Allow custom line color in the charts

chart.go

@@ -653,7 +653,7 @@ func parseFormatChartSet(formatSet string) (*formatChart, error) {
 //
 // values: This is the most important property of a series and is the only mandatory option for every chart object. This option links the chart with the worksheet data that it displays.
 //
-// line: This sets the line format of the line chart. The line property is optional and if it isn't supplied it will default style. The options that can be set is width. The range of width is 0.25pt - 999pt. If the value of width is outside the range, the default width of the line is 2pt.
+// line: This sets the line format of the line chart. The line property is optional and if it isn't supplied it will default style. The options that can be set are width and color. The range of width is 0.25pt - 999pt. If the value of width is outside the range, the default width of the line is 2pt. The value for color should be represented in hex format (e.g., #000000 - #FFFFFF)
 //
 // marker: This sets the marker of the line chart and scatter chart. The range of optional field 'size' is 2-72 (default value is 5). The enumeration value of optional field 'symbol' are (default value is 'auto'):
 //

chart_test.go

@@ -138,7 +138,7 @@ func TestAddChart(t *testing.T) {
 	assert.NoError(t, f.AddChart("Sheet2", "P1", `{"type":"radar","series":[{"name":"Sheet1!$A$30","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$30:$D$30"},{"name":"Sheet1!$A$31","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$31:$D$31"},{"name":"Sheet1!$A$32","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$32:$D$32"},{"name":"Sheet1!$A$33","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$33:$D$33"},{"name":"Sheet1!$A$34","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$34:$D$34"},{"name":"Sheet1!$A$35","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$35:$D$35"},{"name":"Sheet1!$A$36","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$36:$D$36"},{"name":"Sheet1!$A$37","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$37:$D$37"}],"format":{"x_scale":1.0,"y_scale":1.0,"x_offset":15,"y_offset":10,"print_obj":true,"lock_aspect_ratio":false,"locked":false},"legend":{"position":"top_right","show_legend_key":false},"title":{"name":"Radar Chart"},"plotarea":{"show_bubble_size":true,"show_cat_name":false,"show_leader_lines":false,"show_percent":true,"show_series_name":true,"show_val":true},"show_blanks_as":"span"}`))
 	assert.NoError(t, f.AddChart("Sheet2", "X1", `{"type":"scatter","series":[{"name":"Sheet1!$A$30","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$30:$D$30"},{"name":"Sheet1!$A$31","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$31:$D$31"},{"name":"Sheet1!$A$32","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$32:$D$32"},{"name":"Sheet1!$A$33","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$33:$D$33"},{"name":"Sheet1!$A$34","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$34:$D$34"},{"name":"Sheet1!$A$35","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$35:$D$35"},{"name":"Sheet1!$A$36","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$36:$D$36"},{"name":"Sheet1!$A$37","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$37:$D$37"}],"format":{"x_scale":1.0,"y_scale":1.0,"x_offset":15,"y_offset":10,"print_obj":true,"lock_aspect_ratio":false,"locked":false},"legend":{"position":"bottom","show_legend_key":false},"title":{"name":"Scatter Chart"},"plotarea":{"show_bubble_size":true,"show_cat_name":false,"show_leader_lines":false,"show_percent":true,"show_series_name":true,"show_val":true},"show_blanks_as":"zero"}`))
 	assert.NoError(t, f.AddChart("Sheet2", "P16", `{"type":"doughnut","series":[{"name":"Sheet1!$A$30","categories":"Sheet1!$A$30:$D$37","values":"Sheet1!$B$30:$B$37"}],"format":{"x_scale":1.0,"y_scale":1.0,"x_offset":15,"y_offset":10,"print_obj":true,"lock_aspect_ratio":false,"locked":false},"legend":{"position":"right","show_legend_key":false},"title":{"name":"Doughnut Chart"},"plotarea":{"show_bubble_size":false,"show_cat_name":false,"show_leader_lines":false,"show_percent":true,"show_series_name":false,"show_val":false},"show_blanks_as":"zero","hole_size":30}`))
-	assert.NoError(t, f.AddChart("Sheet2", "X16", `{"type":"line","series":[{"name":"Sheet1!$A$30","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$30:$D$30","marker":{"symbol":"none","size":10}},{"name":"Sheet1!$A$31","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$31:$D$31"},{"name":"Sheet1!$A$32","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$32:$D$32"},{"name":"Sheet1!$A$33","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$33:$D$33"},{"name":"Sheet1!$A$34","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$34:$D$34"},{"name":"Sheet1!$A$35","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$35:$D$35"},{"name":"Sheet1!$A$36","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$36:$D$36"},{"name":"Sheet1!$A$37","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$37:$D$37","line":{"width":0.25}}],"format":{"x_scale":1.0,"y_scale":1.0,"x_offset":15,"y_offset":10,"print_obj":true,"lock_aspect_ratio":false,"locked":false},"legend":{"position":"top","show_legend_key":false},"title":{"name":"Line Chart"},"plotarea":{"show_bubble_size":true,"show_cat_name":false,"show_leader_lines":false,"show_percent":true,"show_series_name":true,"show_val":true},"show_blanks_as":"zero","x_axis":{"major_grid_lines":true,"minor_grid_lines":true,"tick_label_skip":1},"y_axis":{"major_grid_lines":true,"minor_grid_lines":true,"major_unit":1}}`))
+	assert.NoError(t, f.AddChart("Sheet2", "X16", `{"type":"line","series":[{"name":"Sheet1!$A$30","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$30:$D$30","marker":{"symbol":"none","size":10}, "line":{"color":"#000000"}},{"name":"Sheet1!$A$31","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$31:$D$31"},{"name":"Sheet1!$A$32","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$32:$D$32"},{"name":"Sheet1!$A$33","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$33:$D$33"},{"name":"Sheet1!$A$34","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$34:$D$34"},{"name":"Sheet1!$A$35","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$35:$D$35"},{"name":"Sheet1!$A$36","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$36:$D$36"},{"name":"Sheet1!$A$37","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$37:$D$37","line":{"width":0.25}}],"format":{"x_scale":1.0,"y_scale":1.0,"x_offset":15,"y_offset":10,"print_obj":true,"lock_aspect_ratio":false,"locked":false},"legend":{"position":"top","show_legend_key":false},"title":{"name":"Line Chart"},"plotarea":{"show_bubble_size":true,"show_cat_name":false,"show_leader_lines":false,"show_percent":true,"show_series_name":true,"show_val":true},"show_blanks_as":"zero","x_axis":{"major_grid_lines":true,"minor_grid_lines":true,"tick_label_skip":1},"y_axis":{"major_grid_lines":true,"minor_grid_lines":true,"major_unit":1}}`))
 	assert.NoError(t, f.AddChart("Sheet2", "P32", `{"type":"pie3D","series":[{"name":"Sheet1!$A$30","categories":"Sheet1!$A$30:$D$37","values":"Sheet1!$B$30:$B$37"}],"format":{"x_scale":1.0,"y_scale":1.0,"x_offset":15,"y_offset":10,"print_obj":true,"lock_aspect_ratio":false,"locked":false},"legend":{"position":"bottom","show_legend_key":false},"title":{"name":"3D Pie Chart"},"plotarea":{"show_bubble_size":true,"show_cat_name":false,"show_leader_lines":false,"show_percent":true,"show_series_name":false,"show_val":false},"show_blanks_as":"zero"}`))
 	assert.NoError(t, f.AddChart("Sheet2", "X32", `{"type":"pie","series":[{"name":"Sheet1!$A$30","categories":"Sheet1!$A$30:$D$37","values":"Sheet1!$B$30:$B$37"}],"format":{"x_scale":1.0,"y_scale":1.0,"x_offset":15,"y_offset":10,"print_obj":true,"lock_aspect_ratio":false,"locked":false},"legend":{"position":"bottom","show_legend_key":false},"title":{"name":"Pie Chart"},"plotarea":{"show_bubble_size":true,"show_cat_name":false,"show_leader_lines":false,"show_percent":true,"show_series_name":false,"show_val":false},"show_blanks_as":"gap"}`))
 	assert.NoError(t, f.AddChart("Sheet2", "P48", `{"type":"bar","series":[{"name":"Sheet1!$A$30","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$30:$D$30"},{"name":"Sheet1!$A$31","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$31:$D$31"},{"name":"Sheet1!$A$32","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$32:$D$32"},{"name":"Sheet1!$A$33","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$33:$D$33"},{"name":"Sheet1!$A$34","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$34:$D$34"},{"name":"Sheet1!$A$35","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$35:$D$35"},{"name":"Sheet1!$A$36","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$36:$D$36"},{"name":"Sheet1!$A$37","categories":"Sheet1!$B$29:$D$29","values":"Sheet1!$B$37:$D$37"}],"format":{"x_scale":1.0,"y_scale":1.0,"x_offset":15,"y_offset":10,"print_obj":true,"lock_aspect_ratio":false,"locked":false},"legend":{"position":"left","show_legend_key":false},"title":{"name":"2D Clustered Bar Chart"},"plotarea":{"show_bubble_size":true,"show_cat_name":false,"show_leader_lines":false,"show_percent":true,"show_series_name":true,"show_val":true},"show_blanks_as":"zero"}`))

drawing.go

@@ -768,6 +768,16 @@ func (f *File) drawChartSeries(formatSet *formatChart) *[]cSer {
 // drawChartSeriesSpPr provides a function to draw the c:spPr element by given
 // format sets.
 func (f *File) drawChartSeriesSpPr(i int, formatSet *formatChart) *cSpPr {
+	var srgbClr *attrValString
+	var schemeClr *aSchemeClr
+
+	if color := stringPtr(formatSet.Series[i].Line.Color); *color != "" {
+		*color = strings.TrimPrefix(*color, "#")
+		srgbClr = &attrValString{Val: color}
+	} else {
+		schemeClr = &aSchemeClr{Val: "accent" + strconv.Itoa((formatSet.order+i)%6+1)}
+	}
+
 	spPrScatter := &cSpPr{
 		Ln: &aLn{
 			W:      25400,
@@ -779,7 +789,8 @@ func (f *File) drawChartSeriesSpPr(i int, formatSet *formatChart) *cSpPr {
 			W:   f.ptToEMUs(formatSet.Series[i].Line.Width),
 			Cap: "rnd", // rnd, sq, flat
 			SolidFill: &aSolidFill{
-				SchemeClr: &aSchemeClr{Val: "accent" + strconv.Itoa((formatSet.order+i)%6+1)},
+				SchemeClr: schemeClr,
+				SrgbClr:   srgbClr,
 			},
 		},
 	}