app/window,app/internal/window: allow min/max window size

The app.MinSize and app.MaxSize options restricts the window size:

w := app.NewWindow(
	app.Size(unit.Dp(600), unit.Dp(596)),
	app.MinSize(unit.Dp(600), unit.Dp(596)),
	app.MaxSize(unit.Dp(600), unit.Dp(596)),
	app.Title(APPNAME),
)

Signed-off-by: Jason <sourcehut@sweatyballs.es>

app/internal/window/os_macos.go

@@ -41,7 +41,7 @@ __attribute__ ((visibility ("hidden"))) CFTypeRef gio_readClipboard(void);
 __attribute__ ((visibility ("hidden"))) void gio_writeClipboard(unichar *chars, NSUInteger length);
 __attribute__ ((visibility ("hidden"))) void gio_setNeedsDisplay(CFTypeRef viewRef);
 __attribute__ ((visibility ("hidden"))) void gio_appTerminate(void);
-__attribute__ ((visibility ("hidden"))) CFTypeRef gio_createWindow(CFTypeRef viewRef, const char *title, CGFloat width, CGFloat height);
+__attribute__ ((visibility ("hidden"))) CFTypeRef gio_createWindow(CFTypeRef viewRef, const char *title, CGFloat width, CGFloat height, CGFloat minWidth, CGFloat minHeight, CGFloat maxWidth, CGFloat maxHeight);
 __attribute__ ((visibility ("hidden"))) void gio_makeKeyAndOrderFront(CFTypeRef windowRef);
 __attribute__ ((visibility ("hidden"))) NSPoint gio_cascadeTopLeftFromPoint(CFTypeRef windowRef, NSPoint topLeft);
 __attribute__ ((visibility ("hidden"))) void gio_close(CFTypeRef windowRef);
@@ -323,12 +323,21 @@ func NewWindow(win Callbacks, opts *Options) error {
 		// Window sizes is in unscaled screen coordinates, not device pixels.
 		width = int(float32(width) / screenScale)
 		height = int(float32(height) / screenScale)
+		minWidth := cfg.Px(opts.MinWidth)
+		minHeight := cfg.Px(opts.MinHeight)
+		minWidth = int(float32(minWidth) / screenScale)
+		minHeight = int(float32(minHeight) / screenScale)
+		maxWidth := cfg.Px(opts.MaxWidth)
+		maxHeight := cfg.Px(opts.MaxHeight)
+		maxWidth = int(float32(maxWidth) / screenScale)
+		maxHeight = int(float32(maxHeight) / screenScale)
 		title := C.CString(opts.Title)
 		defer C.free(unsafe.Pointer(title))
 		errch <- nil
 		win.SetDriver(w)
 		w.w = win
-		w.window = C.gio_createWindow(w.view, title, C.CGFloat(width), C.CGFloat(height))
+		w.window = C.gio_createWindow(w.view, title, C.CGFloat(width), C.CGFloat(height),
+			C.CGFloat(minWidth), C.CGFloat(minHeight), C.CGFloat(maxWidth), C.CGFloat(maxHeight))
 		if nextTopLeft.x == 0 && nextTopLeft.y == 0 {
 			// cascadeTopLeftFromPoint treats (0, 0) as a no-op,
 			// and just returns the offset we need for the first window.

app/internal/window/os_macos.m

@@ -124,7 +124,7 @@ void gio_makeKeyAndOrderFront(CFTypeRef windowRef) {
 	[window makeKeyAndOrderFront:nil];
 }
 
-CFTypeRef gio_createWindow(CFTypeRef viewRef, const char *title, CGFloat width, CGFloat height) {
+CFTypeRef gio_createWindow(CFTypeRef viewRef, const char *title, CGFloat width, CGFloat height, CGFloat minWidth, CGFloat minHeight, CGFloat maxWidth, CGFloat maxHeight) {
 	@autoreleasepool {
 		NSRect rect = NSMakeRect(0, 0, width, height);
 		NSUInteger styleMask = NSTitledWindowMask |
@@ -136,6 +136,12 @@ CFTypeRef gio_createWindow(CFTypeRef viewRef, const char *title, CGFloat width,
 													   styleMask:styleMask
 														 backing:NSBackingStoreBuffered
 														   defer:NO];
+		if (minWidth > 0 || minHeight > 0) {
+			window.contentMinSize = NSMakeSize(minWidth, minHeight);
+		}
+		if (maxWidth > 0 || maxHeight > 0) {
+			window.contentMaxSize = NSMakeSize(maxWidth, maxHeight);
+		}
 		[window setAcceptsMouseMovedEvents:YES];
 		window.title = [NSString stringWithUTF8String: title];
 		NSView *view = (__bridge NSView *)viewRef;

app/internal/window/os_windows.go

@@ -27,6 +27,16 @@ import (
 	"gioui.org/io/system"
 )
 
+type winConstraints struct {
+	minWidth, minHeight int32
+	maxWidth, maxHeight int32
+}
+
+type winDeltas struct {
+	width  int32
+	height int32
+}
+
 type window struct {
 	hwnd        syscall.Handle
 	hdc         syscall.Handle
@@ -39,6 +49,10 @@ type window struct {
 
 	mu        sync.Mutex
 	animating bool
+
+	minmax winConstraints
+	deltas winDeltas
+	opts   *Options
 }
 
 const _WM_REDRAW = windows.WM_USER + 0
@@ -137,6 +151,15 @@ func initResources() error {
 	return nil
 }
 
+func getWindowConstraints(cfg unit.Metric, opts *Options, d winDeltas) winConstraints {
+	var minmax winConstraints
+	minmax.minWidth = int32(cfg.Px(opts.MinWidth)) + d.width
+	minmax.minHeight = int32(cfg.Px(opts.MinHeight)) + d.height
+	minmax.maxWidth = int32(cfg.Px(opts.MaxWidth)) + d.width
+	minmax.maxHeight = int32(cfg.Px(opts.MaxHeight)) + d.height
+	return minmax
+}
+
 func createNativeWindow(opts *Options) (*window, error) {
 	var resErr error
 	resources.once.Do(func() {
@@ -152,7 +175,14 @@ func createNativeWindow(opts *Options) (*window, error) {
 	}
 	dwStyle := uint32(windows.WS_OVERLAPPEDWINDOW)
 	dwExStyle := uint32(windows.WS_EX_APPWINDOW | windows.WS_EX_WINDOWEDGE)
+	deltas := winDeltas{
+		width:  wr.Right,
+		height: wr.Bottom,
+	}
 	windows.AdjustWindowRectEx(&wr, dwStyle, 0, dwExStyle)
+	deltas.width = wr.Right - wr.Left - deltas.width
+	deltas.height = wr.Bottom - wr.Top - deltas.height
+
 	hwnd, err := windows.CreateWindowEx(dwExStyle,
 		resources.class,
 		opts.Title,
@@ -168,7 +198,10 @@ func createNativeWindow(opts *Options) (*window, error) {
 		return nil, err
 	}
 	w := &window{
-		hwnd: hwnd,
+		hwnd:   hwnd,
+		minmax: getWindowConstraints(cfg, opts, deltas),
+		deltas: deltas,
+		opts:   opts,
 	}
 	w.hdc, err = windows.GetDC(hwnd)
 	if err != nil {
@@ -251,6 +284,20 @@ func windowProc(hwnd syscall.Handle, msg uint32, wParam, lParam uintptr) uintptr
 		case windows.SIZE_MAXIMIZED, windows.SIZE_RESTORED:
 			w.setStage(system.StageRunning)
 		}
+	case windows.WM_GETMINMAXINFO:
+		mm := (*windows.MinMaxInfo)(unsafe.Pointer(uintptr(lParam)))
+		if w.minmax.minWidth > 0 || w.minmax.minHeight > 0 {
+			mm.PtMinTrackSize = windows.Point{
+				w.minmax.minWidth,
+				w.minmax.minHeight,
+			}
+		}
+		if w.minmax.maxWidth > 0 || w.minmax.maxHeight > 0 {
+			mm.PtMaxTrackSize = windows.Point{
+				w.minmax.maxWidth,
+				w.minmax.maxHeight,
+			}
+		}
 	}
 
 	return windows.DefWindowProc(hwnd, msg, wParam, lParam)
@@ -375,6 +422,7 @@ func (w *window) draw(sync bool) {
 		return
 	}
 	cfg := configForDC()
+	w.minmax = getWindowConstraints(cfg, w.opts, w.deltas)
 	w.w.Event(FrameEvent{
 		FrameEvent: system.FrameEvent{
 			Now: time.Now(),

app/internal/window/os_x11.go

@@ -514,6 +514,21 @@ func newX11Window(gioWin Callbacks, opts *Options) error {
 	hints.flags = C.InputHint
 	C.XSetWMHints(dpy, win, &hints)
 
+	var shints C.XSizeHints
+	if opts.MinWidth.V != 0 || opts.MinHeight.V != 0 {
+		shints.min_width = C.int(cfg.Px(opts.MinWidth))
+		shints.min_height = C.int(cfg.Px(opts.MinHeight))
+		shints.flags = C.PMinSize
+	}
+	if opts.MaxWidth.V != 0 || opts.MaxHeight.V != 0 {
+		shints.max_width = C.int(cfg.Px(opts.MaxWidth))
+		shints.max_height = C.int(cfg.Px(opts.MaxHeight))
+		shints.flags = shints.flags | C.PMaxSize
+	}
+	if shints.flags != 0 {
+		C.XSetWMNormalHints(dpy, win, &shints)
+	}
+
 	name := C.CString(filepath.Base(os.Args[0]))
 	defer C.free(unsafe.Pointer(name))
 	wmhints := C.XClassHint{name, name}

app/internal/window/window.go

@@ -14,8 +14,10 @@ import (
 )
 
 type Options struct {
-	Width, Height unit.Value
+	Width, Height       unit.Value
-	Title         string
+	MinWidth, MinHeight unit.Value
+	MaxWidth, MaxHeight unit.Value
+	Title               string
 }
 
 type FrameEvent struct {

app/internal/windows/windows.go

@@ -46,6 +46,14 @@ type Point struct {
 	X, Y int32
 }
 
+type MinMaxInfo struct {
+	PtReserved     Point
+	PtMaxSize      Point
+	PtMaxPosition  Point
+	PtMinTrackSize Point
+	PtMaxTrackSize Point
+}
+
 const (
 	CS_HREDRAW = 0x0002
 	CS_VREDRAW = 0x0001
@@ -120,33 +128,34 @@ const (
 
 	UNICODE_NOCHAR = 65535
 
-	WM_CANCELMODE  = 0x001F
+	WM_CANCELMODE    = 0x001F
-	WM_CHAR        = 0x0102
+	WM_CHAR          = 0x0102
-	WM_CREATE      = 0x0001
+	WM_CREATE        = 0x0001
-	WM_DPICHANGED  = 0x02E0
+	WM_DPICHANGED    = 0x02E0
-	WM_DESTROY     = 0x0002
+	WM_DESTROY       = 0x0002
-	WM_ERASEBKGND  = 0x0014
+	WM_ERASEBKGND    = 0x0014
-	WM_KEYDOWN     = 0x0100
+	WM_KEYDOWN       = 0x0100
-	WM_KEYUP       = 0x0101
+	WM_KEYUP         = 0x0101
-	WM_LBUTTONDOWN = 0x0201
+	WM_LBUTTONDOWN   = 0x0201
-	WM_LBUTTONUP   = 0x0202
+	WM_LBUTTONUP     = 0x0202
-	WM_MBUTTONDOWN = 0x0207
+	WM_MBUTTONDOWN   = 0x0207
-	WM_MBUTTONUP   = 0x0208
+	WM_MBUTTONUP     = 0x0208
-	WM_MOUSEMOVE   = 0x0200
+	WM_MOUSEMOVE     = 0x0200
-	WM_MOUSEWHEEL  = 0x020A
+	WM_MOUSEWHEEL    = 0x020A
-	WM_PAINT       = 0x000F
+	WM_PAINT         = 0x000F
-	WM_CLOSE       = 0x0010
+	WM_CLOSE         = 0x0010
-	WM_QUIT        = 0x0012
+	WM_QUIT          = 0x0012
-	WM_SETFOCUS    = 0x0007
+	WM_SETFOCUS      = 0x0007
-	WM_KILLFOCUS   = 0x0008
+	WM_KILLFOCUS     = 0x0008
-	WM_SHOWWINDOW  = 0x0018
+	WM_SHOWWINDOW    = 0x0018
-	WM_SIZE        = 0x0005
+	WM_SIZE          = 0x0005
-	WM_SYSKEYDOWN  = 0x0104
+	WM_SYSKEYDOWN    = 0x0104
-	WM_RBUTTONDOWN = 0x0204
+	WM_RBUTTONDOWN   = 0x0204
-	WM_RBUTTONUP   = 0x0205
+	WM_RBUTTONUP     = 0x0205
-	WM_TIMER       = 0x0113
+	WM_TIMER         = 0x0113
-	WM_UNICHAR     = 0x0109
+	WM_UNICHAR       = 0x0109
-	WM_USER        = 0x0400
+	WM_USER          = 0x0400
+	WM_GETMINMAXINFO = 0x0024
 
 	WS_CLIPCHILDREN     = 0x00010000
 	WS_CLIPSIBLINGS     = 0x04000000

app/window.go

@@ -427,4 +427,32 @@ func Size(w, h unit.Value) Option {
 	}
 }
 
+// MaxSize sets the maximum size of the window.
+func MaxSize(w, h unit.Value) Option {
+	if w.V <= 0 {
+		panic("width must be larger than or equal to 0")
+	}
+	if h.V <= 0 {
+		panic("height must be larger than or equal to 0")
+	}
+	return func(opts *window.Options) {
+		opts.MaxWidth = w
+		opts.MaxHeight = h
+	}
+}
+
+// MinSize sets the minimum size of the window.
+func MinSize(w, h unit.Value) Option {
+	if w.V <= 0 {
+		panic("width must be larger than or equal to 0")
+	}
+	if h.V <= 0 {
+		panic("height must be larger than or equal to 0")
+	}
+	return func(opts *window.Options) {
+		opts.MinWidth = w
+		opts.MinHeight = h
+	}
+}
+
 func (driverEvent) ImplementsEvent() {}