Java Swing - Repaint（）无法正常工作
我从this topic获取计划。我尝试在实时模式下编辑点。我将MouseMotionListener添加到构造函数中并编写一些基本函数以接近鼠标点并编辑此点。当我在构造函数中得到（x，y）点时，repaint()很奇怪。当我在paintComponent得到（x，y）分时，repaint()根本不起作用。因此，这是在构造函数和paintComponent中获取（x，y）的图像。我的错误在哪里？
package simplegrapher2;
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.Stroke;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
import java.awt.geom.Line2D;
import java.awt.geom.Point2D;
import static java.lang.Math.sqrt;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class SimpleGrapher2 extends JPanel {
private int width = 800;
private int heigth = 400;
private int padding = 25;
private int labelPadding = 25;
private Color lineColor = new Color(44, 102, 230, 180);
private Color pointColor = new Color(100, 100, 100, 180);
private Color gridColor = new Color(200, 200, 200, 200);
private static final Stroke GRAPH_STROKE = new BasicStroke(2f);
private int pointWidth = 4;
private int numberYDivisions = 10;
private List<Double> scores;
private static double serieX = 0;
public List<Point2D.Double> graphPoints;
public SimpleGrapher2(List<Double> scores) {
this.scores = scores;
addMouseMotionListener(new MouseMotionListener() {
@Override
public void mouseDragged(MouseEvent me) {
double x = me.getX();
double y = me.getY();
findNearPoint(x, y);
editSerie(x, y);
revalidate();
repaint();
}
@Override
public void mouseMoved(MouseEvent me) {}
});
double xScale = ((double) getWidth() - (2 * padding) - labelPadding) / (scores.size() - 1);
double yScale = ((double) getHeight() - 2 * padding - labelPadding) / (getMaxScore() - getMinScore());
graphPoints = new ArrayList<>();
for (int i = 0; i < scores.size(); i++) {
double x1 = (double) (i * xScale + padding + labelPadding);
double y1 = (double) ((getMaxScore() - scores.get(i)) * yScale + padding);
graphPoints.add(new Point2D.Double(x1, y1));
}
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
/*double xScale = ((double) getWidth() - (2 * padding) - labelPadding) / (scores.size() - 1);
double yScale = ((double) getHeight() - 2 * padding - labelPadding) / (getMaxScore() - getMinScore());
graphPoints = new ArrayList<>();
for (int i = 0; i < scores.size(); i++) {
double x1 = (double) (i * xScale + padding + labelPadding);
double y1 = (double) ((getMaxScore() - scores.get(i)) * yScale + padding);
graphPoints.add(new Point2D.Double(x1, y1));
}*/
// draw white background
g2.setColor(Color.WHITE);
g2.fillRect(padding + labelPadding, padding, getWidth() - (2 * padding) - labelPadding, getHeight() - 2 * padding - labelPadding);
g2.setColor(Color.BLACK);
// create hatch marks and grid lines for y axis.
for (int i = 0; i < numberYDivisions + 1; i++) {
int x0 = padding + labelPadding;
int x1 = pointWidth + padding + labelPadding;
int y0 = getHeight() - ((i * (getHeight() - padding * 2 - labelPadding)) / numberYDivisions + padding + labelPadding);
int y1 = y0;
if (scores.size() > 0) {
g2.setColor(gridColor);
g2.drawLine(padding + labelPadding + 1 + pointWidth, y0, getWidth() - padding, y1);
g2.setColor(Color.BLACK);
String yLabel = ((int) ((getMinScore() + (getMaxScore() - getMinScore()) * ((i * 1.0) / numberYDivisions)) * 100)) / 100.0 + "";
FontMetrics metrics = g2.getFontMetrics();
int labelWidth = metrics.stringWidth(yLabel);
g2.drawString(yLabel, x0 - labelWidth - 5, y0 + (metrics.getHeight() / 2) - 3);
}
g2.drawLine(x0, y0, x1, y1);
}
// and for x axis
for (int i = 0; i < scores.size(); i++) {
if (scores.size() > 1) {
int x0 = i * (getWidth() - padding * 2 - labelPadding) / (scores.size() - 1) + padding + labelPadding;
int x1 = x0;
int y0 = getHeight() - padding - labelPadding;
int y1 = y0 - pointWidth;
if ((i % ((int) ((scores.size() / 20.0)) + 1)) == 0) {
g2.setColor(gridColor);
g2.drawLine(x0, getHeight() - padding - labelPadding - 1 - pointWidth, x1, padding);
g2.setColor(Color.BLACK);
String xLabel = i + "";
FontMetrics metrics = g2.getFontMetrics();
int labelWidth = metrics.stringWidth(xLabel);
g2.drawString(xLabel, x0 - labelWidth / 2, y0 + metrics.getHeight() + 3);
}
g2.drawLine(x0, y0, x1, y1);
}
}
// create x and y axes
g2.drawLine(padding + labelPadding, getHeight() - padding - labelPadding, padding + labelPadding, padding);
g2.drawLine(padding + labelPadding, getHeight() - padding - labelPadding, getWidth() - padding, getHeight() - padding - labelPadding);
Stroke oldStroke = g2.getStroke();
g2.setColor(lineColor);
g2.setStroke(GRAPH_STROKE);
for (int i = 0; i < graphPoints.size() - 1; i++) {
double x1 = graphPoints.get(i).x;
double y1 = graphPoints.get(i).y;
double x2 = graphPoints.get(i + 1).x;
double y2 = graphPoints.get(i + 1).y;
g2.draw(new Line2D.Double(x1, y1, x2, y2));
}
g2.setStroke(oldStroke);
g2.setColor(pointColor);
for (int i = 0; i < graphPoints.size(); i++) {
double x = graphPoints.get(i).x - pointWidth / 2;
double y = graphPoints.get(i).y - pointWidth / 2;
int ovalW = pointWidth;
int ovalH = pointWidth;
//g2.fillOval(x, y, ovalW, ovalH);
}
}
public void findNearPoint(double x, double y) {
double delta = 0;
for (int j = 0; j < graphPoints.size(); j++) {
double sx = graphPoints.get(j).x;
double sy = graphPoints.get(j).y;
double root = sqrt((x-sx)*(x-sx) + (y-sy)*(y-sy));
if (j == 0) {
delta = root;
serieX = sx;
}
else if (root < delta) {
serieX = sx;
delta = root;
}
}
}
public void editSerie(double x, double y) {
double tmpSerieX = serieX;
int ind = 0;
for (int i = 0; i < graphPoints.size(); i++) {
if (graphPoints.get(i).x == tmpSerieX) {
ind = i;
}
}
graphPoints.remove(ind);
graphPoints.add(ind, new Point2D.Double(x, y));
serieX = x;
}
private double getMinScore() {
double minScore = Double.MAX_VALUE;
for (Double score : scores) {
minScore = Math.min(minScore, score);
}
return minScore;
}
private double getMaxScore() {
double maxScore = Double.MIN_VALUE;
for (Double score : scores) {
maxScore = Math.max(maxScore, score);
}
return maxScore;
}
public void setScores(List<Double> scores) {
this.scores = scores;
invalidate();
this.repaint();
}
public List<Double> getScores() {
return scores;
}
private static void createAndShowGui() {
List<Double> scores = new ArrayList<>();
Random random = new Random();
int maxDataPoints = 40;
int maxScore = 10;
for (int i = 0; i < maxDataPoints; i++) {
scores.add((double) random.nextDouble() * maxScore);
}
SimpleGrapher2 mainPanel = new SimpleGrapher2(scores);
mainPanel.setPreferredSize(new Dimension(800, 600));
JFrame frame = new JFrame("DrawGraph");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
1 个答案:
答案 0 :(得分：2)
当您计算x/yScale ...
public SimpleGrapher2(List<Double> scores) {
//...
double xScale = ((double) getWidth() - (2 * padding) - labelPadding) / (scores.size() - 1);
double yScale = ((double) getHeight() - 2 * padding - labelPadding) / (getMaxScore() - getMinScore());
//...
}
在构建组件时，组件大小为0x0。您需要等到组件在计算点之前以某种有意义的方式调整大小...
这也是有问题的，因为当它首次在屏幕上实现时，可以连续多次调整组件的大小。
我过去所做的事情是使用Swing Timer设置一个小的延迟，以允许在很短的时间内调整组件的次数。一旦安顿下来，Timer将触发，您可以执行所需的操作，例如......
public SimpleGrapher2(List<Double> scores) {
//...
addComponentListener(new ComponentAdapter() {
private Timer initTimer = new Timer(200, new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
initTimer.stop();
double xScale = ((double) getWidth() - (2 * padding) - labelPadding) / (scores.size() - 1);
double yScale = ((double) getHeight() - 2 * padding - labelPadding) / (getMaxScore() - getMinScore());
graphPoints = new ArrayList<>();
for (int i = 0; i < scores.size(); i++) {
double x1 = (double) (i * xScale + padding + labelPadding);
double y1 = (double) ((getMaxScore() - scores.get(i)) * yScale + padding);
graphPoints.add(new Point2D.Double(x1, y1));
}
repaint();
}
});
@Override
public void componentResized(ComponentEvent e) {
if (graphPoints == null) {
initTimer.restart();
}
}
});
}
所有这一切都等待，直到compoentResized事件之间的计时器超过200毫秒（您可以使用此值来使其更接近您想要的，但我发现大约250毫秒是一个合理的延迟）
您需要更正paintComponent以允许graphPoints null。
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