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首先要在面板中顯示一個時鐘,我們可以設(shè)計一個ClockPane類來顯示一個時鐘。
最終效果:
若要繪制一個時鐘,需要繪制一個圓并為秒鐘、分鐘和小時繪制三個指針。為了畫一個指針,需要確定一條直線的兩端:一端是時鐘的中央,位于(centerX,centerY);另外一端位于(endX,endY),由一下公式來確定:
endX=centerX+handLength×sin(θ)
endY=centerY-handLength×cos(θ)
(其中θ是指針和豎直方向12點的夾角)
因為一分鐘有60秒,所以第2個指針的角度是:second×(2π/60)
分鐘的位置由分鐘和秒鐘來決定。包含秒數(shù)的確切分鐘數(shù)是minu+second/60。例如,如時間是3分30秒,那么總的分鐘數(shù)就是3.5。由于一小時有60分鐘,因此分針的角度是: (minute+second/60)×(2π/12)
由于一個圓被分為12個小時,所以時針的角度是: (hour+minute/60+second/(60×60))×(2π/12)
為了簡化計算,在計算分針和時針角度的時候,可以忽略秒針,因為它們數(shù)字太小,基本可以忽略。因此,秒針、分針以及時針的端點可以如下計算:
secondX = centerX + secondHandLength × sin(second × (2π/60))
secondY = centerY - secondHandLength × cos(second × (2π/60))
minuteX = centerX + minuteHandLength × sin(minute × (2π/60))
minuteY = centerY - minuteHandLength × cos(minute × (2π/60))
hourX = centerX + hourHandLength × sin((hour+minute/60) × (2π/12))
hourX = centerX + hourHandLength × sin((hour+minute/60) × (2π/12))
這樣就得到了ClockPane類的實現(xiàn)程序:
package com.company; import javafx.scene.layout.Pane; import javafx.scene.paint.Color; import javafx.scene.shape.Circle; import javafx.scene.shape.Line; import javafx.scene.text.Text; import java.util.Calendar; import java.util.GregorianCalendar; public class ClockPane extends Pane{ private int hour; private int minute; private int second; private double w=250,h=250; public ClockPane() { setCurrentTime(); } public ClockPane(int hour,int minute,int second) { this.hour=hour; this.minute=minute; this.second=second; paintClock(); } public int getHour() { return hour; } public void setHour(int hour) { this.hour=hour; paintClock(); } public int getMinute() { return minute; } public void setMinute(int minute) { this.minute=minute; paintClock(); } public int getSecond() { return second; } public void setSecond(int second) { this.second=second; paintClock(); } public double getW() { return w; } public void setW(double w) { this.w=w; paintClock(); } public double getH() { return h; } public void setH(double h) { this.h=h; paintClock(); } public void setCurrentTime() { Calendar calendar=new GregorianCalendar(); this.hour=calendar.get(Calendar.HOUR_OF_DAY); this.minute=calendar.get(Calendar.MINUTE); this.second=calendar.get(Calendar.SECOND); paintClock(); } protected void paintClock() { double clockRadius=Math.min(w,h)*0.8*0.5; double centerX=w/2; double centerY=h/2; Circle circle=new Circle(centerX,centerY,clockRadius); circle.setFill(Color.WHITE); circle.setStroke(Color.BLACK); Text t1=new Text(centerX-5,centerY-clockRadius+12,"12"); Text t2=new Text(centerX-clockRadius+3,centerY+5,"9"); Text t3=new Text(centerX+clockRadius-10,centerY+3,"3"); Text t4=new Text(centerX-3,centerY+clockRadius-3,"6"); double sLength=clockRadius*0.8; double scondX=centerX+sLength*Math.sin(second*(2*Math.PI/60)); double scondY=centerY-sLength*Math.cos(second*(2*Math.PI/60)); Line sline=new Line(centerX,centerY,scondX,scondY); sline.setStroke(Color.RED); double mLength=clockRadius*0.65; double minuteX=centerX+mLength*Math.sin(minute*(2*Math.PI/60)); double minuteY=centerY-mLength*Math.cos(minute*(2*Math.PI)/60); Line mline=new Line(centerX,centerY,minuteX,minuteY); mline.setStroke(Color.BLUE); double hLength=clockRadius*0.5; double hourX=centerX+hLength*Math.sin((hour%12+minute/60.0)*(2*Math.PI/12)); double hourY=centerY-hLength*Math.cos((hour%12+minute/60)*(2*Math.PI/12)); Line hline=new Line(centerX,centerY,hourX,hourY); hline.setStroke(Color.GREEN); getChildren().clear(); getChildren().addAll(circle,t1,t2,t3,t4,sline,mline,hline); } }
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