Search OS paths for fonts that are not found in the data directory.

default_adapter.go

@@ -34,7 +34,7 @@ func CreateDefaultAdapter() *DefaultAdapter {
 
 func (a *DefaultAdapter) SetItemSizeAsLargest(theme Theme) {
 	s := math.Size{}
-	font := theme.DefaultLabelFont()
+	font := theme.DefaultFont()
 	for i := 0; i < a.Count(); i++ {
 		e := a.data.Index(i).Interface()
 		switch t := e.(type) {

driver.go

@@ -15,8 +15,8 @@ type Driver interface {
 	Terminate()
 	SetClipboard(str string)
 	GetClipboard() (string, error)
+	LoadFont(name string, size int) (Font, error)
 	CreateViewport(width, height int, name string) Viewport
 	CreateCanvas(math.Size) Canvas
-	CreateFont(name string, size int) Font
 	CreateTexture(img image.Image, pixelsPerDip float32) Texture
 }

drivers/gl/driver.go

@@ -6,13 +6,15 @@ package gl
 
 import (
 	"container/list"
+	"fmt"
 	"image"
 	"io/ioutil"
 	"path/filepath"
 	"runtime"
 
 	"github.com/go-gl/glfw/v3.1/glfw"
 	"github.com/google/gxui"
+	"github.com/google/gxui/drivers/gl/platform"
 	"github.com/google/gxui/math"
 )
 
@@ -140,6 +142,21 @@ func (d *Driver) GetClipboard() (str string, err error) {
 	return
 }
 
+func (d *Driver) LoadFont(name string, size int) (gxui.Font, error) {
+	// Try the data path first.
+	f, err := ioutil.ReadFile(filepath.Join(d.dataPath, name))
+	if err == nil {
+		return CreateFont(name, f, size)
+	}
+	// No luck. Search the OS font directories next...
+	for _, path := range platform.FontPaths {
+		if f, err := ioutil.ReadFile(filepath.Join(path, name)); err == nil {
+			return CreateFont(name, f, size)
+		}
+	}
+	return nil, fmt.Errorf("Unable to find font '%s'", name)
+}
+
 func (d *Driver) CreateViewport(width, height int, name string) gxui.Viewport {
 	var v *Viewport
 	d.syncDriver(func() {
@@ -159,11 +176,3 @@ func (d *Driver) CreateCanvas(s math.Size) gxui.Canvas {
 func (d *Driver) CreateTexture(img image.Image, pixelsPerDip float32) gxui.Texture {
 	return CreateTexture(img, pixelsPerDip)
 }
-
-func (d *Driver) CreateFont(name string, size int) gxui.Font {
-	f, err := ioutil.ReadFile(filepath.Join(d.dataPath, name))
-	if err != nil {
-		panic(err)
-	}
-	return CreateFont(name, f, size)
-}

drivers/gl/font.go

@@ -31,10 +31,10 @@ type Font struct {
 	quads            []Quad // Reused each call to Draw()
 }
 
-func CreateFont(name string, data []byte, size int) *Font {
+func CreateFont(name string, data []byte, size int) (*Font, error) {
 	ttf, err := truetype.Parse(data)
 	if err != nil {
-		panic(err)
+		return nil, err
 	}
 
 	scale := int32(size << 6)
@@ -55,7 +55,7 @@ func CreateFont(name string, data []byte, size int) *Font {
 		resolutions:      make(map[Resolution]*glyphTable),
 		glyphs:           make(map[rune]*glyph),
 		quads:            []Quad{},
-	}
+	}, nil
 }
 
 func (f *Font) glyph(r rune) *glyph {

drivers/gl/platform/def_constants.go → drivers/gl/platform/linux_constants.go

@@ -2,8 +2,15 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !darwin
+// +build linux
 
 package platform
 
 const ScrollSpeed = 20.0
+
+// Paths to try when a font is not found in the local data directory
+var FontPaths = []string{
+	"/usr/share/fonts",
+	"/usr/local/share/fonts",
+	"~/.fonts",
+}

drivers/gl/platform/osx_constants.go

@@ -7,3 +7,9 @@
 package platform
 
 const ScrollSpeed = 4.0
+
+// Paths to try when a font is not found in the local data directory
+var FontPaths = []string{
+	"/Library/Fonts/",
+	"/System/Library/Fonts/",
+}

drivers/gl/platform/windows_constants.go

@@ -0,0 +1,30 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build windows
+
+package platform
+
+// #cgo LDFLAGS: -lShell32
+// #include <Shlobj.h>
+//
+// void getWindowsFontDirectory(char* path) {
+//   SHGetFolderPath(0, CSIDL_FONTS, 0, 0, path);
+// }
+import "C"
+
+const ScrollSpeed = 20.0
+
+// Paths to try when a font is not found in the local data directory
+var FontPaths = []string{
+	getWindowsFontDirectory(),
+}
+
+const max_path = 260
+
+func getWindowsFontDirectory() string {
+	buf := make([]C.char, max_path)
+	C.getWindowsFontDirectory(&buf[0])
+	return C.GoString(&buf[0])
+}

mixins/label.go

@@ -28,6 +28,9 @@ type Label struct {
 }
 
 func (l *Label) Init(outer LabelOuter, theme gxui.Theme, font gxui.Font, color gxui.Color) {
+	if font == nil {
+		panic("Cannot create a label with a nil font")
+	}
 	l.Control.Init(outer, theme)
 	l.outer = outer
 	l.font = font

theme.go

@@ -6,7 +6,8 @@ package gxui
 
 type Theme interface {
 	Driver() Driver
-	DefaultLabelFont() Font
+	DefaultFont() Font
+	SetDefaultFont(Font)
 	CreateBubbleOverlay() BubbleOverlay
 	CreateButton() Button
 	CreateCodeEditor() CodeEditor

themes/dark/code_editor.go

@@ -18,7 +18,7 @@ type CodeEditor struct {
 func CreateCodeEditor(theme *Theme) gxui.CodeEditor {
 	t := &CodeEditor{}
 	t.theme = theme
-	t.Init(t, theme.driver, theme, theme.DefaultFont)
+	t.Init(t, theme.driver, theme, theme.defaultFont)
 	t.SetTextColor(theme.TextBoxDefaultStyle.FontColor)
 	t.SetMargin(math.Spacing{L: 3, T: 3, R: 3, B: 3})
 	t.SetPadding(math.Spacing{L: 3, T: 3, R: 3, B: 3})

themes/dark/label.go

@@ -12,7 +12,7 @@ import (
 
 func CreateLabel(theme *Theme) gxui.Label {
 	l := &mixins.Label{}
-	l.Init(l, theme, theme.DefaultFont, theme.LabelStyle.FontColor)
+	l.Init(l, theme, theme.defaultFont, theme.LabelStyle.FontColor)
 	l.SetMargin(math.Spacing{L: 3, T: 3, R: 3, B: 3})
 	return l
 }

themes/dark/textbox.go

@@ -17,7 +17,7 @@ type TextBox struct {
 
 func CreateTextBox(theme *Theme) gxui.TextBox {
 	t := &TextBox{}
-	t.Init(t, theme.driver, theme, theme.DefaultFont)
+	t.Init(t, theme.driver, theme, theme.defaultFont)
 	t.SetTextColor(theme.TextBoxDefaultStyle.FontColor)
 	t.SetMargin(math.Spacing{L: 3, T: 3, R: 3, B: 3})
 	t.SetPadding(math.Spacing{L: 3, T: 3, R: 3, B: 3})

themes/dark/theme.go

@@ -5,12 +5,16 @@
 package dark
 
 import (
+	"fmt"
+
 	"github.com/google/gxui"
 )
 
+const defaultFontName = "Arial.ttf"
+
 type Theme struct {
 	driver      gxui.Driver
-	DefaultFont gxui.Font
+	defaultFont gxui.Font
 
 	WindowBackground gxui.Color
 
@@ -40,8 +44,12 @@ type Theme struct {
 }
 
 func CreateTheme(driver gxui.Driver) gxui.Theme {
-	defaultFont := driver.CreateFont("SourceCodePro-Regular.ttf", 12)
-	defaultFont.LoadGlyphs(32, 126)
+	defaultFont, err := driver.LoadFont(defaultFontName, 12)
+	if err == nil {
+		defaultFont.LoadGlyphs(32, 126)
+	} else {
+		fmt.Printf("Warning: Failed to load default font - %v\n", err)
+	}
 
 	scrollBarRailDefaultBg := gxui.Black
 	scrollBarRailDefaultBg.A = 0.7
@@ -54,7 +62,7 @@ func CreateTheme(driver gxui.Driver) gxui.Theme {
 
 	return &Theme{
 		driver:      driver,
-		DefaultFont: defaultFont,
+		defaultFont: defaultFont,
 
 		WindowBackground: gxui.Black,
 
@@ -90,8 +98,12 @@ func (t *Theme) Driver() gxui.Driver {
 	return t.driver
 }
 
-func (t *Theme) DefaultLabelFont() gxui.Font {
-	return t.DefaultFont
+func (t *Theme) DefaultFont() gxui.Font {
+	return t.defaultFont
+}
+
+func (t *Theme) SetDefaultFont(f gxui.Font) {
+	t.defaultFont = f
 }
 
 func (t *Theme) CreateBubbleOverlay() gxui.BubbleOverlay {