added GTK4 support

examples/cairo_anim.nim

@@ -1,44 +0,0 @@
-# https://lists.cairographics.org/archives/cairo/2016-October/027791.html
-# Nim version of that plain cairo animation example
-
-import gintro/[gtk, glib, gobject, gio, cairo]
-import math
-
-const
-  NumPoints = 1000
-  Period = 100.0
-
-proc invalidateCb(w: Widget): bool =
-  queueDraw(w)
-  return SOURCE_CONTINUE
-
-proc sineToPoint(x, width, height: int): float =
-  math.sin(x.float * math.TAU / Period) * height.float * 0.5 + height.float * 0.5
-
-proc drawingAreaDrawCb(widget: DrawingArea; context: Context): bool =
-  var redrawNumber {.global.} : int
-  let width = getAllocatedWidth(widget)
-  let height = getAllocatedHeight(widget)
-  for i in 1 ..< NumPoints:
-    context.lineTo(i.float , sineToPoint(i + redrawNumber, width, height))
-  context.stroke
-  inc(redrawNumber)
-  return true # TRUE to stop other handlers from being invoked for the event. FALSE to propagate the event further.
-
-proc appActivate(app: Application) =
-  let window = newApplicationWindow(app)
-  window.title = "Drawing example"
-  window.defaultSize = (400, 400)
-  let drawingArea = newDrawingArea()
-  window.add(drawingArea)
-  showAll(window)
-  discard timeoutAdd(1000 div 60, invalidateCb, drawingArea)
-  connect(drawingArea, "draw", drawingAreaDrawCb)
-
-proc main =
-  let app = newApplication("org.gtk.example")
-  connect(app, "activate", appActivate)
-  discard run(app)
-
-main()
-