gnu.app.displayhack.eraser.Circle Maven / Gradle / Ivy

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Escher is a collection of libraries for X Window System written purely in Java.

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package gnu.app.displayhack.eraser;


/**
 * Erase by a circle. 
 *
 * Modified from circle_wipe of erase.c in xscreensaver by Johannes
 * Keukelaar .
 */
public class Circle extends Eraser {
  public Circle () { super ("circle-wipe"); }


  public void erase (gnu.app.displayhack.DisplayHack hack) {
    gnu.x11.Window window = hack.window;

    /* Minimum radius = L/sqrt(2) ~= 0.707*L,
     *   where L = max(width, heigth)
     *         sqrt(2) = 1.414213562373095
     *
     * Take radius = L for faster (easier) computation.
     */
    int radius = Math.max (window.width, window.height);

    int full = 360 * 64;
    int delta = (full/200) * hack.eraser_delta;
    int step_count = (int) Math.ceil (1 + full/delta);
    int start = hack.random.nextInt (full);

    // clockwise or counter-clockwise
    if (hack.random.nextBoolean ()) delta = -delta;


    for (int i=0; i