마우스 드래그 이벤트를 사용하여 Java 애플릿에 사각형을 그리는 방법을 유지하는 방법
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12-09-2019 - |
문제
사각형을 그릴 수있는 프로그램이 있습니다. 해결할 수없는 두 가지 문제가 있습니다. 직사각형을 그린 후에는 유지되지 않습니다. 페인트 아래에서 캔버스를 지우는 유일한 코드는 마우스 드래그에서만 리 페인트가 호출됩니다. 마우스 릴리스 또는 마우스 이동이 왜 캔버스가 깨끗해집니다. 두 번째는 문제가되지 않지만 사각형의 높이 나 너비가 음수 일 때 사각형이 검은 색으로 채워질 때 알아낼 수없는 것입니다.
package pracpapp2;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class MouseTracker4July extends JFrame
implements MouseListener, MouseMotionListener {
private static final long serialVersionUID = 1L;
private JLabel mousePosition;
int x, y;
int x1, x2, y1, y2;
int w, h;
private JLabel recStart;
private JLabel recStop;
private JLabel cords;
// set up GUI and register mouse event handlers
public MouseTracker4July()
{
super( "Rectangle Drawer" );
mousePosition = new JLabel();
mousePosition.setHorizontalAlignment(SwingConstants.CENTER);
getContentPane().add( mousePosition, BorderLayout.CENTER );
JLabel text1 = new JLabel();
text1.setText( "At the center the mouse pointer's coordinates will be displayed." );
getContentPane().add( text1, BorderLayout.SOUTH );
recStart = new JLabel();
getContentPane().add(recStart, BorderLayout.WEST);
recStop = new JLabel();
getContentPane().add(recStop, BorderLayout.EAST);
cords = new JLabel();
getContentPane().add(cords, BorderLayout.NORTH);
addMouseListener( this ); // listens for own mouse and
addMouseMotionListener( this ); // mouse-motion events
setSize( 800, 600 );
setVisible( true );
}
// MouseListener event handlers
// handle event when mouse released immediately after press
public void mouseClicked( MouseEvent event )
{
mousePosition.setText( "Clicked at [" + event.getX() +
", " + event.getY() + "]" );
}
// handle event when mouse pressed
public void mousePressed( MouseEvent event )
{
mousePosition.setText( "Pressed at [" +(x1 = event.getX()) +
", " + (y1 = event.getY()) + "]" );
recStart.setText( "Start: [" + x1 +
", " + y1 + "]" );
}
// handle event when mouse released after dragging
public void mouseReleased( MouseEvent event )
{
mousePosition.setText( "Released at [" +(x2 = event.getX()) +
", " + (y2 = event.getY()) + "]" );
recStop.setText( "End: [" + x2 +
", " + y2 + "]" );
}
// handle event when mouse enters area
public void mouseEntered( MouseEvent event )
{
mousePosition.setText( "Mouse entered at [" + event.getX() +
", " + event.getY() + "]" );
}
// handle event when mouse exits area
public void mouseExited( MouseEvent event )
{
mousePosition.setText( "Mouse outside window" );
}
// MouseMotionListener event handlers
// handle event when user drags mouse with button pressed
public void mouseDragged( MouseEvent event )
{
mousePosition.setText( "Dragged at [" + (x = event.getX()) +
", " + (y = event.getY()) + "]" );
// call repaint which calls paint
repaint();
}
// handle event when user moves mouse
public void mouseMoved( MouseEvent event )
{
mousePosition.setText( "Moved at [" + event.getX() +
", " + event.getY() + "]" );
}
public void paint(Graphics g)
{
super.paint(g); // clear the frame surface
g.drawString("Start Rec Here", x1, y1);
g.drawString("End Rec Here", x, y);
w = x1 - x;
h = y1 - y;
w = w * -1;
h = h * -1;
g.drawRect(x1, y1, w, h);
cords.setText( "w = " + w + ", h = " + h);
}
public static void main( String args[] )
{
MouseTracker4July application = new MouseTracker4July();
application.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
}
} // end class MouseTracker
해결책
좋아, 질문을 다시 읽은 후에는 여러 개의 사각형을 갖는 것을 덜 신경 쓰지 않을 것 같습니다 :)
다음은 한 번에 하나씩 단 하나의 솔루션입니다 (처음부터 시작해야 할 것과 가깝습니다).
import java.awt.BorderLayout;
import java.awt.Graphics;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.SwingConstants;
public class MouseTracker4July extends JFrame implements MouseListener, MouseMotionListener {
private static final long serialVersionUID = 1L;
private final JLabel mousePosition;
int x1, x2, y1, y2;
int x, y, w, h;
private final JLabel recStart;
private final JLabel recStop;
private final JLabel cords; // set up GUI and register mouse event handlers
boolean isNewRect = true;
public MouseTracker4July() {
super( "Rectangle Drawer" );
this.mousePosition = new JLabel();
this.mousePosition.setHorizontalAlignment( SwingConstants.CENTER );
getContentPane().add( this.mousePosition, BorderLayout.CENTER );
JLabel text1 = new JLabel();
text1.setText( "At the center the mouse pointer's coordinates will be displayed." );
getContentPane().add( text1, BorderLayout.SOUTH );
this.recStart = new JLabel();
getContentPane().add( this.recStart, BorderLayout.WEST );
this.recStop = new JLabel();
getContentPane().add( this.recStop, BorderLayout.EAST );
this.cords = new JLabel();
getContentPane().add( this.cords, BorderLayout.NORTH );
addMouseListener( this ); // listens for own mouse and
addMouseMotionListener( this ); // mouse-motion events
setSize( 800, 600 );
setVisible( true );
}
// MouseListener event handlers // handle event when mouse released immediately after press
public void mouseClicked( final MouseEvent event ) {
this.mousePosition.setText( "Clicked at [" + event.getX() + ", " + event.getY() + "]" );
repaint();
}
// handle event when mouse pressed
public void mousePressed( final MouseEvent event ) {
this.mousePosition.setText( "Pressed at [" + ( this.x1 = event.getX() ) + ", " + ( this.y1 = event.getY() ) + "]" );
this.recStart.setText( "Start: [" + this.x1 + ", " + this.y1 + "]" );
this.isNewRect = true;
repaint();
}
// handle event when mouse released after dragging
public void mouseReleased( final MouseEvent event ) {
this.mousePosition.setText( "Released at [" + ( this.x2 = event.getX() ) + ", " + ( this.y2 = event.getY() ) + "]" );
this.recStop.setText( "End: [" + this.x2 + ", " + this.y2 + "]" );
repaint();
}
// handle event when mouse enters area
public void mouseEntered( final MouseEvent event ) {
this.mousePosition.setText( "Mouse entered at [" + event.getX() + ", " + event.getY() + "]" );
repaint();
}
// handle event when mouse exits area
public void mouseExited( final MouseEvent event ) {
this.mousePosition.setText( "Mouse outside window" );
repaint();
}
// MouseMotionListener event handlers // handle event when user drags mouse with button pressed
public void mouseDragged( final MouseEvent event ) {
this.mousePosition.setText( "Dragged at [" + ( this.x2 = event.getX() ) + ", " + ( this.y2 = event.getY() ) + "]" ); // call repaint which calls paint repaint();
this.isNewRect = false;
repaint();
}
// handle event when user moves mouse
public void mouseMoved( final MouseEvent event ) {
this.mousePosition.setText( "Moved at [" + event.getX() + ", " + event.getY() + "]" );
repaint();
}
@Override
public void paint( final Graphics g ) {
super.paint( g ); // clear the frame surface
g.drawString( "Start Rec Here", this.x1, this.y1 );
g.drawString( "End Rec Here", this.x2, this.y2 );
int width = this.x1 - this.x2;
int height = this.y1 - this.y2;
this.w = Math.abs( width );
this.h = Math.abs( height );
this.x = width < 0 ? this.x1
: this.x2;
this.y = height < 0 ? this.y1
: this.y2;
if ( !this.isNewRect ) {
g.drawRect( this.x, this.y, this.w, this.h );
}
this.cords.setText( "w = " + this.w + ", h = " + this.h );
}
public static void main( final String args[] ) {
MouseTracker4July application = new MouseTracker4July();
application.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
}
} // end class MouseTracker
다른 팁
그려진 항목을 일부 데이터 구조에 저장하고 구조물의 각 항목이 리 페인트시 캔버스에 페인트되어 있는지 확인해야합니다.
또한 각 마우스 이벤트에 리 페인트를 추가해야합니다.
다음과 같이 : (이것은 모든 직장을 유지한다고 가정합니다) - Arraylist를 제거하고 단일 REST 인스턴스로 교체하여 단일 낙타로 갈 수 있습니다.
import java.awt.BorderLayout;
import java.awt.Graphics;
import java.awt.Rectangle;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.util.ArrayList;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.SwingConstants;
public class MouseTracker4July extends JFrame implements MouseListener, MouseMotionListener {
private static final long serialVersionUID = 1L;
private final JLabel mousePosition;
int x1, x2, y1, y2;
int w, h;
private final JLabel recStart;
private final JLabel recStop;
private final JLabel cords; // set up GUI and register mouse event handlers
private final ArrayList< Rectangle > rectangles = new ArrayList< Rectangle >();
private boolean isNewRect = true;
public MouseTracker4July() {
super( "Rectangle Drawer" );
this.mousePosition = new JLabel();
this.mousePosition.setHorizontalAlignment( SwingConstants.CENTER );
getContentPane().add( this.mousePosition, BorderLayout.CENTER );
JLabel text1 = new JLabel();
text1.setText( "At the center the mouse pointer's coordinates will be displayed." );
getContentPane().add( text1, BorderLayout.SOUTH );
this.recStart = new JLabel();
getContentPane().add( this.recStart, BorderLayout.WEST );
this.recStop = new JLabel();
getContentPane().add( this.recStop, BorderLayout.EAST );
this.cords = new JLabel();
getContentPane().add( this.cords, BorderLayout.NORTH );
addMouseListener( this ); // listens for own mouse and
addMouseMotionListener( this ); // mouse-motion events
setSize( 800, 600 );
setVisible( true );
}
// MouseListener event handlers // handle event when mouse released immediately after press
public void mouseClicked( final MouseEvent event ) {
this.mousePosition.setText( "Clicked at [" + event.getX() + ", " + event.getY() + "]" );
repaint();
}
// handle event when mouse pressed
public void mousePressed( final MouseEvent event ) {
this.mousePosition.setText( "Pressed at [" + ( this.x1 = event.getX() ) + ", " + ( this.y1 = event.getY() ) + "]" );
this.recStart.setText( "Start: [" + this.x1 + ", " + this.y1 + "]" );
repaint();
}
// handle event when mouse released after dragging
public void mouseReleased( final MouseEvent event ) {
this.mousePosition.setText( "Released at [" + ( this.x2 = event.getX() ) + ", " + ( this.y2 = event.getY() ) + "]" );
this.recStop.setText( "End: [" + this.x2 + ", " + this.y2 + "]" );
Rectangle rectangle = getRectangleFromPoints();
this.rectangles.add( rectangle );
this.w = this.h = this.x1 = this.y1 = this.x2 = this.y2 = 0;
this.isNewRect = true;
repaint();
}
private Rectangle getRectangleFromPoints() {
int width = this.x1 - this.x2;
int height = this.y1 - this.y2;
Rectangle rectangle = new Rectangle( width < 0 ? this.x1
: this.x2, height < 0 ? this.y1
: this.y2, Math.abs( width ), Math.abs( height ) );
return rectangle;
}
// handle event when mouse enters area
public void mouseEntered( final MouseEvent event ) {
this.mousePosition.setText( "Mouse entered at [" + event.getX() + ", " + event.getY() + "]" );
repaint();
}
// handle event when mouse exits area
public void mouseExited( final MouseEvent event ) {
this.mousePosition.setText( "Mouse outside window" );
repaint();
}
// MouseMotionListener event handlers // handle event when user drags mouse with button pressed
public void mouseDragged( final MouseEvent event ) {
this.mousePosition.setText( "Dragged at [" + ( this.x2 = event.getX() ) + ", " + ( this.y2 = event.getY() ) + "]" ); // call repaint which calls paint repaint();
this.isNewRect = false;
repaint();
}
// handle event when user moves mouse
public void mouseMoved( final MouseEvent event ) {
this.mousePosition.setText( "Moved at [" + event.getX() + ", " + event.getY() + "]" );
repaint();
}
@Override
public void paint( final Graphics g ) {
super.paint( g ); // clear the frame surface
g.drawString( "Start Rec Here", this.x1, this.y1 );
g.drawString( "End Rec Here", this.x2, this.y2 );
Rectangle newRectangle = getRectangleFromPoints();
if ( !this.isNewRect ) {
g.drawRect( newRectangle.x, newRectangle.y, newRectangle.width, newRectangle.height );
}
for( Rectangle rectangle : this.rectangles ) {
g.drawRect( rectangle.x, rectangle.y, rectangle.width, rectangle.height );
}
this.cords.setText( "w = " + this.w + ", h = " + this.h );
}
public static void main( final String args[] ) {
MouseTracker4July application = new MouseTracker4July();
application.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
}
} // end class MouseTracker
이 두 가지를 읽으십시오 맞춤형 그림 접근. 한 가지 접근법은 위에서 설명하고 두 번째 접근법은 BufferedImage를 사용하는 방법을 보여줍니다. 두 가지 접근 방식에 사용 된 예제를 사용하면 프레임에 여러 사각형을 추가 할 수 있습니다.
디스플레이 정보를 신경 쓰지 않으면 마우스 리스너의 모든 "mouseposition.settext (...)"를 삭제하면 불필요한 리 페인트 () 호출이 발생합니다.
그런 다음 두 개의 필드를 추가하십시오 : "int rx, ry;", 다음과 같이 여러 가지 방법을 추가/수정하십시오.
public void mouseDragged(MouseEvent event) {
// mousePosition.setText("Dragged at [" + (x = event.getX()) + ", "
// + (y = event.getY()) + "]");
// call repaint which calls paint
x = event.getX();
y = event.getY();
compRectPos();
repaint();
}
private void compRectPos()
{
rx = x1;
ry = y1;
w = x - x1;
h = y - y1;
if ( w < 0)
rx += w;
if (h < 0)
ry += h;
w = Math.abs(w);
h = Math.abs(h);
}
public void paint(Graphics g) {
super.paint(g); // clear the frame surface
g.drawString("Start Rec Here", x1, y1);
g.drawString("End Rec Here", x, y);
g.drawRect(rx, ry, w, h);
cords.setText("w = " + w + ", h = " + h);
}
내가 찾은 유일한 문제는 처음으로 그려 졌을 때 직사각형이 나타나지 않는다는 것입니다.