internal/ui: add SetWindowKeepAspectRatio (#1985)

Updates #1804

internal/glfw/glfw_notwindows.go

@@ -208,6 +208,14 @@ func (w *Window) SetSizeLimits(minw, minh, maxw, maxh int) {
 	w.w.SetSizeLimits(minw, minh, maxw, maxh)
 }
 
+func (w *Window) SetKeepAspectRatio(keep bool) {
+	n, d := glfw.DontCare, glfw.DontCare
+	if keep {
+		n, d = w.GetSize()
+	}
+	w.w.SetAspectRatio(n, d)
+}
+
 func (w *Window) SetIcon(images []image.Image) {
 	w.w.SetIcon(images)
 }

internal/glfw/glfw_windows.go

@@ -261,6 +261,15 @@ func (w *Window) SetSizeLimits(minw, minh, maxw, maxh int) {
 	panicError()
 }
 
+func (w *Window) SetKeepAspectRatio(keep bool) {
+	n, d := -1, -1
+	if keep {
+		n, d = w.GetSize()
+	}
+	glfwDLL.call("glfwSetWindowAspectRatio", w.w, uintptr(n), uintptr(d))
+	panicError()
+}
+
 func (w *Window) SetIcon(images []image.Image) {
 	gimgs := make([]glfwImage, len(images))
 	defer runtime.KeepAlive(gimgs)

internal/ui/ui_glfw.go

@@ -95,6 +95,7 @@ type UserInterface struct {
 	initWindowHeightInDIP     int
 	initWindowFloating        bool
 	initWindowMaximized       bool
+	initWindowKeepAspectRatio bool
 	initScreenTransparent     bool
 	initFocused               bool
 
@@ -279,6 +280,19 @@ func (u *UserInterface) setWindowSizeLimitsInDIP(minw, minh, maxw, maxh int) boo
 	return true
 }
 
+func (u *UserInterface) isInitWindowKeepAspectRatio() bool {
+	u.m.RLock()
+	v := u.initWindowKeepAspectRatio
+	u.m.RUnlock()
+	return v
+}
+
+func (u *UserInterface) setInitWindowKeepAspectRatio(keep bool) {
+	u.m.Lock()
+	u.initWindowKeepAspectRatio = keep
+	u.m.Unlock()
+}
+
 func (u *UserInterface) isInitFullscreen() bool {
 	u.m.RLock()
 	v := u.initFullscreen
@@ -918,6 +932,9 @@ func (u *UserInterface) init() error {
 		u.window.Maximize()
 	}
 
+	keepAspectRatio := u.isInitWindowKeepAspectRatio()
+	u.window.SetKeepAspectRatio(keepAspectRatio)
+
 	u.window.Show()
 
 	if g, ok := Graphics().(interface{ SetWindow(uintptr) }); ok {

internal/ui/window_glfw.go

@@ -227,6 +227,16 @@ func (w *Window) SetSizeLimits(minw, minh, maxw, maxh int) {
 	w.ui.t.Call(w.ui.updateWindowSizeLimits)
 }
 
+func (w *Window) SetKeepAspectRatio(keep bool) {
+	if !w.ui.isRunning() {
+		w.ui.setInitWindowKeepAspectRatio(keep)
+		return
+	}
+	w.ui.t.Call(func() {
+		w.ui.window.SetKeepAspectRatio(keep)
+	})
+}
+
 func (w *Window) SetIcon(iconImages []image.Image) {
 	// The icons are actually set at (*UserInterface).loop.
 	w.ui.setIconImages(iconImages)

internal/ui/window_null.go

@@ -79,6 +79,9 @@ func (*Window) IsMinimized() bool {
 	return false
 }
 
+func (*Window) SetKeepAspectRatio(keep bool) {
+}
+
 func (*Window) SetIcon(iconImages []image.Image) {
 }
 

window.go

@@ -72,6 +72,13 @@ func SetWindowResizable(resizable bool) {
 	ui.Get().Window().SetResizable(resizable)
 }
 
+// SetWindowKeepAspectRatio sets whether the window should keep its aspect ratio while resizing.
+func SetWindowKeepAspectRatio(keep bool) {
+	if w := ui.Get().Window(); w != nil {
+		w.SetKeepAspectRatio(keep)
+	}
+}
+
 // SetWindowTitle sets the title of the window.
 //
 // SetWindowTitle does nothing on browsers or mobiles.