refactor: adjust font size of mark point

README.md

@@ -5,7 +5,7 @@
 
 [中文](./README_zh.md)
 
-`go-charts` base on [go-chart](https://github.com/wcharczuk/go-chart)，it is simpler way for generating charts, which supports `svg` and `png` format and themes: `light`, `dark`, `grafana` and `ant`.
+`go-charts` base on [go-chart](https://github.com/wcharczuk/go-chart)，it is simpler way for generating charts, which supports `svg` and `png` format and themes: `light`, `dark`, `grafana` and `ant`. The default format is `png` and the default theme is `light`.
 
 `Apache ECharts` is popular among Front-end developers, so `go-charts` supports the option of `Apache ECharts`. Developers can generate charts almost the same as `Apache ECharts`. 
 

README_zh.md

@@ -3,7 +3,7 @@
 [![license](https://img.shields.io/badge/license-MIT-blue.svg)](https://github.com/vicanso/go-charts/blob/master/LICENSE)
 [![Build Status](https://github.com/vicanso/go-charts/workflows/Test/badge.svg)](https://github.com/vicanso/go-charts/actions)
 
-`go-charts`基于[go-chart](https://github.com/wcharczuk/go-chart)，更简单方便的形式生成数据图表，支持`svg`与`png`两种方式的输出，支持主题`light`, `dark`, `grafana`以及`ant`。
+`go-charts`基于[go-chart](https://github.com/wcharczuk/go-chart)，更简单方便的形式生成数据图表，支持`svg`与`png`两种方式的输出，支持主题`light`, `dark`, `grafana`以及`ant`。默认的输入格式为`png`，默认主题为`light`。
 
 `Apache ECharts`在前端开发中得到众多开发者的认可，因此`go-charts`提供了兼容`Apache ECharts`的配置参数，简单快捷的生成相似的图表(`svg`或`png`)，方便插入至Email或分享使用。下面为常用的图表截图(主题为light与grafana)：
 

charts.go

@@ -28,6 +28,7 @@ import (
 )
 
 const labelFontSize = 10
+const smallLabelFontSize = 8
 const defaultDotWidth = 2.0
 const defaultStrokeWidth = 2.0
 

mark_point.go

@@ -24,6 +24,7 @@ package charts
 
 import (
 	"github.com/golang/freetype/truetype"
+	"github.com/wcharczuk/go-chart/v2/drawing"
 )
 
 func NewMarkPoint(markPointTypes ...string) SeriesMarkPoint {
@@ -63,7 +64,6 @@ func NewMarkPointPainter(p *Painter) *markPointPainter {
 
 func (m *markPointPainter) Render() (Box, error) {
 	painter := m.p
-	theme := m.p.theme
 	for _, opt := range m.options {
 		s := opt.Series
 		if len(s.MarkPoint.Data) == 0 {
@@ -75,15 +75,23 @@ func (m *markPointPainter) Render() (Box, error) {
 		if symbolSize == 0 {
 			symbolSize = 30
 		}
-		painter.OverrideDrawingStyle(Style{
-			FillColor: opt.FillColor,
-		}).OverrideTextStyle(Style{
-			FontColor:   theme.GetTextColor(),
+		textStyle := Style{
+			FontColor: drawing.Color{
+				R: 238,
+				G: 238,
+				B: 238,
+				A: 255,
+			},
 			FontSize:    labelFontSize,
 			StrokeWidth: 1,
 			Font:        opt.Font,
-		})
+		}
+		painter.OverrideDrawingStyle(Style{
+			FillColor: opt.FillColor,
+		}).OverrideTextStyle(textStyle)
 		for _, markPointData := range s.MarkPoint.Data {
+			textStyle.FontSize = labelFontSize
+			painter.OverrideTextStyle(textStyle)
 			p := points[summary.MinIndex]
 			value := summary.MinValue
 			switch markPointData.Type {
@@ -95,6 +103,11 @@ func (m *markPointPainter) Render() (Box, error) {
 			painter.Pin(p.X, p.Y-symbolSize>>1, symbolSize)
 			text := commafWithDigits(value)
 			textBox := painter.MeasureText(text)
+			if textBox.Width() > symbolSize {
+				textStyle.FontSize = smallLabelFontSize
+				painter.OverrideTextStyle(textStyle)
+				textBox = painter.MeasureText(text)
+			}
 			painter.Text(text, p.X-textBox.Width()>>1, p.Y-symbolSize>>1-2)
 		}
 	}

mark_point_test.go

@@ -69,7 +69,7 @@ func TestMarkPoint(t *testing.T) {
 				}
 				return p.Bytes()
 			},
-			result: "<svg xmlns=\"http://www.w3.org/2000/svg\" xmlns:xlink=\"http://www.w3.org/1999/xlink\" width=\"600\" height=\"400\">\\n<path  d=\"M 67 62\nA 15 15 330.00 1 1 73 62\nL 70 48\nZ\" style=\"stroke-width:0;stroke:none;fill:rgba(0,0,0,1.0)\"/><path  d=\"M 55 48\nQ70,85 85,48\nZ\" style=\"stroke-width:0;stroke:none;fill:rgba(0,0,0,1.0)\"/><text x=\"66\" y=\"53\" style=\"stroke-width:0;stroke:none;fill:rgba(70,70,70,1.0);font-size:12.8px;font-family:'Roboto Medium',sans-serif\">3</text></svg>",
+			result: "<svg xmlns=\"http://www.w3.org/2000/svg\" xmlns:xlink=\"http://www.w3.org/1999/xlink\" width=\"600\" height=\"400\">\\n<path  d=\"M 67 62\nA 15 15 330.00 1 1 73 62\nL 70 48\nZ\" style=\"stroke-width:0;stroke:none;fill:rgba(0,0,0,1.0)\"/><path  d=\"M 55 48\nQ70,85 85,48\nZ\" style=\"stroke-width:0;stroke:none;fill:rgba(0,0,0,1.0)\"/><text x=\"66\" y=\"53\" style=\"stroke-width:0;stroke:none;fill:rgba(238,238,238,1.0);font-size:12.8px;font-family:'Roboto Medium',sans-serif\">3</text></svg>",
 		},
 	}