feat: support axis render

axis.go

@@ -0,0 +1,192 @@
+// 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 (
+	"github.com/golang/freetype/truetype"
+)
+
+type axisPainter struct {
+	p   *Painter
+	opt *AxisPainterOption
+}
+
+func NewAxisPainter(p *Painter, opt AxisPainterOption) *axisPainter {
+	return &axisPainter{
+		p:   p,
+		opt: &opt,
+	}
+}
+
+type AxisPainterOption struct {
+	// The label of axis
+	Data []string
+	// The boundary gap on both sides of a coordinate axis.
+	// Nil or *true means the center part of two axis ticks
+	BoundaryGap *bool
+	// The position of axis, it can be 'left', 'top', 'right' or 'bottom'
+	Position string
+	// Number of segments that the axis is split into. Note that this number serves only as a recommendation.
+	SplitNumber int
+	// The line color of axis
+	StrokeColor Color
+	// The line width
+	StrokeWidth float64
+	// The length of the axis tick
+	TickLength int
+	// The margin value of label
+	LabelMargin int
+	// The font size of label
+	FontSize float64
+	// The font of label
+	Font *truetype.Font
+	// The color of label
+	FontColor Color
+	// The flag for show axis split line, set this to true will show axis split line
+	SplitLineShow bool
+	// The color of split line
+	SplitLineColor Color
+}
+
+func (a *axisPainter) Render() (Box, error) {
+	opt := a.opt
+	p := a.p
+
+	strokeWidth := opt.StrokeWidth
+	if strokeWidth == 0 {
+		strokeWidth = 1
+	}
+
+	tickCount := opt.SplitNumber
+	if tickCount == 0 {
+		tickCount = len(opt.Data)
+	}
+
+	boundaryGap := true
+	if opt.BoundaryGap != nil && !*opt.BoundaryGap {
+		boundaryGap = false
+	}
+
+	labelPosition := ""
+	if !boundaryGap {
+		tickCount--
+		labelPosition = PositionLeft
+	}
+
+	// TODO 计算unit
+	unit := 1
+	// 如果小于0，则表示不处理
+	tickLength := getDefaultInt(opt.TickLength, 5)
+	labelMargin := getDefaultInt(opt.LabelMargin, 5)
+
+	textMaxWidth, textMaxHeight := p.MeasureTextMaxWidthHeight(opt.Data)
+
+	width := 0
+	height := 0
+	// 垂直
+	if opt.Position == PositionLeft ||
+		opt.Position == PositionRight {
+		width = textMaxWidth + tickLength<<1
+		height = p.Height()
+	} else {
+		width = p.Width()
+		height = tickLength<<1 + textMaxHeight
+	}
+	padding := Box{}
+	switch opt.Position {
+	case PositionTop:
+		padding.Top = p.Height() - height
+	case PositionLeft:
+		padding.Right = p.Width() - width
+	}
+	p = p.Child(PainterPaddingOption(padding))
+	p.SetDrawingStyle(Style{
+		StrokeColor: opt.StrokeColor,
+		StrokeWidth: strokeWidth,
+	}).OverrideTextStyle(Style{
+		Font:      opt.Font,
+		FontColor: opt.FontColor,
+		FontSize:  opt.FontSize,
+	})
+
+	x0 := 0
+	y0 := 0
+	x1 := 0
+	y1 := 0
+	ticksPadding := 0
+	labelPadding := 0
+	orient := ""
+	textAlign := ""
+
+	switch opt.Position {
+	case PositionTop:
+		labelPadding = labelMargin
+		x1 = p.Width()
+		y0 = labelMargin + int(opt.FontSize)
+		ticksPadding = int(opt.FontSize)
+		y1 = y0
+		orient = OrientHorizontal
+	case PositionLeft:
+		orient = OrientVertical
+		textAlign = AlignRight
+	default:
+		labelPadding = height
+		x1 = p.Width()
+		orient = OrientHorizontal
+	}
+
+	p.Child(PainterPaddingOption(Box{
+		Top: ticksPadding,
+	})).Ticks(TicksOption{
+		Count:  tickCount,
+		Length: tickLength,
+		Unit:   unit,
+		Orient: orient,
+	})
+
+	p.LineStroke([]Point{
+		{
+			X: x0,
+			Y: y0,
+		},
+		{
+			X: x1,
+			Y: y1,
+		},
+	})
+
+	p.Child(PainterPaddingOption(Box{
+		Top: labelPadding,
+	})).MultiText(MultiTextOption{
+		Align:    textAlign,
+		TextList: opt.Data,
+		Orient:   orient,
+		Unit:     unit,
+		Position: labelPosition,
+	})
+
+	return Box{
+		Bottom: height,
+		Right:  width,
+	}, nil
+}