/*======================================================== Beats: by Eduardo Sanchez Velasco. 05/10/97 A Java Applet that shows beats. This applet uses antiflikering tricks in method update(). Like any applet with Runnable threads, it implements: init() start() run() -> repaint() -> update() -> myPaint() stop() Call the applet from a HTML file with the line: A width XXX = 301 and height YYY = 161 works well. If the background color is set to: then the applet is transparent (if you have a 24-bit color display). ==========================================================*/ import java.util.*; import java.awt.*; import java.applet.*; public class beats extends Applet implements Runnable { Thread timer = null; int Width, Height; final Color Bgd = new Color(0xEA,0xFF,0xFF); int time=0; // Current time step int tPoints[], yPoints[]; // Array storing the wave int yEnv1[], yEnv2[]; // Arrays for the envelope boolean envelope = false; // To display the envelope boolean MouseClick = false;// flag is true if click int x0Label, y0Label; // Location of "time" label // Private variables used in update() to avoid flikering private Image offScreenImage; private Graphics offScreenGraphics; // ----------------- METHODS ---------------------------- public void init() { double K1,K2,A,Zero,sk1,sk2; Font Fnt = new Font("Helvetica", Font.PLAIN, 14); FontMetrics Fmetric = getFontMetrics(Fnt); // Set background color setBackground(Bgd); Width = size().width; Height = size().height; // Location of the "time" label x0Label = Width-Fmetric.stringWidth("time")-4; y0Label = Height/2+Fmetric.getAscent()+3; // Compute the angular freqencies & parameters K1 = (1.5*2*Math.PI)/Width; // 1.5 Periods K2 = (20.0*2*Math.PI)/Width; // 20 Periods Zero = (Height-1.0)/2.0; // Location of origin A = (Height-1.0)/2.0; // Amplitude of wave // Define and compute the wave tPoints = new int[Width]; yPoints = new int[Width]; yEnv1 = new int[Width]; yEnv2 = new int[Width]; for(int t=0; t