Merge pull request fyne-io#1199 from andydotxyz/feature/macOStheme

match macOS/Windows system theme

app/app_darwin.go

@@ -11,7 +11,9 @@ package app
 #include <AppKit/AppKit.h>
 
 bool isBundled();
+bool isDarkMode();
 void sendNotification(const char *title, const char *content);
+void watchTheme();
 */
 import "C"
 import (
@@ -31,8 +33,10 @@ func defaultTheme() fyne.Theme {
 	if fyne.CurrentDevice().IsMobile() { // this is called in mobile simulate mode
 		return theme.LightTheme()
 	}
-	// TODO read the macOS setting in Mojave onwards
-	return theme.DarkTheme()
+	if C.isDarkMode() {
+		return theme.DarkTheme()
+	}
+	return theme.LightTheme()
 }
 
 func rootConfigDir() string {
@@ -74,3 +78,12 @@ func escapeNotificationString(in string) string {
 	noSlash := strings.ReplaceAll(in, "\\", "\\\\")
 	return strings.ReplaceAll(noSlash, "\"", "\\\"")
 }
+
+//export themeChanged
+func themeChanged() {
+	fyne.CurrentApp().Settings().(*settings).setupTheme()
+}
+
+func watchTheme() {
+	C.watchTheme()
+}

app/app_darwin.m

@@ -1,6 +1,8 @@
 // +build !ci
 // +build !ios
 
+extern void themeChanged();
+
 #import <Foundation/Foundation.h>
 
 @interface FyneUserNotificationCenterDelegate : NSObject<NSUserNotificationCenterDelegate>
@@ -28,6 +30,11 @@ bool isBundled() {
     return [[NSBundle mainBundle] bundleIdentifier] != nil;
 }
 
+bool isDarkMode() {
+    NSString *style = [[NSUserDefaults standardUserDefaults] stringForKey:@"AppleInterfaceStyle"];
+    return [@"Dark" isEqualToString:style];
+}
+
 void sendNotification(const char *title, const char *body) {
     NSUserNotificationCenter *center = [NSUserNotificationCenter defaultUserNotificationCenter];
     if (center.delegate == nil) {
@@ -39,3 +46,10 @@ void sendNotification(const char *title, const char *body) {
     notification.identifier = [NSString stringWithFormat:@"%@-fyne-notify-%d", [[NSBundle mainBundle] bundleIdentifier], ++notifyNum];
     [center scheduleNotification:notification];
 }
+
+void watchTheme() {
+    [[NSDistributedNotificationCenter defaultCenter] addObserverForName:@"AppleInterfaceThemeChangedNotification" object:nil queue:nil
+        usingBlock:^(NSNotification *note) {
+        themeChanged(); // calls back into Go
+    }];
+}

app/app_other.go

@@ -25,3 +25,7 @@ func (app *fyneApp) OpenURL(_ *url.URL) error {
 func (app *fyneApp) SendNotification(_ *fyne.Notification) {
 	fyne.LogError("Refusing to show notification for unknown operating system", nil)
 }
+
+func watchTheme() {
+	// no-op
+}

app/app_windows.go

@@ -14,6 +14,8 @@ import (
 	"strings"
 	"syscall"
 
+	"golang.org/x/sys/windows/registry"
+
 	"fyne.io/fyne"
 	"fyne.io/fyne/theme"
 )
@@ -32,8 +34,26 @@ $xml.LoadXml($toastXml.OuterXml)
 $toast = [Windows.UI.Notifications.ToastNotification]::new($xml)
 [Windows.UI.Notifications.ToastNotificationManager]::CreateToastNotifier("appID").Show($toast);`
 
+func isDark() bool {
+	k, err := registry.OpenKey(registry.CURRENT_USER, `SOFTWARE\Microsoft\Windows\CurrentVersion\Themes\Personalize`, registry.QUERY_VALUE)
+	if err != nil { // older version of Windows will not have this key
+		return false
+	}
+	defer k.Close()
+
+	useLight, _, err := k.GetIntegerValue("AppsUseLightTheme")
+	if err != nil { // older version of Windows will not have this value
+		return false
+	}
+
+	return useLight == 0
+}
+
 func defaultTheme() fyne.Theme {
-	return theme.DarkTheme()
+	if isDark() {
+		return theme.DarkTheme()
+	}
+	return theme.LightTheme()
 }
 
 func rootConfigDir() string {
@@ -85,3 +105,6 @@ func runScript(name, script string) {
 		fyne.LogError("Failed to launch windows notify script", err)
 	}
 }
+func watchTheme() {
+	// TODO monitor the Windows theme
+}

app/app_xdg.go

@@ -51,3 +51,7 @@ func rootConfigDir() string {
 	desktopConfig := filepath.Join(homeDir, ".config")
 	return filepath.Join(desktopConfig, "fyne")
 }
+
+func watchTheme() {
+	// no-op, not able to read linux theme in a standard way
+}

app/settings_desktop.go

@@ -61,6 +61,8 @@ func watchFile(path string, callback func()) *fsnotify.Watcher {
 
 func (s *settings) watchSettings() {
 	s.watcher = watchFile(s.schema.StoragePath(), s.fileChanged)
+
+	watchTheme()
 }
 
 func (s *settings) stopWatching() {

app/settings_desktop_test.go

@@ -5,6 +5,7 @@ package app
 import (
 	"os"
 	"path/filepath"
+	"runtime"
 	"testing"
 	"time"
 
@@ -15,7 +16,9 @@ import (
 )
 
 func TestDefaultTheme(t *testing.T) {
-	assert.Equal(t, theme.DarkTheme(), defaultTheme())
+	if runtime.GOOS != "darwin" { // system defines default for macOS
+		assert.Equal(t, theme.DarkTheme(), defaultTheme())
+	}
 }
 
 func TestEnsureDir(t *testing.T) {

cmd/fyne_settings/settings/appearance.go

@@ -5,6 +5,7 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
+	"runtime"
 
 	"fyne.io/fyne"
 	"fyne.io/fyne/app"
@@ -14,6 +15,10 @@ import (
 	"fyne.io/fyne/widget"
 )
 
+const (
+	systemThemeName = "system default"
+)
+
 // Settings gives access to user interfaces to control Fyne settings
 type Settings struct {
 	fyneSettings app.SettingsSchema
@@ -40,7 +45,14 @@ func (s *Settings) LoadAppearanceScreen(w fyne.Window) fyne.CanvasObject {
 	s.preview.FillMode = canvas.ImageFillContain
 
 	def := s.fyneSettings.ThemeName
-	themes := widget.NewSelect([]string{"dark", "light"}, s.chooseTheme)
+	themeNames := []string{"dark", "light"}
+	if runtime.GOOS == "darwin" || runtime.GOOS == "windows" {
+		themeNames = append(themeNames, systemThemeName)
+		if s.fyneSettings.ThemeName == "" {
+			def = systemThemeName
+		}
+	}
+	themes := widget.NewSelect(themeNames, s.chooseTheme)
 	themes.SetSelected(def)
 
 	scale := s.makeScaleGroup(w.Canvas().Scale())
@@ -61,6 +73,9 @@ func (s *Settings) LoadAppearanceScreen(w fyne.Window) fyne.CanvasObject {
 }
 
 func (s *Settings) chooseTheme(name string) {
+	if name == systemThemeName {
+		name = ""
+	}
 	s.fyneSettings.ThemeName = name
 
 	switch name {

go.mod

@@ -23,7 +23,7 @@ require (
 	golang.org/x/image v0.0.0-20200430140353-33d19683fad8
 	golang.org/x/mod v0.2.0
 	golang.org/x/net v0.0.0-20200324143707-d3edc9973b7e // indirect
-	golang.org/x/sys v0.0.0-20200327173247-9dae0f8f5775 // indirect
+	golang.org/x/sys v0.0.0-20200720211630-cb9d2d5c5666
 	golang.org/x/text v0.3.2 // indirect
 	golang.org/x/tools v0.0.0-20200328031815-3db5fc6bac03
 	gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f // indirect

go.sum

@@ -67,8 +67,8 @@ golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5h
 golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191005200804-aed5e4c7ecf9/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200323222414-85ca7c5b95cd/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20200327173247-9dae0f8f5775 h1:TC0v2RSO1u2kn1ZugjrFXkRZAEaqMN/RW+OTZkBzmLE=
-golang.org/x/sys v0.0.0-20200327173247-9dae0f8f5775/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200720211630-cb9d2d5c5666 h1:gVCS+QOncANNPlmlO1AhlU3oxs4V9z+gTtPwIk3p2N8=
+golang.org/x/sys v0.0.0-20200720211630-cb9d2d5c5666/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.3.0 h1:g61tztE5qeGQ89tm6NTjjM9VPIm088od1l6aSorWRWg=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.2 h1:tW2bmiBqwgJj/UpqtC8EpXEZVYOwU0yG4iWbprSVAcs=