import java.awt.*; import java.awt.event.*; import java.applet.Applet; abstract public class MagnetGUI extends PhysicsApplet{ double[][] A; double[][] Bx; double[][] By; int[][] State; VectorDisplay D; TitleCanvas Legend; double Icell = 100.0; /* current in a square, in A */ double a = 1.0e-3; /* grid spacing, in m */ int displayB; /* = 1 to display B, = -1 to display H */ double Bscale = 5.0; double mu = 50.0; // mouse modes: static final int NormalMode = 0; static final int UpWireMode = 1; static final int DownWireMode = 2; static final int IronMode = 3; static final int EraseWireMode = 4; static final int EraseIronMode = 5; static final int MeasureMode = 6; // button codes: static final int FieldResetCode = 1; static final int AllResetCode = 2; static final int MeasureBCode = 3; static final int StartCode = 4; static final int StopCode = 5; static final int BScrollBarCode = 6; static final int muScrollBarCode = 7; static final int BHCode = 8; static final int CurrentsCode = 9; // array states: static final int NormalState = 0; static final int UpWireState = 1; static final int DownWireState = 2; static final int IronState = 3; // Scrollbars and labels PhysicsScrollbar PSBmu, PSBB; BoldLabel SBmuLabel, SBBLabel; MagnetGUI(){ super("Magnet Applet",100,100,4); A = new double[Nx+1][Ny+1]; Bx = new double[Nx+1][Ny+1]; By = new double[Nx+1][Ny+1]; displayB = 1; State = new int[Nx+1][Ny+1]; for (int i = 0; i <= Nx; i++){ for (int j = 0; j <= Ny; j++){ A[i][j] = 0.0; State[i][j] = 0; } } } void fillB(){ if (displayB == 1){ for (int i =1; i < Nx; i++){ for (int j = 1; j < Ny; j++){ Bx[i][j] = (A[i][j]-A[i][j-1])/a; By[i][j] = - (A[i][j]-A[i-1][j])/a; } } } else { /* fill Bx, By with Hx, Hy */ for (int i =1; i < Nx; i++){ for (int j = 1; j < Ny; j++){ double mui = 1.0; if (State[i][j] == IronState) mui = mu; Bx[i][j] = (A[i][j]-A[i][j-1])/(mui * a); By[i][j] = - (A[i][j]-A[i-1][j])/(mui * a); } } } } void resetArrays(){ for (int mx = 0; mx <= Nx; mx++){ for (int my = 0; my <= Ny; my++){ A[mx][my] = 0.0; } } refreshPicture(); } void resetAll(){ for (int mx = 0; mx <= Nx; mx++){ for (int my = 0; my <= Ny; my++){ A[mx][my] = 0.0; State[mx][my] = 0; } } refreshPicture(); } void buildPicture(){ D = new VectorDisplay(Bx,By,State,Bscale,Color.black,Color.magenta); Picture.add(D,"Center"); Legend = new TitleCanvas(" ", 16); Picture.add(Legend,"South"); } void refreshPicture(){ fillB(); D.refresh(); } void buildControls(){ Controls.setLayout(new GridLayout(0,6,10,10)); ModeButton B1 = new ModeButton("Wire Up", UpWireMode); Controls.add(B1); ModeButton B2 = new ModeButton("Wire Down", DownWireMode); Controls.add(B2); ModeButton B3 = new ModeButton("Erase Wire", EraseWireMode); Controls.add(B3); CommandButton B7 = new CommandButton("Currents", CurrentsCode); Controls.add(B7); ModeButton B5 = new ModeButton("Iron", IronMode); Controls.add(B5); ModeButton B6 = new ModeButton("Erase Iron", EraseIronMode); Controls.add(B6); CommandButton B9 = new CommandButton("Solve", StartCode); Controls.add(B9); CommandButton B10 = new CommandButton("Stop", StopCode); Controls.add(B10); ModeButton B11 = new ModeButton("Measure", MeasureMode); Controls.add(B11); CommandButton B12 = new CommandButton("Toggle B/H", BHCode); Controls.add(B12); CommandButton B8 = new CommandButton("Reset Fields", FieldResetCode); Controls.add(B8); CommandButton B4 = new CommandButton("Reset All", AllResetCode); Controls.add(B4); BoldLabel B13 = new BoldLabel(" Mu "); Controls.add(B13); PSBmu = new PhysicsScrollbar(mu, 1.0, 100.0, muScrollBarCode); Controls.add(PSBmu); SBmuLabel = new BoldLabel(" "+mu); Controls.add(SBmuLabel); BoldLabel B17 = new BoldLabel(" Scale of B/H "); Controls.add(B17); PSBB = new PhysicsScrollbar(Bscale, 1.0, 50.0, BScrollBarCode); Controls.add(PSBB); SBBLabel = new BoldLabel(" "+Bscale+" gauss"); Controls.add(SBBLabel); } Color findColor(double A, int S){ if (S == NormalState) return Color.white; if (S == IronState) return Color.yellow; if (S == UpWireState) return Color.green; if (S == DownWireState) return Color.red; return Color.black; } void writeVectorValue(double Vx, double Vy, int mode){ if (mode == MeasureMode){ if (displayB == 1){ Legend.write(" B = ( "+ Vx + " , " + Vy + " ) gauss "); } else { Legend.write(" H = ( "+ Vx + " , " + Vy + " ) gauss "); } } } void setArrays(int i, int j, int mode){ switch(mode){ case UpWireMode : State[i][j] = UpWireState; break; case DownWireMode : State[i][j] = DownWireState; break; case IronMode : if (State[i][j] == NormalState) State[i][j] = IronState; break; case EraseWireMode : if (State[i][j] == UpWireState || State[i][j] == DownWireState) State[i][j] = NormalState; break; case EraseIronMode : if (State[i][j] == IronState) State[i][j] = NormalState; break; default : break; } } void doAction(int Code){ switch(Code){ case FieldResetCode: resetArrays(); break;; case AllResetCode: resetAll(); break; case BHCode: displayB *= -1; refreshPicture(); break; case StartCode: startThread(); break; case StopCode: stopThread(); break; case muScrollBarCode: mu = PSBmu.getReading(); SBmuLabel.setText(mu+" "); break; case BScrollBarCode: Bscale = PSBB.getReading(); SBBLabel.setText(" "+Bscale+" gauss"); D.resetscale(Bscale); break; case CurrentsCode: int upc = 0, downc = 0; for (int i = 1; i < Nx ; i++){ for (int j =1 ; j < Ny; j++){ if (State[i][j] == UpWireState) upc++; if (State[i][j] == DownWireState) downc++; } } double upcurrent = Icell * upc; double downcurrent = Icell * downc; Legend.write( " Total current : "+upcurrent+" A up; "+downcurrent+" A down"); break; default: break; } } void writeFieldValue(double Val, int mode){}; }