JavaMe開發：繪制文本框TextEdit(1)

【問題描述】在JavaMe連載(3)-也說MVC設計模式 一文中提到了一個TextEdit類，但沒有給出具體實現，TextEdit是采用GameCanvas繪制的文本編輯器。本文結合實例給出實現的方法。

【原理】

1 運用Graphics、GameCanvas繪制文本框和光標。

2 檢測到輸入事件時，跳轉到 高級界面->TextBox 。通過系統調用輸入法完成輸入。

3 將TextBox輸入的值返回給TextEdit對象。

【設計模式】

這個過程有點類似裝飾模式，實際上，實現輸入的還是TextBox，只是給TextBox裝飾了一下，形成了一個漂亮的外觀。

【代碼清單】

TextEdit.Java

package com.token.vIEw.components;  
 
import Javax.microedition.lcdui.Font;  
import Javax.microedition.lcdui.Graphics;  
import Javax.microedition.lcdui.game.GameCanvas;  
 
public class TextEdit extends GameCanvas  
{  
    private Font ft;  
      
    public int width;  
    public int height;  
      
    public TextEdit(GameCanvas canvas)   
    {  
        super(false);  
          
    }  
      
    //繪制文本框  
    public void drawTextBox(GameCanvas canvas, Graphics graphics, String text, int x, int y, boolean cursorBlinkOn)  
    {  
        //System.out.println("draw");  
        int padding = 4;  
        int margin = 2;  
          
        ft = Font.getFont(Font.FACE_PROPORTIONAL,Font.STYLE_PLAIN,Font.SIZE_MEDIUM);  
        graphics.setFont(ft);  
          
        width = 3*canvas.getWidth()/5+2*padding;  
        height = ft.getHeight()+2*padding;  
 
        graphics.setColor(Color.frame);  
        graphics.fillRect(x+1,y+1,width+margin,height+margin);  
          
        graphics.setColor(Color.frameBg);  
        graphics.drawRect(x, y,width, height);  
        graphics.setColor(Color.background);  
        graphics.fillRect(x+1, y+1,width-1,height-1);  
          
        graphics.setColor(Color.text);  
        graphics.drawString(text, x+padding, y+padding, Graphics.TOP|Graphics.LEFT);  
          
        drawCursor(graphics, x+ft.stringWidth(text)+padding, y+padding, 1, ft.getHeight(), cursorBlinkOn);  
          
        canvas.flushGraphics(x,y,width,height);  
    }  
 
 
    //繪制光標  
    public void drawCursor(Graphics graphics, int x, int y, int width, int height, boolean cursorBlinkOn)  
    {  
        if(cursorBlinkOn)  
        {  
            ft = Font.getFont(Font.FACE_PROPORTIONAL,Font.STYLE_PLAIN,Font.SIZE_MEDIUM);  
            graphics.setFont(ft);  
            graphics.setColor(0x0,0x0,0x0);  
            graphics.drawLine(x+width,y,x+width,y+height);  
        }  
    }  
}  

PopUpTextBox.Java

package com.token.vIEw;  
 
import Javax.microedition.lcdui.Command;  
import Javax.microedition.lcdui.CommandListener;  
import Javax.microedition.lcdui.Displayable;  
import Javax.microedition.lcdui.TextBox;  
 
import com.token.util.UIController;  
 
public class PopUpTextBox extends TextBox {  
 
      private UIController controller;  
      protected String canvasText = "";  
      private Command okCommand;  
      private Command cancelCommand;  
      private String object_name = null;  
      private String editor = null;  
      private Object args_t[];  
      private Object[] args;  
        
      
      public PopUpTextBox(UIController control, String title, String text, int maxsize, int constraints)   
      {  
          super(title, text, maxsize, constraints);  
          controller = control;  
            
          args = new Object[6];  
            
          okCommand = new Command("確定", Command.OK, 1);  
          cancelCommand = new Command("取消", Command.CANCEL, 1);  
            
          this.addCommand(okCommand);  
          this.addCommand(cancelCommand);  
          this.setCommandListener(new TextBoxListener());  
      }  
        
      public void init(Object[] args)  
      {  
          object_name = ((String)args[0]!=null)?(String)args[0]:"";  
          editor = ((String)args[1]!=null)?(String)args[1]:"";  
          //System.out.println(object_name);  
          //System.out.println(editor);  
          args_t = args;  
          this.setString("");  
      }  
            
      protected void closeTextBox(boolean update) {  
            if (update) canvasText = this.getString();  
            //System.out.println(canvasText);  
 
            if(object_name.equals("registScreen"))  
            {  
                if(editor.equals("regist_name"))  
                {  
                    if(args_t[3]!=""||args_t[3]!=null||args_t[4]!=""||args_t[4]!=null)  
                    {  
                        args[0] = object_name;  
                        args[1] = editor;  
                        args[2] = this.canvasText;  
                        args[3] = args_t[3];  
                        args[4] = args_t[4];  
                    }  
                    controller.handleEvent(UIController.EventID.EVENT_USER_REGIST_EDIT_BACK,args);  
                }  
                else if(editor.equals("regist_passwd"))  
                {  
                    if(args_t[2]!=""||args_t[2]!=null||args_t[4]!=""||args_t[4]!=null)  
                    {  
                        args[0] = object_name;  
                        args[1] = editor;  
                        args[2] = args_t[2];  
                        args[3] = this.canvasText;  
                        args[4] = args_t[4];  
                    }  
                    controller.handleEvent(UIController.EventID.EVENT_USER_REGIST_EDIT_BACK,args);  
                }  
                else if(editor.equals("regist_passwd_re"))  
                {  
                    if(args_t[2]!=""||args_t[2]!=null||args_t[3]!=""||args_t[3]!=null)  
                    {  
                        args[0] = object_name;  
                        args[1] = editor;  
                        args[2] = args_t[2];  
                        args[3] = args_t[3];  
                        args[4] = this.canvasText;  
                    }  
                    controller.handleEvent(UIController.EventID.EVENT_USER_REGIST_EDIT_BACK,args);  
                }  
            }  
              
           //...  
    }  
        
     private class TextBoxListener implements CommandListener  
     {   
        public void commandAction(Command command, Displayable disp)  
        {  
            if(command==okCommand)  
            {  
                closeTextBox(true);  
            }  
            else if(command==cancelCommand)  
            {  
                closeTextBox(false);  
            }  
        }  
    }  
}