マウスドラッグイベントを使用してJavaアプレットに長方形を描き、それを維持する方法
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12-09-2019 - |
質問
長方形を描くことができるプログラムがあります。解決できない2つの問題があります。長方形を描いた後、それはとどまりません。私が持っている唯一のコードは、塗料の下でキャンバスをクリアします、塗り直しはマウスの抗力でのみ呼び出されます。マウスの放出またはマウスの動きがキャンバスをクリアするのはなぜですか。 2番目のことはそれほど問題ではありませんが、長方形の高さまたは幅が負の場合、長方形が黒で満たされている場合、私は理解できません。
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
解決
わかりました、あなたの質問を読み直した後、あなたは複数の長方形を持っているように気にすることができるようです:)
これは、一度に1つだけのソリューションです(これは、最初に必要なものに近いものです):
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
他のヒント
描かれたアイテムを一部のデータ構造に保存し、構造内の各アイテムが塗り直しのキャンバスに塗装されていることを確認する必要があります。
また、マウスイベントのそれぞれに塗り直しを追加する必要があります。
このように:(これはすべての長方を維持したいと仮定します) - アレイリストを排除し、単一の長方インスタンスに置き換えることで、単一の長方を使用することができます。
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
これら2つを読んでください カスタムペインティングアプローチ. 。 1つのアプローチについては上記で説明し、2番目のアプローチは緩衝液の使用方法を示しています。両方のアプローチに使用される例を使用すると、フレームに複数の長方形を追加できます。
いくつかの表示情報を気にしない場合は、マウスリスナーのすべての「mouseposition.settext(...)」を削除するだけで、不必要なrepaint()コールが生成されます。
次に、2つのフィールドを追加します。 "int rx、ry;"、以下のようにいくつかの方法を追加/変更します。
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);
}
私が見つけた唯一の問題は、最初に描画されたときに長方形が表示されないことです。