積少成多Flash(7) - ActionScript 3.0 互動之滑鼠事件和鍵盤事件

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積少成多Flash(7) - ActionScript 3.0 互動之滑鼠事件和鍵盤事件

介紹

示範使用 Flash ActionScript 3.0 來監聽使用者的鍵盤事件和滑鼠事件，并對其作相應的處理

鍵盤事件 - 在 flash.events.KeyboardEvent 類下。隻有兩個事件類型 KeyboardEvent.KEY_DOWN 和 KeyboardEvent.KEY_UP 。

滑鼠事件 - 在 flash.events.MouseEvent 類下。常用的事件類型有 MouseEvent.MOUSE_DOWN, MouseEvent.DOUBLE_CLICK, MouseEvent.MOUSE_UP, MouseEvent.MOUSE_OVER, MouseEvent.MOUSE_MOVE 和 MouseEvent.MOUSE_OUT 等。

1、處理鍵盤事件

做 4 個隻有兩幀的 MovieClip 并放到 UI 上，分别用于提示上/下/左/右鍵的按鍵情況，預設情況下顯示第一幀，當使用者按下了對應的鍵時則顯示第二幀。這 4 個 MovieClip 的名稱分别為 btnUp, btnDown, btnLeft, btnRight

再在 UI 上畫一個物體，由于顯示使用者的鍵盤事件（上/下/左/右）所産生的結果

Main.as

package 

{ 

        import flash.events.Event; 

        import flash.events.KeyboardEvent; 

        import flash.display.MovieClip; 

        import flash.ui.Keyboard; 

        import flash.events.MouseEvent; 

        public class Main extends MovieClip 

        { 

                // 儲存使用者是否按下了上/下/左/右鍵 

                public var isUp:Boolean = false; 

                public var isDown:Boolean = false; 

                public var isLeft:Boolean = false; 

                public var isRight:Boolean = false; 

                // 每次 ENTER_FRAME 物體所需移動的距離 

                public var step:Number = 5; 

                public function Main() 

                { 

                        // 設定四個用于顯示方向的 MovieClip 的初始狀态為停在第一幀 

                        btnUp.stop(); 

                        btnDown.stop(); 

                        btnLeft.stop(); 

                        btnRight.stop();                         

                        // 處理按鍵的按下、放開事件（在舞台上偵測該事件） 

                        stage.addEventListener(KeyboardEvent.KEY_DOWN, keyPressHandler); 

                        stage.addEventListener(KeyboardEvent.KEY_UP, keyReleaseHandler); 

                        // 用于響應按鍵事件的 ENTER_FRAME 

                        this.addEventListener(Event.ENTER_FRAME, enterFrameHandlerForKeyboard); 

                } 

                protected function keyPressHandler(event:KeyboardEvent):void 

                        // 檢測使用者按下的鍵 

                        switch (event.keyCode) 

                        { 

                                case Keyboard.UP:    

                                        isUp = true; 

                                        btnUp.gotoAndStop(2); 

                                        block.rotation = 0; 

                                        break; 

                                case Keyboard.DOWN: // 按的是“下”鍵 

                                        isDown = true; // 儲存使用者的按鍵資訊。即使用者正在按“下”鍵 

                                        btnDown.gotoAndStop(2); // 用于顯示方向“下”的 MovieClip 停到第二幀 

                                        block.rotation = 180; // 物體旋轉 180 度 

                                case Keyboard.LEFT: 

                                        isLeft = true; 

                                        btnLeft.gotoAndStop(2); 

                                        block.rotation = 270; 

                                case Keyboard.RIGHT: 

                                        isRight = true; 

                                        btnRight.gotoAndStop(2); 

                                        block.rotation = 90; 

                        } 

                protected function keyReleaseHandler(event:KeyboardEvent):void 

                        // 檢測使用者放開的鍵 

                        switch( event.keyCode ) 

                                case Keyboard.UP: // 按的是“上”鍵 

                                        isUp = false; // 儲存使用者的按鍵資訊。即使用者已經不再按“上”鍵了 

                                        btnUp.gotoAndStop(1); // 用于顯示方向“上”的 MovieClip 停到第一幀 

                                case Keyboard.DOWN: 

                                        isDown = false; 

                                        btnDown.gotoAndStop(1); 

                                        isLeft = false; 

                                        btnLeft.gotoAndStop(1); 

                                        isRight = false; 

                                        btnRight.gotoAndStop(1); 

                protected function enterFrameHandlerForKeyboard(event:Event):void 

                        // 根據使用者的按鍵情況。将物體向上/下/左/右移動指定的距離 

                        if (isLeft)    

                                block.x -= step; 

                        if (isRight)    

                                block.x += step; 

                        if (isUp)    

                                block.y -= step; 

                        if (isDown)    

                                block.y += step; 

        } 

}

2、處理滑鼠事件

在 UI 上畫一個物體，由于顯示使用者的滑鼠事件所産生的結果，即該物體會向使用者在舞台上所單擊的位置移動

                // 滑鼠單擊位置的坐标 

                public var targetX:Number = 0; 

                public var targetY:Number = 0; 

                // 物體是否再向滑鼠單擊的位置移動 

                public var moving:Boolean = false; 

                        // 處理滑鼠的按下事件（在舞台上偵測該事件） 

                        stage.addEventListener(MouseEvent.MOUSE_DOWN, mouseDownHandler); 

                        // 用于響應滑鼠按下事件的 ENTER_FRAME 

                        this.addEventListener(Event.ENTER_FRAME, enterFrameHandlerForMouse); 

                protected function mouseDownHandler(event:MouseEvent):void 

                        // 當使用者在舞台上按下滑鼠後，擷取滑鼠的坐标 

                        targetX = event.stageX; 

                        targetY = event.stageY; 

                        // 物體正在向滑鼠單擊的位置移動 

                        moving = true; 

                }                 

                protected function enterFrameHandlerForMouse(event:Event):void 

                        if (moving) 

                                // 計算物體在 X 方向和 Y 方向上分别需要移動的距離 

                                var offsetX:Number = block.x - targetX; 

                                var offsetY:Number = block.y - targetY; 

                                // 計算物體需要旋轉的角度 

                                var targetRotation:Number = -Math.atan2(offsetX, offsetY) / (Math.PI / 180); 

                                block.rotation = targetRotation; 

                                if( Math.sqrt((offsetX*offsetX) + (offsetY*offsetY)) &gt; step ) 

                                { 

                                        // 如果還沒有移動到目标位，則繼續移動指定的距離 

                                        block.y -= step * Math.cos(targetRotation * (Math.PI/180)); 

                                        block.x += step * Math.sin(targetRotation * (Math.PI/180)); 

                                } 

                                else 

                                        // 物體已經移動到滑鼠所單擊的位置 

                                        moving = false; 

OK

     本文轉自webabcd 51CTO部落格，原文連結：http://blog.51cto.com/webabcd/342199，如需轉載請自行聯系原作者