我正在尝试使用GUI滑块制作矩形更改颜色。我知道这可以通过改变背景来完成，但我正在尝试使用重绘。
我知道重绘会保留请求并随意执行。我正试图寻找一种解决方法因为我被卡住了。
我已经阅读了repaint（）;和repaintManager并试图操纵我的代码，但我仍然无法得到我想要的输出。
任何帮助将不胜感激。
import java.awt.BorderLayout;
import javax.swing.*;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Graphics;
import javax.swing.SwingConstants;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
/**
*
*
*/
public class MyColorChooser2 extends JPanel {
private JFrame frame;
private JLabel redLabel, greenLabel, blueLabel;
private JSlider redSlider, greenSlider, blueSlider;
private JTextField redTextField, greenTextField, blueTextField;
private JPanel redPanel, greenPanel, bluePanel, colorPanel, paintPanel;
private int holdNbr1, holdNbr2, holdNbr3;
DrawPanel rect = new DrawPanel();
public MyColorChooser2() {
JFrame frame = new JFrame();
frame.setTitle("Color Chooser");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// set up labels
redLabel = new JLabel("Red:");
greenLabel = new JLabel("Green:");
blueLabel = new JLabel("Blue:");
// set up sliders and register their event handler:
redSlider = new JSlider(SwingConstants.HORIZONTAL, 0, 255, 50);
redSlider.setMajorTickSpacing(10); // create tick every 10
redSlider.setPaintTicks(true); // paint ticks on slider
greenSlider = new JSlider(SwingConstants.HORIZONTAL, 0, 255, 100);
greenSlider.setMajorTickSpacing(10); // create tick every 10
greenSlider.setPaintTicks(true); // paint ticks on slider
blueSlider = new JSlider(SwingConstants.HORIZONTAL, 0, 255, 200);
blueSlider.setMajorTickSpacing(10); // create tick every 10
blueSlider.setPaintTicks(true); // paint ticks on slider
//slider event handling:
SliderHandler sliderHandler = new SliderHandler();
redSlider.addChangeListener(sliderHandler);
greenSlider.addChangeListener(sliderHandler);
blueSlider.addChangeListener(sliderHandler);
//set up textFields and register their event handler:
redTextField = new JTextField(3);
redTextField.setText("50"); //initialize
redTextField.setEditable(false);
redTextField.setText("" + redSlider.getValue());
greenTextField = new JTextField(3);
greenTextField.setText("100"); //initialize
greenTextField.setEditable(false);
greenTextField.setText("" + greenSlider.getValue());
blueTextField = new JTextField(3);
blueTextField.setText("200"); //initialize
blueTextField.setEditable(false);
blueTextField.setText("" + blueSlider.getValue());
// build colorPanel:
// build redPanel:
redPanel = new JPanel();
redPanel.setLayout(new FlowLayout(FlowLayout.LEFT));
redPanel.add(redLabel);
redPanel.setLayout(new FlowLayout(FlowLayout.CENTER));
redPanel.add(redSlider);
redPanel.add(redTextField);
// build greenPanel:
greenPanel = new JPanel();
greenPanel.setLayout(new FlowLayout(FlowLayout.LEFT));
greenPanel.add(greenLabel);
greenPanel.setLayout(new FlowLayout(FlowLayout.CENTER));
greenPanel.add(greenSlider);
greenPanel.add(greenTextField);
// build bluePanel:
bluePanel = new JPanel();
bluePanel.setLayout(new FlowLayout(FlowLayout.LEFT));
bluePanel.add(blueLabel);
bluePanel.setLayout(new FlowLayout(FlowLayout.CENTER));
bluePanel.add(blueSlider);
bluePanel.add(blueTextField);
colorPanel = new JPanel();
colorPanel.add(redPanel);
colorPanel.add(greenPanel);
colorPanel.add(bluePanel);
frame.setLayout(new BorderLayout());
frame.add(rect, BorderLayout.CENTER);
frame.add(colorPanel, BorderLayout.SOUTH);
frame.setPreferredSize(new Dimension(900, 300));
frame.setVisible(true);
frame.pack();
}
public class DrawPanel extends JPanel {
private Color color;
private int red = 50, blue = 100, green = 200;
private Graphics g;
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
changeColor();
g.setColor(color);
g.fillRect(10, 10, 880, 200);
g.dispose();
}
public void DrawPanel(Color c) {
color = c;
red = color.getRed();
green = color.getGreen();
blue = color.getBlue();
}
void changeColor() {
color = new Color(red, green, blue);
this.color = color;
}
public void setRed(int r) {
red = r;
changeColor();
}
public void setBlue(int b) {
blue = b;
changeColor();
}
public void setGreen(int g) {
green = g;
changeColor();
}
}
private class SliderHandler implements ChangeListener {
@Override
public void stateChanged(ChangeEvent e) {
JSlider change = (JSlider) e.getSource();
DrawPanel draw = new DrawPanel();
int value;
if (change == redSlider) {
value = change.getValue();
redTextField.setText(String.valueOf(value));
draw.setRed(value);
} else if (change == greenSlider) {
value = change.getValue();
greenTextField.setText(String.valueOf(value));
draw.setGreen(value);
} else if (change == blueSlider) {
value = change.getValue();
blueTextField.setText(String.valueOf(value));
draw.setBlue(value);
}
draw.changeColor();
draw.repaint();
}
}
public static void main(String args[]) {
MyColorChooser2 color = new MyColorChooser2();
}
}
答案 0 :(得分：1)
并不是说它没有做任何事情。问题是你被困住了，因为每次你做出改变时你都试图更新不同的组件。您正在重新创建状态更改的多个面板。
我添加了有关我为使其正常工作所做的更改的评论。如果您需要更多帮助，请询问。干杯！
您是否愿意尝试使用此代码：
public class MyColorChooser2 extends JPanel {
private JFrame frame;
private DrawPanel drawPanel;
private JLabel redLabel, greenLabel, blueLabel;
private JSlider redSlider, greenSlider, blueSlider;
private JTextField redTextField, greenTextField, blueTextField;
private JPanel redPanel, greenPanel, bluePanel, colorPanel, paintPanel;
private int holdNbr1, holdNbr2, holdNbr3;
private Color initialColor = Color.RED;
public MyColorChooser2() {
JFrame frame = new JFrame();
frame.setTitle("Color Chooser");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Let DrawPanel choose the initial color. I don't care.
drawPanel = new DrawPanel();
// This way I control what is the initial color
//drawPanel = new DrawPanel(initialColor);
// set up labels
redLabel = new JLabel("Red:");
greenLabel = new JLabel("Green:");
blueLabel = new JLabel("Blue:");
// set up sliders and register their event handler:
redSlider = new JSlider(SwingConstants.HORIZONTAL, 0, 255, initialColor.getRed());
redSlider.setMajorTickSpacing(10); // create tick every 10
redSlider.setPaintTicks(true); // paint ticks on slider
greenSlider = new JSlider(SwingConstants.HORIZONTAL, 0, 255, initialColor.getGreen());
greenSlider.setMajorTickSpacing(10); // create tick every 10
greenSlider.setPaintTicks(true); // paint ticks on slider
blueSlider = new JSlider(SwingConstants.HORIZONTAL, 0, 255, initialColor.getBlue());
blueSlider.setMajorTickSpacing(10); // create tick every 10
blueSlider.setPaintTicks(true); // paint ticks on slider
// slider event handling:
SliderHandler sliderHandler = new SliderHandler();
redSlider.addChangeListener(sliderHandler);
greenSlider.addChangeListener(sliderHandler);
blueSlider.addChangeListener(sliderHandler);
// set up textFields and register their event handler:
redTextField = new JTextField(3);
redTextField.setText("50"); // initialize
redTextField.setEditable(false);
redTextField.setText("" + redSlider.getValue());
greenTextField = new JTextField(3);
greenTextField.setText("100"); // initialize
greenTextField.setEditable(false);
greenTextField.setText("" + greenSlider.getValue());
blueTextField = new JTextField(3);
blueTextField.setText("200"); // initialize
blueTextField.setEditable(false);
blueTextField.setText("" + blueSlider.getValue());
// build colorPanel:
// build redPanel:
redPanel = new JPanel();
redPanel.setLayout(new FlowLayout(FlowLayout.LEFT));
redPanel.add(redLabel);
redPanel.setLayout(new FlowLayout(FlowLayout.CENTER));
redPanel.add(redSlider);
redPanel.add(redTextField);
// build greenPanel:
greenPanel = new JPanel();
greenPanel.setLayout(new FlowLayout(FlowLayout.LEFT));
greenPanel.add(greenLabel);
greenPanel.setLayout(new FlowLayout(FlowLayout.CENTER));
greenPanel.add(greenSlider);
greenPanel.add(greenTextField);
// build bluePanel:
bluePanel = new JPanel();
bluePanel.setLayout(new FlowLayout(FlowLayout.LEFT));
bluePanel.add(blueLabel);
bluePanel.setLayout(new FlowLayout(FlowLayout.CENTER));
bluePanel.add(blueSlider);
bluePanel.add(blueTextField);
colorPanel = new JPanel();
colorPanel.add(redPanel);
colorPanel.add(greenPanel);
colorPanel.add(bluePanel);
frame.setLayout(new BorderLayout());
frame.add(drawPanel, BorderLayout.CENTER);
frame.add(colorPanel, BorderLayout.SOUTH);
frame.setPreferredSize(new Dimension(900, 300));
frame.setVisible(true);
frame.pack();
}
private class DrawPanel extends JPanel {
private Color color;
private int red = 255, blue = 0, green = 0;
@Override
protected void paintComponent(Graphics g) {
// I've removed the call to changeColor because it was creating
// an infinite loop of revalidates and repaints.
// Now, the paintComponent just finishes the job it was required to.
super.paintComponent(g);
g.setColor(color);
g.fillRect(10, 10, 880, 200);
}
public DrawPanel() {
this(Color.BLUE);
}
public DrawPanel(Color c) {
color = c;
red = color.getRed();
green = color.getGreen();
blue = color.getBlue();
// I'm calling this first repaint here just to make
// sure the panel is initiated the way we want with
// the given Color
repaint();
}
void changeColor() {
color = new Color(red, green, blue);
// We just need to change the color and call this repaint here
// so that the paintComponent can do its job
repaint();
}
public void setRed(int r) {
red = r;
changeColor();
}
public void setBlue(int b) {
blue = b;
changeColor();
}
public void setGreen(int g) {
green = g;
changeColor();
}
}
private class SliderHandler implements ChangeListener {
@Override
public void stateChanged(ChangeEvent e) {
JSlider change = (JSlider) e.getSource();
int value;
// I've removed this line of code because you were
// recreating the drawingPanel. That's not what you want.
// You want to reuse the same panel.
// DrawPanel draw = new DrawPanel();
if (change == redSlider) {
value = change.getValue();
redTextField.setText(String.valueOf(value));
drawPanel.setRed(value);
} else if (change == greenSlider) {
value = change.getValue();
greenTextField.setText(String.valueOf(value));
drawPanel.setGreen(value);
} else if (change == blueSlider) {
value = change.getValue();
blueTextField.setText(String.valueOf(value));
drawPanel.setBlue(value);
}
// You don't need to call those methods, because the
// changeColor will be called by the settings
// of Red, Green and Blue
// draw.changeColor();
// draw.repaint();
}
}
public static void main(String args[]) {
MyColorChooser2 color = new MyColorChooser2();
}
}