A quick sample of graphics, commands, and event handling.
/* * @(#)Sample.java 1.9 01/06/08 * Copyright (c) 1999-2001 Sun Microsystems, Inc. All Rights Reserved. */ import javax.microedition.midlet.*; import javax.microedition.lcdui.*; /* * A quick sample of graphics, commands, and event handling. */ public class SampleCanvasMIDlet extends MIDlet implements CommandListener { Display display; Command exitCommand; Command backCommand; Command okCommand; SampleCanvas sample; // Instance of sample canvas List itemMenu; List exclusiveList; List multipleList; TextBox textbox; Ticker ticker; Alert alert; Form form; StringItem stringItem; ImageItem imageItem; Image image; TextField textItem; ChoiceGroup choiceItem; DateField dateItem; Gauge gaugeItem; public SampleCanvasMIDlet() { display = Display.getDisplay(this); exitCommand = new Command("Exit", Command.EXIT, 1); backCommand = new Command("Back", Command.BACK, 2); okCommand = new Command("OK", Command.OK, 3); ticker = new Ticker("Select an item to display"); itemMenu = new List(null, Choice.IMPLICIT); itemMenu.append("Canvas", null); itemMenu.append("Form", null); itemMenu.append("Alert", null); itemMenu.append("TextBox", null); itemMenu.append("Exclusive List", null); itemMenu.append("Multiple Choice", null); itemMenu.setCommandListener(this); itemMenu.addCommand(exitCommand); itemMenu.setTicker(ticker); display.setCurrent(itemMenu); } public void startApp () { } public void destroyApp (boolean unconditional) { } public void pauseApp () { } public void commandAction(Command c, Displayable s) { if (c == backCommand) { display.setCurrent(itemMenu); } else if (s == itemMenu) { if (c == List.SELECT_COMMAND) { // Handle the item sected to be displayed int i = itemMenu.getSelectedIndex(); switch (i) { case 0: // Show Sample canvas display.setCurrent(getCanvas()); break; case 1: // Show the form display.setCurrent(getForm()); break; case 2: // Show an alert display.setCurrent(getAlert("Warning", "This window will dismiss in two seconds.")); break; case 3: // Show TextBox display.setCurrent(getTextBox()); break; case 4: // Show Exclusive list display.setCurrent(getExclusiveList()); break; case 5: // Show Multiple List display.setCurrent(getMultipleList()); break; } } else if (c == exitCommand) { notifyDestroyed(); } } else if (s == exclusiveList) { int i = exclusiveList.getSelectedIndex(); String value = exclusiveList.getString(i); alert = getAlert("Border selected:", value); display.setCurrent(alert, itemMenu); } else if (s == multipleList) { StringBuffer b = new StringBuffer(); for (int i = 0; i <= 2; i++) { if (multipleList.isSelected(i)) { b.append(multipleList.getString(i)); b.append("\n"); } } alert = getAlert("Colors selected:", b.toString()); display.setCurrent(alert, itemMenu); } else if (s == textbox) { String value = textbox.getString(); alert = getAlert("Text Entered:", value); display.setCurrent(alert, itemMenu); } else if (s == form) { alert = getAlert("Image options saved", ""); display.setCurrent(alert, itemMenu); } } SampleCanvas getCanvas() { if (sample == null) { sample = new SampleCanvas(); sample.addCommand(backCommand); sample.setCommandListener(this); } return sample; } List getExclusiveList() { if (exclusiveList == null) { exclusiveList = new List("Border Style", Choice.EXCLUSIVE); exclusiveList.append("None", null); exclusiveList.append("Plain", null); exclusiveList.append("Fancy", null); exclusiveList.addCommand(backCommand); exclusiveList.addCommand(okCommand); exclusiveList.setCommandListener(this); } return exclusiveList; } List getMultipleList() { if (multipleList == null) { multipleList = new List("Colors to mix", Choice.MULTIPLE); multipleList.append("Red", null); multipleList.append("Green", null); multipleList.append("Blue", null); multipleList.addCommand(backCommand); multipleList.addCommand(okCommand); multipleList.setCommandListener(this); } return multipleList; } TextBox getTextBox() { if (textbox == null) { textbox = new TextBox("Enter a phone number","", 40, TextField.PHONENUMBER); textbox.addCommand(backCommand); textbox.addCommand(okCommand); textbox.setCommandListener(this); } return textbox; } Alert getAlert(String title, String contents) { if (alert == null) { alert = new Alert(title); alert.setType(AlertType.WARNING); alert.setTimeout(2000); alert.setString(contents); } else { alert.setTitle(title); alert.setString(contents); } return alert; } Form getForm() { if (form == null) { form = new Form("Options"); try { image = Image.createImage("/images/PhotoAlbum.png"); imageItem = new ImageItem("Preview:", image, ImageItem.LAYOUT_NEWLINE_BEFORE, "Mountain"); form.append(imageItem); } catch (java.io.IOException ex) { } textItem = new TextField("Title:", "Mountain", 32, TextField.ANY); form.append(textItem); dateItem = new DateField("Date:", DateField.DATE); dateItem.setDate(new java.util.Date()); form.append(dateItem); choiceItem = new ChoiceGroup("Size:", Choice.EXCLUSIVE); choiceItem.append("Small", null); choiceItem.append("Large", null); form.append(choiceItem); gaugeItem = new Gauge("Speed:", true, 10, 5); form.append(gaugeItem); form.addCommand(backCommand); form.addCommand(okCommand); form.setCommandListener(this); } return form; } } class SampleCanvas extends Canvas { int x, y; // Location of cross hairs String event = ""; // Last key event type int keyCode; // Last keyCode pressed Font font; // Font used for drawing text int fh; // height of the font int w, h; // width and height of the canvas int titleHeight; // Height of the title int pieSize; // Size of the Pie chart used for width and height int barSize; // Size of the Bar chart used for width and height int eventHeight; // Size of the event region int pad; // Padding used between items SampleCanvas() { w = getWidth(); h = getHeight(); font = Font.getFont(Font.FACE_SYSTEM, Font.STYLE_PLAIN, Font.SIZE_SMALL); fh = font.getHeight(); /* Compute the sizes of the bar and pie charts * It should use all the space except for the title * and event regions. * Don't let the charts get too small */ pad = 2; titleHeight = fh + pad * 2; eventHeight = fh * 3; barSize = h - (titleHeight + pad) - (eventHeight + pad); if (barSize < 20) // Don't let them get too small barSize = 20; if (barSize > (w - pad) / 2) // Shrink to 1/2 width barSize = (w - pad) / 2; pieSize = barSize; } protected void keyPressed(int key) { keyCode = key; event = "Pressed"; handleActions(key); repaint(); } protected void keyRepeated(int key) { keyCode = key; event = "Repeated"; handleActions(key); repaint(); } protected void keyReleased(int key) { keyCode = key; event = "Released"; repaint(); } protected void pointerPressed(int x, int y) { this.x = x; this.y = y; keyCode = 0; event = "Pressed"; repaint(); } protected void pointerReleased(int x, int y) { this.x = x; this.y = y; keyCode = 0; event = "Released"; repaint(); } protected void pointerDragged(int x, int y) { this.x = x; this.y = y; keyCode = 0; event = "Dragged"; } void handleActions(int keyCode) { int action = getGameAction(keyCode); switch (action) { case LEFT: x -= 1; break; case RIGHT: x += 1; break; case UP: y -= 1; break; case DOWN: y += 1; break; } } protected void paint(Graphics g) { g.setFont(font); g.setGrayScale(255); g.fillRect(0, 0, w, h); x = (x < 0) ? w - 1 : x; y = (y < 0) ? h - 1 : y; x = x % w; y = y % h; // Draw Fill and outline for background of title Text int swidth = pad * 2 + font.stringWidth("Pie and Bar Samples"); int title_x = (w - swidth)/2; g.setGrayScale(128); g.fillRoundRect(title_x, 0, swidth, fh, 5, 5); g.setGrayScale(0); g.drawRoundRect(title_x, 0, swidth, fh, 5, 5); // Sample Text g.setColor(0, 0, 0); g.drawString("Pie and Bar Samples", title_x + pad, pad, Graphics.TOP|Graphics.LEFT); // Translate to below title text g.translate(0, titleHeight + pad); /* * Draw pie chart on the left side * using the barSize for width and height */ g.setColor(255, 0, 0); g.fillArc(0, 0, pieSize, pieSize, 45, 270); g.setColor(0, 255, 0); g.fillArc(0, 0, pieSize, pieSize, 0, 45); g.setColor(0, 0, 255); g.fillArc(0, 0, pieSize, pieSize, 0, -45); g.setColor(0); g.drawArc(0, 0, pieSize, pieSize, 0, 360); // Draw Bar chart on right side of the display // scale the values to the pieSize maximum value int yorig = barSize; int h1 = barSize / 3, h2 = barSize / 2, h3 = barSize; int avg = (h1 + h2 + h3) / 3; // Move over to draw Bar chart g.translate((w + pad) / 2, 0); int bw = pieSize / 7; if (bw < 2) bw = 2; g.setColor(255, 0, 0); g.fillRect(bw*1, yorig-h1, bw+1, h1); g.setColor(0, 255, 0); g.fillRect(bw*3, yorig-h2, bw+1, h2); g.setColor(0, 0, 255); g.fillRect(bw*5, yorig-h3, bw+1, h3); g.setColor(0); g.drawRect(bw*1, yorig-h1, bw, h1); g.drawRect(bw*3, yorig-h2, bw, h2); g.drawRect(bw*5, yorig-h3, bw, h3); // Draw axis for bar chart. g.setGrayScale(0); g.drawLine(0, 0, 0, yorig); g.drawLine(0, yorig, barSize, yorig); g.setStrokeStyle(Graphics.DOTTED); g.drawLine(0, yorig - avg, barSize, yorig-avg); g.setStrokeStyle(Graphics.SOLID); // Restore to left and move down g.translate(-(w + pad) / 2, pieSize + pad); // Draw the key and pointer status g.setColor(128, 128, 128); int col1 = font.stringWidth("Action:"); g.drawString("Key: ", col1, 0, Graphics.TOP|Graphics.RIGHT); g.drawString(keyString(keyCode), col1, 0, Graphics.TOP|Graphics.LEFT); g.drawString("Action:", col1, fh, Graphics.TOP|Graphics.RIGHT); g.drawString(actionString(keyCode), col1, fh, Graphics.TOP|Graphics.LEFT); g.drawString("Event:", col1, fh*2, Graphics.TOP|Graphics.RIGHT); g.drawString(event, col1, fh*2, Graphics.TOP|Graphics.LEFT); int col2 = 80; g.drawString("x:", col2, 0, Graphics.TOP|Graphics.RIGHT); g.drawString(Integer.toString(x), col2, 0, Graphics.TOP|Graphics.LEFT); g.drawString("y:", col2, fh, Graphics.TOP|Graphics.RIGHT); g.drawString(Integer.toString(y), col2, fh, Graphics.TOP|Graphics.LEFT); // Restore the origin and draw the crosshairs on top g.translate(-g.getTranslateX(), -g.getTranslateY()); g.setColor(0, 0, 0); g.drawLine(x, y - 5, x, y + 5); g.drawLine(x - 5, y, x + 5, y); } String keyString(int keyCode) { if (keyCode == 0) { return ""; } return Integer.toString(keyCode); } String actionString(int keyCode) { if (keyCode == 0) { return ""; } int action = getGameAction(keyCode); switch (action) { case FIRE: return "Fire"; case LEFT: return "Left"; case RIGHT: return "Right"; case DOWN: return "Down"; case UP: return "Up"; case GAME_A: return "Game A"; case GAME_B: return "Game B"; case GAME_C: return "Game C"; case GAME_D: return "Game D"; case 0: return ""; default: return Integer.toString(action); } } }