Flash/Flex学习笔记(14)：按键捕获
先来看简单的单个按键捕获：
package { ?import flash.display.Sprite;
?import fl.controls.Label;
?import flash.events.KeyboardEvent;
import flash.ui.Keyboard;
public class KeyDown extends Sprite {
?private var lbl:Label;
private var ball:Sprite;????????
?public function KeyDown():void {
init();
?}
?
private function init():void {
?stage.focus=this;//N多资料上说要先设置焦点，但是在实际测试中，发现不加这一行，好象也能处理键盘事件?
?lbl = new Label();
?lbl.text="请按键，这里将显示您的按键值，按方向键可以移动小球";
?lbl.autoSize="center";
?addChild(lbl);
?lbl.width=stage.stageWidth;
?lbl.height=20;
?lbl.move(0,10);
ball = new Sprite();
?addChild(ball);
?//画小球?
?ball.graphics.beginFill(0xff0000);
?ball.graphics.drawCircle(0,0,30);
?ball.graphics.endFill();
//定位到舞台中心
?ball.x=stage.stageWidth/2;
?ball.y=stage.stageHeight/2;
stage.addEventListener(KeyboardEvent.KEY_DOWN,KeyDownHandler);??????????
?}
?public function KeyDownHandler(e:KeyboardEvent):void {
?lbl.text="您的按键值是："+e.keyCode.toString()+"；按键是："+String.fromCharCode(e.keyCode);
switch (e.keyCode) {
?case Keyboard.UP :
ball.y-=10;
break;
?case Keyboard.DOWN :
?ball.y+=10;
?break;
?case Keyboard.LEFT :
?ball.x-=10;
?break;
?
case Keyboard.RIGHT :
?ball.x+=10;
?default :
?break;
?}
?if (e.ctrlKey) {
lbl.text="您按下了Ctrl键!";
?}
?if (e.shiftKey) {
?lbl.text="您按下了Shift键!";
?}
?//注:实际上，在很多浏览器，包括flash播放器里，Alt都是默认用做菜单激活键的，所以Alt键会被他们拦截，从而导致Flash无法捕获
?if (e.altKey) {
lbl.text="您按下了Alt键!";
?}
}
}
?}
再来看下类似: A + B + C 的这种组合键捕获：
先分析一下过程，比如用户按下Ctrl + A 时，实际上是先按下Ctrl键，同时触发KeyDown事件，然后在Ctrl不放的同时，再按下A键，再次触发KeyDown事件，然后松开(触发KeyUp事件)，这是一个顺序的过程。
思路：在用户按下键且尚未松开任何键时，可以考虑用一个数据，把本次按下的所有的键值都存储起来，然后等待用户松开，一旦松开，就可以认为本次组合键 输入完成，这时再清空数据，准备下次使用，这样数组中保存的就是用户按下的组合键。
按这个思路把上面的代码改进一下：
? package {
?import flash.display.Sprite;
import fl.controls.Label;
?import flash.events.KeyboardEvent;
import flash.ui.Keyboard;
?import flash.ui.*;
?public class KeyDown extends Sprite {
?private var lbl:Label;
?private var ball:Sprite;
?private var keyValueArr:Array;//捕获组合键时，用来存放本次（在未触KeyUp事件前）所有按下的所有键值
?private var keyNameArr:Array;//按键值对应的字符
public function KeyDown():void {
?init();
?}
private function init():void {
stage.focus=this;//N多资料上说要先设置焦点，但是在实际测试中，发现不加这一行，好象也能处理键盘事件?
?lbl = new Label();
?lbl.text="请按键(支持Ctrl,Shift组合键)，这里将显示您的按键值，按方向键可以移动小球";
?lbl.autoSize="center";
?addChild(lbl);
lbl.width=stage.stageWidth;
?lbl.height=20;
?lbl.move(0,10);
?ball = new Sprite();
?addChild(ball);
//画小球?
ball.graphics.beginFill(0xff0000);
?ball.graphics.drawCircle(0,0,30);
?ball.graphics.endFill();
//定位到舞台中心
?ball.x=stage.stageWidth/2;
ball.y=stage.stageHeight/2;
stage.addEventListener(KeyboardEvent.KEY_DOWN,KeyDownHandler);
?stage.addEventListener(KeyboardEvent.KEY_UP,KeyUpHandler);
?keyValueArr = new Array();
keyNameArr = new Array();
?}
?public function KeyDownHandler(e:KeyboardEvent):void {
?//注:既然Alt总是被浏览器或播放器菜单栏 拦截，干脆就不检测了
?if (!(e.keyCode==Keyboard.SHIFT||e.keyCode==Keyboard.CONTROL)) {
?keyValueArr.push(e.keyCode);
?keyNameArr.push(String.fromCharCode(e.keyCode));
?}
lbl.text="您的按键值是：" + e.keyCode.toString()+"；按键是：" + String.fromCharCode(e.keyCode);
?switch (e.keyCode) {
?case Keyboard.UP :
?ball.y-=10;
?break;
?case Keyboard.DOWN :
ball.y+=10;
?break;
?case Keyboard.LEFT :
?ball.x-=10;
?break;
?case Keyboard.RIGHT :
?ball.x+=10;
default :
?break;
?}
?if (e.ctrlKey) {
?if (keyValueArr.length>0) {
lbl.text="您按下了Ctrl + "+keyNameArr.join(',');
?}
?}
?if (e.shiftKey) {
?if (keyValueArr.length>0) {
?lbl.text="您按下了Shift + "+keyNameArr.join(',');
?}
?}???????
}
?public function KeyUpHandler(e:KeyboardEvent):void {
?keyValueArr.length=0;
?keyNameArr.length=0;
?}
}
?}
最后再来看看所谓的"八方向"移动：很多小游戏都可以用方向键控制人物的移动方向，上面的示例中，只能沿水平垂直四个方向移动，如果要做到8方向移动，就要用到组合键，仍然在上面的代码基本上做些修改：
package { import flash.display.Sprite;
import fl.controls.Label;
?import flash.events.KeyboardEvent;
?import flash.ui.Keyboard;
?import flash.ui.*;
public class KeyDown extends Sprite {
?private var lbl:Label;
private var ball:Sprite;
?private var keyValueArr:Array;//捕获组合键时，用来存放本次（在未触KeyUp事件前）所有按下的所有键值
private var keyNameArr:Array;//按键值对应的字符
?public function KeyDown():void {
?init();
}
?private function init():void {
stage.focus=this;//N多资料上说要先设置焦点，但是在实际测试中，发现不加这一行，好象也能处理键盘事件?
lbl = new Label();
?lbl.text="请按键(支持Ctrl,Shift组合键)，这里将显示您的按键值，按方向键可以移动小球(支持8方向)";
lbl.autoSize="center";
?addChild(lbl);
lbl.width=stage.stageWidth;
?lbl.height=20;
lbl.move(0,10);
ball = new Sprite();
addChild(ball);
//画小球?
ball.graphics.beginFill(0xff0000);
ball.graphics.drawCircle(0,0,30);
ball.graphics.endFill();
//定位到舞台中心
ball.x=stage.stageWidth/2;
ball.y=stage.stageHeight/2;
?stage.addEventListener(KeyboardEvent.KEY_DOWN,KeyDownHandler);
?stage.addEventListener(KeyboardEvent.KEY_UP,KeyUpHandler);
keyValueArr = new Array();
?keyNameArr = new Array();
}
public function KeyDownHandler(e:KeyboardEvent):void {
?//注:既然Alt总是被浏览器或播放器菜单栏 拦截，干脆就不检测了
if (!(e.keyCode==Keyboard.SHIFT||e.keyCode==Keyboard.CONTROL)) {
?if (keyValueArr.indexOf(e.keyCode)==-1) {
?keyValueArr.push(e.keyCode);
?keyNameArr.push(String.fromCharCode(e.keyCode));
?}
?}
?lbl.text="您的按键值是："+ keyValueArr.join('，') +"；按键是：" + keyNameArr.join('，');
//单方向移动
?if (keyValueArr.length==1) {
switch (e.keyCode) {
?case Keyboard.UP :
?ball.y-=10;
?break;
?case Keyboard.DOWN :
?ball.y+=10;
?break;
?case Keyboard.LEFT :
ball.x-=10;
?break;
case Keyboard.RIGHT :
?ball.x+=10;
default :
break;
?}
} else if (keyValueArr.length>1) {
?//trace(keyValueArr.join('，'));?????????????
?if (keyValueArr.indexOf(Keyboard.UP)!=-1 && keyValueArr.indexOf(Keyboard.LEFT)!=-1) {???????
?//左上
?ball.x -= 10;
?ball.y -= 10;
?} else if (keyValueArr.indexOf(Keyboard.UP)!=-1 && keyValueArr.indexOf(Keyboard.RIGHT)!=-1) {
?//右上
?ball.x += 10;
ball.y -= 10;
}
else if (keyValueArr.indexOf(Keyboard.DOWN)!=-1 && keyValueArr.indexOf(Keyboard.RIGHT)!=-1) {
//右下
ball.x += 10;
?ball.y += 10;
?}
else if (keyValueArr.indexOf(Keyboard.DOWN)!=-1 && keyValueArr.indexOf(Keyboard.LEFT)!=-1) {
//左下
?ball.x -= 10;
ball.y += 10;
}
}
?if (e.ctrlKey) {
?if (keyValueArr.length>0) {
?lbl.text="您按下了Ctrl + "+keyNameArr.join(',');
?}
?}
?if (e.shiftKey) {
?if (keyValueArr.length>0) {
?lbl.text="您按下了Shift + "+keyNameArr.join(',');
?}
?}
?}
?public function KeyUpHandler(e:KeyboardEvent):void {
?keyValueArr.length=0;
keyNameArr.length=0;
?}
?}
}
?