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41 import java.awt.*;
42 import java.awt.event.*;
43 import java.applet.*;
44
45
50 public class ArcTest extends Applet {
51 ArcControls controls; ArcCanvas canvas;
54 public void init() {
55 setLayout(new BorderLayout());
56 canvas = new ArcCanvas();
57 add("Center", canvas);
58 add("South", controls = new ArcControls(canvas));
59 }
60
61 public void destroy() {
62 remove(controls);
63 remove(canvas);
64 }
65
66 public void start() {
67 controls.setEnabled(true);
68 }
69
70 public void stop() {
71 controls.setEnabled(false);
72 }
73
74 public void processEvent(AWTEvent e) {
75 if (e.getID() == Event.WINDOW_DESTROY) {
76 System.exit(0);
77 }
78 }
79
80 public static void main(String  args[]) {
81 Frame f = new Frame("ArcTest");
82 ArcTest arcTest = new ArcTest();
83
84 arcTest.init();
85 arcTest.start();
86
87 f.add("Center", arcTest);
88 f.setSize(300, 300);
89 f.show();
90 }
91
92 public String getAppletInfo() {
93 return "An interactive test of the Graphics.drawArc and \nGraphics.fillArc routines. Can be run \neither as a standalone application by typing 'java ArcTest' \nor as an applet in the AppletViewer.";
94 }
95 }
96
97 class ArcCanvas extends Canvas {
98 int startAngle = 0;
99 int extent = 45;
100 boolean filled = false;
101 Font font = new java.awt.Font ("SansSerif", Font.PLAIN, 12);
102
103 public void paint(Graphics g) {
104 Rectangle r = getBounds();
105 int hlines = r.height / 10;
106 int vlines = r.width / 10;
107
108 g.setColor(Color.pink);
109 for (int i = 1; i <= hlines; i++) {
110 g.drawLine(0, i * 10, r.width, i * 10);
111 }
112 for (int i = 1; i <= vlines; i++) {
113 g.drawLine(i * 10, 0, i * 10, r.height);
114 }
115
116 g.setColor(Color.red);
117 if (filled) {
118 g.fillArc(0, 0, r.width - 1, r.height - 1, startAngle, extent);
119 } else {
120 g.drawArc(0, 0, r.width - 1, r.height - 1, startAngle, extent);
121 }
122
123 g.setColor(Color.black);
124 g.setFont(font);
125 g.drawLine(0, r.height / 2, r.width, r.height / 2);
126 g.drawLine(r.width / 2, 0, r.width / 2, r.height);
127 g.drawLine(0, 0, r.width, r.height);
128 g.drawLine(r.width, 0, 0, r.height);
129 int sx = 10;
130 int sy = r.height - 28;
131 g.drawString("Start = " + startAngle, sx, sy);
132 g.drawString("Extent = " + extent, sx, sy + 14);
133 }
134
135 public void redraw(boolean filled, int start, int extent) {
136 this.filled = filled;
137 this.startAngle = start;
138 this.extent = extent;
139 repaint();
140 }
141 }
142
143 class ArcControls extends Panel
144 implements ActionListener {
145 TextField startTF;
146 TextField extentTF;
147 ArcCanvas canvas;
148
149 public ArcControls(ArcCanvas canvas) {
150 Button b = null;
151
152 this.canvas = canvas;
153 add(startTF = new IntegerTextField("0", 4));
154 add(extentTF = new IntegerTextField("45", 4));
155 b = new Button("Fill");
156 b.addActionListener(this);
157 add(b);
158 b = new Button("Draw");
159 b.addActionListener(this);
160 add(b);
161 }
162
163 public void actionPerformed(ActionEvent ev) {
164 String label = ev.getActionCommand();
165
166 int start, extent;
167 try {
168 start = Integer.parseInt(startTF.getText().trim());
169 } catch (NumberFormatException nfe) {
170 start = 0;
171 }
172 try {
173 extent = Integer.parseInt(extentTF.getText().trim());
174 } catch (NumberFormatException nfe) {
175 extent = 0;
176 }
177
178 canvas.redraw(label.equals("Fill"), start, extent);
179 }
180 }
181
182 class IntegerTextField extends TextField {
183
184 String oldText = null;
185
186 public IntegerTextField(String text, int columns) {
187 super(text, columns);
188 enableEvents(AWTEvent.KEY_EVENT_MASK | AWTEvent.TEXT_EVENT_MASK);
189 oldText = getText();
190 }
191
192 protected void processEvent(AWTEvent evt) {
198 int id = evt.getID();
199 if (id != KeyEvent.KEY_TYPED) {
200 super.processEvent(evt);
201 return;
202 }
203
204 KeyEvent kevt = (KeyEvent) evt;
205 char c = kevt.getKeyChar();
206
207 if (Character.isDigit(c) || (c == '\b') || (c == '\u007f') ||
210 (c == '\u002d')) {
211 super.processEvent(evt);
212 return;
213 }
214
215 Toolkit.getDefaultToolkit().beep();
216 kevt.consume();
217 }
218
219 protected void processTextEvent(TextEvent te) {
225 String newText = getText();
227 if (newText.equals("") || textIsInteger(newText)) {
228 oldText = newText;
229 super.processTextEvent(te);
230 return;
231 }
232
233 Toolkit.getDefaultToolkit().beep();
234 setText(oldText);
235 }
236
237 private boolean textIsInteger(String textToCheck) {
242 int value = -1;
243
244 try {
245 value = Integer.parseInt(textToCheck, 10);
246 return true;
247 } catch (NumberFormatException nfe) {
248 return false;
249 }
250 }
251 }
252
253
254
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Java API By Example, From Geeks To Geeks.