Android Tutorial Android Charts Framework

The purpose of this framework is to allow you to easily add different types of charts to your projects.
The current version supports pie charts, line charts and bar charts.

The framework is implemented as code modules. You are free to customize the code as needed.

I also recommend you to go over the code. It demonstrates several concepts including: usage of custom types, drawings, string measurements and region clipping.

The code module is attached as part of the example project.
Questions, comments and suggestions are welcomed.

Klaus has posted a version that includes automatic scaling: http://www.b4x.com/android/forum/threads/android-charts-framework.8260/page-7#post-240181

 

[CharlesR]

Here you are.
No change in the Graph module, the clearing is done in the main code.
The modified lines have a 'klaus comment.

Best regards.

Hi Klaus

Thanks very much for that. I will study your code and hopefully improve my knowledge. I am wondering if there is a memory problem with erase graph as it produces "Unfortunately, USB Serial Example has stopped" after 23 graphs have been drawn on my Asus Transformer. I have run it 5 times and this is consistent.

I would appreciate your thoughts.

Thanks again.

Charles

 

[klaus]

Sorry, I hadn't seen this.
Here you are, the modifications are commented with 'klaus1.
I had to move
pnl2Lines.Initialize("pnl2Lines") 'klaus1
pnlPgraph.AddView(pnl2Lines, 0, 0, 55%x, 100%y - 100dip) 'klaus1
from btnGraph_Click to Activity_Create.

Best regards.

 

[CharlesR]

Sorry, I hadn't seen this.
Here you are, the modifications are commented with 'klaus1.
I had to move
pnl2Lines.Initialize("pnl2Lines") 'klaus1
pnlPgraph.AddView(pnl2Lines, 0, 0, 55%x, 100%y - 100dip) 'klaus1
from btnGraph_Click to Activity_Create.

Best regards.

Thank you very much Klaus.

Kind regards

Charles

 

[lorebarita]

Hi. I dont know if I am asking for too much but is there a way I can combine two graphs in the same panel like I show a bargraph and a linegraph at the same time. I have tried but it first draws one chart but then the second overwrites it. See what I have tried

 

[klaus]

Directly it's not possible.
You would need to modify the Charts module to do this.

Best regards.

 

[Mashiane]

To have the bar chart draw different colors each time its redrawn change the AddBarColor sub to this..

Sub AddBarColor(BD As BarData, Color As Int)
    If BD.BarsColors.IsInitialized = False Then BD.BarsColors.Initialize
    'the line below is taken from the add pie point method
    If Color = 0 Then Color = Colors.RGB(Rnd(0, 255), Rnd(0, 255), Rnd(0, 255))
    BD.BarsColors.Add(Color)
End Sub

 

[Mashiane]

Have modified the module to draw different colors per bar of the chart. This will not well for stacked bar charts or grouped charts though but only single point bar charts.

 

[Mashiane]

If you have your axis labels being cut, you can increase the 60dip number in this line of the drawGraph method

GI.originY = Target.Height - 60dip

to perhaps 100dip, that worked for me.

 

[Mashiane]

The x axis values are drawn at 45 degrees. By changing the value to 90 degrees, the axis text will appear straight up

From

Canvas.DrawTextRotated(p.x, x, GI.originY + 12dip, Typeface.DEFAULT, 12, G.AxisColor, "RIGHT", -45)

To

Canvas.DrawTextRotated(p.x, x, GI.originY + 12dip, Typeface.DEFAULT, 12, G.AxisColor, "RIGHT", -90)

 

[MichaelAust]

Nice Framework, I would suggest in Sub DrawBarsChart that

  If BD.Points.Size = 0 Then

be changed to

  If (BD.Points.IsInitialized=False) OR (BD.Points.Size = 0) Then

otherwise you get an error if you added no points (did that when I was debugging)

Also it would be great if you could add an option for X,Y Graphs, ie points or lines that can go to any X,Y point rather than simply going from left to right (sometimes called a Scatter plot).

 

[qsrtech]

Has anybody updated the chart framework to do horizontal bar charts yet?

 

[klaus]

Not that I know.

 

[cedrick]

can b4a line graph do this? sir?

 

[Erel]

Yes.

 

[TedDog]

Very helpful module, Erel. Thank you. Is it possible to save a chart as a jpg or gif? I'd like to allow users to email their charts as an attachment.

 

[klaus]

Yes, with the routine below you get the bitmap of the chart panel.

Sub GetBitmap(pnl As Panel) As Bitmap
    Dim bdw As BitmapDrawable
  
    bdw = pnlLines.Background
    Return bdw.Bitmap
End Sub

Then you can save it with the code below

Dim bmp As Bitmap
bmp = GetBitmap(pnlChart)
Dim Out As OutputStream
Out = File.OpenOutput(File.DirRootExternal, "Test.png", False)
bmp.WriteToStream(out, 100, "PNG")
Out.Close

 

[enrico]

I'd like to use StackedBarsChart but I have different numbers of y values for every x value.
How can I modifiy Charts.AddBarPoint to add arrays with indefinite size ?
And colors with Charts.AddBarColor ?

 

[Erel]

Can't you use 0 to hide the non-existent values?

 

[enrico]

That's a good idea. Thanks.
What about having different bars colors ?
For example in a day I can have item1 with value1 and item2 with value2 (in the stacked bar).
Next bar is next day where I can have item3, item4 and item5 with their values.
And I'd like to keep the colors of the same item (I already have a map with item as keys and colors as values).
After that the desire is to create a legend showing items and associated colors (probably using scrollview because items are many).

 

[Erel]

I recommend you to "delve" into the code. It is not too complicated. It will allow you to modify it to meet your requirements.