Add chart components 216-245; step-aware ticks, font-aware labels

Bars, lines, areas, pies, donuts, radar, histogram, scatter, bubbles,
heatmaps, gauge, bullet, funnel, waterfall, treemap, candles, box
plots, steps, rings, legend, axis, crosshair, polar area, pyramid,
spectrum bars and win-loss strips, each drawn dot by dot. Ticks follow
1-2-5 steps and print as precisely as their step needs; a label row
uses micro letters or the pixel font as a whole. Descriptions carry the
data in numbers. Bad data panics.

chart/bars_test.go

@@ -0,0 +1,100 @@
+package chart_test
+
+import (
+	"testing"
+
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/chart"
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+)
+
+var days = []string{"MON", "TUE", "WED", "THU"}
+
+func TestBarChartHeightsAndHover(t *testing.T) {
+	tt := view(400, 200, newClock(), func(c *ui.Context) {
+		chart.BarChart(c, "Gold", days, []float64{10, 40, 20, 0}, chart.BarChartOptions{})
+	})
+	img := tt.Image()
+	// Bars stand mid-category, past the 13-dot label gutter.
+	var heights []int
+	for i := range 4 {
+		x := 13 + (2*i+1)*146/8
+		_, n := column(t, img, x, 80, pixel.Accent)
+		heights = append(heights, n)
+	}
+	// Topped at tick 40, that bar spans the 66-dot plot.
+	if heights[1] != 66 || heights[2] != 33 || heights[0] < 16 || heights[0] > 17 || heights[3] != 1 {
+		t.Fatalf("bar heights %v for 10, 40, 20, 0", heights)
+	}
+	keeps(t, img)
+	tt.Move(2*(13+3*146/8), 2*40)
+	if n := count(t, tt.Image(), 0, 0, 160, 80, pixel.Lit); n == 0 {
+		t.Fatal("hovering a bar showed no readout")
+	}
+	// The value gutter left of the plot reads nothing.
+	tt.Move(2*8, 2*40)
+	if n := count(t, tt.Image(), 0, 0, 160, 80, pixel.Lit); n != 0 {
+		t.Fatal("hovering the gutter showed a readout")
+	}
+	panics(t, "a short label list", func() {
+		view(100, 100, newClock(), func(c *ui.Context) { chart.BarChart(c, "x", days[:1], []float64{1, 2}, chart.BarChartOptions{}) })
+	})
+}
+
+func TestStackedBarStacksSeriesInOrder(t *testing.T) {
+	tt := view(400, 200, newClock(), func(c *ui.Context) {
+		chart.StackedBar(c, "Loot", days[:2], []chart.Series{
+			{Name: "Gold", Values: []float64{10, 5}, Slot: pixel.Warn},
+			{Name: "Gems", Values: []float64{10, 15}, Slot: pixel.Info},
+		}, chart.StackedBarOptions{})
+	})
+	img := tt.Image()
+	x := 9 + 150/4
+	warnTop, warn := column(t, img, x, 80, pixel.Warn)
+	infoTop, info := column(t, img, x, 80, pixel.Info)
+	if warn == 0 || info == 0 || infoTop >= warnTop || warn < info-3 || warn > info+3 {
+		t.Fatalf("first stack: gold %d from %d, gems %d from %d", warn, warnTop, info, infoTop)
+	}
+	keeps(t, img)
+	panics(t, "a negative stack", func() {
+		view(100, 100, newClock(), func(c *ui.Context) {
+			chart.StackedBar(c, "x", days[:1], []chart.Series{{Name: "a", Values: []float64{-1}}}, chart.StackedBarOptions{})
+		})
+	})
+}
+
+func TestHorizontalBarLongestReachesTheEdge(t *testing.T) {
+	tt := view(400, 200, newClock(), func(c *ui.Context) {
+		chart.HorizontalBar(c, "Kills", []string{"Aria", "Brom"}, []float64{50, 100}, chart.HorizontalBarOptions{})
+	})
+	img := tt.Image()
+	a, b := count(t, img, 0, 0, 160, 16, pixel.Accent), count(t, img, 0, 16, 160, 16, pixel.Accent)
+	if a == 0 || b < 2*a-10 || b > 2*a+10 {
+		t.Fatalf("bar dots %d and %d for 50 and 100", a, b)
+	}
+	keeps(t, img)
+}
+
+func TestHistogramBinsValues(t *testing.T) {
+	tt := view(400, 200, newClock(), func(c *ui.Context) {
+		chart.Histogram(c, "Damage", []float64{1, 1, 1, 2, 2, 9}, chart.HistogramOptions{Bins: 2})
+	})
+	img := tt.Image()
+	_, low := column(t, img, 40, 80, pixel.Accent)
+	_, high := column(t, img, 120, 80, pixel.Accent)
+	if low == 0 || high == 0 || low < 4*high-6 {
+		t.Fatalf("bins of 5 and 1 stand %d and %d dots", low, high)
+	}
+}
+
+func TestWaterfallInksStepsByDirection(t *testing.T) {
+	tt := view(400, 200, newClock(), func(c *ui.Context) {
+		chart.Waterfall(c, "Gold", []string{"QUEST", "SHOP"}, []float64{30, -10}, chart.WaterfallOptions{})
+	})
+	img := tt.Image()
+	if count(t, img, 0, 0, 80, 80, pixel.Good) == 0 || count(t, img, 80, 0, 80, 80, pixel.Bad) == 0 {
+		t.Fatal("the up step is not Good, or the down step not Bad")
+	}
+	keeps(t, img)
+}