MIDP: Form Custom and Image Items

MIDP: Form Custom and Image Items

• 1.
  MIDP GUI: Custom and Image Items Jussi Pohjolainen TAMK University of Applied Sciences
• 2.
  Displayable Class Hierarchyjavax.microedition.lcdui javax.microedition.lcdui.game Displayable Alert List Form TextBox Screen Canvas GameCanvas
• 3.
  Form Form ItemChoiceGroup CustomItem DateField Gauge ImageItem StringItem TextField *
• 4.
  Custom Items CustomItems = Making your own custom item. Inherit your own Custom Item from CustomItem class. CustomItem has following abstract methods int getPrefContentWidth(int height) Item's preferred width int getPrefContentHeight(int width) Item's preferred height int getMinContentWidth() Item's minimum width int getMinContentHeight() Item's minimum height void paint(Graphics g, int w, int h)
• 5.
  Own Custom Item{abstract} CustomItem {abstract} int getPrefContentWidth(int height) {abstract} int getPrefContentHeight(int width) {abstract} int getMinContentWidth() {abstract} int getMinContentHeight() {abstract} void paint(Graphics g, int w, int h) MyItem Form Item * Create a class that inherites CustomItem Gauge ImageItem StringItem TextField
• 6.
  Custom Items method'sint getPrefContentWidth(int height) returns the item's width The parameter is height! "What width do you want, if the height is 18?" int getPrefContentHeight(int width) "What height do you want, if the width is 18?"
• 7.
  Events It ispossible to write the following methods in your own Custom Item-class: void keyPressed(int keyCode) void keyReleased(int keyCode) void keyRepeated(int keyCode) void pointerPressed(int x, int y) void pointerReleased(int x, int y) void pointerDragged(int x, int y) KeyCode can be found in Canvas-class: Canvas.FIRE, Canvas.DOWN, Canvas.UP ... Canvas.NUM0, Canvas.NUM1 ...
• 8.
  Example class MyItemextends CustomItem { public MyItem(String a){ super(a); } public int getMinContentWidth(){ return 100; } public int getMinContentHeight(){ return 30; } public int getPrefContentWidth(int h){ return getMinContentWidth(); } public int getPrefContentHeight(int w){ return getMinContentHeight();} public void paint(Graphics g, int w, int h){ g.setColor(0xffffffff); g.fillRect(0,0,w,h); } protected void keyPressed(int keyCode){ if(getGameAction(keyCode) == Canvas.FIRE){ // Do Something } } }
• 9.
  Image Item DisplayingImage in Form. Constructors ImageItem(String label, Image img, int layout, String altText) ImageItem(String label, Image image, int layout, String altText, int appearanceMode) Typical set/get methods
• 10.
  Image MIDP devicesshould support atleast png-format. Creating Image-object: Image picture = Image.createImage(...); There are many createImage-methods (see the api). Maybe the easiest: public static Image createImage(String name)
• 11.
  Example // [Save the picture in the res-folder ] // Creating picture-object (must be inside // try-catch... Image picture = Image.createImage("picture.png"); // Creating ImageItem-object ImageItem item = new ImageItem("My Picture", picture, Item.LAYOUT_CENTER, ""); // Adding ImageItem to Form mMainForm.append(item);