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我試着去創造一些撥號慣量模擬等，我想避免的OpenGL如果這是可能看中，順利和快速的模擬儀表。
問題
我在Java代碼中是比我預期的要慢得多。我想讓我的錶盤在從最小值（0）到最大值（1024，我可以改變這個，但我需要平滑度）短於0.5秒的時間內移動。
我試着測量花在重繪和paintComponent方法上的時間來查找問題。
重繪需要大約40us，paintComponent需要300us，在我的機器上（Core Duo 2GHz，Windows 7）。
它似乎足夠快（1/0.000340s =〜3000「運行」每秒）。
我認爲視頻卡是瓶頸，它會減慢我的代碼，但我不知道該如何處理它。
問題
如何使我的速度更快，並保持流暢的動畫儘可能？
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.Stroke;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.Point2D;
import java.awt.image.BufferedImage;
import javax.swing.*;
public class Main extends JPanel {
private static final Point2D CENTER = new Point2D.Double(PREF_W/2.0,
PREF_W/2.0);
private static final double RADIUS = PREF_W/2.0;
private static final Color LARGE_TICK_COLOR = Color.DARK_GRAY;
private static final Color CENTER_HUB_COLOR = Color.DARK_GRAY;
private static final Stroke LARGE_TICK_STROKE = new BasicStroke(4f);
private static final Stroke LINE_TICK_STROKE = new BasicStroke(8f);
private static final int LRG_TICK_COUNT = 18;
private static final double TOTAL_LRG_TICKS = 24;
private static final double LRG_TICK_OUTER_RAD = 0.9;
private static final double LRG_TICK_INNER_RAD = 0.8;
private static final int START_TICK = 10;
private static final double CENTER_HUB_RADIUS = 10;
private static final double DIAL_INNER_RAD = 0.00;
private static final double DIAL_OUTER_RAD = 0.75;
private static final Color DIAL_COLOR = Color.DARK_GRAY;
private BufferedImage backgroundImg;
private static final int PREF_W = 400; //
private static final int PREF_H = 400;
private static final double INIT_VALUE = 0;
public static final int MAX_VALUE = 1024; // resolution
public static int delay = 1; // delay (ms) between value changes
private double theta;
private double cosTheta;
private double sinTheta;
private static long microtime;
public Main() {
setBackground(Color.white);
backgroundImg = createBackgroundImg();
setSpeed(INIT_VALUE);
}
public void setSpeed(double speed) {
if (speed < 0) {
speed = 0;
} else if (speed > MAX_VALUE) {
speed = MAX_VALUE;
}
this.theta = ((speed/MAX_VALUE) * LRG_TICK_COUNT * 2.0 + START_TICK)
* Math.PI/TOTAL_LRG_TICKS;
cosTheta = Math.cos(theta);
sinTheta = Math.sin(theta);
microtime = System.nanoTime()/1000;
repaint();
System.out.println("Repaint (us) = " + (System.nanoTime()/1000 - microtime));
}
private BufferedImage createBackgroundImg() {
BufferedImage img = new BufferedImage(PREF_W, PREF_H,
BufferedImage.TYPE_INT_ARGB);
Graphics2D g2 = img.createGraphics();
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2.setColor(LARGE_TICK_COLOR);
g2.setStroke(LARGE_TICK_STROKE);
for (double i = 0; i < LRG_TICK_COUNT; i++) {
double theta = (i * 2.0 + START_TICK) * Math.PI/TOTAL_LRG_TICKS;
double cosTheta = Math.cos(theta);
double sinTheta = Math.sin(theta);
int x1 = (int) (LRG_TICK_INNER_RAD * RADIUS * cosTheta + CENTER.getX());
int y1 = (int) (LRG_TICK_INNER_RAD * RADIUS * sinTheta + CENTER.getY());
int x2 = (int) (LRG_TICK_OUTER_RAD * RADIUS * cosTheta + CENTER.getX());
int y2 = (int) (LRG_TICK_OUTER_RAD * RADIUS * sinTheta + CENTER.getY());
g2.drawLine(x1, y1, x2, y2);
}
g2.setColor(CENTER_HUB_COLOR);
int x = (int) (CENTER.getX() - CENTER_HUB_RADIUS);
int y = (int) (CENTER.getY() - CENTER_HUB_RADIUS);
int width = (int) (2 * CENTER_HUB_RADIUS);
int height = width;
g2.fillOval(x, y, width, height);
g2.dispose();
return img;
}
@Override
protected void paintComponent(Graphics g) {
System.out.println("Paint component (us) = " + (System.nanoTime()/1000 - microtime));
super.paintComponent(g);
if (backgroundImg != null) {
g.drawImage(backgroundImg, 0, 0, this);
}
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2.setStroke(LINE_TICK_STROKE);
g.setColor(DIAL_COLOR);
int x1 = (int) (DIAL_INNER_RAD * RADIUS * cosTheta + CENTER.getX());
int y1 = (int) (DIAL_INNER_RAD * RADIUS * sinTheta + CENTER.getY());
int x2 = (int) (DIAL_OUTER_RAD * RADIUS * cosTheta + CENTER.getX());
int y2 = (int) (DIAL_OUTER_RAD * RADIUS * sinTheta + CENTER.getY());
g.drawLine(x1, y1, x2, y2);
microtime = System.nanoTime()/1000;
}
@Override
public Dimension getPreferredSize() {
return new Dimension(PREF_W, PREF_H);
}
private static void createAndShowGui() {
final Main mainPanel = new Main();
JFrame frame = new JFrame("DailAnimation");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
new Timer(delay, new ActionListener() {
double speed = 0;
@Override
public void actionPerformed(ActionEvent evt) {
speed ++;
if (speed > Main.MAX_VALUE) {
speed = 0;
}
mainPanel.setSpeed(speed);
}
}).start();
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
小代碼描述：
有一個計時器，改變計數值。定時器間隔在開始時由變量delay定義。
這是完整的，一個文件代碼，您可以將它粘貼到您的IDE並編譯。