Android Tutorial Android Charts Framework

Erel · Mar 15, 2011

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

chrjak · Sep 10, 2015

Lykaion said:

i developed that function modifying the line chart, if somebody need it...

B4X:

Sub DrawAreaChart(G As Graph, LD As LineData, BackColor As Int)
    Dim aree As Map
    If Not(aree.IsInitialized) Then
        aree.Initialize
        aree.Clear
    End If
  
    If LD.Points.Size = 0 Then
        ToastMessageShow("Missing line points.", True)
        Return
    End If
    LD.Canvas.Initialize(LD.Target)
    LD.Canvas.DrawColor(BackColor)

    If LD.AutomaticScale = True Then
        GetLineMinMaxValues(LD)
        CalcScale(G, LD)
    End If

    drawGraph(G, LD.Canvas, LD.Target, LD.Points, False, 0)
    'Draw data lines
    Dim point As LinePoint
    point = LD.Points.Get(0)
  
    'multiple lines
    Dim py2(point.YArray.Length) As Double
    'initialize first point
    For i = 0 To py2.Length - 1
        py2(i) = point.YArray(i)
    Next
    'draw all points
    For i = 1 To LD.Points.Size - 1
        point = LD.Points.Get(i)
        For a = 0 To py2.Length - 1
            If aree.ContainsKey(LD.LinesColors.Get(a)) Then
                Dim linee As Path
                linee = aree.Get(LD.LinesColors.Get(a))
                linee.LineTo(G.GI.originX + G.GI.intervalX * i, calcPointToPixel(point.YArray(a), G))
                If i = LD.Points.Size-1 Then
                    linee.LineTo(G.GI.originX + G.GI.intervalX * i, G.GI.originY)
                End If
                aree.Put(LD.LinesColors.Get(a), linee)
            Else
                Dim linee As Path
                linee.Initialize(G.GI.originX + G.GI.intervalX * (i - 1), G.GI.originY)
                linee.LineTo(G.GI.originX + G.GI.intervalX * (i - 1), calcPointToPixel(py2(a), G))
                linee.LineTo(G.GI.originX + G.GI.intervalX * i, calcPointToPixel(point.YArray(a), G))
                aree.Put(LD.LinesColors.Get(a), linee)
            End If
            py2(a) = point.YArray(a)
        Next
    Next

    For i=0 To aree.Size-1
        LD.Canvas.DrawPath(aree.GetValueAt(i), Colors.Transparent, True, 2dip)
        LD.Canvas.DrawPath(aree.GetValueAt(i), aree.GetKeyAt(i), True, 2dip)
    Next
    drawGraph(G, LD.Canvas, LD.Target, LD.Points, False, 0)

    LD.Target.Invalidate
End Sub

Am I missing something? calcPointToPixel is marked red...

deantangNYP · Sep 18, 2015

HI Erel, Possible to have the X-Axis in float or integer?
Can it be done? This will allow it to space the values on the x-axis correctly. Thanks

AddLinePoint (LD As LineData, X As String, Y As Float, ShowTick As Boolean)

Erel said:
First post was updated with a new version. This version adds support for line charts.
A line chart can show a single line or multiple lines.
Some notes about the line chart:
- The X axis values are treated as strings.
- The Y axis values are treated as numbers.
- The data is added by adding the next X point. For this point you need to supply the Y value in case of a single line, or an array of Y values in case of multiple lines.

The code in the first post demonstrates both a single line and multiple lines charts.

All the drawing code is included in the Charts module. You are free to customize it as needed.

klaus · Sep 18, 2015

You can already set x as Float or Int.
If you look at the LineChart and LineChart1 example projects in the User's Guide.
This works:

B4X:

' Add the line points.
For i = 0 To 360 Step 10
    ' In the case of 2 lines or more we are adding an array of values.
    ' One for each line.
    ' Make sure to create an array for each point.
    ' You cannot reuse a single array for all points.
    Charts.AddLineMultiplePoints(LD, i, Array As Float(SinD(i), CosD(i)), i Mod 90 = 0)
Next

This too:

B4X:

' Add the line points.
Dim x As Float
For i = 0 To 500 Step 10
    ' In the case of 2 lines or more we are adding an array of values.
    ' One for each line.
    ' Make sure to create an array for each point.
    ' You cannot reuse a single array for all points.
    x = i / 100
    Charts.AddLineMultiplePoints(LD, x, Array As Float(Rnd(-20,21) + 20, Rnd(-15,16) - 20, CosD(3 * i) * 35), i Mod 50 = 0)
Next

deantangNYP · Sep 18, 2015

Hi Klaus, thanks for the reply. If that's the case, how can i have a correct spacing proportional to the reading on the x-axis?
Please see the picture. Spacing between unit 1 and 2 , should not be the same as spacing between unit 4 and 10.
Thanks. Please advise. Did i do something incorrect?
I am using a simple AddLinePoint for testing.

B4X:

       Charts.AddLinePoint(LD, 0, 0, True )
    Charts.AddLinePoint(LD, 1, 80, True )
    Charts.AddLinePoint(LD, 2, 70, True )
    Charts.AddLinePoint(LD, 3, 40, True )
    Charts.AddLinePoint(LD, 4, 40, True )
    Charts.AddLinePoint(LD, 10, 70, True )

https://www.dropbox.com/s/c9cnrnrs48vauco/chart1.JPG?dl=0

klaus said:

You can already set x as Float or Int.
If you look at the LineChart and LineChart1 example projects in the User's Guide.
This works:

B4X:

' Add the line points.
For i = 0 To 360 Step 10
    ' In the case of 2 lines or more we are adding an array of values.
    ' One for each line.
    ' Make sure to create an array for each point.
    ' You cannot reuse a single array for all points.
    Charts.AddLineMultiplePoints(LD, i, Array As Float(SinD(i), CosD(i)), i Mod 90 = 0)
Next

This too:

B4X:

' Add the line points.
Dim x As Float
For i = 0 To 500 Step 10
    ' In the case of 2 lines or more we are adding an array of values.
    ' One for each line.
    ' Make sure to create an array for each point.
    ' You cannot reuse a single array for all points.
    x = i / 100
    Charts.AddLineMultiplePoints(LD, x, Array As Float(Rnd(-20,21) + 20, Rnd(-15,16) - 20, CosD(3 * i) * 35), i Mod 50 = 0)
Next

klaus · Sep 18, 2015

Now I understand what you mean.
The LineChart doesn't support what you want to do it supposes equal distances between points.
You would need to add this feature yourself or write your own routine.
That's what I did in the DynSim simulation program.
You might have a look at chapter 11.3.1 Diagrams / Graph example program in the B4A User's Guide.
There are also other diagram or chart libraries in the forum.

deantangNYP · Sep 21, 2015

klaus said:
Now I understand what you mean.
The LineChart doesn't support what you want to do it supposes equal distances between points.
You would need to add this feature yourself or write your own routine.
That's what I did in the DynSim simulation program.
You might have a look at chapter 11.3.1 Diagrams / Graph example program in the B4A User's Guide.
There are also other diagram or chart libraries in the forum.

THANKS for the reply

trueboss323 · Nov 1, 2015

Hello, how to save the chart as an image to the device's gallery?

klaus · Nov 1, 2015

Have a look at THIS post.

trueboss323 · Nov 13, 2015

klaus said:
Have a look at THIS post.

The code you provided saves the image to the SD root directly. What happens if the user doesnt have an SD card? Moreover, the image does not appear in the Gallery app, how can I get it to appear there?

klaus · Nov 13, 2015

I have never tried it, you should search in the forum if somebody has already done it.
To answer your question I would also need to search for it.

swChef · May 31, 2017

Has anyone looked into making this available as/in a service, to create a chart for a purpose other than live Activity display ?
Or is there a better alternative for that case?

Erel · May 31, 2017

You can change the Target field to be a Bitmap and then draw over a mutable bitmap instead of the panel. You will need to make a few changes but it shouldn't be difficult.

swChef · Jun 1, 2017

I didn't have time to review it today, but did you mean (a few changes) in the library itself, or is it possible on the application side? From my efforts this past weekend I think modifying the library is necessary.

Erel · Jun 1, 2017

You will need to modify the module code.

Rob Bliss · Sep 3, 2018

Has anyone been clever enough to show a popup panel when clicking a portion of a Stacked Bar Chart?? I've tried replacing the panel and canvas from BarData with ones created in the activity, but can't get the panel_touch/click events to fire (I figured BD.Target_Click wouldn't work either due to the fullstop), let alone register which section of the chart it has touched.

Any help is much appreciated.

Erel · Sep 4, 2018

I recommend you to use xCharts for any new project. This solution was written in 2011.

klaus · Sep 5, 2018

Rob Bliss said:
Has anyone been clever enough to show a popup panel when clicking a portion of a Stacked Bar Chart??

What exactly do you want to do?
What kind of data do you want to display?

Rob Bliss · Sep 6, 2018

klaus said:
What exactly do you want to do?
What kind of data do you want to display?

I've done it now, after a bit of fiddling, using xCharts, but the idea was to click/touch a section of a stacked column, or just the column, then for a panel to appear displaying things like the value of the section, the column. Maybe colour the section names and display all the values at once. Just anything to give that bit more information. The solution given with xCharts more than suits my needs.

pazzokli · Oct 15, 2018

Hi, I would like keep tablet in portrait mode but see line graph with x axis in vertical
Is it possible?

Erel · Oct 16, 2018

There is no reason to use these modules. You should switch to xCharts instead.

Android Tutorial Android Charts Framework

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