go-charts/bar_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"
)

type barChartOption struct {
	// The series list fo bar chart
	SeriesList SeriesList
	// The theme
	Theme string
	// The font
	Font *truetype.Font
}

func barChartRender(opt barChartOption, result *basicRenderResult) ([]markPointRenderOption, error) {
	d, err := NewDraw(DrawOption{
		Parent: result.d,
	}, PaddingOption(chart.Box{
		Top: result.titleBox.Height(),
		// TODO 后续考虑是否需要根据左侧是否展示y轴再生成对应的left
		Left: YAxisWidth,
	}))
	if err != nil {
		return nil, err
	}
	xRange := result.xRange
	x0, x1 := xRange.GetRange(0)
	width := int(x1 - x0)
	// 每一块之间的margin
	margin := 10
	// 每一个bar之间的margin
	barMargin := 5
	if width < 20 {
		margin = 2
		barMargin = 2
	} else if width < 50 {
		margin = 5
		barMargin = 3
	}

	seriesCount := len(opt.SeriesList)
	// 总的宽度-两个margin-(总数-1)的barMargin
	barWidth := (width - 2*margin - barMargin*(seriesCount-1)) / len(opt.SeriesList)

	barMaxHeight := result.getYRange(0).Size
	theme := NewTheme(opt.Theme)

	seriesNames := opt.SeriesList.Names()

	r := d.Render

	markPointRenderOptions := make([]markPointRenderOption, 0)

	for i, s := range opt.SeriesList {
		// 由于series是for range，为同一个数据，因此需要clone
		// 后续需要使用，如mark point
		series := s
		yRange := result.getYRange(series.YAxisIndex)
		points := make([]Point, len(series.Data))
		index := series.index
		if index == 0 {
			index = i
		}
		seriesColor := theme.GetSeriesColor(index)
		// mark line
		markLineRender(markLineRenderOption{
			Draw:        d,
			FillColor:   seriesColor,
			FontColor:   theme.GetTextColor(),
			StrokeColor: seriesColor,
			Font:        opt.Font,
			Series:      &series,
			Range:       yRange,
		})
		divideValues := xRange.AutoDivide()
		for j, item := range series.Data {
			if j >= len(divideValues) {
				continue
			}
			x := divideValues[j]
			x += margin
			if i != 0 {
				x += i * (barWidth + barMargin)
			}

			h := int(yRange.getHeight(item.Value))
			fillColor := seriesColor
			if !item.Style.FillColor.IsZero() {
				fillColor = item.Style.FillColor
			}
			top := barMaxHeight - h
			d.Bar(chart.Box{
				Top:    top,
				Left:   x,
				Right:  x + barWidth,
				Bottom: barMaxHeight - 1,
			}, BarStyle{
				FillColor: fillColor,
			})
			// 用于生成marker point
			points[j] = Point{
				// 居中的位置
				X: x + barWidth>>1,
				Y: top,
			}
			// 如果label不需要展示，则返回
			if !series.Label.Show {
				continue
			}
			distance := series.Label.Distance
			if distance == 0 {
				distance = 5
			}
			text := NewValueLabelFormater(seriesNames, series.Label.Formatter)(i, item.Value, -1)
			labelStyle := chart.Style{
				FontColor: theme.GetTextColor(),
				FontSize:  labelFontSize,
				Font:      opt.Font,
			}
			if !series.Label.Color.IsZero() {
				labelStyle.FontColor = series.Label.Color
			}
			labelStyle.GetTextOptions().WriteToRenderer(r)
			textBox := r.MeasureText(text)
			d.text(text, x+(barWidth-textBox.Width())>>1, barMaxHeight-h-distance)
		}

		// 生成mark point的参数
		markPointRenderOptions = append(markPointRenderOptions, markPointRenderOption{
			Draw:      d,
			FillColor: seriesColor,
			Font:      opt.Font,
			Points:    points,
			Series:    &series,
		})
	}

	return markPointRenderOptions, nil
}