叶凡网络：JavaMe开发：绘制文本框TextEdit
- 2013-11-29 10:01:25 | 新闻来源：叶凡网络 | 点击量：477
【问题描述】在JavaMe连载(3)-也说MVC设计模式 一文中提到了一个TextEdit类，但没有给出具体实现，TextEdit是采用GameCanvas绘制的文本编辑器。本文结合实例给出实现的方法。
【原理】
1 运用Graphics、GameCanvas绘制文本框和光标。
2 检测到输入事件时，跳转到 高级界面->TextBox 。通过系统调用输入法完成输入。
3 将TextBox输入的值返回给TextEdit对象。
【设计模式】
这个过程有点类似装饰模式，实际上，实现输入的还是TextBox，只是给TextBox装饰了一下，形成了一个漂亮的外观。
【代码清单】
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);
}
//绘制文本框
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);
}
//绘制光标
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("确定", 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);
}
}
}
}
UserRegist.java
package com.token.view;
import javax.microedition.lcdui.Font;
import javax.microedition.lcdui.Graphics;
import javax.microedition.lcdui.game.GameCanvas;
import com.token.model.*;
import com.token.util.*;
import com.token.view.components.*;
public class UserRegist extends GameCanvas implements Runnable {
private UIController controller;
private Graphics graphics;
private Font ft;
private Menu menu;
private Head head;
private BackGroud backGroud;
private UserDataRecord userRecord;
private String title;
private TextEdit textEdit_name;
private TextEdit textEdit_passwd;
private TextEdit textEdit_passwd_re;
private int textEdit_name_x;
private int textEdit_name_y;
private int textEdit_passwd_x;
private int textEdit_passwd_y;
private int textEdit_passwd_re_x;
private int textEdit_passwd_re_y;
private int currentlySelectedIndex = 0;
private String username;
private String passwd;
private String passwd_re;
long caretBlinkDelay = 500L;
long lastCaretBlink = 0;
private String object_name;
private String editor;
private boolean cursorBlinkOn1;
private boolean cursorBlinkOn2;
private boolean cursorBlinkOn3;
private int width;
private int height;
public UserRegist(UIController control)
{
super(false);
this.controller=control;
this.title = "用户注册";
setFullScreenMode(true);
graphics = getGraphics();
width = getWidth();
height = getHeight();
menu = new Menu(this);
head = new Head(this);
backGroud = new BackGroud(this);
userRecord = new UserDataRecord();
textEdit_name = new TextEdit(this);
textEdit_passwd = new TextEdit(this);
textEdit_passwd_re = new TextEdit(this);
}
public void show(Object[] args) {
// TODO Auto-generated method stub
setFullScreenMode(true);
object_name = ((String)args[0]!=null)?(String)args[0]:"";
editor = ((String)args[1]!=null)?(String)args[1]:"";
username = ((String)args[2]!=null)?(String)args[2]:"";
passwd = ((String)args[3]!=null)?(String)args[3]:"";
passwd_re = ((String)args[4]!=null)?(String)args[4]:"";
if(editor.equals("regist_name"))
{
cursorBlinkOn1 = true;
cursorBlinkOn2 = false;
cursorBlinkOn3 = false;
currentlySelectedIndex =0;
}
else if(editor.equals("regist_passwd"))
{
cursorBlinkOn1 = false;
cursorBlinkOn2 = true;
cursorBlinkOn3 = false;
currentlySelectedIndex =1;
}
else if(editor.equals("regist_passwd_re"))
{
cursorBlinkOn1 = false;
cursorBlinkOn2 = false;
cursorBlinkOn3 = true;
currentlySelectedIndex =2;
}
//System.out.println(object_name);
//System.out.println(editor);
draw();
redraw();
}
public void draw()
{
//clearScreen();
backGroud.drawBackGroud(this, graphics);
head.drawHead(this,graphics,this.title);
menu.drawMenu(this,graphics,"下一步","退出");
drawBody();
}
private void redraw()
{
switch(currentlySelectedIndex)
{
case 0:
{
cursorBlinkOn2 = false;
cursorBlinkOn3 = false;
editor = "regist_name";
break;
}
case 1:
{
cursorBlinkOn1 = false;
cursorBlinkOn3 = false;
editor = "regist_passwd";
break;
}
case 2:
{
cursorBlinkOn1 = false;
cursorBlinkOn2 = false;
editor = "regist_passwd_re";
break;
}
default:;
}
textEdit_name.drawTextBox(this, graphics, username, textEdit_name_x, textEdit_name_y, cursorBlinkOn1);
textEdit_passwd.drawTextBox(this, graphics, passwd, textEdit_passwd_x, textEdit_passwd_y, cursorBlinkOn2);
textEdit_passwd.drawTextBox(this, graphics, passwd_re, textEdit_passwd_re_x, textEdit_passwd_re_y, cursorBlinkOn3);
textEdit_name.flushGraphics();
}
public void drawBody()
{
int margin =5;
ft = Font.getFont(Font.FACE_PROPORTIONAL,Font.STYLE_BOLD,Font.SIZE_LARGE);
String info = "用户名：\n";
String info_wrap1[] = StringDealMethod.format(info, width-10, ft);
graphics.setFont(ft);
graphics.setColor(Color.text);
for(int i=0; i<info_wrap1.length; i++)
{
graphics.drawString(info_wrap1[i],5, (i) * ft.getHeight()+40, Graphics.TOP|Graphics.LEFT);
}
textEdit_name_x = 5;
textEdit_name_y = info_wrap1.length * ft.getHeight()+40;
textEdit_name.drawTextBox(this, graphics, username, textEdit_name_x, textEdit_name_y, cursorBlinkOn1);
info = "用户密码：\n";
String info_wrap2[] = StringDealMethod.format(info, width-10, ft);
graphics.setFont(ft);
graphics.setColor(Color.text);
for(int i=0; i<info_wrap2.length; i++)
{
graphics.drawString(info_wrap2[i],5, (i+info_wrap1.length) * ft.getHeight()+textEdit_name.height+margin+40, Graphics.TOP|Graphics.LEFT);
}
textEdit_passwd_x = 5;
textEdit_passwd_y = (info_wrap1.length+info_wrap2.length) * ft.getHeight()+textEdit_name.height+margin+40;
textEdit_passwd.drawTextBox(this, graphics, passwd, textEdit_passwd_x, textEdit_passwd_y, cursorBlinkOn2);
info = "密码确认：\n";
String info_wrap3[] = StringDealMethod.format(info, width-10, ft);
graphics.setFont(ft);
graphics.setColor(Color.text);
for(int i=0; i<info_wrap3.length; i++)
{
graphics.drawString(info_wrap3[i],5, (i+info_wrap1.length+info_wrap2.length) * ft.getHeight()+textEdit_name.height+textEdit_passwd.height+2*margin+40, Graphics.TOP|Graphics.LEFT);
}
textEdit_passwd_re_x = 5;
textEdit_passwd_re_y = (info_wrap1.length+info_wrap2.length+info_wrap3.length) * ft.getHeight()+textEdit_name.height+textEdit_passwd.height+2*margin+40;
textEdit_passwd_re.drawTextBox(this, graphics, passwd_re, textEdit_passwd_re_x, textEdit_passwd_re_y, cursorBlinkOn3);
}
public void clearScreen()
{
graphics.setColor(0xff,0xff,0xff);
graphics.fillRect(0, 0, width, height);
}
public void checkTimeStamp()
{
long currentTime = System.currentTimeMillis();
//System.out.println("1");
if(lastCaretBlink + caretBlinkDelay < currentTime)
{
//System.out.println("2");
if(editor.equals("regist_name"))
{
cursorBlinkOn1 =! cursorBlinkOn1;
cursorBlinkOn2 = false;
cursorBlinkOn3 = false;
}
else if(editor.equals("regist_passwd"))
{
cursorBlinkOn1 = false;
cursorBlinkOn2 =! cursorBlinkOn2;
cursorBlinkOn3 = false;
}
else if(editor.equals("regist_passwd_re"))
{
cursorBlinkOn1 = false;
cursorBlinkOn2 = false;
cursorBlinkOn3 =! cursorBlinkOn3;
}
lastCaretBlink = currentTime;
}
}
public void run()
{
//System.out.println("run");
while(true)
{
checkTimeStamp();
redraw();
try
{
synchronized(this)
{
//System.out.println("3");
wait(50L);
}
}
catch(Exception e)
{
e.printStackTrace();
}
}
}
protected void keyPressed(int keyCode)
{
switch(keyCode)
{
case KeyID.SOFT_RIGHT:
{
controller.handleEvent(UIController.EventID.EVENT_EXIT,null);
break;
}
case KeyID.SOFT_LEFT:
{
if(username!="" && passwd!=""&&passwd_re!="")
{
if(passwd.equals(passwd_re))
{
userRecord.db_deleteAllRecord();
if(userRecord.db_getRecord(1)==null)
{
UserDataItem userItem = new UserDataItem(1,(username+","+passwd).getBytes());
userRecord.db_addRecord(userItem);
userItem = null;
System.gc();
}
String update = "start";
Object [] args = {"activeScreen", null, update};
controller.handleEvent(UIController.EventID.EVENT_NEXT_ACTIVE_TOKEN_SCREEN,args);
}
}
break;
}
case KeyID.KEY_EDIT:
case KEY_NUM0:
case KEY_NUM1:
case KEY_NUM2:
case KEY_NUM3:
case KEY_NUM4:
case KEY_NUM5:
case KEY_NUM6:
case KEY_NUM7:
case KEY_NUM8:
case KEY_NUM9:
{
//System.out.println(editor);
Object[] args = {object_name,editor,username,passwd,passwd_re};
controller.handleEvent(UIController.EventID.EVENT_USER_REGIST_EDIT,args);
break;
}
default:;
}
keyCode = getGameAction(keyCode);
switch(keyCode)
{
case UP:
case LEFT:
{
currentlySelectedIndex--;
if(currentlySelectedIndex<0)
{
currentlySelectedIndex=0;
}
else
{
redraw();
}
break;
}
case DOWN:
case RIGHT:
{
currentlySelectedIndex++;
if(currentlySelectedIndex>2)
{
currentlySelectedIndex=2;
}
else
{
redraw();
}
break;
}
【分析】
1 文本框的绘制(TextEdit.java)
需要传递GameCanvas、Graphics对象，实现绘图，策略是谁使用，谁传递该参数。此外需要床底文本框左上角坐标(x，y)以及控制光标闪烁的变量cursorBlinkOn。
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);
}
2 绘制光标(TextEdit.java)
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);
}
}
3 实现光标闪烁
光标闪烁的实现需要用到线程，在UIController.java类中，需要绘制文本框的视图类，需要实现线程接口。
UIController.java
case EventID.EVENT_NEXT_USER_REGIST_SCREEN:
case EventID.EVENT_USER_REGIST_EDIT_BACK:
{
reg.show(args);
Thread thread = new Thread(reg);
thread.start();
midlet.setCurrent(reg);
break;
}
UserRegist.java
public void checkTimeStamp()
{
long currentTime = System.currentTimeMillis();
//System.out.println("1");
if(lastCaretBlink + caretBlinkDelay < currentTime)
{
//System.out.println("2");
if(editor.equals("regist_name"))
{
cursorBlinkOn1 =! cursorBlinkOn1;
cursorBlinkOn2 = false;
cursorBlinkOn3 = false;
}
else if(editor.equals("regist_passwd"))
{
cursorBlinkOn1 = false;
cursorBlinkOn2 =! cursorBlinkOn2;
cursorBlinkOn3 = false;
}
else if(editor.equals("regist_passwd_re"))
{
cursorBlinkOn1 = false;
cursorBlinkOn2 = false;
cursorBlinkOn3 =! cursorBlinkOn3;
}
lastCaretBlink = currentTime;
}
}
public void run()
{
//System.out.println("run");
while(true)
{
checkTimeStamp();
redraw();
try
{
synchronized(this)
{
//System.out.println("3");
wait(50L);
}
}
catch(Exception e)
{
e.printStackTrace();
}
}
}
4 调用高级界面TextBox子类PopUpTextBox
调用时，将调用对象名、编辑对象名、以及编辑框参数传递给PopUpTextBox对象(一定要有，目的是保存编辑框的值，否则多次调用返回时，不同编辑框的值被刷新为空了)
UserRegist.java(KeyPressed)
case KeyID.KEY_EDIT:
case KEY_NUM0:
case KEY_NUM1:
case KEY_NUM2:
case KEY_NUM3:
case KEY_NUM4:
case KEY_NUM5:
case KEY_NUM6:
case KEY_NUM7:
case KEY_NUM8:
case KEY_NUM9:
{
//System.out.println(editor);
Object[] args = {object_name,editor,username,passwd,passwd_re};
controller.handleEvent(UIController.EventID.EVENT_USER_REGIST_EDIT,args);
break;
}
UIController.java
case EventID.EVENT_USER_REGIST_EDIT:
{
textBox.init(args);
midlet.setCurrent(textBox);
break;
}
5 PopUpTextBox参数的接收
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("");
}
6 PopUpTextBox返回输入法输入的值
if (update) canvasText = this.getString();
7 PopUpTextBox输入值处理
依据调用的对象，以及编辑对象，对输入的值进行处理，传递给父对象编辑框
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);
}
}
8 输入值的显示
(1) 新建对象
private TextEdit textEdit_name;
textEdit_name = new TextEdit(this);
(2) 接受输入的参数
object_name = ((String)args[0]!=null)?(String)args[0]:"";
editor = ((String)args[1]!=null)?(String)args[1]:"";
username = ((String)args[2]!=null)?(String)args[2]:"";
passwd = ((String)args[3]!=null)?(String)args[3]:"";
passwd_re = ((String)args[4]!=null)?(String)args[4]:"";
(3) 光标控制，定位到编辑对象，控制编辑对象的光标闪烁(run方法)
private void redraw()
{
switch(currentlySelectedIndex)
{
case 0:
{
cursorBlinkOn2 = false;
cursorBlinkOn3 = false;
editor = "regist_name";
break;
}
case 1:
{
cursorBlinkOn1 = false;
cursorBlinkOn3 = false;
editor = "regist_passwd";
break;
}
case 2:
{
cursorBlinkOn1 = false;
cursorBlinkOn2 = false;
editor = "regist_passwd_re";
break;
}
default:;
}
//...
}
(4) 编辑框的绘制
private void redraw()
{
...
textEdit_name.drawTextBox(this, graphics, username, textEdit_name_x, textEdit_name_y, cursorBlinkOn1);
textEdit_passwd.drawTextBox(this, graphics, passwd, textEdit_passwd_x, textEdit_passwd_y, cursorBlinkOn2);
textEdit_passwd.drawTextBox(this, graphics, passwd_re, textEdit_passwd_re_x, textEdit_passwd_re_y, cursorBlinkOn3);
textEdit_name.flushGraphics();
}
实现的效果如图1所示：
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