Improved automatic color selection for pie charts

The previously used random colors could be very similar to each other, making it hard to distinguish them. This commit changes color selection to be deterministic and to choose visually different colors.
Bioruebe · Sep 18, 2020 · 9115b19 · 9115b19
1 parent c8740ce
commit 9115b19
Showing 1 changed file with 52 additions and 31 deletions.
diff --git a/Pie.au3 b/Pie.au3
@@ -30,7 +30,7 @@ Const $NUM_VALUES = 8
 Local $aChartValues[$NUM_VALUES][2]
 For $i = 0 To $NUM_VALUES - 1
     $aChartValues[$i][0] = Random(5, 25, 1)
-	$aChartValues[$i][1] = "Caption " & $i + 1
+	$aChartValues[$i][1] = "Value: " & $aChartValues[$i][0]
 Next
 
 ; Create the GUI
@@ -39,11 +39,12 @@ $idPic = GUICtrlCreatePic("", 0, 0, $PIE_AREA, $PIE_AREA)
 $idLegend = GUICtrlCreatePic("", 0, $PIE_AREA, $PIE_AREA, 100)
 GUISetState()
 
+_ArraySort($aChartValues, 1)
+
 ; Prepare values for the pie chart and setup GDI+ for both picture controls
 $aHandles = _Pie_PrepareValues($aChartValues, $idPic)
 $aLegendHandles = _Pie_CreateContext($idLegend, 0)
 
-_ArraySort($aChartValues)
 ;~ _ArrayDisplay($aChartValues)
 
 ; Draw the initial pie chart and legend
@@ -64,30 +65,6 @@ _Pie_Shutdown($aLegendHandles)
 #ce
 #EndRegion
 
-; #FUNCTION# ====================================================================================================================
-; Name ..........: _GetDarkerColour
-; Description ...: Get a darker version of a colour by extracting the RGB components
-; Syntax ........: _GetDarkerColour($Colour)
-; Parameters ....: $Colour              - the base color.
-; Return values .: The new color
-; Author ........: WideBoyDixon
-; Modified ......:
-; Remarks .......:
-; Related .......:
-; Link ..........: https://www.autoitscript.com/forum/topic/97241-3d-pie-chart/
-; Example .......: No
-; ===============================================================================================================================
-Func _GetDarkerColour($Colour)
-    Local $Red, $Green, $Blue
-    $Red = (BitAND($Colour, 0xff0000) / 0x10000) - 40
-    $Green = (BitAND($Colour, 0x00ff00) / 0x100) - 40
-    $Blue = (BitAND($Colour, 0x0000ff)) - 40
-    If $Red < 0 Then $Red = 0
-    If $Green < 0 Then $Green = 0
-    If $Blue < 0 Then $Blue = 0
-    Return ($Red * 0x10000) + ($Green * 0x100) + $Blue
-EndFunc
-
 ; #FUNCTION# ====================================================================================================================
 ; Name ..........: _Pie_Draw
 ; Description ...: Draw the pie chart
@@ -241,7 +218,7 @@ EndFunc
 ; Parameters ....: $aValues             - [in/out] the values to draw as a 2-dimensional array:
 ;											[$i][0] - absolute values
 ;											[$i][1] - captions
-;											[$i][2] - [optional] a third dimension might specify the colors to draw the pie pieces
+;											[$i][2] - [optional] a third dimension might specify the colors of the pie pieces
 ;                  $hControl            - [optional] the handle to the control. This is a convenience argument to call
 ;													_Pie_CreateContext and return it's result
 ; Return values .: Either the return of _Pie_CreateContext (if $hControl is specified) or 0
@@ -253,8 +230,7 @@ EndFunc
 ; Example .......: No
 ; ===============================================================================================================================
 Func _Pie_PrepareValues(ByRef $aValues, $hControl = 0)
-	Local $iSize = UBound($aValues), $nTotal = 0, $bSetColors = False
-	If UBound($aValues, 2) < 3 Then $bSetColors = True
+	Local $iSize = UBound($aValues), $nTotal = 0, $bSetColors = UBound($aValues, 2) < 3
 	ReDim $aValues[$iSize][7]
 
 	; Calculate percentage values
@@ -268,9 +244,9 @@ Func _Pie_PrepareValues(ByRef $aValues, $hControl = 0)
 		; Set the fractional values
 		$aValues[$i][3] = $aValues[$i][0] / $nTotal
 
-		; Create the brushes and pens
-		If $bSetColors Then $aValues[$i][2] = (Random(0, 255, 1) * 0x10000) + (Random(0, 255, 1) * 0x100) + Random(0, 255, 1)
+		If $bSetColors Then $aValues[$i][2] = _GetDistinguishableColor($i, 20)
 
+		; Create the brushes and pens
 		$aValues[$i][4] = _GDIPlus_BrushCreateSolid(BitOR(0xff000000, $aValues[$i][2]))
 		$aValues[$i][5] = _GDIPlus_BrushCreateSolid(BitOR(0xff000000, _GetDarkerColour($aValues[$i][2])))
 		$aValues[$i][6] = _GDIPlus_PenCreate(BitOR(0xff000000, _GetDarkerColour(_GetDarkerColour($aValues[$i][2]))))
@@ -484,6 +460,51 @@ Func _MouseOverRotation(ByRef $rot, ByRef $asp, $aHandles, $aValues, $hWnd, $hCo
 	_Pie_Draw($aHandles, $aValues, $asp, $rot, False)
 EndFunc
 
+; #FUNCTION# ====================================================================================================================
+; Name ..........: _GetDarkerColour
+; Description ...: Get a darker version of a colour by extracting the RGB components
+; Syntax ........: _GetDarkerColour($Colour)
+; Parameters ....: $Colour              - the base color.
+; Return values .: The new color
+; Author ........: WideBoyDixon
+; Modified ......:
+; Remarks .......:
+; Related .......:
+; Link ..........: https://www.autoitscript.com/forum/topic/97241-3d-pie-chart/
+; Example .......: No
+; ===============================================================================================================================
+Func _GetDarkerColour($Colour)
+    Local $Red, $Green, $Blue
+    $Red = (BitAND($Colour, 0xff0000) / 0x10000) - 40
+    $Green = (BitAND($Colour, 0x00ff00) / 0x100) - 40
+    $Blue = (BitAND($Colour, 0x0000ff)) - 40
+    If $Red < 0 Then $Red = 0
+    If $Green < 0 Then $Green = 0
+    If $Blue < 0 Then $Blue = 0
+    Return ($Red * 0x10000) + ($Green * 0x100) + $Blue
+EndFunc
+
+; #FUNCTION# ====================================================================================================================
+; Name ..........: _GetDistinguishableColor
+; Description ...: Return a color, which is visually different from the last color. This is a deterministic function: the colors
+;				   are calculated with the golden ratio along the hue circle and not randomly generated.
+; Syntax ........: _GetDistinguishableColor($iIndex)
+; Parameters ....: $iIndex              - the n-th color to get
+;                  $iStartHue           - [optional] The hue [0-240] of the first color; all other colors are affected by this
+; Return values .: A color in standard hex format
+; Author ........: Bioruebe
+; Modified ......:
+; Remarks .......:
+; Related .......:
+; Link ..........:
+; Example .......: No
+; ===============================================================================================================================
+Func _GetDistinguishableColor($iIndex, $iStartHue = 0)
+	If $iIndex < 0 Then Return SetError(1)
+
+	Return _WinAPI_ColorHLSToRGB(Mod($iStartHue + $iIndex * 91.67, 240), 120, 180)
+EndFunc
+
 ; #FUNCTION# ====================================================================================================================
 ; Name ..........: _Lerp
 ; Description ...: Linear interpolation between $a and $b by $t