Pixie and NiGui

[Trustable]

Here an example program, which uses `copyMem` from a Pixie image to a NiGui 
canvas.

(Tested under Linux/Gtk)
    
    
    import std/math
    import pixie
    import NiGui
    
    const width = 500
    const height = 500
    
    app.init()
    var window = newWindow("Pixie+NiGui Example")
    window.width = width
    window.height = height
    
    var control1 = newControl()
    window.add(control1)
    
    control1.widthMode = WidthMode_Fill
    control1.heightMode = HeightMode_Fill
    
    var niGuiImage = nigui.newImage()
    niGuiImage.resize(width, height)
    
    control1.onDraw = proc (event: DrawEvent) =
      let canvas = event.control.canvas
      
      let image = newImage(width, height)
      let ctx = newContext(image)
      
      # Background
      image.fill(rgba(255, 255, 255, 255))
      
      # Line
      ctx.strokeStyle = rgba(0, 0, 255, 255)
      ctx.lineWidth = 10
      ctx.lineCap = RoundCap
      ctx.strokeSegment(segment(vec2(10, 10), vec2(width - 10, height - 10)))
      
      # Rect
      ctx.fillStyle = rgba(0, 255, 0, 255)
      ctx.translate(100, 200)
      ctx.rotate(45 * PI / 180)
      ctx.fillRect(rect(vec2(0, 0), vec2(100, 100)))
      ctx.strokeRect(rect(vec2(0, 0), vec2(100, 100)))
      
      # Text
      block:
        const text = "Text with Pixie"
        let font = readFont("/usr/share/fonts/noto/NotoSans-Regular.ttf")
        font.size = 40
        font.paint.color = color(0, 0, 0)
        image.fillText(font.typeset(text), translate(vec2(200, 40)))
      
      # Draw Pixie image to drawing area
      var niGuiImageData = niGuiImage.beginPixelDataAccess()
      copyMem(niGuiImageData[0].addr, image.data[0].addr, width * height * 4)
      niGuiImage.endPixelDataAccess()
      event.control.canvas.drawImage(niGuiImage, 0, 0)
      
      # Text native
      block:
        const text = "Text with NiGui"
        canvas.fontSize = 40 * 1.1
        canvas.textColor = nigui.rgb(0, 0, 0)
        canvas.drawText(text, 200, 90)
    
    window.show()
    app.run()
    
    
    Run