95 lines
3 KiB
C#
95 lines
3 KiB
C#
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using System;
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using Gtk;
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using Pango;
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namespace GtkDemo
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{
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[Demo ("Rotated Text", "DemoRotatedText.cs")]
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public class DemoRotatedText : Window
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{
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const int RADIUS = 150;
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const int N_WORDS = 10;
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public DemoRotatedText () : base ("Rotated text")
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{
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DrawingArea drawingArea = new DrawingArea ();
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Gdk.Color white = new Gdk.Color (0xff, 0xff, 0xff);
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// This overrides the background color from the theme
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drawingArea.ModifyBg (StateType.Normal, white);
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drawingArea.ExposeEvent += new ExposeEventHandler (RotatedTextExposeEvent);
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this.Add (drawingArea);
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this.DeleteEvent += new DeleteEventHandler (OnWinDelete);
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this.SetDefaultSize (2 * RADIUS, 2 * RADIUS);
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this.ShowAll ();
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}
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void RotatedTextExposeEvent (object sender, ExposeEventArgs a)
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{
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DrawingArea drawingArea = sender as DrawingArea;
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int width = drawingArea.Allocation.Width;
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int height = drawingArea.Allocation.Height;
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double deviceRadius;
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// Get the default renderer for the screen, and set it up for drawing
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Gdk.PangoRenderer renderer = new Gdk.PangoRenderer (drawingArea.Screen);
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renderer.Drawable = drawingArea.GdkWindow;
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renderer.Gc = drawingArea.Style.BlackGC;
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// Set up a transformation matrix so that the user space coordinates for
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// the centered square where we draw are [-RADIUS, RADIUS], [-RADIUS, RADIUS]
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// We first center, then change the scale
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deviceRadius = Math.Min (width, height) / 2;
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Matrix matrix = new Matrix ();
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matrix.Translate (deviceRadius + (width - 2 * deviceRadius) / 2, deviceRadius + (height - 2 * deviceRadius) / 2);
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matrix.Scale (deviceRadius / RADIUS, deviceRadius / RADIUS);
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// Create a PangoLayout, set the font and text
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Context context = drawingArea.CreatePangoContext ();
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Pango.Layout layout = new Pango.Layout (context);
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layout.SetText ("Text");
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FontDescription desc = FontDescription.FromString ("Sans Bold 27");
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layout.FontDescription = desc;
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// Draw the layout N_WORDS times in a circle
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for (int i = 0; i < N_WORDS; i++)
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{
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Gdk.Color color = new Gdk.Color ();
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Matrix rotatedMatrix = matrix;
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int w, h;
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double angle = (360 * i) / N_WORDS;
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// Gradient from red at angle == 60 to blue at angle == 300
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color.Red = (ushort) (65535 * (1 + Math.Cos ((angle - 60) * Math.PI / 180)) / 2);
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color.Green = 0;
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color.Blue = (ushort) (65535 - color.Red);
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renderer.SetOverrideColor (RenderPart.Foreground, color);
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rotatedMatrix.Rotate (angle);
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context.Matrix = rotatedMatrix;
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// Inform Pango to re-layout the text with the new transformation matrix
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layout.ContextChanged ();
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layout.GetSize (out w, out h);
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renderer.DrawLayout (layout, - w / 2, (int) (- RADIUS * Pango.Scale.PangoScale));
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}
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// Clean up default renderer, since it is shared
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renderer.SetOverrideColor (RenderPart.Foreground, Gdk.Color.Zero);
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renderer.Drawable = null;
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renderer.Gc = null;
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}
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void OnWinDelete (object sender, DeleteEventArgs a)
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{
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this.Hide ();
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this.Dispose ();
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}
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}
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}
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