ChartsDevice.dll thick line at bottom of chart

[RB Smissaert]

For some reason when I use the ChartsDevice dll (and same on the desktop)
I get a thick line just above the x-axis going from position 0 to about 9 tenth
of the x-axis. I noticed the provided example (the line chart) does the same and I have no idea how to get rid of it.
Any ideas?

RBS

 

[agraham]

Assuming that you mean the line at y = 0 it is there by design to show the y axis origin.

 

[RB Smissaert]

I attached a .gif file that shows what I am talking about.
The line in this image runs till the 9 in the second date.

RBS

 

[agraham]

I don't see anything like that in the line chart example, Can you post the code that created the chart so I can try it on my system.

 

[RB Smissaert]

This code shows it with me:

Sub DrawLineChart

LineChart.New1(Image1.Width, Image1.Height)
LineChart.Text = "BP values"
LineChart.Color = Rgb(255,255,230)
LineChart.ColorGradient = cBlue
LineChart.GridSpacingValue = 20
LineChart.MaxScaleValue = 180
LineChart.MinScaleValue = 80
LineChart.ShowGrid = False
LineChart.BorderSize = 10
LineChart.MarginForTextOnAxis = 10

LineChart.XAxisIntervalValue = 1
LineChart.AddXAxisText(240,240, "")

LineChart.NewLine(cRed)
LineChart.AddPoint(0, 160)
LineChart.AddPoint(1, 150)
LineChart.AddPoint(2, 155)
LineChart.AddPoint(3, 170)
LineChart.AddPoint(4, 180)
LineChart.AddPoint(5, 150)
LineChart.AddPoint(6, 140)
linechart.ShowGrid = True
LineChart.AddLine

LineChart.NewLine(cBlue)
LineChart.AddPoint(0, 90)
LineChart.AddPoint(1, 85)
LineChart.AddPoint(2, 90)
LineChart.AddPoint(3, 100)
LineChart.AddPoint(4, 110)
LineChart.AddPoint(5, 80)
LineChart.AddPoint(6, 140)
LineChart.AddLine

LineChart.NewLine(cGreen)
LineChart.LineWidth = 1
LineChart.AddPoint(0, 85)
LineChart.AddPoint(5, 25)
LineChart.AddPoint(10, 65)
LineChart.AddPoint(15, 75)
LineChart.AddPoint(20, 10)
LineChart.AddTrendLine

Image1.Image =LineChart.Draw

End Sub


RBS

 

[klaus]

I have looked at your code.
The code you posted doesn't match your image, why didn't you post the right code?

The problem lies in the line

[FONT=Courier New][SIZE=2][FONT=Courier New][SIZE=2]LineChart.AddXAxisText([/SIZE][/FONT][/SIZE][/FONT][FONT=Courier New][SIZE=2][COLOR=#800080][FONT=Courier New][SIZE=2][COLOR=#800080][FONT=Courier New][SIZE=2][COLOR=#800080]240[/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][FONT=Courier New][SIZE=2][FONT=Courier New][SIZE=2],[/SIZE][/FONT][/SIZE][/FONT][FONT=Courier New][SIZE=2][COLOR=#800080][FONT=Courier New][SIZE=2][COLOR=#800080][FONT=Courier New][SIZE=2][COLOR=#800080]240[/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][FONT=Courier New][SIZE=2][FONT=Courier New][SIZE=2], [/SIZE][/FONT][/SIZE][/FONT][FONT=Courier New][SIZE=2][COLOR=#800000][FONT=Courier New][SIZE=2][COLOR=#800000][FONT=Courier New][SIZE=2][COLOR=#800000]""[/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][FONT=Courier New][SIZE=2][FONT=Courier New][SIZE=2])[/SIZE][/FONT][/SIZE][/FONT]

if you replae it by

[FONT=Courier New][SIZE=2][FONT=Courier New][SIZE=2]LineChart.AddXAxisText([/SIZE][/FONT][/SIZE][/FONT][FONT=Courier New][SIZE=2][COLOR=#800080][FONT=Courier New][SIZE=2][COLOR=#800080][FONT=Courier New][SIZE=2][COLOR=#800080]0[/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][FONT=Courier New][SIZE=2][FONT=Courier New][SIZE=2],[/SIZE][/FONT][/SIZE][/FONT][FONT=Courier New][SIZE=2][COLOR=#800080][FONT=Courier New][SIZE=2][COLOR=#800080][FONT=Courier New][SIZE=2][COLOR=#800080]20[/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][FONT=Courier New][SIZE=2][FONT=Courier New][SIZE=2], [/SIZE][/FONT][/SIZE][/FONT][FONT=Courier New][SIZE=2][COLOR=#800000][FONT=Courier New][SIZE=2][COLOR=#800000][FONT=Courier New][SIZE=2][COLOR=#800000]""[/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][FONT=Courier New][SIZE=2][FONT=Courier New][SIZE=2])[/SIZE][/FONT][/SIZE][/FONT]

you get a 'normal' X axis.

With you code the program tries to draw no text at position 240.

Attached 2 images.


@agraham
In trying this example I noticed that the parameter MinScaleValue with posutive values has no effect.

[FONT=Courier New][SIZE=2][FONT=Courier New][SIZE=2]LineChart.MinScaleValue=[/SIZE][/FONT][/SIZE][/FONT][FONT=Courier New][SIZE=2][COLOR=#800080][FONT=Courier New][SIZE=2][COLOR=#800080][FONT=Courier New][SIZE=2][COLOR=#800080]20[/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT]

Best regards.

 

[agraham]

There are two problems here

First this statment "LineChart.XAxisIntervalValue = 1" puts the X-axis ticks too close together for a maximum scale value of 240 so they run into each other as a grey bar.

Second, why then does the grey bar not extend to the end? The answer is that there is a bug in drawing the ticks when the max value of the X axis (which is determined by the max value defined in the AddXAxisText statements) is greater than the number of display pixels along the the X-axis. If you need a larger value than this the solution is to scale the X values to be less than that number of pixels.

@Klaus

In trying this example I noticed that the parameter MinScaleValue with posutive values has no effect.

That is correct. MinScaleValue is intended for extending the Y value range into negative values. If it is greater than 0 it has no effect.

 

[klaus]

In my mind I would have expected, that if I had a chart with values between 80 and 100 and setting the MinScaleValue to 80 and MaxScaleValue to 100, getting a diagram with a streched Y scale from 80 to 100.

Unfortunately this seems not beeing the case.

Best regards.

 

[RB Smissaert]

> The code you posted doesn't match your image, why didn't you post the right code?

The code that produced the image I posted is a lot more complex and I would have to simplify it a lot. The code I posted is simple and shows the problem.
Will look at Graham's post now.

RBS

 

[agraham]

Bug fixed - http://www.b4x.com/forum/additional-libraries/1703-charting-library.html

 

[RB Smissaert]

> First this statment "LineChart.XAxisIntervalValue = 1" puts the X-axis ticks too close together for a maximum scale value of 240 so they run into each other as a grey bar.

Yes, thanks that was the problem and I can simply do:
LineChart.XAxisIntervalValue = 240

As Klaus mentioned, it would be nice if you could make:
LineChart.MinScaleValue =
respond to positive values, so setting a positive lowest value for the Y-axis.


RBS