The drawing with SkiaSharp page described how to use Skia to render graphics on a Bitmap and display them in a PictureBox. In this project we will use the skglControl user control to create an OpenGL-accelerated surface for us to draw on. OpenGL will offer an excellent performance enhancement, especially when creating large or full-screen animations.

Code

• You must target 32-bit or 64-bit, not “any CPU”
• Install the SkiaSharp.Views.WindowsForms NuGet package
• Drag a SKGLControl onto the form

Render In the PaintSurface Event

The SKGLControl you created has a PaintSurface event that can be used for rendering. This event is especially useful because the SKSurface is passed in as an argument.

private void skglControl1_PaintSurface(object sender, SkiaSharp.Views.Desktop.SKPaintGLSurfaceEventArgs e)
{
    e.Surface.Canvas.Clear(SKColor.Parse("#003366"));
    for (int i = 0; i < lineCount; i++)
    {
        var paint = new SKPaint
        {
            Color = new SKColor(
                red: (byte)rand.Next(255),
                green: (byte)rand.Next(255),
                blue: (byte)rand.Next(255),
                alpha: (byte)rand.Next(255)),
            StrokeWidth = rand.Next(1, 10),
            IsAntialias = true
        };
        e.Surface.Canvas.DrawLine(
            x0: rand.Next(skglControl1.Width),
            y0: rand.Next(skglControl1.Height),
            x1: rand.Next(skglControl1.Width),
            y1: rand.Next(skglControl1.Height),
            paint: paint);
    }
}

Trigger a Render

Rendering only occurs when our control is re-painted, but painting doesn’t happen continuously. To trigger renders we must indicate a new paint is required by calling the control’s invalidate method.

skglControl1.Invalidate();

Render Continuously

To create animations you can call Invalidate using a Timer set to 1ms:

private void timer1_Tick(object sender, EventArgs e)
{
    skglControl1.Invalidate();
}

Source Code

Source code for this project is on GitHub: SkiaSharpOpenGLBenchmark