = this.bitmap.PixelHeight;
 
                this.bitmap.Lock();
 
                using (Bitmap backBufferBitmap = new Bitmap(width, height,
                    this.bitmap.BackBufferStride, System.Drawing.Imaging.PixelFormat.Format24bppRgb,
                    this.bitmap.BackBuffer))
                {
                    using (Graphics backBufferGraphics = Graphics.FromImage(backBufferBitmap))
                    {
                        backBufferGraphics.Clear(System.Drawing.Color.WhiteSmoke);
                        backBufferGraphics.Flush();
                    }
                }
 
                this.bitmap.AddDirtyRect(new Int32Rect(0, 0, width, height));
                this.bitmap.Unlock();
            }
            else
            {
                System.Drawing.Point[] points = new System.Drawing.Point[ordinal + 1];
                float dy = (float)(ROWS / (this.maxPrice * 1.3));
                for (int i = 0; i <= ordinal; i++)
                {
                    points[i].X = i * dx;
                    points[i].Y = (int)(this.prices[i] * dy);
                }
 
                int width = ordinal * dx + 1;
                int height = this.bitmap.PixelHeight;
 
                this.bitmap.Lock();
 
                using (Bitmap backBufferBitmap = new Bitmap(width, height,
                    this.bitmap.BackBufferStride, System.Drawing.Imaging.PixelFormat.Format24bppRgb,
                    this.bitmap.BackBuffer))
                {
                    using (Graphics backBufferGraphics = Graphics.FromImage(backBufferBitmap))
                    {
                        backBufferGraphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighSpeed;
                        backBufferGraphics.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighSpeed;
 
                        if (redraw)
                            backBufferGraphics.Clear(System.Drawing.Color.WhiteSmoke);
                        backBufferGraphics.DrawLines(System.Drawing.Pens.Green, points);
                        backBufferGraphics.Flush();
                    }
                }
 
                this.bitmap.AddDirtyRect(new Int32Rect(0, 0, width, height));
                this.bitmap.Unlock();
            }
        }
 
        private void DrawTrendLineF(int ordinal, float latestPrice)
        {
            if (double.IsNaN(latestPrice))
                return;
 
            this.prices[ordinal] = latestPrice;
            if (ordinal == 0)
            {
                this.maxPrice = latestPrice;
            }
            else
            {
                if (latestPrice > this.maxPrice)
                {
                    this.maxPrice = latestPrice;
                }
            }
 
            if (ordinal == 0)
            {
                int width = this.bitmap.PixelWidth;
                int height = this.bitmap.PixelHeight;
 
                this.bitmap.Lock();
 
                using (Bitmap backBufferBitmap = new Bitmap(width, height,
                    this.bitmap.BackBufferStride, System.Drawing.Imaging.PixelFormat.Format24bppRgb,
                    this.bitmap.BackBuffer))
                {
                    using (Graphics backBufferGraphics = Graphics.FromImage(backBufferBitmap))
                    {
                        backBufferGraphics.Clear(System.Drawing.Color.WhiteSmoke);
                        backBufferGraphics.Flush();
                    }
                }
 
                this.bitmap.AddDirtyRect(new Int32Rect(0, 0, width, height));
                this.bitmap.Unlock();
            }
            else
            {
                int count = this.prices.Length;
                PointF[] points = new PointF[ordinal + 1];
                float dy = (float)(ROWS / this.maxPrice);
                for (int i = 0; i <= ordinal; i++)
                {
                    points[i].X = i;
                    points[i].Y = (float)Math.Floor(this.prices[i] * dy);
 
                    if (float.IsNaN(points[i].Y))
                        points[i].Y = 0.0F;
                }
 
                int width = ordinal + 1;
                int height = this.bitmap.PixelHeight;
 
                this.bitmap.Lock();
 
                using (Bitmap backBufferBitmap = new Bitmap(width, height,
                    this.bitmap.BackBufferStride, System.Drawing.Imaging.PixelFormat.Format24bppRgb,
                    this.bitmap.BackBuffer))
                {
                    using (Graphics backBufferGraphics = Graphics.FromImage(backBufferBitmap))
                    {
                        backBufferGraphics.DrawLines(System.Drawing.Pens.Green, points);
                        backBufferGraphics.Flush();
                    }
                }
 
                this.bitmap.AddDirtyRect(new Int32Rect(0, 0, width, height));
                this.bitmap.Unlock();
            }
        }
 
        protected override void OnRender(DrawingContext drawingContext)
        {
            drawingContext.PushTransform(new ScaleTransform(1, -1, 0, RenderSize.Height / 2));
            drawingContext.DrawImage(bitmap, new Rect(0, 0, RenderSize.Width, RenderSize.Height));
        }
    }


public class MinuteQuoteViewModel : INotifyPropertyChanged
    {
        private int ordinal;
        public int Ordinal
        {
            get { return this.ordinal; }
            set { if (this.ordinal != value) { this.ordinal = value; this.OnPropertyChanged("Ordinal"); } }
        }
 
        private DateTime quoteTime;
        public DateTime QuoteTime
        {
            get { return this.quoteTime; }
            set { if (this.quoteTime != value) { this.quoteTime = value; this.OnPropertyChanged("QuoteTime"); } }
        }
 
        private double lastPx = double.NaN;
        public double LastPx
        {
            get { return this.lastPx; }
            set { if (this.lastPx != value) { this.lastPx = value; this.OnPropertyChanged("LastPx"); } }
        }
 
        private double avgPx = double.NaN;
        public double AvgPx
        {
            get { return this.avgPx; }
            set { if (this.avgPx != value) { this.avgPx = value; this.OnPropertyChanged("AvgPx"); } }
        }
 
        private int volume;
        public int Volume
        {
            get { return this.volume; }
            set { if (this.volume != value) { this.volume = value; this.OnPropertyChanged("Volume"); } }
        }
 
        private double amount = double.NaN;
        public double Amount
        {
            get { return this.amount; }
            set { if (this.amount != value) { this.amount = value; this.OnPropertyChanged("Amount"); } }
        }
 
        #region INotifyPropertyChanged 成员
 
        public event PropertyChangedEventHandler PropertyChanged;
        protected virtual void OnPropertyChanged(string propertyName)
        {
            if (this.PropertyChanged != null)
                this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
 
        #endregion
    }

他这个应该是直接从项目上拔下来的，看着比较费劲，我在vs2013下写了一个简单的示例，取消了固定区域，转为自适应界面。

代码下载:http://download.csdn.net/detail/waleswood/7079287

http://social.msdn.microsoft.com/Forums/zh-CN/febcee07-dc8b-44b4-8c0a-246daffdbe2b/wpf-?forum=wpfzhchs#bfadef47-ab7b-4f8b-9340-e3c7a2782b76

http://social.msdn.microsoft.com/Forums/zh-CN/b156e12b-bc52-44a9-b2f9-26fff723cff5/wpf-inkcanvas?forum=wpfzhchs#de6c4b50-7036-4823-bbec-4e9ba309a600

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关于WPF画图性能问题_wpf stroke 太多 卡顿

关于WPF画图性能问题_wpf stroke 太多卡顿