WPF在Canvas中绘图实现折线统计图

最近在WPF中做一个需要实现统计的功能，其中需要用到统计图，之前也没有接触过，度娘上大多都是各种收费或者免费的第三方控件，不想用第三方控件那就自己画一个吧。

在园子还找到一篇文章，思路来自这篇文章，文章链接：http://www.cnblogs.com/endlesscoding/p/6670432.html

不过根据我的需求，数据每次都在变化，所以都只能从后台绑定，先来看一下完成后的效果吧

可以看到，数据源是一年内一到十二月的金额，所以X轴是固定的，而Y轴标尺是根据数据源的最大值向上取100。再来计算每个标尺该显示的数值。

数据点的显示，也是根据提供数据的比例，来计算出像素值的

从头开始吧，先来说xaml，xaml中需要一个Canvas控件，之后所有的图形就是画在这里面

不会用Canvas的话可以先学习下官方文档：https://msdn.microsoft.com/zh-cn/library/system.windows.controls.canvas(v=vs.110).aspx

 <Grid Height="400" Width="645">
                         <Grid.ColumnDefinitions>
                             <ColumnDefinition Width="150" />
                             <ColumnDefinition Width="330"/>
                             <ColumnDefinition Width="*"/>
                         </Grid.ColumnDefinitions>
                         <Grid.RowDefinitions>
                             <RowDefinition Height="25" />
                             <RowDefinition />
                         </Grid.RowDefinitions>
                         <j:JLabel Label="企业账号：" Grid.Column="0" Grid.Row="0">
                             <TextBlock Text="{Binding Userid}" HorizontalAlignment="Left"  Foreground="Red"/>
                         </j:JLabel>
                         <j:JLabel Label="企业名称：" Grid.Column="1" Grid.Row="0">
                             <TextBlock Text="{Binding Username}" HorizontalAlignment="Left" Foreground="Red"/>
                         </j:JLabel>
                         <j:JLabel Label="总金额（元）：" Grid.Column="2" Grid.Row="0">
                             <TextBlock Text="{Binding Pay_Total}" HorizontalAlignment="Left" Foreground="Red"/>
                         </j:JLabel>
                         <Canvas x:Name="chartCanvas" Margin="5" Grid.Column="0" Grid.Row="1" Grid.ColumnSpan="4">
                         </Canvas>
                     </Grid>

先来画横纵坐标和箭头吧，x1,y1,x2,y2这四个参数是Line在Canvas中的起点终点位置像素值

同样，Line类官方文档：https://msdn.microsoft.com/zh-cn/library/system.windows.shapes.line(v=vs.110).aspx

         /// <summary>
         /// 生成横纵坐标及箭头
         /// </summary>
         private void DrawArrow()
         {
             Line x_axis = new Line();//x轴
             Line y_axis = new Line();//y轴
             x_axis.Stroke = System.Windows.Media.Brushes.Black;
             y_axis.Stroke = System.Windows.Media.Brushes.Black;
             x_axis.StrokeThickness = ;
             y_axis.StrokeThickness = ;
             x_axis.X1 = ;
             x_axis.Y1 = ;
             x_axis.X2 = ;
             x_axis.Y2 = ;
             y_axis.X1 = ;
             y_axis.Y1 = ;
             y_axis.X2 = ;
             y_axis.Y2 = ;
             this.chartCanvas.Children.Add(x_axis);
             this.chartCanvas.Children.Add(y_axis);

             Line y_scale1 = new Line(); //坐标原点直角
             y_scale1.Stroke = System.Windows.Media.Brushes.Black;
             y_scale1.StrokeThickness =;
             y_scale1.X1 = ;
             y_scale1.Y1 = ;
             y_scale1.X2 = ;
             y_scale1.Y2 = ;
             y_scale1.StrokeStartLineCap = PenLineCap.Triangle;
             this.chartCanvas.Children.Add(y_scale1);

             Path x_axisArrow = new Path();//x轴箭头
             Path y_axisArrow = new Path();//y轴箭头
             x_axisArrow.Fill = new SolidColorBrush(Color.FromRgb(, , ));
             y_axisArrow.Fill = new SolidColorBrush(Color.FromRgb(, , ));
             PathFigure x_axisFigure = new PathFigure();
             x_axisFigure.IsClosed = true;
             x_axisFigure.StartPoint = new Point(, );                          //路径的起点
             x_axisFigure.Segments.Add(new LineSegment(new Point(, ), false)); //第2个点
             x_axisFigure.Segments.Add(new LineSegment(new Point(, ), false)); //第3个点
             PathFigure y_axisFigure = new PathFigure();
             y_axisFigure.IsClosed = true;
             y_axisFigure.StartPoint = new Point(, );                          //路径的起点
             y_axisFigure.Segments.Add(new LineSegment(new Point(, ), false)); //第2个点
             y_axisFigure.Segments.Add(new LineSegment(new Point(, ), false)); //第3个点
             PathGeometry x_axisGeometry = new PathGeometry();
             PathGeometry y_axisGeometry = new PathGeometry();
             x_axisGeometry.Figures.Add(x_axisFigure);
             y_axisGeometry.Figures.Add(y_axisFigure);
             x_axisArrow.Data = x_axisGeometry;
             y_axisArrow.Data = y_axisGeometry;
             this.chartCanvas.Children.Add(x_axisArrow);
             this.chartCanvas.Children.Add(y_axisArrow);

             TextBlock x_label =new TextBlock();
             TextBlock y_label =new TextBlock();
             TextBlock o_label =new TextBlock();
             x_label.Text = "月";
             y_label.Text = "元";
             o_label.Text = "";
             Canvas.SetLeft(x_label, );
             Canvas.SetLeft(y_label, );
             Canvas.SetLeft(o_label, );
             Canvas.SetTop(x_label, );
             Canvas.SetTop(y_label, );
             Canvas.SetTop(o_label, );
             x_label.FontSize = ;
             y_label.FontSize = ;
             o_label.FontSize = ;
             this.chartCanvas.Children.Add(x_label);
             this.chartCanvas.Children.Add(y_label);
             this.chartCanvas.Children.Add(o_label);

         }

标尺，X轴以45为间隔单位，Y轴以10px为单位，且没5格显示一个大标尺

         /// <summary>
         /// 作出x轴和y轴的标尺
         /// </summary>
         private void DrawScale()
         {
             for (int i = ; i < ; i++)//作12个刻度
             {
                 //原点 O=(40,320)
                 Line x_scale = new Line(); //主x轴标尺
                 x_scale.StrokeEndLineCap = PenLineCap.Triangle;
                 x_scale.StrokeThickness = ;
                 x_scale.Stroke = new SolidColorBrush(Color.FromRgb(, , ));
                 x_scale.X1 =  + i * ;
                 x_scale.X2 = x_scale.X1;
                 x_scale.Y1 = ;
                 x_scale.StrokeThickness = ;
                 x_scale.Y2 = x_scale.Y1 - ;
                 this.chartCanvas.Children.Add(x_scale);

                 Line x_in = new Line();//x轴轴辅助标尺
                 x_in.Stroke = System.Windows.Media.Brushes.LightGray;
                 x_in.StrokeThickness = 0.5;
                 x_in.X1 =  + i * ;
                 x_in.Y1 = ;
                 x_in.X2 =  + i * ;
                 x_in.Y2 = ;
                 this.chartCanvas.Children.Add(x_in);
             }
             for (int j = ; j < ; j++ )
             {
                 Line y_scale = new Line(); //主Y轴标尺
                 y_scale.StrokeEndLineCap = PenLineCap.Triangle;
                 y_scale.StrokeThickness = ;
                 y_scale.Stroke = new SolidColorBrush(Color.FromRgb(, , ));

                 y_scale.X1 = ;            //原点x=40
                 if (j %  == )
                 {
                     y_scale.StrokeThickness = ;
                     y_scale.X2 = y_scale.X1 + ;//大刻度线
                 }
                 else
                 {
                     y_scale.X2 = y_scale.X1 + ;//小刻度线
                 }

                 y_scale.Y1 =  - j * ;  //每10px作一个刻度
                 y_scale.Y2 = y_scale.Y1;
                 this.chartCanvas.Children.Add(y_scale);
             }
             for (int i = ; i < ; i++)
             {
                 Line y_in = new Line();//y轴辅助标尺
                 y_in.Stroke = System.Windows.Media.Brushes.LightGray;
                 y_in.StrokeThickness = 0.5;
                 y_in.X1 = ;
                 y_in.Y1 =  - i * ;
                 y_in.X2 = ;
                 y_in.Y2 =  - i * ;
                 this.chartCanvas.Children.Add(y_in);
             }

         }

刻度标签的话，X轴是固定的，并且其中用到了一个把阿拉伯数字转换为中文的方法 NumberToChinese()，

Y轴标尺标签，是用出入的 list<double>,计算出最大值再向上取100整，再分成五份，每份的值就是五个标签了

list最大值向上取100的方法：（除100向上取整再乘100）

Math.Ceiling(list.Max() / 100) * 100

         /// <summary>
         /// 添加刻度标签
         /// </summary>
         private void DrawScaleLabel(List<double> list)
         {
             for (int i = ; i < ; i++)
             {
                 TextBlock x_ScaleLabel = new TextBlock();
                 x_ScaleLabel.Text = NumberToChinese(i.ToString());
                 if (x_ScaleLabel.Text == "一零")
                 {
                     x_ScaleLabel.Text = "十";
                     Canvas.SetLeft(x_ScaleLabel,  +  * i - );
                 }
                 else if (x_ScaleLabel.Text == "一一")
                 {
                     x_ScaleLabel.Text = "十一";
                     Canvas.SetLeft(x_ScaleLabel,  +  * i - );
                 }

                 else if (x_ScaleLabel.Text == "一二")
                 {
                     x_ScaleLabel.Text = "十二";
                     Canvas.SetLeft(x_ScaleLabel,  +  * i - );
                 }
                 else
                 {
                     Canvas.SetLeft(x_ScaleLabel,  +  * i - );
                 }
                 Canvas.SetTop(x_ScaleLabel,  + );
                 this.chartCanvas.Children.Add(x_ScaleLabel);
             }

             for (int i = ; i < ; i++)
             {
                 TextBlock y_ScaleLabel = new TextBlock();
                 double max = Math.Ceiling(list.Max() / ) * ;
                 y_ScaleLabel.Text = (i * (max/)).ToString();
                 Canvas.SetLeft(y_ScaleLabel,  - );
                 Canvas.SetTop(y_ScaleLabel,  -  *  * i - );  

                 this.chartCanvas.Children.Add(y_ScaleLabel);
             }
         }

         /// <summary>
         /// 数字转汉字
         /// </summary>
         /// <param name="numberStr"></param>
         /// <returns></returns>
         public static string NumberToChinese(string numberStr)
         {
             string numStr = "";
             string chineseStr = "零一二三四五六七八九";
             char[] c = numberStr.ToCharArray();
             for (int i = ; i < c.Length; i++)
             {
                 int index = numStr.IndexOf(c[i]);
                 if (index != -)
                     c[i] = chineseStr.ToCharArray()[index];
             }
             numStr = null;
             chineseStr = null;
             return new string(c);
         } 

接下来就是计算数据点了，难点在于计算像素点，X轴是固定的，所以不用关注

直接算好的X轴十二个数值

double[] left = { 85, 130, 175, 220, 265, 310, 355, 400, 445, 490, 535, 580 };

而Y轴就要自己算了，提供一个思路：

区域总像素 - 区域总像素 * （数值/最大值）

         /// <summary>
         /// 计算数据点并添加
         /// </summary>
         /// <param name="list"></param>
         private void DrawPoint(List<double> list)
         {
             double[] left = { , , , , , , , , , , ,  };
             List<double> leftlist = new List<double>();
             leftlist.AddRange(left);

             for (int i = ; i < ; i++)
             {
                 Ellipse Ellipse = new Ellipse();
                 Ellipse .Fill = new SolidColorBrush(Color.FromRgb(, , 0xff));
                 Ellipse .Width = ;
                 Ellipse .Height = ;
                 Canvas.SetLeft(Ellipse,leftlist[i-]- );
                 double y_Max = Math.Ceiling(list.Max() / ) * ;
                 Canvas.SetTop(Ellipse,  -  * (list[i-] / y_Max) - );
                 coordinatePoints.Add(new Point(leftlist[i-],  -  * (list[i-] / y_Max)));
                 this.chartCanvas.Children.Add(Ellipse);
                 //值显示
                 TextBlock EP_Label = new TextBlock();
                 EP_Label.Foreground = System.Windows.Media.Brushes.Red;
                 EP_Label.Text = list[i-].ToString();
                 Canvas.SetLeft(EP_Label, leftlist[i-] - );
                 Canvas.SetTop(EP_Label,  -  * (list[i-] / y_Max) - );
                 this.chartCanvas.Children.Add(EP_Label);
             }
         }

在绘制数据点的时候，每一次的位置都保存了：  coordinatePoints.Add(new Point(leftlist[i-1], 320 - 250 * (list[i-1] / y_Max)));

先得定义：

/// <summary>
        /// 折线图坐标点
        /// </summary>
        private PointCollection coordinatePoints = new PointCollection();

最后直接连连看就好了

         /// <summary>
         /// 绘制连接折线
         /// </summary>
         private void DrawCurve()
         {
             Polyline curvePolyline = new Polyline();

             curvePolyline.Stroke = Brushes.Green;
             curvePolyline.StrokeThickness = ;

             curvePolyline.Points = coordinatePoints;
             this.chartCanvas.Children.Add(curvePolyline);
         }

由于我项目的关系，数据是从DataGrid控件行数据来的，所以每一次都不一样，只能在弹出窗体时调用这几个方法

由于每一都不一样，在窗口关闭时需要清空画布内的所有控件，否则画布内控件会一直覆盖

chartCanvas.Children.Clear();
coordinatePoints.Clear();

我的邮箱：alonezying@163.com 欢迎交流学习