Java Swing – Repaint（）无法正常工作
我从这个主题中选择了程序。 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()工作很奇怪。 当我在paintComponent得到（x，y）点时， repaint()根本不起作用。 因此，这是在构造函数和paintComponent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 scores; private static double serieX = 0; public List graphPoints; public SimpleGrapher2(List 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 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 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 scores) { this.scores = scores; invalidate(); this.repaint(); } public List getScores() { return scores; } private static void createAndShowGui() { List 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(); } }); } }
当您计算x/yScale时，问题出在构造x/yScale …
public SimpleGrapher2(List scores) { //... double xScale = ((double) getWidth() - (2 * padding) - labelPadding) / (scores.size() - 1); double yScale = ((double) getHeight() - 2 * padding - labelPadding) / (getMaxScore() - getMinScore()); //... }
在构造组件时，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resize…
这也是有问题的，因为当组件首次在屏幕上实现时，可以快速连续地重新调整组件的大小。
我过去所做的是使用摆动Timer设置为一个小的延迟，以允许组件在很短的时间内resize。 一旦它全部安定下来， Timer将触发，你可以执行所需的操作，例如……
public SimpleGrapher2(List 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毫秒是合理的延迟）
您需要更正paintComponent以允许graphPoints也为null 。