[bb] Pie chart code by Ross C [ 1+ years ago ]

[BlitzBot]

Title : Pie chart code
Author : Ross C
Posted : 1+ years ago

Description : This code will create a pie chart, based on the number of entries in a type collection. It is coded in such a way, that it's size, text positions etc, are all easily changable. It currently will scale to fit the screen resolution.

Code :

Code (blitzbasic) Select Expand

Graphics 640,480
SetBuffer BackBuffer()
SeedRnd MilliSecs()

Type segment
   Field angle#
   Field value#
End Type

; just some sizes for the pie chart, based on the graphics resolution, so it will scale ok.
Global pie_chart_start_x# = GraphicsWidth()/2
Global pie_chart_start_y# = GraphicsHeight()/2

Global pie_chart_size# = GraphicsHeight()/2.2
Global segment_text_position# = 0.75 ; a value between 0 and 1: 0 = at the middle. 1 = at the edge.

Global total_value ; this is calculated below, when generating the type object segments.

; create 6 chart segments
For loop = 1 To 6
s.segment = New segment
svalue# = Rand(10,100)
total_value = total_value + svalue
Next

While Not KeyHit(1)

Cls

draw_pie_chart()

Flip
Wend

Function draw_pie_chart()

    ; draw the circle shape of the pie chart. use the start X and Y and the pie chart size here.
Oval pie_chart_start_x - pie_chart_size, pie_chart_start_y - pie_chart_size,pie_chart_size*2,pie_chart_size*2,0

Local angle# = 90 ; set this to 90 to overcome blitz rotation system, so it start vertically.
Local angle_gap# ; used to work out the angle size, based on the value in the type object.
                ; as always: (value / total value)*100 gives you a percentage.
Local text_angle#; i take half of the angle_gap and use this angle to place the visual value.

; draw initial line
Line pie_chart_start_x, pie_chart_start_y, pie_chart_start_x - (Cos(angle)*pie_chart_size), pie_chart_start_y - (Sin(angle)*pie_chart_size)
; draw the total value
Text pie_chart_start_x, pie_chart_start_y - (pie_chart_size*1.05), total_value,True,True

For s.segment = Each segment

angle_gap = 360 * (svalue / total_value)
text_angle = angle_gap/2
angle = angle + angle_gap

; BELOW: draw a line to show the segment.
Line pie_chart_start_x, pie_chart_start_y, pie_chart_start_x - (Cos(angle)*pie_chart_size), pie_chart_start_y - (Sin(angle)*pie_chart_size)
; BELOW: place the visual value of the type object, halfway between the centre and circumfirance.
Text pie_chart_start_x - (Cos(angle - text_angle)*(pie_chart_size*segment_text_position)), pie_chart_start_y - (Sin(angle - text_angle)*(pie_chart_size*segment_text_position)),svalue,True,True


Next

End Function

Comments :


Ross C(Posted 1+ years ago)

 Would be nice to codebox that )


Ross C(Posted 1+ years ago)

 Why have i commented on my own code... Odd.


Warpy(Posted 1+ years ago)

 You're cracking up, Ross.


Ross C(Posted 1+ years ago)

 That's comforting coming from you ;o)


Adam Novagen(Posted 1+ years ago)

 Tastes great, but no filling. XDSeriously though, this'd be a whole lot cooler if it actually filled the individual regions of the chart.


Ross C(Posted 1+ years ago)

 There is a fill command in the archives, although, i could just use the line command at small intervals to fill. I will update it!


Ross C(Posted 1+ years ago)

 Scratch that, too much work for me as i'm in the middle of summit else


DheDarkhCustard(Posted 1+ years ago)

 Nice example. It would be good with colour though. draw it once on an image buffer and draw the image. That way it won't slow down the process.