Add portable runtime VSync control

src/windy/platforms/linux/x11.nim

@@ -47,6 +47,7 @@ type
     innerDecorated: bool
     innerFocused: bool
     mouseCaptured: bool
+    vsyncEnabled: bool
 
     # XDnD state
     xdndSource: XWindow
@@ -406,6 +407,34 @@ proc makeContextCurrent*(window: Window) =
 proc swapBuffers*(window: Window) =
   display.glXSwapBuffers(window.handle)
 
+proc applyVsync(window: Window, enabled: bool) =
+  window.makeContextCurrent()
+  let interval = if enabled: 1.cint else: 0.cint
+  if glXSwapIntervalEXT != nil:
+    display.glXSwapIntervalEXT(window.handle, interval)
+  elif glXSwapIntervalMESA != nil:
+    if glXSwapIntervalMESA(interval) != 0:
+      raise WindyError.newException("Error setting the GLX swap interval")
+  elif glXSwapIntervalSGI != nil:
+    if not enabled:
+      raise WindyError.newException(
+        "Disabling VSync is not supported by GLX_SGI_swap_control"
+      )
+    if glXSwapIntervalSGI(interval) != 0:
+      raise WindyError.newException("Error setting the GLX swap interval")
+  else:
+    raise WindyError.newException("VSync control is not supported")
+  window.vsyncEnabled = enabled
+
+proc vsync*(window: Window): bool =
+  ## Returns true when vertical sync is enabled for this window.
+  window.vsyncEnabled
+
+proc `vsync=`*(window: Window, enabled: bool) =
+  ## Changes the GLX swap interval without recreating the window.
+  if window.vsyncEnabled != enabled:
+    window.applyVsync(enabled)
+
 template blockUntil(expression: untyped) {.dirty.} =
   ## In X11 many properties are async, you change them and then it takes
   ## time for them to take effect. This is different from Win/Mac. This
@@ -819,15 +848,7 @@ proc newWindow*(
 
   makeContextCurrent result
 
-  if vsync:
-    if glXSwapIntervalEXT != nil:
-      display.glXSwapIntervalEXT(result.handle, 1)
-    elif glXSwapIntervalMESA != nil:
-      glXSwapIntervalMESA(1)
-    elif glXSwapIntervalSGI != nil:
-      glXSwapIntervalSGI(1)
-    else:
-      raise WindyError.newException("VSync is not supported")
+  result.applyVsync(vsync)
 
   if visible:
     result.visible = true

src/windy/platforms/linux/x11/glx.nim

@@ -30,5 +30,5 @@ proc glXSwapBuffers*(d: Display, drawable: Drawable) {.libglx.}
 
 proc glXSwapIntervalEXT*(d: Display, drawable: Drawable,
     interval: cint) {.libglx.}
-proc glXSwapIntervalMESA*(interval: cint) {.libglx.}
-proc glXSwapIntervalSGI*(interval: cint) {.libglx.}
+proc glXSwapIntervalMESA*(interval: cint): cint {.libglx.}
+proc glXSwapIntervalSGI*(interval: cint): cint {.libglx.}

src/windy/platforms/macos/platform.nim

@@ -41,6 +41,7 @@ type
     minimizedState: bool
     cpuImage: NSImage
     activationSettlePolls: int
+    vsyncEnabled: bool
 
 const
   ActivationSettlePolls = 60
@@ -1090,6 +1091,23 @@ proc swapBuffers*(window: Window) =
   else:
     window.inner.contentView.NSOpenGLView.openGLContext.flushBuffer()
 
+proc vsync*(window: Window): bool =
+  ## Returns true when vertical sync is enabled for this window.
+  window.vsyncEnabled
+
+proc `vsync=`*(window: Window, enabled: bool) =
+  ## Changes the OpenGL swap interval without recreating the window.
+  if window.vsyncEnabled == enabled:
+    return
+  when not defined(useMetal4) and not defined(useCpu):
+    window.makeContextCurrent()
+    var swapInterval: GLint = if enabled: 1 else: 0
+    window.inner.contentView.NSOpenGLView.openGLContext.setValues(
+      swapInterval.addr,
+      NSOpenGLContextParameterSwapInterval
+    )
+  window.vsyncEnabled = enabled
+
 proc presentPixels*(window: Window, image: Image) =
   ## Presents a CPU-rendered Pixie image into the macOS window content view.
   when defined(useCpu):
@@ -1142,6 +1160,7 @@ proc newWindow*(
   stencilBits = 8
 ): Window =
   result = Window()
+  result.vsyncEnabled = vsync
 
   init()
 

src/windy/platforms/win32/platform.nim

@@ -84,7 +84,7 @@ type
     hdc: HDC
     hglrc: HGLRC
     cpuPresentBuffer: seq[uint8]
-    vsync*: bool
+    vsyncEnabled: bool
     iconHandle: HICON
     customCursor: HCURSOR
 
@@ -1339,7 +1339,7 @@ proc newWindow*(
   result.title = title
   result.hWnd = createWindow(windowClassName, title)
   result.size = size
-  result.vsync = vsync
+  result.vsyncEnabled = vsync
 
   discard SetPropW(result.hWnd, cast[ptr WCHAR](windowPropKey[0].addr), 1)
 
@@ -1366,7 +1366,17 @@ proc title*(window: Window): string =
 
 proc vsync*(window: Window): bool =
   ## Returns true when vertical sync is enabled for this window.
-  window.vsync
+  window.vsyncEnabled
+
+proc `vsync=`*(window: Window, enabled: bool) =
+  ## Changes the OpenGL swap interval without recreating the window.
+  if window.vsyncEnabled == enabled:
+    return
+  when not defined(useDirectX) and not defined(useVulkan) and not defined(useCpu):
+    window.makeContextCurrent()
+    if wglSwapIntervalEXT(if enabled: 1 else: 0) == 0:
+      raise newException(WindyError, "Error setting swap interval")
+  window.vsyncEnabled = enabled
 
 proc icon*(window: Window): Image =
   window.state.icon

tests/test.nim

@@ -1 +1,5 @@
 import windy
+
+proc checkVsyncApi(window: Window) {.used.} =
+  window.vsync = false
+  discard window.vsync