JavaMe连载(5)-绘制文本框TextEdit (一)

【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

[html] 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);
}
}
}
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+p