line_chart.go

// 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"
	"github.com/wcharczuk/go-chart/v2/drawing"
)

type lineChart struct {
	p   *Painter
	opt *LineChartOption
}

// NewLineChart returns a line chart render
func NewLineChart(p *Painter, opt LineChartOption) *lineChart {
	if opt.Theme == nil {
		opt.Theme = defaultTheme
	}
	return &lineChart{
		p:   p,
		opt: &opt,
	}
}

type LineChartOption struct {
	// The theme
	Theme ColorPalette
	// The font size
	Font *truetype.Font
	// The data series list
	SeriesList SeriesList
	// The x axis option
	XAxis XAxisOption
	// The padding of line chart
	Padding Box
	// The y axis option
	YAxisOptions []YAxisOption
	// The option of title
	Title TitleOption
	// The legend option
	Legend LegendOption
	// background is filled
	backgroundIsFilled bool
}

func (l *lineChart) render(result *defaultRenderResult, seriesList SeriesList) (Box, error) {
	p := l.p
	opt := l.opt
	boundaryGap := true
	if isFalse(opt.XAxis.BoundaryGap) {
		boundaryGap = false
	}

	seriesPainter := result.seriesPainter

	xDivideCount := len(opt.XAxis.Data)
	if !boundaryGap {
		xDivideCount--
	}
	xDivideValues := autoDivide(seriesPainter.Width(), xDivideCount)
	xValues := make([]int, len(xDivideValues)-1)
	if boundaryGap {
		for i := 0; i < len(xDivideValues)-1; i++ {
			xValues[i] = (xDivideValues[i] + xDivideValues[i+1]) >> 1
		}
	} else {
		xValues = xDivideValues
	}
	markPointPainter := NewMarkPointPainter(seriesPainter)
	markLinePainter := NewMarkLinePainter(seriesPainter)
	rendererList := []Renderer{
		markPointPainter,
		markLinePainter,
	}
	for index := range seriesList {
		series := seriesList[index]
		seriesColor := opt.Theme.GetSeriesColor(series.index)
		drawingStyle := Style{
			StrokeColor: seriesColor,
			StrokeWidth: defaultStrokeWidth,
		}

		seriesPainter.SetDrawingStyle(drawingStyle)
		yRange := result.axisRanges[series.AxisIndex]
		points := make([]Point, 0)
		for i, item := range series.Data {
			h := yRange.getRestHeight(item.Value)
			p := Point{
				X: xValues[i],
				Y: h,
			}
			points = append(points, p)
		}
		// 画线
		seriesPainter.LineStroke(points)

		// 画点
		if opt.Theme.IsDark() {
			drawingStyle.FillColor = drawingStyle.StrokeColor
		} else {
			drawingStyle.FillColor = drawing.ColorWhite
		}
		drawingStyle.StrokeWidth = 1
		seriesPainter.SetDrawingStyle(drawingStyle)
		seriesPainter.Dots(points)
		markPointPainter.Add(markPointRenderOption{
			FillColor: seriesColor,
			Font:      opt.Font,
			Points:    points,
			Series:    series,
		})
		markLinePainter.Add(markLineRenderOption{
			FillColor:   seriesColor,
			FontColor:   opt.Theme.GetTextColor(),
			StrokeColor: seriesColor,
			Font:        opt.Font,
			Series:      series,
			Range:       yRange,
		})
	}
	// 最大、最小的mark point
	err := doRender(rendererList...)
	if err != nil {
		return BoxZero, err
	}

	return p.box, nil
}

func (l *lineChart) Render() (Box, error) {
	p := l.p
	opt := l.opt

	renderResult, err := defaultRender(p, defaultRenderOption{
		Theme:              opt.Theme,
		Padding:            opt.Padding,
		SeriesList:         opt.SeriesList,
		XAxis:              opt.XAxis,
		YAxisOptions:       opt.YAxisOptions,
		TitleOption:        opt.Title,
		LegendOption:       opt.Legend,
		backgroundIsFilled: opt.backgroundIsFilled,
	})
	if err != nil {
		return BoxZero, err
	}
	seriesList := opt.SeriesList.Filter(ChartTypeLine)

	return l.render(renderResult, seriesList)
}