fonts: fix race condition (#963)

render/fonts.go

@@ -4,13 +4,15 @@ package render
 
 import (
 	"encoding/base64"
-	"log"
+	"fmt"
+	"sync"
 
 	"github.com/zachomedia/go-bdf"
 	"golang.org/x/image/font"
 )
 
 var fontCache = map[string]font.Face{}
+var fontMutex = &sync.Mutex{}
 
 func GetFontList() []string {
 	fontNames := []string{}
@@ -20,26 +22,29 @@ func GetFontList() []string {
 	return fontNames
 }
 
-func GetFont(name string) font.Face {
+func GetFont(name string) (font.Face, error) {
+	fontMutex.Lock()
+	defer fontMutex.Unlock()
+
 	if font, ok := fontCache[name]; ok {
-		return font
+		return font, nil
 	}
 
 	dataB64, ok := fontDataRaw[name]
 	if !ok {
-		log.Panicf("Unknown font '%s', the available fonts are: %v", name, GetFontList())
+		return nil, fmt.Errorf("unknown font '%s'", name)
 	}
 
 	data, err := base64.StdEncoding.DecodeString(dataB64)
 	if err != nil {
-		log.Panicf("couldn't decode %s: %s", name, err)
+		return nil, fmt.Errorf("decoding font '%s': %w", name, err)
 	}
 
 	f, err := bdf.Parse(data)
 	if err != nil {
-		log.Panicf("couldn't parse %s: %s", name, err)
+		return nil, fmt.Errorf("parsing font '%s': %w", name, err)
 	}
 
 	fontCache[name] = f.NewFace()
-	return fontCache[name]
+	return fontCache[name], nil
 }

render/stack.go

@@ -16,11 +16,13 @@ import (
 //
 // EXAMPLE BEGIN
 // render.Stack(
-//      children=[
-//           render.Box(width=50, height=25, color="#911"),
-//           render.Text("hello there"),
-//           render.Box(width=4, height=32, color="#119"),
-//      ],
+//
+//	children=[
+//	     render.Box(width=50, height=25, color="#911"),
+//	     render.Text("hello there"),
+//	     render.Box(width=4, height=32, color="#119"),
+//	],
+//
 // )
 // EXAMPLE END
 type Stack struct {

render/text.go

@@ -57,7 +57,10 @@ func (t *Text) Init() error {
 	if t.Font == "" {
 		t.Font = DefaultFontFace
 	}
-	face := GetFont(t.Font)
+	face, err := GetFont(t.Font)
+	if err != nil {
+		return err
+	}
 
 	dc := gg.NewContext(0, 0)
 	dc.SetFontFace(face)

render/text_test.go

@@ -192,3 +192,11 @@ func TestTextFonts(t *testing.T) {
 	assert.Equal(t, 17, w)
 	assert.Equal(t, 8, h)
 }
+
+func TestTextMissingFont(t *testing.T) {
+	text := &Text{
+		Content: "QqÖ!",
+		Font:    "missing",
+	}
+	assert.Error(t, text.Init())
+}

render/wrappedtext.go

@@ -5,6 +5,8 @@ import (
 	"image/color"
 
 	"github.com/tidbyt/gg"
+
+	"golang.org/x/image/font"
 )
 
 // WrappedText draws multi-line text.
@@ -27,9 +29,11 @@ import (
 // DOC(Align): Text Alignment
 // EXAMPLE BEGIN
 // render.WrappedText(
-//       content="this is a multi-line text string",
-//       width=50,
-//       color="#fa0",
+//
+//	content="this is a multi-line text string",
+//	width=50,
+//	color="#fa0",
+//
 // )
 // EXAMPLE END
 type WrappedText struct {
@@ -42,13 +46,26 @@ type WrappedText struct {
 	LineSpacing int
 	Color       color.Color
 	Align       string
+
+	face font.Face
 }
 
-func (tw WrappedText) PaintBounds(bounds image.Rectangle, frameIdx int) image.Rectangle {
+func (tw *WrappedText) Init() error {
 	if tw.Font == "" {
 		tw.Font = DefaultFontFace
 	}
-	face := GetFont(tw.Font)
+
+	face, err := GetFont(tw.Font)
+	if err != nil {
+		return err
+	}
+
+	tw.face = face
+
+	return nil
+}
+
+func (tw *WrappedText) PaintBounds(bounds image.Rectangle, frameIdx int) image.Rectangle {
 	// The bounds provided by user or parent widget
 	width := tw.Width
 	if width == 0 {
@@ -67,7 +84,7 @@ func (tw WrappedText) PaintBounds(bounds image.Rectangle, frameIdx int) image.Re
 	// NOTE: Can't use dc.MeasureMultilineString() here. It only
 	// deals with texts that have actual \n in them.
 	dc := gg.NewContext(width, 0)
-	dc.SetFontFace(face)
+	dc.SetFontFace(tw.face)
 	w := 0.0
 	h := 0.0
 	for _, line := range dc.WordWrap(tw.Content, float64(width)) {
@@ -98,11 +115,7 @@ func (tw WrappedText) PaintBounds(bounds image.Rectangle, frameIdx int) image.Re
 	return image.Rect(0, 0, width, height)
 }
 
-func (tw WrappedText) Paint(dc *gg.Context, bounds image.Rectangle, frameIdx int) {
-	if tw.Font == "" {
-		tw.Font = DefaultFontFace
-	}
-	face := GetFont(tw.Font)
+func (tw *WrappedText) Paint(dc *gg.Context, bounds image.Rectangle, frameIdx int) {
 	// Text alignment
 	align := gg.AlignLeft
 	if tw.Align == "center" {
@@ -113,10 +126,10 @@ func (tw WrappedText) Paint(dc *gg.Context, bounds image.Rectangle, frameIdx int
 
 	width := tw.PaintBounds(bounds, frameIdx).Dx()
 
-	metrics := face.Metrics()
+	metrics := tw.face.Metrics()
 	descent := metrics.Descent.Floor()
 
-	dc.SetFontFace(face)
+	dc.SetFontFace(tw.face)
 	if tw.Color != nil {
 		dc.SetColor(tw.Color)
 	} else {
@@ -135,6 +148,6 @@ func (tw WrappedText) Paint(dc *gg.Context, bounds image.Rectangle, frameIdx int
 	)
 }
 
-func (tw WrappedText) FrameCount() int {
+func (tw *WrappedText) FrameCount() int {
 	return 1
 }

render/wrappedtext_test.go

@@ -8,7 +8,8 @@ import (
 )
 
 func TestWrappedTextWithBounds(t *testing.T) {
-	text := WrappedText{Content: "AB CD."}
+	text := &WrappedText{Content: "AB CD."}
+	assert.NoError(t, text.Init())
 
 	// Sufficient space to fit on single line
 	im := PaintWidget(text, image.Rect(0, 0, 25, 8), 0)
@@ -62,9 +63,10 @@ func TestWrappedTextWithBounds(t *testing.T) {
 	}, im))
 }
 
-func TestWrappedTextWithSize(t *testing.T) {
+func TestWrappedTextWithsize(t *testing.T) {
 	// Weight and Height parameters override the bounds
-	text := WrappedText{Content: "AB CD.", Width: 7, Height: 12}
+	text := &WrappedText{Content: "AB CD.", Width: 7, Height: 12}
+	assert.NoError(t, text.Init())
 	im := PaintWidget(text, image.Rect(0, 0, 40, 40), 0)
 	assert.Equal(t, nil, checkImage([]string{
 		"....." + "..",
@@ -82,7 +84,8 @@ func TestWrappedTextWithSize(t *testing.T) {
 	}, im))
 
 	// Height can be overridden separately
-	text = WrappedText{Content: "AB CD.", Height: 12}
+	text = &WrappedText{Content: "AB CD.", Height: 12}
+	assert.NoError(t, text.Init())
 	im = PaintWidget(text, image.Rect(0, 0, 9, 40), 0)
 	assert.Equal(t, nil, checkImage([]string{
 		"....." + "....",
@@ -100,7 +103,8 @@ func TestWrappedTextWithSize(t *testing.T) {
 	}, im))
 
 	// Ditto for Width
-	text = WrappedText{Content: "AB CD.", Width: 3}
+	text = &WrappedText{Content: "AB CD.", Width: 3}
+	assert.NoError(t, text.Init())
 	im = PaintWidget(text, image.Rect(0, 0, 9, 5), 0)
 	assert.Equal(t, nil, checkImage([]string{
 		"...",
@@ -114,7 +118,8 @@ func TestWrappedTextWithSize(t *testing.T) {
 func TestWrappedTextLineSpacing(t *testing.T) {
 
 	// Single pixel line space
-	text := WrappedText{Content: "AB CD.", LineSpacing: 1}
+	text := &WrappedText{Content: "AB CD.", LineSpacing: 1}
+	assert.NoError(t, text.Init())
 	im := PaintWidget(text, image.Rect(0, 0, 21, 16), 0)
 	assert.Equal(t, nil, checkImage([]string{
 		"....." + ".......",
@@ -136,7 +141,8 @@ func TestWrappedTextLineSpacing(t *testing.T) {
 	}, im))
 
 	// Add another one
-	text = WrappedText{Content: "AB CD.", LineSpacing: 2}
+	text = &WrappedText{Content: "AB CD.", LineSpacing: 2}
+	assert.NoError(t, text.Init())
 	im = PaintWidget(text, image.Rect(0, 0, 21, 16), 0)
 	assert.Equal(t, nil, checkImage([]string{
 		"....." + ".......",
@@ -160,7 +166,8 @@ func TestWrappedTextLineSpacing(t *testing.T) {
 
 func TestWrappedTextAlignment(t *testing.T) {
 	// Default to left align.
-	text := WrappedText{Content: "AB CD."}
+	text := &WrappedText{Content: "AB CD."}
+	assert.NoError(t, text.Init())
 	im := PaintWidget(text, image.Rect(0, 0, 21, 16), 0)
 	assert.Equal(t, nil, checkImage([]string{
 		"......." + ".....",
@@ -182,7 +189,8 @@ func TestWrappedTextAlignment(t *testing.T) {
 	}, im))
 
 	// Right alignment.
-	text = WrappedText{Content: "AB CD.", Align: "right"}
+	text = &WrappedText{Content: "AB CD.", Align: "right"}
+	assert.NoError(t, text.Init())
 	im = PaintWidget(text, image.Rect(0, 0, 21, 16), 0)
 	assert.Equal(t, nil, checkImage([]string{
 		"......." + ".....",
@@ -204,7 +212,8 @@ func TestWrappedTextAlignment(t *testing.T) {
 	}, im))
 
 	// Center alignment.
-	text = WrappedText{Content: "AB CD.", Align: "center"}
+	text = &WrappedText{Content: "AB CD.", Align: "center"}
+	assert.NoError(t, text.Init())
 	im = PaintWidget(text, image.Rect(0, 0, 21, 16), 0)
 	assert.Equal(t, nil, checkImage([]string{
 		"......." + ".....",
@@ -225,3 +234,8 @@ func TestWrappedTextAlignment(t *testing.T) {
 		"......." + ".....",
 	}, im))
 }
+
+func TestWrappedTextMissingFont(t *testing.T) {
+	text := &WrappedText{Content: "AB CD.", Font: "missing"}
+	assert.Error(t, text.Init())
+}