replace default gofont with source sans pro (decred#208)

main.go

@@ -8,6 +8,10 @@ import (
 	"strings"
 	"sync"
 
+	"gioui.org/font/gofont"
+	"gioui.org/font/opentype"
+	"gioui.org/text"
+
 	_ "net/http/pprof"
 
 	"gioui.org/app"
@@ -79,7 +83,26 @@ func main() {
 		wg.Done()
 	}()
 
-	win, err := ui.CreateWindow(wal, decredIcons)
+	var collection []text.FontFace
+	source, err := pkger.Open("/ui/assets/fonts/source_sans_pro_regular.otf")
+	if err != nil {
+		fmt.Println("Failed to load font")
+		collection = gofont.Collection()
+	} else {
+		stat, err := source.Stat()
+		if err != nil {
+			fmt.Println(err)
+		}
+		bytes := make([]byte, stat.Size())
+		source.Read(bytes)
+		fnt, err := opentype.Parse(bytes)
+		if err != nil {
+			fmt.Println(err)
+		}
+		collection = append(collection, text.FontFace{Font: text.Font{}, Face: fnt})
+	}
+
+	win, err := ui.CreateWindow(wal, decredIcons, collection)
 	if err != nil {
 		fmt.Printf("Could not initialize window: %s\ns", err)
 		return

ui/window.go

@@ -5,9 +5,10 @@ import (
 	"image"
 	"time"
 
+	"gioui.org/text"
+
 	"github.com/raedahgroup/godcr/ui/values"
 
-	"gioui.org/font/gofont"
 	"gioui.org/op"
 
 	"gioui.org/app"
@@ -56,10 +57,10 @@ type Window struct {
 // Should never be called more than once as it calls
 // app.NewWindow() which does not support being called more
 // than once.
-func CreateWindow(wal *wallet.Wallet, decredIcons map[string]image.Image) (*Window, error) {
+func CreateWindow(wal *wallet.Wallet, decredIcons map[string]image.Image, collection []text.FontFace) (*Window, error) {
 	win := new(Window)
 	win.window = app.NewWindow(app.Title("godcr"))
-	theme := decredmaterial.NewTheme(gofont.Collection())
+	theme := decredmaterial.NewTheme(collection)
 	if theme == nil {
 		return nil, errors.New("Unexpected error while loading theme")
 	}