From 42b1c8148883844cf80b70a3096e6ee67be01f61 Mon Sep 17 00:00:00 2001
From: "Huy Bui (Kevin)" <2992996+huybuidev@users.noreply.github.com>
Date: Sat, 11 Jul 2020 01:07:41 +0800
Subject: Resolve #661 Add Logarithmic scale option support on Y axis (#662)

* Resolve #661 Add Logarithmic scale option support on Y axis

Example usage:
Add the following option into the format string when using AddChart:

"y_axis":{"scaling":{"logbase":"10"}}

* Change type of LogBase from attrValString to attrVarFloat

* Add test case for testing Logarithmic Option in Y axis of charts

* Move field `LogBase` in the format string up one level (remove `Scaling`) as suggested the owner

Test cases are updated accordingly.
---
 drawing.go | 7 +++++++
 1 file changed, 7 insertions(+)

(limited to 'drawing.go')

diff --git a/drawing.go b/drawing.go
index ea75e82..3ce1282 100644
--- a/drawing.go
+++ b/drawing.go
@@ -1000,10 +1000,17 @@ func (f *File) drawPlotAreaValAx(formatSet *formatChart) []*cAxs {
 	if formatSet.YAxis.Maximum == 0 {
 		max = nil
 	}
+	var logBase *attrValFloat
+	// Follow OOXML requirements on
+	// [https://github.com/sc34wg4/OOXMLSchemas/blob/2b074ca2c5df38b18ac118646b329b508b5bdecc/Part1/OfficeOpenXML-XMLSchema-Strict/dml-chart.xsd#L1142-L1147]
+	if formatSet.YAxis.LogBase >= 2 && formatSet.YAxis.LogBase <= 1000 {
+		logBase = &attrValFloat{Val: float64Ptr(formatSet.YAxis.LogBase)}
+	}
 	axs := []*cAxs{
 		{
 			AxID: &attrValInt{Val: intPtr(753999904)},
 			Scaling: &cScaling{
+				LogBase:     logBase,
 				Orientation: &attrValString{Val: stringPtr(orientation[formatSet.YAxis.ReverseOrder])},
 				Max:         max,
 				Min:         min,
-- 
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