我正在尝试制作一个简单的绘画程序。我正在尝试制作像铅笔一样的工具,允许自由绘图。到目前为止,我的代码是:
NPaintMain
public class NPaintMain {
public static void main(String[] args) {
new NPaintWindow();
}
}
NPaintWindow
public class NPaintWindow {
private JFrame windowFrame;
private String windowTitle;
private NPaintCanvas canvas;
private Container easel;
public NPaintWindow() {
windowTitle = "NPaint - a simple paint program.";
windowFrame = new JFrame(windowTitle);
windowFrame.setDefaultCloseOperation(windowFrame.EXIT_ON_CLOSE);
windowFrame.setSize(500, 500);
windowFrame.setLocationRelativeTo(null);
canvas = new NPaintCanvas();
easel = windowFrame.getContentPane();
easel.add(canvas);
windowFrame.setVisible(true);
}
}
NPaintCanvas
public class NPaintCanvas extends JPanel {
double x, y, px, py;
ArrayList<Line2D> l;
public NPaintCanvas() {
new NPaintMouseEvents(this);
x = y = px = py = 0;
l = new ArrayList<>();
}
@Override
public void paintComponent(Graphics g){
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
for(Line2D ll: l){
g2d.draw(ll);
}
l.add(new Line2D.Double(px, py, x, y));
g.dispose();
repaint();
}
}
NPaintMouseEvents
public class NPaintMouseEvents implements MouseListener,MouseMotionListener {
NPaintCanvas canvas;
public NPaintMouseEvents(NPaintCanvas canvas) {
this.canvas = canvas;
this.canvas.addMouseMotionListener(this);
this.canvas.addMouseListener(this);
}
@Override
public void mouseDragged(MouseEvent e) {
if(canvas.px == 0 && canvas.py == 0){
canvas.px = e.getX();
canvas.py = e.getY();
}
canvas.x = e.getPoint().x;
canvas.y = e.getPoint().y;
canvas.px = canvas.x;
canvas.py = canvas.y;
}
}
我的主要问题是虽然拖动了点但是它们之间有空格like this。我想加入连续线。任何有关进一步提示的帮助将不胜感激。
答案 0 :(得分:2)
您正在paintXXX
修改对象状态 - 这是错误的。
paint
方法仅用于绘制当前状态。
您应该在MouseListener
的列表中添加鼠标点,然后致电rapaint
,以便在canvas
中标记要重新绘制的EDT
课程。
paintComponent
应该始终只绘制当前列表。
所以你应该这样做:
public class NPaintCanvas extends JPanel {
ArrayList<Line2D> l;
public NPaintCanvas() {
new NPaintMouseEvents(this);
l = new ArrayList<>();
}
@Override
public void paintComponent(Graphics g){
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
for(Line2D ll: l){
g2d.draw(ll);
}
}
}
public class NPaintMouseEvents implements MouseListener,MouseMotionListener {
NPaintCanvas canvas;
Point2D prev;
public NPaintMouseEvents(NPaintCanvas canvas) {
this.canvas = canvas;
this.canvas.addMouseMotionListener(this);
this.canvas.addMouseListener(this);
}
@Override
public void mouseDragged(MouseEvent e) {
if (prev==null) {
prev=e.getPoint();
return;
}
Point2D p = new Line2D.Double(e.getPoint().x,e.getPoint().y);
if (p.equals(prev)) return ; //not really moved
canvas.l.add(prev, p);
p=prev;
canvas.repaint();
}
}
注意:要获得最佳解决方案,您应该保留点并使用GeneralPath
。
答案 1 :(得分:2)
您的问题是您为每个鼠标拖动移动绘制一个点。
对于每条绘制的线:x1和x2相同,y1和y2相同。
您应该在两个不同点之间追踪一条线。
我已经更新了你的代码,通过引入两个不同的点来处理它:prev和实际点。
简单地说,仅当前一个点和实际点具有值时才绘制线。
当绘制线时,最后一个实际绘制点成为下一个绘制线的前一个点。这样,线之间就没有孔了。
在画布类:
if (previousPoint != null && actualPoint != null) {
l.add(new Line2D.Double(previousPoint.x, previousPoint.y, actualPoint.x, actualPoint.y));
previousPoint = new Point(actualPoint.x, actualPoint.y);
}
如果松开鼠标按钮,则先前和实际点将设置为空。
在Event类中:
@Override
public void mouseReleased(MouseEvent e) {
canvas.mouseReleased();
}
在画布类:
public void mouseReleased() {
previousPoint = null;
actualPoint = null;
}
通过这种方式,您可以根据需要以独立方式绘制多条线。
此外,我通过使用Point实例(而不是双打)简化了代码,它使用了坐标的int,但是你可以使用多个双打字段,它在实践中不会改变很多东西。
package paint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.geom.Line2D;
import java.util.ArrayList;
import javax.swing.JPanel;
public class NPaintCanvas extends JPanel {
ArrayList<Line2D> l;
Point actualPoint;
Point previousPoint;
public NPaintCanvas() {
new NPaintMouseEvents(this);
l = new ArrayList<>();
}
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
for (Line2D ll : l) {
g2d.draw(ll);
}
if (previousPoint != null && actualPoint != null) {
l.add(new Line2D.Double(previousPoint.x, previousPoint.y, actualPoint.x, actualPoint.y));
previousPoint = new Point(actualPoint.x, actualPoint.y);
}
g.dispose();
repaint();
}
public void mouseReleased() {
previousPoint = null;
actualPoint = null;
}
public void mousePressed(int x, int y) {
previousPoint = new Point(x, y);
}
}
NPaintMouseEvent
package paint;
import java.awt.Point;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
public class NPaintMouseEvents implements MouseListener, MouseMotionListener {
NPaintCanvas canvas;
public NPaintMouseEvents(NPaintCanvas canvas) {
this.canvas = canvas;
this.canvas.addMouseMotionListener(this);
this.canvas.addMouseListener(this);
}
@Override
public void mouseDragged(MouseEvent e) {
if (canvas.actualPoint == null) {
canvas.actualPoint = new Point();
}
canvas.actualPoint.x = e.getPoint().x;
canvas.actualPoint.y = e.getPoint().y;
}
@Override
public void mouseMoved(MouseEvent e) {
}
@Override
public void mouseClicked(MouseEvent e) {
}
@Override
public void mousePressed(MouseEvent e) {
canvas.mousePressed((int) e.getX(), (int) e.getY());
}
@Override
public void mouseReleased(MouseEvent e) {
canvas.mouseReleased();
}
@Override
public void mouseEntered(MouseEvent e) {
}
@Override
public void mouseExited(MouseEvent e) {
}
}