Tutorial13 - Custom Drawing on the Chart Panel

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TeeChart offers extensive custom drawing facilities via the Canvas object. With Canvas you may add shapes, lines and text anywhere on the Chart Panel and define their colours, pen and brush styles.


Contents

TeeChart Canvas

    Drawing order 
    Ensuring that custom drawn items are saved to the Canvas 
    Drawing Lines 
    Canvas Pen and Brush 
    Adding 2D Shapes 
    Adding 3D Shapes 
    Adding text 
    Applied example 


TeeChart Canvas

Drawing order When using TeeChart's Canvas methods remember that drawing order is important. Drawing a Line on the Chart then adding Series data points will cause the Line to be overdrawn. There are four principle Chart draw events, which are, in order:

BeforeDraw event

BeforeDrawAxes event

BeforeDrawSeries event

AfterDraw event

Example:

[C#] private bool afterDraw; private bool beforeDraw; private bool beforeDrawAxis; private bool beforeDrawSeries; private void Form1_Load(object sender, System.EventArgs e) { SetFlags(ref beforeDraw); Bar bar1 = new Bar(tChart1.Chart); bar1.FillSampleValues(20); radioButton1.Checked = true; } private void SetFlags(ref bool Flag) { beforeDraw = false; afterDraw = false; beforeDrawAxis = false; beforeDrawSeries = false; Flag = true; } private void DrawShape(Steema.TeeChart.Drawing.Graphics3D gg) { gg.Brush.Color = Color.Yellow; gg.Pen.Visible = true; gg.Pen.Style = System.Drawing.Drawing2D.DashStyle.Dash; gg.Brush.Visible = true; gg.Ellipse(1,1,gg.Chart.Width - 1,gg.Chart.Height - 1); } private void tChart1_AfterDraw(object sender, Steema.TeeChart.Drawing.Graphics3D g) { if(afterDraw) { DrawShape(g); } } private void tChart1_BeforeDraw(object sender, Steema.TeeChart.Drawing.Graphics3D g) { if(beforeDraw) { DrawShape(g); } } private void tChart1_BeforeDrawAxes(object sender, Steema.TeeChart.Drawing.Graphics3D g) { if(beforeDrawAxis) { DrawShape(g); } } private void tChart1_BeforeDrawSeries(object sender, Steema.TeeChart.Drawing.Graphics3D g) { if(beforeDrawSeries) { DrawShape(g); } } private void radioButton4_Click(object sender, System.EventArgs e) { SetFlags(ref afterDraw); tChart1.Refresh(); } private void radioButton3_Click(object sender, System.EventArgs e) { SetFlags(ref beforeDrawSeries); tChart1.Refresh(); } private void radioButton2_Click(object sender, System.EventArgs e) { SetFlags(ref beforeDrawAxis); tChart1.Refresh(); } private void radioButton1_Click(object sender, System.EventArgs e) { SetFlags(ref beforeDraw); tChart1.Refresh(); } [VB.Net] Private BeforeDraw As Boolean Private BeforeDrawAxis As Boolean Private BeforeDrawSeries As Boolean Private AfterDraw As Boolean Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load SetFlags(BeforeDraw) Dim Bar1 As New Steema.TeeChart.Styles.Bar(TChart1.Chart) Bar1.FillSampleValues(20) RadioButton1.Checked = True End Sub Private Sub SetFlags(ByRef Flag As Boolean) BeforeDraw = False BeforeDrawAxis = False BeforeDrawSeries = False AfterDraw = False Flag = True End Sub Private Sub DrawShape(ByVal gg As Steema.TeeChart.Drawing.Graphics3D) gg.Brush.Color = Color.Yellow gg.Pen.Visible = True gg.Pen.Style = Drawing.Drawing2D.DashStyle.Dash gg.Brush.Visible = True gg.Ellipse(1, 1, gg.Chart.Width - 1, gg.Chart.Height - 1) End Sub Private Sub TChart1_AfterDraw(ByVal sender As Object, ByVal g As Steema.TeeChart.Drawing.Graphics3D) Handles TChart1.AfterDraw If AfterDraw = True Then DrawShape(g) End If End Sub Private Sub TChart1_BeforeDraw(ByVal sender As Object, ByVal g As Steema.TeeChart.Drawing.Graphics3D) Handles TChart1.BeforeDraw If BeforeDraw = True Then DrawShape(g) End If End Sub Private Sub TChart1_BeforeDrawAxes(ByVal sender As Object, ByVal g As Steema.TeeChart.Drawing.Graphics3D) Handles TChart1.BeforeDrawAxes If BeforeDrawAxis = True Then DrawShape(g) End If End Sub Private Sub TChart1_BeforeDrawSeries(ByVal sender As Object, ByVal g As Steema.TeeChart.Drawing.Graphics3D) Handles TChart1.BeforeDrawSeries If BeforeDrawSeries = True Then DrawShape(g) End If End Sub Private Sub RadioButton4_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles RadioButton4.Click SetFlags(AfterDraw) TChart1.Refresh() End Sub Private Sub RadioButton3_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles RadioButton3.Click SetFlags(BeforeDrawSeries) TChart1.Refresh() End Sub Private Sub RadioButton2_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles RadioButton2.Click SetFlags(BeforeDrawAxis) TChart1.Refresh() End Sub Private Sub RadioButton1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles RadioButton1.Click SetFlags(BeforeDraw) TChart1.Refresh() End Sub

Ensuring that custom drawn items are saved to the Canvas If you do not place calls to Canvas draw code in one of the Chart events, custom drawing will not be saved to the Canvas permanently thus causing any addition to be lost when an application is minimised or another Window placed over it. Your code does not need to reside directly in the Chart events; user drawn items can be saved for the life of the Chart window if you place code in BeforeDrawSeries/AfterDraw and check for flags set by your runtime Draw methods thus running your draw code when activity is flagged as true, as in the example above.

Drawing Lines Let's add a Canvas Line: Example (drawing a line diagonally from top left to bottom right)


[C#] private void Form1_Load(object sender, System.EventArgs e) { line1.FillSampleValues(20); line1.VertAxis = VerticalAxis.Both; line1.HorizAxis = HorizontalAxis.Both; tChart1.Aspect.View3D = false; } private void tChart1_AfterDraw(object sender, Steema.TeeChart.Drawing.Graphics3D g) { Point s = new Point(tChart1.Axes.Left.Position, tChart1.Axes.Top.Position); Point e = new Point(tChart1.Axes.Right.Position, tChart1.Axes.Bottom.Position); g.MoveTo(s); g.LineTo(e,0); } [VB.Net] Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load Line1.FillSampleValues(20) Line1.VertAxis = Steema.TeeChart.VerticalAxis.Both Line1.HorizAxis = Steema.TeeChart.HorizontalAxis.Both TChart1.Aspect.View3D = False End Sub Private Sub TChart1_AfterDraw(ByVal sender As Object, ByVal g As Steema.TeeChart.Drawing.Graphics3D) Handles TChart1.AfterDraw Dim S As New Point(TChart1.Axes.Left.Position, TChart1.Axes.Top.Position) Dim E As New Point(TChart1.Axes.Right.Position, TChart1.Axes.Bottom.Position) g.MoveTo(S) g.LineTo(E, 0) End Sub


On a 3D Chart the Axis positions are offset from the Chart area due to 3D orthogonal displacement. We can move the Line accordingly: Example (drawing a Line diagonally from top left to bottom right in the Chart Area of a 3D Chart)


[C#] private void Form1_Load(object sender, System.EventArgs e) { line1.FillSampleValues(20); line1.VertAxis = VerticalAxis.Both; line1.HorizAxis = HorizontalAxis.Both; tChart1.Aspect.Chart3DPercent = 50; } private void tChart1_AfterDraw(object sender, Steema.TeeChart.Drawing.Graphics3D g) { Steema.TeeChart.Drawing.Point3D s = new Steema.TeeChart.Drawing.Point3D(); s.X = tChart1.Axes.Left.Position; s.Y = tChart1.Axes.Top.Position; s.Z = 0; Steema.TeeChart.Drawing.Point3D e = new Steema.TeeChart.Drawing.Point3D(); e.X = tChart1.Axes.Right.Position; e.Y = tChart1.Axes.Bottom.Position; e.Z = tChart1.Aspect.Width3D; g.MoveTo(s); g.LineTo(e); } [VB.Net] Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load Line1.FillSampleValues(20) Line1.VertAxis = Steema.TeeChart.VerticalAxis.Both Line1.HorizAxis = Steema.TeeChart.HorizontalAxis.Both TChart1.Aspect.Chart3DPercent = 50 End Sub Private Sub TChart1_AfterDraw(ByVal sender As Object, ByVal g As Steema.TeeChart.Drawing.Graphics3D) Handles TChart1.AfterDraw Dim S As New Steema.TeeChart.Drawing.Point3D() S.X = TChart1.Axes.Left.Position S.Y = TChart1.Axes.Top.Position S.Z = 0 Dim E As New Steema.TeeChart.Drawing.Point3D() E.X = TChart1.Axes.Right.Position E.Y = TChart1.Axes.Bottom.Position E.Z = TChart1.Aspect.Width3D g.MoveTo(S) g.LineTo(E) End Sub

Canvas Pen and Brush The Line above is drawn using the Pen and Brush defined for the last object drawn before the Line is drawn. That may or may not be the Pen you want. Change the Pen accordingly: Example (define Pen before drawing the Line)


[C#] private void tChart1_AfterDraw(object sender, Steema.TeeChart.Drawing.Graphics3D g) { Point p5 = new Point(line1.CalcXPos(5), line1.CalcYPos(5)); Point p15 = new Point(line1.CalcXPos(15), line1.CalcYPos(15)); g.Pen.DashCap = System.Drawing.Drawing2D.DashCap.Triangle; g.Pen.EndCap = System.Drawing.Drawing2D.LineCap.DiamondAnchor; g.Pen.Style = System.Drawing.Drawing2D.DashStyle.DashDotDot; g.Pen.Transparency = 70; g.Pen.Width = 3; g.Pen.Color = Color.BlueViolet; g.MoveTo(p5); g.LineTo(p15, 0); } [VB.Net] Private Sub TChart1_AfterDraw(ByVal sender As Object, ByVal g As Steema.TeeChart.Drawing.Graphics3D) Handles TChart1.AfterDraw Dim P5 As New Point(Line1.CalcXPos(5), Line1.CalcYPos(5)) Dim P15 As New Point(Line1.CalcXPos(15), Line1.CalcYPos(15)) g.Pen.DashCap = System.Drawing.Drawing2D.DashCap.Triangle g.Pen.EndCap = System.Drawing.Drawing2D.LineCap.DiamondAnchor g.Pen.Style = System.Drawing.Drawing2D.DashStyle.DashDotDot g.Pen.Transparency = 70 g.Pen.Width = 3 g.Pen.Color = Color.BlueViolet g.MoveTo(P5) g.LineTo(P15, 0) End Sub

Adding 2D Shapes Add Canvas Shapes in a similar manner to Canvas Lines. The following example adds a Rectangle in the centre of the Chart Area:

2D Charts 2D Charts only support 2D shapes. Example


[C#] private void tChart1_AfterDraw(object sender, Steema.TeeChart.Drawing.Graphics3D g) { Size s = new Size(100,100); Point l = new Point(g.ChartXCenter - (s.Width / 2), g.ChartYCenter - (s.Height / 2)); Rectangle r = new Rectangle(l,s); g.Pen.Color = Color.Aquamarine; g.Brush.Color = Color.Blue; g.Rectangle(r); } [VB.Net] Private Sub TChart1_AfterDraw(ByVal sender As Object, ByVal g As Steema.TeeChart.Drawing.Graphics3D) Handles TChart1.AfterDraw Dim S As New Size(100, 100) Dim L As New Point(g.ChartXCenter - (S.Width / 2), g.ChartYCenter - (S.Height / 2)) Dim R As New Rectangle(L, S) g.Pen.Color = Color.Aquamarine g.Brush.Color = Color.Blue g.Rectangle(R) End Sub


3D Charts On a 3D Chart you can move the Rectangle in a Z plane too. See the RectangleWithZ method. This example places the Rectangle on the Left Wall but displaces it halfway towards the rear of the Chart (towards the Back Wall).


[C#] private void Form1_Load(object sender, System.EventArgs e) { point3DSeries1.LinePen.Visible = false; point3DSeries1.FillSampleValues(20); point3DSeries1.VertAxis = VerticalAxis.Both; point3DSeries1.HorizAxis = HorizontalAxis.Both; tChart1.Aspect.Chart3DPercent = 50; tChart1.Axes.Depth.Visible = true; } private void tChart1_AfterDraw(object sender, Steema.TeeChart.Drawing.Graphics3D g) { Size s = new Size(100,100); Point l = new Point(tChart1.Axes.Left.Position, g.ChartYCenter - (s.Height / 2)); Rectangle r = new Rectangle(l,s); g.Pen.Color = Color.Aquamarine; g.Brush.Color = Color.Blue; g.Rectangle(r, tChart1.Aspect.Width3D/2); } [VB.Net] Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load Point3DSeries1.LinePen.Visible = False Point3DSeries1.FillSampleValues(20) Point3DSeries1.VertAxis = Steema.TeeChart.VerticalAxis.Both Point3DSeries1.HorizAxis = Steema.TeeChart.HorizontalAxis.Both TChart1.Aspect.Chart3DPercent = 50 TChart1.Axes.Depth.Visible = True End Sub Private Sub TChart1_AfterDraw(ByVal sender As Object, ByVal g As Steema.TeeChart.Drawing.Graphics3D) Handles TChart1.AfterDraw Dim S As New Size(100, 100) Dim L As New Point(TChart1.Axes.Left.Position, g.ChartYCenter - (S.Height / 2)) Dim R As New Rectangle(L, S) g.Pen.Color = Color.Aquamarine g.Brush.Color = Color.Blue g.Rectangle(R, TChart1.Aspect.Width3D / 2) End Sub

Adding 3D Shapes You may add 3D shapes to 3D Charts. This example draws a Cube in the middle of the Chart rectangle:


[C#] private void Form1_Load(object sender, System.EventArgs e) { point3DSeries1.LinePen.Visible = false; point3DSeries1.FillSampleValues(20); tChart1.Aspect.Chart3DPercent = 50; tChart1.Legend.Visible = false; tChart1.Axes.Depth.Visible = true; } private void tChart1_AfterDraw(object sender, Steema.TeeChart.Drawing.Graphics3D g) { Size s = new Size(50,50); Point p = new Point(g.ChartXCenter - (s.Width/2), g.ChartYCenter - (s.Height/2)); Rectangle r = new Rectangle(p,s); g.Cube(r, 0, 20, true); } [VB.Net] Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load Point3DSeries1.LinePen.Visible = False Point3DSeries1.FillSampleValues(20) TChart1.Aspect.Chart3DPercent = 50 TChart1.Legend.Visible = False TChart1.Axes.Depth.Visible = True End Sub Private Sub TChart1_AfterDraw(ByVal sender As Object, ByVal g As Steema.TeeChart.Drawing.Graphics3D) Handles TChart1.AfterDraw Dim S As New Size(50, 50) Dim P As New Point(g.ChartXCenter - (S.Width / 2), g.ChartYCenter - (S.Height / 2)) Dim R As New Rectangle(P, S) g.Cube(R, 0, 20, True) End Sub

Adding text

2D Text location Add Text to the last Rectangle: Example


[C#] private void tChart1_AfterDraw(object sender, Steema.TeeChart.Drawing.Graphics3D g) { string text = "My Text"; Size s = new Size(150, 50); Point p = new Point(g.ChartXCenter - (s.Width/2), g.ChartYCenter - (s.Height/2)); Rectangle r = new Rectangle(p,s); g.Pen.Color = Color.Blue; g.Rectangle(r); g.TextOut(Convert.ToInt32(g.ChartXCenter - (g.TextWidth(text)/2)), Convert.ToInt32(g.ChartYCenter - (g.TextHeight(text)/2)), text); } [VB.Net] Private Sub TChart1_AfterDraw(ByVal sender As Object, ByVal g As Steema.TeeChart.Drawing.Graphics3D) Handles TChart1.AfterDraw Dim Text As String = "My Text" Dim S As New Size(50, 50) Dim P As New Point(g.ChartXCenter - (S.Width / 2), g.ChartYCenter - (S.Height / 2)) Dim R As New Rectangle(P, S) g.Pen.Color = Color.Blue g.Rectangle(R) g.TextOut(Convert.ToInt32(g.ChartXCenter - (g.TextWidth(Text) / 2)), Convert.ToInt32(g.ChartYCenter - (g.TextHeight(Text) / 2)), Text) End Sub


3D Text location You can place Text in a differing 3D plane by using the TextOut overload with a z coordinate. Example


[C#] private void Form1_Load(object sender, System.EventArgs e) { point3DSeries1.FillSampleValues(20); point3DSeries1.LinePen.Visible = false; tChart1.Aspect.Chart3DPercent = 50; } private void tChart1_AfterDraw(object sender, Steema.TeeChart.Drawing.Graphics3D g) { string text = "My Text"; g.TextOut(g.ChartXCenter, g.ChartYCenter, tChart1.Aspect.Width3D / 2, text); } [VB.Net] Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load Point3DSeries1.FillSampleValues(20) Point3DSeries1.LinePen.Visible = False TChart1.Aspect.Chart3DPercent = 50 End Sub Private Sub TChart1_AfterDraw(ByVal sender As Object, ByVal g As Steema.TeeChart.Drawing.Graphics3D) Handles TChart1.AfterDraw Dim Text As String = "My Text" g.TextOut(g.ChartXCenter, g.ChartYCenter, TChart1.Aspect.Width3D / 2, Text) End Sub

Applied example This example takes the 3rd and 10th values of a Series, plots a Line between them and tells us the value of the first and Last point of the new Line and the difference between them: Example


[C#] private void Form1_Load(object sender, System.EventArgs e) { tChart1.Aspect.View3D = false; line1.FillSampleValues(20); } private void tChart1_AfterDraw(object sender, Steema.TeeChart.Drawing.Graphics3D g) { if(tChart1.Series.Count > 0){ if(tChart1.Series[0].Count > 10) { Series s = tChart1.Series[0]; int h = Convert.ToInt32(g.TextHeight("H")); Point p1 = new Point(s.CalcXPos(3), s.CalcYPos(3)); Point p2 = new Point(s.CalcXPos(10), s.CalcYPos(10)); g.Pen.Color = Color.Blue; g.Pen.Width = 2; g.Pen.Style = System.Drawing.Drawing2D.DashStyle.Dash; g.MoveTo(p1); g.LineTo(p2, 0); g.TextOut(p1.X, p1.Y - h, "Point value: " + s.YValues[3].ToString()); g.TextOut(p2.X, p2.Y, "Point value: " + s.YValues[10].ToString()); g.TextOut(p2.X, p2.Y + h, "Change is: " + Convert.ToString(s.YValues[3] - s.YValues[10])); } } } [VB.Net] Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load TChart1.Aspect.View3D = False Line1.FillSampleValues(20) End Sub Private Sub TChart1_AfterDraw(ByVal sender As Object, ByVal g As Steema.TeeChart.Drawing.Graphics3D) Handles TChart1.AfterDraw If TChart1.Series.Count > 0 Then If TChart1.Series(0).Count > 10 Then Dim S As Steema.TeeChart.Series = TChart1.Series(0) Dim H As Integer = Convert.ToInt32(g.TextHeight("H")) Dim P1 As New Point(S.CalcXPos(3), S.CalcYPos(3)) Dim P2 As New Point(S.CalcXPos(10), S.CalcYPos(10)) g.Pen.Color = Color.Blue g.Pen.Width = 2 g.Pen.Style = System.Drawing.Drawing2D.DashStyle.Dash g.MoveTo(P1) g.LineTo(P2, 0) g.TextOut(P1.X, P1.Y - H, "Point value: " & S.YValues(3)) g.TextOut(P2.X, P2.Y, "Point value: " & S.YValues(10)) g.TextOut(P2.X, P2.Y + H, "Change is: " & (S.YValues(3) - S.YValues(10))) End If End If End Sub