Java在框架上移动正方形-如何在框架边缘停止?
我有一个用键盘移动方块的程序。当我按下其中一个箭头键时,它可以很好地移动,但是如果我将它移动到帧的边缘,我希望它停止。然而,它并没有做到这一点。如果我把方块移到画面的边缘,它会继续移动,并正好越过屏幕的边缘 我在我的代码中加入了一些控件,试图阻止方块,但它们似乎不起作用。我不太确定这里出了什么问题 这是设置和绘制正方形的代码:Java在框架上移动正方形-如何在框架边缘停止?,java,graphics,shapes,Java,Graphics,Shapes,我有一个用键盘移动方块的程序。当我按下其中一个箭头键时,它可以很好地移动,但是如果我将它移动到帧的边缘,我希望它停止。然而,它并没有做到这一点。如果我把方块移到画面的边缘,它会继续移动,并正好越过屏幕的边缘 我在我的代码中加入了一些控件,试图阻止方块,但它们似乎不起作用。我不太确定这里出了什么问题 这是设置和绘制正方形的代码: import javax.swing.*; import java.awt.*; import java.awt.event.*; import java.awt.geo
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
@SuppressWarnings("serial")
public class MovingSquare extends JPanel implements ActionListener, KeyListener
{
// We need a timer to move the shape
Timer shapeTimer = new Timer(5, this);
// X and Y coordinates of square (top left corner), and the factors by which it will move or resize each time
double xPos = 0, yPos = 0, movementX = 0, movementY = 0;
// Size of the square
int squareSize = 40;
// Width and height of the parent frame
int windowWidth;
int windowHeight;
// Movement bounds of the square
// These will prevent it from being moved off the edge of the frame
int xBound;
int yBound;
// Constructor method for our class
public MovingSquare(int w, int h) // Constructor is passed the size of the parent frame
{
// Start the timer
shapeTimer.start();
addKeyListener(this);
setFocusable(true);
setFocusTraversalKeysEnabled(false);
windowWidth = w;
windowHeight = h;
xBound = (windowWidth - squareSize);
yBound = (windowHeight - squareSize);
}
// This is where the fun starts! Painting the graphics object
public void paintComponent(Graphics g)
{
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
// Create a new rectangle (which is actually a square!)
Rectangle2D movableSquare = new Rectangle2D.Double(xPos, yPos, squareSize, squareSize);
// Draw the above square on the graphics object
g2.draw(movableSquare);
}
public void actionPerformed(ActionEvent e)
{
// Redraw the square when something happens
repaint();
// Set the new x and y coordinates, depending on which direction we have moved
xPos += movementX;
yPos += movementY;
}
public void moveUp()
{
// Check to see if the shape is already at the top edge of the screen
if (yPos == 0)
{
movementY = 0;
movementX = 0;
}
// Set the movement factor - negative Y because we are moving UP!
movementY = -0.5;
movementX = 0;
}
public void moveDown()
{
// Check to see if the shape is already at the bottom edge of the screen - specified by the X and Y bounds
if (yPos == yBound)
{
movementY = 0;
movementX = 0;
}
// Set the movement factor - positive Y because we are moving DOWN!
movementY = 0.5;
movementX = 0;
}
public void moveLeft()
{
// Check to see if the shape is already at the left hand edge of the screen
if (xPos == 0)
{
movementY = 0;
movementX = 0;
}
// Set the movement factor - negative X because we are moving LEFT!
movementX = -0.5;
movementY = 0;
}
public void moveRight()
{
// Check to see if the shape is already at the right hand edge of the screen - specified by the X and Y bounds
if (xPos == xBound)
{
movementY = 0;
movementX = 0;
}
// Set the movement factor - positive X because we are moving RIGHT!
movementX = 0.5;
movementY = 0;
}
public void enlargeSquare()
{
// Make the square larger
squareSize++;
}
public void shrinkSquare()
{
// Make the square smaller
squareSize--;
}
public void keyPressed(KeyEvent e)
{
// Get the Key Code of the key that has been pressed
int keyCode = e.getKeyCode();
// If the up key has been pressed
if (keyCode == KeyEvent.VK_UP)
{
// Move shape up
moveUp();
}
// If the down key has been pressed
if (keyCode == KeyEvent.VK_DOWN)
{
// Move shape down
moveDown();
}
// If the right key is pressed
if (keyCode == KeyEvent.VK_RIGHT)
{
// Move shape right
moveRight();
}
// If the left key is pressed
if (keyCode == KeyEvent.VK_LEFT)
{
// Move shape left
moveLeft();
}
// If the left brace key is pressed
if (keyCode == KeyEvent.VK_OPEN_BRACKET)
{
shrinkSquare();
}
// If the right brace key is pressed
if (keyCode == KeyEvent.VK_CLOSE_BRACKET)
{
enlargeSquare();
}
}
public void keyTyped(KeyEvent e)
{
}
public void keyReleased(KeyEvent e)
{
// Get the Key Code of the key that has been released
int keyCode = e.getKeyCode();
// If the down key was released
if (keyCode == KeyEvent.VK_UP)
{
movementX = 0;
movementY = 0;
}
// If the down key was released
if (keyCode == KeyEvent.VK_DOWN)
{
movementX = 0;
movementY = 0;
}
// If the right key was released
if (keyCode == KeyEvent.VK_RIGHT)
{
movementX = 0;
movementY = 0;
}
// If the left key was released
if (keyCode == KeyEvent.VK_UP)
{
movementX = 0;
movementY = 0;
}
}
}
这是主要课程:
import javax.swing.JFrame;
public class Square
{
public static void main(String args[])
{
// Set width and height of frame
int frameWidth = 1024;
int frameHeight = 768;
// Create new frame and set size
JFrame frmMain = new JFrame();
frmMain.setSize(frameWidth, frameHeight);
// Create a moving square and add to the frame
MovingSquare mySquare = new MovingSquare(frameWidth, frameHeight);
frmMain.add(mySquare);
// Final configuration settings for frame.
frmMain.setVisible(true);
frmMain.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frmMain.setTitle("Moving Square");
}
}
你的方法是更新正方形的位置,远远超过你的moveXxx方法,你应该在那里进行范围检查
@Override
public void actionPerformed(ActionEvent e)
{
// Set the new x and y coordinates, depending on which direction we have moved
xPos += movementX;
yPos += movementY;
if (xPos < 0) {
xPos = 0;
} else if (xPos + squareSize > xBound) {
xPos = xBound - squareSize;
}
if (yPos < 0) {
yPos = 0;
} else if (yPos + squareSize > yBound) {
yPos = yBound - squareSize;
}
// Redraw the square when something happens
repaint();
}
如果你知道屏幕和矩形的宽度和高度,你可以很容易地检查它是否在里面:
int fX0 = 0, // left x border
fX1 = frameWidth, // right x border
fY0 = 0, // top y border
fY1 = frameHeight; // bottom y border
int rX0, rX1, rY0, rY1; // keep these values updated width the rectangles position:
//rX0 = rectangle position x
//rX1 = rectangle position x + rectangle width
//rY0 = rectangle position y
//rY1 = rectangle position y + rectangle height
// Then, to check if the rect is inside the frame:
if (
rX0 >= fX0 &&
rX1 < fX1 &&
rY0 >= fY0 &&
rY1 < fY1
) { /* the rectangle is inside the frame bounds */ }
else { /* it's not inside the bounds, e.g. cancel movement */ }
您可以制作一个额外的方法:
public boolean Check(){
if(xPos >0 && xPos-squareSize<frameWidth && yPos>0 && yPos-squareSize<frameHeight){
//use a flag for example and make it false
}else
//flag==true
return flag;
}
好的,这似乎起作用了!如果你不是天才的话,你肯定是个专家-
public boolean Check(){
if(xPos >0 && xPos-squareSize<frameWidth && yPos>0 && yPos-squareSize<frameHeight){
//use a flag for example and make it false
}else
//flag==true
return flag;
}
public void KeyPressed(KeyEvent key){
if(Check()==true){
..........//the code you have into KeyPressed method
}
}//end of method KeyPressed