Split into category packages; module github.com/ZacharyZhang-NY/MujicaUI

chart/chart_grid.go

@@ -0,0 +1,69 @@
+package chart
+
+import (
+	"math"
+
+	"github.com/egoist/mygo/ui"
+
+	"github.com/ZacharyZhang-NY/MujicaUI/core"
+	"github.com/ZacharyZhang-NY/MujicaUI/internal"
+)
+
+// ChartGridOptions configure a ChartGrid.
+type ChartGridOptions struct {
+	// X and Y provide grid ticks; either may be nil.
+	X, Y *ChartAxisPart
+	// Minor subdivides major intervals with fainter lines.
+	Minor int
+}
+
+// ChartGridPart is a grid ready to draw in a plot.
+type ChartGridPart struct {
+	opts         ChartGridOptions
+	major, minor ui.Color
+}
+
+// ChartGrid draws pixel-aligned major and minor lines.
+func ChartGrid(c *ui.Context, opts ChartGridOptions) ChartGridPart {
+	if opts.Minor < 0 || opts.X == nil && opts.Y == nil {
+		panic("mujica: ChartGrid needs an axis and Minor ≥ 0")
+	}
+	for _, a := range []*ChartAxisPart{opts.X, opts.Y} {
+		if a != nil && a.opts.Kind == AxisCategory && opts.Minor > 0 {
+			panic("mujica: ChartGrid has no minor lines on a category axis")
+		}
+	}
+	k := core.Tokens(c)
+	return ChartGridPart{opts: opts, major: k.Border, minor: k.Border.Mix(k.Surface, 0.55)}
+}
+
+// Draw paints minor lines, then major ones, inside plot.
+func (g ChartGridPart) Draw(p *ui.Painter, plot ui.Rect) {
+	for _, a := range []*ChartAxisPart{g.opts.X, g.opts.Y} {
+		if a == nil {
+			continue
+		}
+		line := func(v float64, col ui.Color) {
+			at := a.Map(plot, v)
+			if a.horizontal() {
+				internal.RuleV(p, at, plot.Y, plot.Y+plot.H, col)
+			} else {
+				internal.Rule(p, plot.X, plot.X+plot.W, at, col)
+			}
+		}
+		ticks := a.drawTicks(plot, 4)
+		for i := 1; i < len(ticks) && g.opts.Minor > 0; i++ {
+			for j := 1; j < g.opts.Minor; j++ {
+				f := float64(j) / float64(g.opts.Minor)
+				v := ticks[i-1] + (ticks[i]-ticks[i-1])*f
+				if a.opts.Kind == AxisLog {
+					v = math.Pow(10, math.Log10(ticks[i-1])+(math.Log10(ticks[i])-math.Log10(ticks[i-1]))*f)
+				}
+				line(v, g.minor)
+			}
+		}
+		for _, t := range ticks {
+			line(t, g.major)
+		}
+	}
+}