Style and minor performance improvements

This change updates `golangci-lint` to include a range of linters not previously used. The goal of this is to help maintain a consistent style across the project.

Style changes were made as found from the linter, in addition to some manual review.

Performance gains were from preallocating slice sizes and also reducing the usage of `fmt.Sprintf`.

Makefile

@@ -14,4 +14,5 @@ bench:
 	go test -parallel=$(CORES_HALF) --benchmem -benchtime=20s -bench=. -run='^$$' ./...
 
 lint:
-	golangci-lint run
+	golangci-lint run --timeout=600s --enable=asasalint,asciicheck,bidichk,containedctx,contextcheck,exportloopref,decorder,durationcheck,errorlint,exptostd,fatcontext,forbidigo,gocheckcompilerdirectives,gochecksumtype,goconst,gofmt,goimports,gosmopolitan,grouper,iface,importas,mirror,misspell,nilerr,nilnil,perfsprint,prealloc,reassign,recvcheck,sloglint,testifylint,unconvert,wastedassign,whitespace
+

assert_test.go

@@ -6,25 +6,25 @@ import (
 	"strings"
 	"testing"
 
-	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 func assertEqualSVG(t *testing.T, expected string, actual []byte) {
 	t.Helper()
 
 	actualStr := string(actual)
 	if expected != actualStr {
-		actualFile, err := writeTempFile(actual, t.Name()+"-actual", "svg")
-		assert.NoError(t, err)
+		actualFile, err1 := writeTempFile(actual, t.Name()+"-actual", "svg")
 
 		if expected == "" {
-			t.Fatalf("SVG written to %s", actualFile)
+			t.Errorf("SVG written to %s", actualFile)
 		} else {
-			expectedFile, err := writeTempFile([]byte(expected), t.Name()+"-expected", "svg")
-			assert.NoError(t, err)
-			t.Fatalf("SVG content does not match. Expected file: %s, Actual file: %s",
+			expectedFile, err2 := writeTempFile([]byte(expected), t.Name()+"-expected", "svg")
+			t.Errorf("SVG content does not match. Expected file: %s, Actual file: %s",
 				expectedFile, actualFile)
+			require.NoError(t, err2)
 		}
+		require.NoError(t, err1)
 	}
 }
 

axis.go

@@ -97,8 +97,7 @@ func (a *axisPainter) Render() (Box, error) {
 
 	textMaxWidth, textMaxHeight := top.measureTextMaxWidthHeight(opt.Data, opt.TextRotation, fontStyle)
 
-	width := 0
-	height := 0
+	var width, height int
 	if isVertical {
 		width = textMaxWidth + tickLength<<1
 		height = top.Height()

benchmark_test.go

@@ -143,7 +143,9 @@ func renderPainterMultiChartPNGRender(painter *Painter) {
 			Max: FloatPointer(90),
 		},
 	}
-	painter.LineChart(lineOpt)
+	if err := painter.LineChart(lineOpt); err != nil {
+		panic(err)
+	}
 
 	barOpt := NewBarChartOptionWithData([][]float64{
 		{40.1, 62.2, 69.5, 36.4, 45.2, 32.5},
@@ -152,7 +154,9 @@ func renderPainterMultiChartPNGRender(painter *Painter) {
 	barOpt.Legend = lineOpt.Legend
 	barOpt.XAxis = lineOpt.XAxis
 	barOpt.YAxis = lineOpt.YAxis
-	painter.BarChart(barOpt)
+	if err := painter.BarChart(barOpt); err != nil {
+		panic(err)
+	}
 
 	pieOpt := PieChartOption{
 		SeriesList: NewSeriesListPie([]float64{
@@ -169,7 +173,9 @@ func renderPainterMultiChartPNGRender(painter *Painter) {
 		Theme: GetDefaultTheme(),
 		Font:  GetDefaultFont(),
 	}
-	painter.PieChart(pieOpt)
+	if err := painter.PieChart(pieOpt); err != nil {
+		panic(err)
+	}
 
 	if buf, err := painter.Bytes(); err != nil {
 		panic(err)

chart_option.go

@@ -1,7 +1,7 @@
 package charts
 
 import (
-	"fmt"
+	"errors"
 
 	"github.com/golang/freetype/truetype"
 )
@@ -228,7 +228,7 @@ func (o *ChartOption) fillDefault() error {
 
 	yaxisCount := o.SeriesList.getYAxisCount()
 	if yaxisCount < 0 {
-		return fmt.Errorf("series specified invalid y-axis index")
+		return errors.New("series specified invalid y-axis index")
 	}
 	if len(o.YAxis) < yaxisCount {
 		yAxisOptions := make([]YAxisOption, yaxisCount)

chartdraw/annotation_series.go

@@ -1,7 +1,7 @@
 package chartdraw
 
 import (
-	"fmt"
+	"errors"
 	"math"
 )
 
@@ -87,7 +87,7 @@ func (as AnnotationSeries) Render(r Renderer, canvasBox Box, xrange, yrange Rang
 // Validate validates the series.
 func (as AnnotationSeries) Validate() error {
 	if len(as.Annotations) == 0 {
-		return fmt.Errorf("annotation series requires annotations to be set and not empty")
+		return errors.New("annotation series requires annotations to be set and not empty")
 	}
 	return nil
 }

chartdraw/bar_chart.go

@@ -2,7 +2,6 @@ package chartdraw
 
 import (
 	"errors"
-	"fmt"
 	"io"
 	"math"
 
@@ -33,8 +32,7 @@ type BarChart struct {
 	UseBaseValue bool
 	BaseValue    float64
 
-	Font        *truetype.Font
-	defaultFont *truetype.Font
+	Font *truetype.Font
 
 	Bars     []Value
 	Elements []Renderable
@@ -50,9 +48,6 @@ func (bc BarChart) GetDPI() float64 {
 
 // GetFont returns the text font.
 func (bc BarChart) GetFont() *truetype.Font {
-	if bc.Font == nil {
-		return bc.defaultFont
-	}
 	return bc.Font
 }
 
@@ -97,7 +92,7 @@ func (bc BarChart) Render(rp RendererProvider, w io.Writer) error {
 	r := rp(bc.GetWidth(), bc.GetHeight())
 
 	if bc.Font == nil {
-		bc.defaultFont = GetDefaultFont()
+		bc.Font = GetDefaultFont()
 	}
 	r.SetDPI(bc.GetDPI())
 
@@ -111,7 +106,7 @@ func (bc BarChart) Render(rp RendererProvider, w io.Writer) error {
 	canvasBox = bc.getDefaultCanvasBox()
 	yr = bc.getRanges()
 	if yr.GetMax()-yr.GetMin() == 0 {
-		return fmt.Errorf("invalid data range; cannot be zero")
+		return errors.New("invalid data range; cannot be zero")
 	}
 	yr = bc.setRangeDomains(canvasBox, yr)
 	yf = bc.getValueFormatters()
@@ -367,7 +362,7 @@ func (bc BarChart) getAdjustedCanvasBox(r Renderer, canvasBox Box, yrange Range,
 
 		cursor := canvasBox.Left
 		for _, bar := range bc.Bars {
-			if len(bar.Label) > 0 {
+			if bar.Label != "" {
 				barLabelBox := Box{
 					Top:    canvasBox.Bottom + DefaultXAxisMargin,
 					Left:   cursor,

chartdraw/bar_chart_test.go

@@ -50,9 +50,9 @@ func TestBarChartProps(t *testing.T) {
 
 	bc := BarChart{}
 
-	assert.Equal(t, DefaultDPI, bc.GetDPI())
+	assert.InDelta(t, DefaultDPI, bc.GetDPI(), 0)
 	bc.DPI = 100
-	assert.Equal(t, float64(100), bc.GetDPI())
+	assert.InDelta(t, float64(100), bc.GetDPI(), 0)
 
 	assert.Nil(t, bc.GetFont())
 	bc.Font = GetDefaultFont()
@@ -91,8 +91,8 @@ func TestBarChartGetRanges(t *testing.T) {
 	assert.NotNil(t, yr)
 	assert.False(t, yr.IsZero())
 
-	assert.Equal(t, -math.MaxFloat64, yr.GetMax())
-	assert.Equal(t, math.MaxFloat64, yr.GetMin())
+	assert.InDelta(t, -math.MaxFloat64, yr.GetMax(), 0)
+	assert.InDelta(t, math.MaxFloat64, yr.GetMin(), 0)
 }
 
 func TestBarChartGetRangesBarsMinMax(t *testing.T) {
@@ -109,8 +109,8 @@ func TestBarChartGetRangesBarsMinMax(t *testing.T) {
 	assert.NotNil(t, yr)
 	assert.False(t, yr.IsZero())
 
-	assert.Equal(t, float64(10), yr.GetMax())
-	assert.Equal(t, float64(1), yr.GetMin())
+	assert.InDelta(t, float64(10), yr.GetMax(), 0)
+	assert.InDelta(t, float64(1), yr.GetMin(), 0)
 }
 
 func TestBarChartGetRangesMinMax(t *testing.T) {
@@ -137,8 +137,8 @@ func TestBarChartGetRangesMinMax(t *testing.T) {
 	assert.NotNil(t, yr)
 	assert.False(t, yr.IsZero())
 
-	assert.Equal(t, float64(15), yr.GetMax())
-	assert.Equal(t, float64(5), yr.GetMin())
+	assert.InDelta(t, float64(15), yr.GetMax(), 0)
+	assert.InDelta(t, float64(5), yr.GetMin(), 0)
 }
 
 func TestBarChartGetRangesTicksMinMax(t *testing.T) {
@@ -161,8 +161,8 @@ func TestBarChartGetRangesTicksMinMax(t *testing.T) {
 	assert.NotNil(t, yr)
 	assert.False(t, yr.IsZero())
 
-	assert.Equal(t, float64(11), yr.GetMax())
-	assert.Equal(t, float64(7), yr.GetMin())
+	assert.InDelta(t, float64(11), yr.GetMax(), 0)
+	assert.InDelta(t, float64(7), yr.GetMin(), 0)
 }
 
 func TestBarChartHasAxes(t *testing.T) {
@@ -294,13 +294,13 @@ func TestBarChatGetTitleFontSize(t *testing.T) {
 	t.Parallel()
 
 	size := BarChart{Width: 2049, Height: 2049}.getTitleFontSize()
-	assert.Equal(t, float64(48), size)
+	assert.InDelta(t, float64(48), size, 0)
 	size = BarChart{Width: 1025, Height: 1025}.getTitleFontSize()
-	assert.Equal(t, float64(24), size)
+	assert.InDelta(t, float64(24), size, 0)
 	size = BarChart{Width: 513, Height: 513}.getTitleFontSize()
-	assert.Equal(t, float64(18), size)
+	assert.InDelta(t, float64(18), size, 0)
 	size = BarChart{Width: 257, Height: 257}.getTitleFontSize()
-	assert.Equal(t, float64(12), size)
+	assert.InDelta(t, float64(12), size, 0)
 	size = BarChart{Width: 128, Height: 128}.getTitleFontSize()
-	assert.Equal(t, float64(10), size)
+	assert.InDelta(t, float64(10), size, 0)
 }

chartdraw/benchmark_test.go

@@ -38,14 +38,18 @@ func makeBenchmarkLineChart() Chart {
 func BenchmarkLineChartPNGRender(b *testing.B) {
 	for i := 0; i < b.N; i++ {
 		buffer := bytes.Buffer{}
-		makeBenchmarkLineChart().Render(PNG, &buffer)
+		if err := makeBenchmarkLineChart().Render(PNG, &buffer); err != nil {
+			panic(err)
+		}
 	}
 }
 
 func BenchmarkLineChartSVGRender(b *testing.B) {
 	for i := 0; i < b.N; i++ {
 		buffer := bytes.Buffer{}
-		makeBenchmarkLineChart().Render(SVG, &buffer)
+		if err := makeBenchmarkLineChart().Render(SVG, &buffer); err != nil {
+			panic(err)
+		}
 	}
 }
 
@@ -75,14 +79,18 @@ func makeBenchmarkBarChart() BarChart {
 func BenchmarkBarChartPNGRender(b *testing.B) {
 	for i := 0; i < b.N; i++ {
 		buffer := bytes.Buffer{}
-		makeBenchmarkBarChart().Render(PNG, &buffer)
+		if err := makeBenchmarkBarChart().Render(PNG, &buffer); err != nil {
+			panic(err)
+		}
 	}
 }
 
 func BenchmarkBarChartSVGRender(b *testing.B) {
 	for i := 0; i < b.N; i++ {
 		buffer := bytes.Buffer{}
-		makeBenchmarkBarChart().Render(SVG, &buffer)
+		if err := makeBenchmarkBarChart().Render(SVG, &buffer); err != nil {
+			panic(err)
+		}
 	}
 }
 
@@ -115,13 +123,17 @@ func makeBenchmarkPieChart() PieChart {
 func BenchmarkPieChartPNGRender(b *testing.B) {
 	for i := 0; i < b.N; i++ {
 		buffer := bytes.Buffer{}
-		makeBenchmarkPieChart().Render(PNG, &buffer)
+		if err := makeBenchmarkPieChart().Render(PNG, &buffer); err != nil {
+			panic(err)
+		}
 	}
 }
 
 func BenchmarkPieChartSVGRender(b *testing.B) {
 	for i := 0; i < b.N; i++ {
 		buffer := bytes.Buffer{}
-		makeBenchmarkPieChart().Render(SVG, &buffer)
+		if err := makeBenchmarkPieChart().Render(SVG, &buffer); err != nil {
+			panic(err)
+		}
 	}
 }

chartdraw/bollinger_band_series.go

@@ -1,7 +1,7 @@
 package chartdraw
 
 import (
-	"fmt"
+	"errors"
 )
 
 // Interface Assertions.
@@ -129,7 +129,7 @@ func (bbs *BollingerBandsSeries) Render(r Renderer, canvasBox Box, xrange, yrang
 // Validate validates the series.
 func (bbs *BollingerBandsSeries) Validate() error {
 	if bbs.InnerSeries == nil {
-		return fmt.Errorf("bollinger bands series requires InnerSeries to be set")
+		return errors.New("bollinger bands series requires InnerSeries to be set")
 	}
 	return nil
 }

chartdraw/bollinger_band_series_test.go

@@ -1,7 +1,6 @@
 package chartdraw
 
 import (
-	"fmt"
 	"math"
 	"testing"
 
@@ -29,7 +28,7 @@ func TestBollingerBandSeries(t *testing.T) {
 	}
 
 	for x := bbs.GetPeriod(); x < 100; x++ {
-		assert.True(t, y1values[x] > y2values[x], fmt.Sprintf("%v vs. %v", y1values[x], y2values[x]))
+		assert.Greater(t, y1values[x], y2values[x])
 	}
 }
 
@@ -46,7 +45,7 @@ func TestBollingerBandLastValue(t *testing.T) {
 	}
 
 	x, y1, y2 := bbs.GetBoundedLastValues()
-	assert.Equal(t, 100.0, x)
-	assert.Equal(t, float64(101), math.Floor(y1))
-	assert.Equal(t, float64(83), math.Floor(y2))
+	assert.InDelta(t, 100.0, x, 0)
+	assert.InDelta(t, float64(101), math.Floor(y1), 0)
+	assert.InDelta(t, float64(83), math.Floor(y2), 0)
 }

chartdraw/box.go

@@ -1,6 +1,7 @@
 package chartdraw
 
 import (
+	"errors"
 	"fmt"
 	"math"
 )
@@ -305,16 +306,16 @@ func (b Box) OuterConstrain(bounds, other Box) Box {
 
 func (b Box) Validate() error {
 	if b.Left < 0 {
-		return fmt.Errorf("invalid left; must be >= 0")
+		return errors.New("invalid left; must be >= 0")
 	}
 	if b.Right < 0 {
-		return fmt.Errorf("invalid right; must be > 0")
+		return errors.New("invalid right; must be > 0")
 	}
 	if b.Top < 0 {
-		return fmt.Errorf("invalid top; must be > 0")
+		return errors.New("invalid top; must be > 0")
 	}
 	if b.Bottom < 0 {
-		return fmt.Errorf("invalid bottom; must be > 0")
+		return errors.New("invalid bottom; must be > 0")
 	}
 	return nil
 }