feat: support title render function

title.go

@@ -0,0 +1,112 @@
+// MIT License
+
+// Copyright (c) 2022 Tree Xie
+
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package charts
+
+import (
+	"strconv"
+	"strings"
+
+	"github.com/wcharczuk/go-chart/v2"
+)
+
+type TitleOption struct {
+	Text  string
+	Style chart.Style
+	Left  string
+	Top   string
+}
+type titleMeasureOption struct {
+	width  int
+	height int
+	text   string
+}
+
+func drawTitle(d *Draw, opt *TitleOption) (int, int, error) {
+	if len(opt.Text) == 0 {
+		return 0, 0, nil
+	}
+
+	padding := opt.Style.Padding
+	titleDraw, err := NewDraw(DrawOption{
+		Parent: d,
+	}, PaddingOption(padding))
+	if err != nil {
+		return 0, 0, err
+	}
+
+	r := titleDraw.Render
+	opt.Style.GetTextOptions().WriteToRenderer(r)
+	arr := strings.Split(opt.Text, "\n")
+	textMaxWidth := 0
+	textMaxHeight := 0
+	width := 0
+	measureOptions := make([]titleMeasureOption, len(arr))
+	for index, str := range arr {
+		textBox := r.MeasureText(str)
+
+		w := textBox.Width()
+		h := textBox.Height()
+		if w > textMaxWidth {
+			textMaxWidth = w
+		}
+		if h > textMaxHeight {
+			textMaxHeight = h
+		}
+		measureOptions[index] = titleMeasureOption{
+			text:   str,
+			width:  w,
+			height: h,
+		}
+	}
+	width = textMaxWidth
+	titleX := 0
+	b := titleDraw.Box
+	switch opt.Left {
+	case PositionRight:
+		titleX = b.Width() - textMaxWidth
+	case PositionCenter:
+		titleX = b.Width()>>1 - (textMaxWidth >> 1)
+	default:
+		if strings.HasSuffix(opt.Left, "%") {
+			value, _ := strconv.Atoi(strings.ReplaceAll(opt.Left, "%", ""))
+			titleX = b.Width() * value / 100
+		} else {
+			value, _ := strconv.Atoi(opt.Left)
+			titleX = value
+		}
+	}
+	titleY := 0
+	// TODO TOP 暂只支持数值
+	if opt.Top != "" {
+		value, _ := strconv.Atoi(opt.Top)
+		titleY += value
+	}
+	for _, item := range measureOptions {
+		x := titleX + (textMaxWidth-item.width)>>1
+		titleDraw.text(item.text, x, titleY)
+		titleY += textMaxHeight
+	}
+	height := titleY + padding.Top + padding.Bottom
+
+	return width, height, nil
+}