Fix #63: add experimental support for setting custom app font

backend/config.go

@@ -27,6 +27,10 @@ type AppConfig struct {
 	LastCheckedVersion string
 	EnableSystemTray   bool
 	CloseToSystemTray  bool
+
+	// Experimental - may be removed in future
+	FontNormalTTF string
+	FontBoldTTF   string
 }
 
 type AlbumPageConfig struct {

main.go

@@ -27,7 +27,10 @@ func main() {
 	}
 
 	fyneApp := app.New()
-	fyneApp.Settings().SetTheme(&theme.MyTheme{})
+	fyneApp.Settings().SetTheme(&theme.MyTheme{
+		NormalFont: myApp.Config.Application.FontNormalTTF,
+		BoldFont:   myApp.Config.Application.FontBoldTTF,
+	})
 	w := float32(myApp.Config.Application.WindowWidth)
 	if w <= 1 {
 		w = 1000

ui/controller/controller.go

@@ -319,7 +319,7 @@ func (c *Controller) ShowSettingsDialog() {
 		devs = []player.AudioDevice{{Name: "auto", Description: "Autoselect device"}}
 	}
 
-	dlg := dialogs.NewSettingsDialog(c.App.Config, devs)
+	dlg := dialogs.NewSettingsDialog(c.App.Config, devs, c.MainWindow)
 	dlg.OnReplayGainSettingsChanged = func() {
 		c.App.PlaybackManager.SetReplayGainOptions(c.App.Config.ReplayGain)
 	}

ui/dialogs/settingsdialog.go

@@ -1,8 +1,11 @@
 package dialogs
 
 import (
+	"errors"
 	"math"
+	"os"
 	"strconv"
+	"strings"
 	"supersonic/backend"
 	"supersonic/player"
 	"supersonic/ui/layouts"
@@ -13,7 +16,9 @@ import (
 	"fyne.io/fyne/v2"
 	"fyne.io/fyne/v2/container"
 	"fyne.io/fyne/v2/data/binding"
+	"fyne.io/fyne/v2/dialog"
 	"fyne.io/fyne/v2/layout"
+	"fyne.io/fyne/v2/storage"
 	"fyne.io/fyne/v2/theme"
 	"fyne.io/fyne/v2/widget"
 )
@@ -36,13 +41,14 @@ type SettingsDialog struct {
 }
 
 // TODO: having this depend on the player package for the AudioDevice type is kinda gross. Refactor.
-func NewSettingsDialog(config *backend.Config, audioDeviceList []player.AudioDevice) *SettingsDialog {
+func NewSettingsDialog(config *backend.Config, audioDeviceList []player.AudioDevice, window fyne.Window) *SettingsDialog {
 	s := &SettingsDialog{config: config, audioDevices: audioDeviceList}
 	s.ExtendBaseWidget(s)
 
 	tabs := container.NewAppTabs(
 		s.createGeneralTab(),
 		s.createPlaybackTab(),
+		s.createExperimentalTab(window),
 	)
 	s.promptText = widget.NewRichTextWithText("")
 	s.content = container.NewVBox(tabs, widget.NewSeparator(),
@@ -258,6 +264,73 @@ func (s *SettingsDialog) createPlaybackTab() *container.TabItem {
 	))
 }
 
+func (s *SettingsDialog) createExperimentalTab(window fyne.Window) *container.TabItem {
+	warningLabel := widget.NewLabel("WARNING: these settings are experimental and may " +
+		"make the application buggy or increase system resource use. " +
+		"They may be removed in future versions.")
+	warningLabel.Wrapping = fyne.TextWrapWord
+
+	normalFontEntry := widget.NewEntry()
+	normalFontEntry.SetPlaceHolder("path to .ttf or empty to use default")
+	normalFontEntry.Text = s.config.Application.FontNormalTTF
+	normalFontEntry.Validator = s.ttfPathValidator
+	normalFontEntry.OnChanged = func(path string) {
+		if normalFontEntry.Validate() == nil {
+			s.setRestartRequired()
+			s.config.Application.FontNormalTTF = path
+		}
+	}
+	normalFontBrowse := widget.NewButtonWithIcon("", theme.FolderOpenIcon(), func() {
+		s.doChooseTTFFile(window, normalFontEntry)
+	})
+
+	boldFontEntry := widget.NewEntry()
+	boldFontEntry.SetPlaceHolder("path to .ttf or empty to use default")
+	boldFontEntry.Text = s.config.Application.FontBoldTTF
+	boldFontEntry.Validator = s.ttfPathValidator
+	boldFontEntry.OnChanged = func(path string) {
+		if boldFontEntry.Validate() == nil {
+			s.setRestartRequired()
+			s.config.Application.FontBoldTTF = path
+		}
+	}
+	boldFontBrowse := widget.NewButtonWithIcon("", theme.FolderOpenIcon(), func() {
+		s.doChooseTTFFile(window, boldFontEntry)
+	})
+
+	return container.NewTabItem("Experimental", container.NewVBox(
+		warningLabel,
+		s.newSectionSeparator(),
+		widget.NewRichText(&widget.TextSegment{Text: "Application Font", Style: boldStyle}),
+		container.New(layout.NewFormLayout(),
+			widget.NewLabel("Normal font"), container.NewBorder(nil, nil, nil, normalFontBrowse, normalFontEntry),
+			widget.NewLabel("Bold font"), container.NewBorder(nil, nil, nil, boldFontBrowse, boldFontEntry),
+		),
+	))
+}
+
+func (s *SettingsDialog) doChooseTTFFile(window fyne.Window, entry *widget.Entry) {
+	callback := func(urirc fyne.URIReadCloser, err error) {
+		if err == nil && urirc != nil {
+			entry.SetText(urirc.URI().Path())
+		}
+	}
+	dlg := dialog.NewFileOpen(callback, window)
+	dlg.SetFilter(&storage.ExtensionFileFilter{Extensions: []string{".ttf"}})
+	dlg.Show()
+}
+
+func (s *SettingsDialog) ttfPathValidator(path string) error {
+	if path == "" {
+		return nil
+	}
+	if !strings.HasSuffix(path, ".ttf") {
+		return errors.New("only .ttf fonts supported")
+	}
+	_, err := os.Stat(path)
+	return err
+}
+
 func (s *SettingsDialog) setRestartRequired() {
 	ts := s.promptText.Segments[0].(*widget.TextSegment)
 	if ts.Text != "" {

ui/theme/theme.go

@@ -1,7 +1,11 @@
 package theme
 
 import (
+	"errors"
 	"image/color"
+	"io/ioutil"
+	"log"
+	"strings"
 
 	"fyne.io/fyne/v2"
 	"fyne.io/fyne/v2/theme"
@@ -9,11 +13,19 @@ import (
 
 const ColorNamePageBackground fyne.ThemeColorName = "PageBackground"
 
-type MyTheme struct{}
+var (
+	normalFont fyne.Resource
+	boldFont   fyne.Resource
+)
+
+type MyTheme struct {
+	NormalFont string
+	BoldFont   string
+}
 
 var _ fyne.Theme = (*MyTheme)(nil)
 
-func (m MyTheme) Color(name fyne.ThemeColorName, variant fyne.ThemeVariant) color.Color {
+func (m *MyTheme) Color(name fyne.ThemeColorName, variant fyne.ThemeVariant) color.Color {
 	switch name {
 	case ColorNamePageBackground:
 		return color.RGBA{R: 15, G: 15, B: 15, A: 255}
@@ -29,14 +41,56 @@ func (m MyTheme) Color(name fyne.ThemeColorName, variant fyne.ThemeVariant) colo
 	return theme.DarkTheme().Color(name, variant)
 }
 
-func (m MyTheme) Icon(name fyne.ThemeIconName) fyne.Resource {
+func (m *MyTheme) Icon(name fyne.ThemeIconName) fyne.Resource {
 	return theme.DefaultTheme().Icon(name)
 }
 
-func (m MyTheme) Font(style fyne.TextStyle) fyne.Resource {
+func (m *MyTheme) Font(style fyne.TextStyle) fyne.Resource {
+	switch style {
+	case fyne.TextStyle{}:
+		if m.NormalFont != "" && normalFont == nil {
+			if content, err := readTTFFile(m.NormalFont); err != nil {
+				m.NormalFont = ""
+				m.BoldFont = ""
+			} else {
+				normalFont = fyne.NewStaticResource("normalFont", content)
+			}
+		}
+		if normalFont != nil {
+			return normalFont
+		}
+	case fyne.TextStyle{Bold: true}:
+		if m.BoldFont != "" && boldFont == nil {
+			if content, err := ioutil.ReadFile(m.BoldFont); err != nil {
+				m.BoldFont = ""
+			} else {
+				normalFont = fyne.NewStaticResource("boldFont", content)
+			}
+		}
+		if boldFont != nil {
+			return boldFont
+		}
+		if normalFont != nil {
+			return normalFont
+		}
+	}
+
 	return theme.DefaultTheme().Font(style)
 }
 
-func (m MyTheme) Size(name fyne.ThemeSizeName) float32 {
+func (m *MyTheme) Size(name fyne.ThemeSizeName) float32 {
 	return theme.DefaultTheme().Size(name)
 }
+
+func readTTFFile(filepath string) ([]byte, error) {
+	if !strings.HasSuffix(filepath, ".ttf") {
+		err := errors.New("only .ttf fonts are supported")
+		log.Printf("error loading custom font %q: %s", filepath, err.Error())
+		return nil, err
+	}
+	content, err := ioutil.ReadFile(filepath)
+	if err != nil {
+		log.Printf("error loading custom font %q: %s", filepath, err.Error())
+	}
+	return content, err
+}