Merge pull request #125 from mum4k/custom-scale

Allow users to provide custom Y axis scale for the LineChart.

CHANGELOG.md

@@ -11,12 +11,21 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - A function that draws text in vertically.
 - The LineChart widget can display X axis labels in vertical orientation.
+- The LineChart widget allows the user to specify a custom scale for the Y
+  axis.
 
 ### Changed
 
 - Termbox is now initialized in 256 color mode by default.
 - Generalized mouse button FSM for use in widgets that need to track mouse
   button clicks.
+- The constructor of the LineChart widget now also returns an error so that it
+  can validate its options. This is a breaking change on the LineChart API.
+
+### Fixed
+
+- The LineChart widget now correctly determines the Y axis scale when multiple
+  series are provided.
 
 ## [0.6.1] - 12-Feb-2019
 

termdashdemo/termdashdemo.go

@@ -77,6 +77,10 @@ func layout(ctx context.Context, t terminalapi.Terminal) (*container.Container,
 		),
 	}
 
+	heartLC, err := newHeartbeat(ctx)
+	if err != nil {
+		return nil, err
+	}
 	gaugeAndHeartbeat := []container.Option{
 		container.SplitHorizontal(
 			container.Top(
@@ -88,7 +92,7 @@ func layout(ctx context.Context, t terminalapi.Terminal) (*container.Container,
 			container.Bottom(
 				container.Border(draw.LineStyleLight),
 				container.BorderTitle("A LineChart"),
-				container.PlaceWidget(newHeartbeat(ctx)),
+				container.PlaceWidget(heartLC),
 			),
 			container.SplitPercent(20),
 		),
@@ -107,6 +111,10 @@ func layout(ctx context.Context, t terminalapi.Terminal) (*container.Container,
 		return nil, err
 	}
 
+	sineLC, err := newSines(ctx)
+	if err != nil {
+		return nil, err
+	}
 	rightSide := []container.Option{
 		container.SplitHorizontal(
 			container.Top(
@@ -127,7 +135,7 @@ func layout(ctx context.Context, t terminalapi.Terminal) (*container.Container,
 						container.Border(draw.LineStyleLight),
 						container.BorderTitle("Multiple series"),
 						container.BorderTitleAlignRight(),
-						container.PlaceWidget(newSines(ctx)),
+						container.PlaceWidget(sineLC),
 					),
 					container.SplitPercent(30),
 				),
@@ -317,18 +325,21 @@ func newDonut(ctx context.Context) (*donut.Donut, error) {
 }
 
 // newHeartbeat returns a line chart that displays a heartbeat-like progression.
-func newHeartbeat(ctx context.Context) *linechart.LineChart {
+func newHeartbeat(ctx context.Context) (*linechart.LineChart, error) {
 	var inputs []float64
 	for i := 0; i < 100; i++ {
 		v := math.Pow(math.Sin(float64(i)), 63) * math.Sin(float64(i)+1.5) * 8
 		inputs = append(inputs, v)
 	}
 
-	lc := linechart.New(
+	lc, err := linechart.New(
 		linechart.AxesCellOpts(cell.FgColor(cell.ColorRed)),
 		linechart.YLabelCellOpts(cell.FgColor(cell.ColorGreen)),
 		linechart.XLabelCellOpts(cell.FgColor(cell.ColorGreen)),
 	)
+	if err != nil {
+		return nil, err
+	}
 	step := 0
 	go periodic(ctx, redrawInterval/3, func() error {
 		step = (step + 1) % len(inputs)
@@ -339,7 +350,7 @@ func newHeartbeat(ctx context.Context) *linechart.LineChart {
 			}),
 		)
 	})
-	return lc
+	return lc, nil
 }
 
 // newBarChart returns a BarcChart that displays random values on multiple bars.
@@ -380,18 +391,21 @@ func newBarChart(ctx context.Context) *barchart.BarChart {
 }
 
 // newSines returns a line chart that displays multiple sine series.
-func newSines(ctx context.Context) *linechart.LineChart {
+func newSines(ctx context.Context) (*linechart.LineChart, error) {
 	var inputs []float64
 	for i := 0; i < 200; i++ {
 		v := math.Sin(float64(i) / 100 * math.Pi)
 		inputs = append(inputs, v)
 	}
 
-	lc := linechart.New(
+	lc, err := linechart.New(
 		linechart.AxesCellOpts(cell.FgColor(cell.ColorRed)),
 		linechart.YLabelCellOpts(cell.FgColor(cell.ColorGreen)),
 		linechart.XLabelCellOpts(cell.FgColor(cell.ColorGreen)),
 	)
+	if err != nil {
+		return nil, err
+	}
 	step1 := 0
 	go periodic(ctx, redrawInterval/3, func() error {
 		step1 = (step1 + 1) % len(inputs)
@@ -404,7 +418,7 @@ func newSines(ctx context.Context) *linechart.LineChart {
 		step2 := (step1 + 100) % len(inputs)
 		return lc.Series("second", rotateFloats(inputs, step2), linechart.SeriesCellOpts(cell.FgColor(cell.ColorWhite)))
 	})
-	return lc
+	return lc, nil
 }
 
 // rotateFloats returns a new slice with inputs rotated by step.

widgets/linechart/linechart.go

@@ -90,13 +90,16 @@ type LineChart struct {
 }
 
 // New returns a new line chart widget.
-func New(opts ...Option) *LineChart {
+func New(opts ...Option) (*LineChart, error) {
 	opt := newOptions(opts...)
+	if err := opt.validate(); err != nil {
+		return nil, err
+	}
 	return &LineChart{
 		series: map[string]*seriesValues{},
 		yAxis:  axes.NewY(0, 0),
 		opts:   opt,
-	}
+	}, nil
 }
 
 // SeriesOption is used to provide options to Series.
@@ -136,6 +139,27 @@ func SeriesXLabels(labels map[int]string) SeriesOption {
 	})
 }
 
+// yMinMax determines the min and max values for the Y axis.
+func (lc *LineChart) yMinMax() (float64, float64) {
+	var (
+		minimums []float64
+		maximums []float64
+	)
+	for _, sv := range lc.series {
+		minimums = append(minimums, sv.min)
+		maximums = append(maximums, sv.max)
+	}
+
+	if lc.opts.yAxisCustomScale != nil {
+		minimums = append(minimums, lc.opts.yAxisCustomScale.min)
+		maximums = append(maximums, lc.opts.yAxisCustomScale.max)
+	}
+
+	min, _ := numbers.MinMax(minimums)
+	_, max := numbers.MinMax(maximums)
+	return min, max
+}
+
 // Series sets the values that should be displayed as the line chart with the
 // provided label.
 // Subsequent calls with the same label replace any previously provided values.
@@ -164,7 +188,7 @@ func (lc *LineChart) Series(label string, values []float64, opts ...SeriesOption
 	}
 
 	lc.series[label] = series
-	lc.yAxis = axes.NewY(series.min, series.max)
+	lc.yAxis = axes.NewY(lc.yMinMax())
 	return nil
 }