void RotatedTextExposeEvent(object sender, ExposeEventArgs a)
{
DrawingArea drawingArea = sender as DrawingArea;
int width = drawingArea.Allocation.Width;
int height = drawingArea.Allocation.Height;
double deviceRadius;
// Get the default renderer for the screen, and set it up for drawing
Gdk.PangoRenderer renderer = Gdk.PangoRenderer.GetDefault(drawingArea.Screen);
renderer.Drawable = drawingArea.GdkWindow;
renderer.Gc = drawingArea.Style.BlackGC;
// Set up a transformation matrix so that the user space coordinates for
// the centered square where we draw are [-RADIUS, RADIUS], [-RADIUS, RADIUS]
// We first center, then change the scale
deviceRadius = Math.Min(width, height) / 2;
Matrix matrix = Pango.Matrix.Identity;
matrix.Translate(deviceRadius + (width - 2 * deviceRadius) / 2, deviceRadius + (height - 2 * deviceRadius) / 2);
matrix.Scale(deviceRadius / RADIUS, deviceRadius / RADIUS);
// Create a PangoLayout, set the font and text
Context context = drawingArea.CreatePangoContext();
Pango.Layout layout = new Pango.Layout(context);
layout.SetText("Text");
FontDescription desc = FontDescription.FromString("Sans Bold 27");
layout.FontDescription = desc;
// Draw the layout N_WORDS times in a circle
for (int i = 0; i < N_WORDS; i++)
{
Gdk.Color color = new Gdk.Color();
Matrix rotatedMatrix = matrix;
int w, h;
double angle = (360 * i) / N_WORDS;
// Gradient from red at angle == 60 to blue at angle == 300
color.Red = (ushort)(65535 * (1 + Math.Cos((angle - 60) * Math.PI / 180)) / 2);
color.Green = 0;
color.Blue = (ushort)(65535 - color.Red);
renderer.SetOverrideColor(RenderPart.Foreground, color);
rotatedMatrix.Rotate(angle);
context.Matrix = rotatedMatrix;
// Inform Pango to re-layout the text with the new transformation matrix
layout.ContextChanged();
layout.GetSize(out w, out h);
renderer.DrawLayout(layout, -w / 2, (int)(-RADIUS * Pango.Scale.PangoScale));
}
// Clean up default renderer, since it is shared
renderer.SetOverrideColor(RenderPart.Foreground, Gdk.Color.Zero);
renderer.Drawable = null;
renderer.Gc = null;
}
