我正在尝试创建一个界面，用户可以在其中更改线条的颜色来标记图像的背景或前景。到目前为止我已经编码了:
private class ImageLine extends JComponent
{
java.awt.Point p1,p2;
BufferedImage show;
ArrayList <Shape> shapes = new ArrayList<Shape>();
int flag = 0;
Color color = Color.ORANGE;
public ImageLine(BufferedImage img)
{
show = img;
setPreferredSize(new Dimension(img.getWidth(), img.getHeight()));
this.addMouseListener
(
new MouseAdapter()
{
@Override
public void mousePressed(MouseEvent e)
{
p1 = e.getPoint();
}
@Override
public void mouseReleased(MouseEvent e)
{
p2 = e.getPoint();
Shape r = createLine(p1.x,p1.y,e.getX(),e.getY());
shapes.add(r);
repaint();
}
@Override
public void mouseDragged(MouseEvent e)
{
mouseReleased(e);
repaint();
}
}
);
this.addKeyListener(
new KeyAdapter()
{
@Override
public void keyPressed(KeyEvent e)
{
if(e.getKeyChar() == 'b')
{
color = Color.GREEN;
System.out.println("bck");
}
if(e.getKeyChar() == 'f')
{
color = Color.RED;
System.out.println("fgr");
}
}
}
);
this.setFocusable(true);
}
private Line2D.Float createLine(int x1, int y1, int x2, int y2)
{
return new Line2D.Float(x1,y1 ,x2, y2);
}
直到这部分一切正常，我真正的问题出现在我尝试重写 PaintComponent() 方法时，实际上我不知道如何按照按键监听器指示设置颜色，在这种情况下，如果用户按“b”键，线条的颜色必须更改为绿色，另一方面，如果用户按“f”键，线条的颜色必须更改为红色，而且如果用户绘制不同的线条，这些线条必须更改为红色。保持显示。我尝试使用此代码但没有成功:
public void paintComponent(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2.setStroke(new BasicStroke(10));
g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.50f));
for (Shape s : shapes) {
//g2.setPaint(Color.BLACK);
g2.draw(s);
g2.setPaint(color);
//g2.fill(s);
}
if (p1 != null && p2 != null) {
g2.setPaint(Color.CYAN);
Shape r = createLine(p1.x, p1.y, p2.x, p2.y);
g2.draw(r);
}
}
但是结果不是我想要的，我画了线条并改变了颜色，但是当这种情况发生时，我之前画的线条会自动将其颜色更改为所选的颜色，并且它们不会保留它的“原始颜色” ”。有什么建议吗？提前致谢。
最佳答案
有几种方法可以实现这一点，我有点喜欢将 Shape 和 Color 结合到一个对象中的想法，但是这个添加更多形状时可能会带来更多工作。
另一种解决方案可能是使用Map简单地将线条映射到颜色，例如
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.Shape;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.geom.Line2D;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.swing.AbstractAction;
import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class DrawLines {
public static void main(String[] args) {
new DrawLines();
}
public DrawLines() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private Line2D currentLine;
private Map<Shape, Color> mapColors;
private Color currentColor;
private List<Shape> shapes;
public TestPane() {
mapColors = new HashMap<>(25);
shapes = new ArrayList<>(25);
InputMap inputMap = getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
ActionMap actionMap = getActionMap();
inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_F, 0), "foreground");
inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_B, 0), "background");
actionMap.put("foreground", new AbstractAction() {
@Override
public void actionPerformed(ActionEvent e) {
currentColor = Color.GREEN;
if (currentLine != null) {
mapColors.put(currentLine, currentColor);
repaint();
}
}
});
actionMap.put("background", new AbstractAction() {
@Override
public void actionPerformed(ActionEvent e) {
currentColor = Color.RED;
if (currentLine != null) {
mapColors.put(currentLine, currentColor);
repaint();
}
}
});
MouseAdapter ma = new MouseAdapter() {
private Point p1, p2;
@Override
public void mousePressed(MouseEvent e) {
p1 = e.getPoint();
currentLine = null;
}
@Override
public void mouseReleased(MouseEvent e) {
p2 = e.getPoint();
if (currentLine == null) {
currentLine = createLine(p1.x, p1.y, e.getX(), e.getY());
} else {
currentLine.setLine(p1, p2);
}
mapColors.put(currentLine, currentColor);
shapes.add(currentLine);
repaint();
}
@Override
public void mouseDragged(MouseEvent e) {
p2 = e.getPoint();
if (currentLine == null) {
currentLine = createLine(p1.x, p1.y, e.getX(), e.getY());
} else {
currentLine.setLine(p1, p2);
}
repaint();
}
private Line2D.Float createLine(int x1, int y1, int x2, int y2) {
return new Line2D.Float(x1, y1, x2, y2);
}
};
addMouseListener(ma);
addMouseMotionListener(ma);
}
@Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
for (Shape shape : shapes) {
Color color = mapColors.get(shape);
if (color == null) {
color = Color.BLACK;
}
g2d.setColor(color);
g2d.draw(shape);
}
if (currentLine != null) {
Color color = mapColors.get(currentLine);
if (color == null) {
color = currentColor;
}
g2d.setColor(color);
g2d.draw(currentLine);
}
g2d.dispose();
}
}
}
此外，我避免使用 KeyListener 并使用按键绑定(bind) API，这样更省事
参见How to Use Key Bindings了解更多详情
关于java - 如何在JAVA运行时设置描边颜色？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/32979814/