[英]Java Swing: how to get the color of a pixel of a JFrame
我正在嘗試為組件的選定(x,y)
像素獲取 Swing JFrame 的顏色。
例如,我想知道給定JFrame
在(0,0)
點的顏色。
原因是我的組件是一個部分透明的覆蓋層,下面有一個JPanel
。 對於不透明的像素,鼠標事件應由覆蓋層處理。 對於透明的像素,鼠標事件應該轉發到下面的JPanel
。
這是一種方法嗎?
是的,這是可能的。 使用以下示例中的函數getColorAt
:
import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.image.BufferedImage;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
public class GUI {
public static void main(String[] args) {
SwingUtilities.invokeLater(GUI::startUp);
}
private static void startUp() {
JFrame frame = new JFrame("Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(1020,760);
frame.setResizable(false);
frame.setLayout(new FlowLayout());
frame.getContentPane().setBackground(Color.BLUE);
JTextArea jta = new JTextArea(40,40);
jta.setEditable(false);
jta.setBackground(Color.WHITE);
frame.add(new JScrollPane(jta));
frame.setVisible(true);
SwingUtilities.invokeLater(() -> printColors(frame));
}
private static void printColors(JFrame frm) {
System.out.println("Color at (1, 1): " + getColorAt(frm, new Point(1, 1)));
System.out.println("Color at (300, 100): " + getColorAt(frm, new Point(300, 100)));
}
public static Color getColorAt(JFrame frm, Point p) {
Rectangle rect = frm.getContentPane().getBounds();
BufferedImage img = new BufferedImage(rect.width, rect.height, BufferedImage.TYPE_INT_ARGB);
frm.getContentPane().paintAll(img.createGraphics());
return new Color(img.getRGB(p.x, p.y), true);
}
}
我想說(希望這會帶來更好的性能),如果您願意為此使用Image
方法,那么創建一個尺寸為 1x1 像素的圖像然后轉換其創建的圖形以匹配要求的點。 並且還將此圖像重用於同一Component
(甚至GraphicsConfiguration
)的后續采樣。
我通過創建以下方法進行了一些性能測試:
getColorAtClipped
的方法,它設置創建的Image
Graphics
的剪輯,因此不必繪制所有操作。getColorAtRelocation
的方法將組件的位置臨時設置在需要采樣的位置,然后(實際上使它更快)創建一個尺寸為 1x1 的圖像並在其上繪制父級。 盡管這個方法對於 Swing 來說並不是真正的線程安全,因為它需要來回設置Component
的位置。 它還為父Container
調用printAll
,這意味着要繪制更多Component
。getColorAtTranslation
的方法創建一個 1x1 圖像並轉換其Graphics
實例,以便實際繪制所需的位置(0,0),這是圖像中真正的唯一像素。 事實證明,對於前 3 種方法來說,這種方法是最快的。ComponentColorSampler
的類本節后面是測試上述方法性能的代碼。 如果不正確,請在評論中告訴我,但請注意,我對每種方法運行了大約 300 萬次采樣,希望可以減少附帶延遲。 測試方法的每百萬個樣本,我打印一些時間,然后重新啟動該過程以測試另外一百萬個,最多 3 個。
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.image.BufferedImage;
import java.lang.reflect.InvocationTargetException;
import java.util.Objects;
import java.util.function.IntBinaryOperator;
import java.util.function.Supplier;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class Main {
public static Color getColorAtClipped(final Component comp, final Point p) {
final BufferedImage bimg = comp.getGraphicsConfiguration().createCompatibleImage(comp.getWidth(), comp.getHeight());
final Graphics2D g2d = (Graphics2D) bimg.createGraphics();
g2d.setClip(p.x, p.y, 1, 1);
comp.printAll(g2d);
g2d.dispose();
final Color c = new Color(bimg.getRGB(p.x, p.y), true);
bimg.flush();
return c;
}
public static Color getColorAtRelocation(final Component comp, final Point p) {
final Point loc = comp.getLocation();
final BufferedImage bimg = comp.getGraphicsConfiguration().createCompatibleImage(1, 1);
comp.setLocation(loc.x - p.x, loc.y - p.y);
final Graphics2D g2d = (Graphics2D) bimg.createGraphics();
//g2d.setClip(0, 0, 1, 1);
comp.getParent().printAll(g2d);
comp.setLocation(loc);
g2d.dispose();
final Color c = new Color(bimg.getRGB(0, 0), true);
bimg.flush();
return c;
}
public static Color getColorAtTranslation(final Component comp, final Point p) {
final BufferedImage bimg = comp.getGraphicsConfiguration().createCompatibleImage(1, 1);
final Graphics2D g2d = (Graphics2D) bimg.createGraphics();
g2d.translate(-p.x, -p.y);
//g2d.setClip(0, 0, 1, 1);
comp.printAll(g2d);
g2d.dispose();
final Color c = new Color(bimg.getRGB(0, 0), true);
bimg.flush();
return c;
}
public static class ComponentColorSampler<C extends Component> implements AutoCloseable, IntBinaryOperator, Supplier<C> {
private final C comp;
private final BufferedImage bimg;
private final Graphics2D g2d;
private int x, y;
public ComponentColorSampler(final C comp) {
this.comp = Objects.requireNonNull(comp);
bimg = comp.getGraphicsConfiguration().createCompatibleImage(1, 1);
g2d = bimg.createGraphics();
//g2d.setClip(0, 0, 1, 1);
x = y = 0;
}
@Override
public C get() {
return comp;
}
@Override
public int applyAsInt(final int x, final int y) {
g2d.clearRect(0, 0, 1, 1);
g2d.translate(this.x - x, this.y - y);
this.x = x;
this.y = y;
comp.printAll(g2d);
return bimg.getRGB(0, 0);
}
public Color sample(final int x, final int y) {
return new Color(applyAsInt(x, y), true);
}
@Override
public void close() {
g2d.dispose();
bimg.flush();
}
}
public static class DrawPanel extends JPanel {
private final int x, y;
private Color c;
public DrawPanel(final int x, final int y) {
this.x = x;
this.y = y;
c = Color.BLUE;
}
@Override
protected void paintComponent(final Graphics g) {
super.paintComponent(g);
g.setColor(c);
g.fillRect(x, y, 1, 1);
}
public void setColor(final Color c) {
this.c = Objects.requireNonNull(c);
paintImmediately(0, 0, getWidth(), getHeight()); //Not sure yet.
repaint(); //Just to be sure now.
}
}
//@SuppressWarnings("SleepWhileInLoop")
public static boolean checkValid(final DrawPanel dp, final Supplier<Color> sampler) throws InterruptedException, InvocationTargetException {
for (final Color c: new Color[]{Color.BLUE, Color.RED, Color.BLACK, Color.WHITE, Color.BLACK, Color.CYAN}) {
SwingUtilities.invokeAndWait(() -> dp.setColor(c));
Thread.sleep(250); //Let it some time to change (not sure if needed).
if (!Objects.equals(c, sampler.get()))
return false;
}
return true;
}
public static long checkTime(final Supplier<Color> sampler) {
final long start = System.currentTimeMillis();
for (int i = 0; i < 1000000; ++i)
sampler.get();
return System.currentTimeMillis() - start;
}
public static void main(final String[] args) throws InterruptedException, InvocationTargetException {
final Point p = new Point(100, 100);
final DrawPanel contents = new DrawPanel(p.x, p.y);
contents.setPreferredSize(new Dimension(200, 200));
final JFrame frame = new JFrame("Printed!");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(contents);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setResizable(false);
frame.setVisible(true);
final ComponentColorSampler<Component> sampler = new ComponentColorSampler<>(contents);
final Supplier<Color> clipped = () -> getColorAtClipped(contents, p),
relocation = () -> getColorAtRelocation(contents, p),
translation = () -> getColorAtTranslation(contents, p),
samplerSampler = () -> sampler.sample(p.x, p.y);
System.out.println("#### Validity checks...");
for (int i = 0; i < 3; ++i) {
System.out.println("Batch " + (i + 1) + ':');
System.out.println("> Clipped: " + checkValid(contents, clipped) + '.');
System.out.println("> Relocation: " + checkValid(contents, relocation) + '.');
System.out.println("> Translation: " + checkValid(contents, translation) + '.');
System.out.println("> Sampler: " + checkValid(contents, samplerSampler) + '.');
}
System.out.println("#### Timings...");
for (int i = 0; i < 3; ++i) {
System.out.println("Batch " + (i + 1) + ':');
System.out.println("> Clipped: " + checkTime(clipped) + "ms.");
System.out.println("> Relocation: " + checkTime(relocation) + "ms.");
System.out.println("> Translation: " + checkTime(translation) + "ms.");
System.out.println("> Sampler: " + checkTime(samplerSampler) + "ms.");
}
System.out.println("#### Done.");
}
}
程序的輸出:
#### Validity checks...
Batch 1:
> Clipped: true.
> Relocation: true.
> Translation: true.
> Sampler: true.
Batch 2:
> Clipped: true.
> Relocation: true.
> Translation: true.
> Sampler: true.
Batch 3:
> Clipped: true.
> Relocation: true.
> Translation: true.
> Sampler: true.
#### Timings...
Batch 1:
> Clipped: 34668ms.
> Relocation: 22737ms.
> Translation: 5416ms.
> Sampler: 1152ms.
Batch 2:
> Clipped: 38521ms.
> Relocation: 22805ms.
> Translation: 5451ms.
> Sampler: 1156ms.
Batch 3:
> Clipped: 38275ms.
> Relocation: 22864ms.
> Translation: 5415ms.
> Sampler: 1163ms.
#### Done.
因此,對於一百萬個樣本,第一種方法大約為 37 秒,第二種方法大約為 22 秒,第三種方法為 5 秒,最后最后一種方法略高於 1 秒(對於一百萬個樣本)。 所以ComponentColorSampler
是這些測試中最快的實現(大約每毫秒 865 個樣本)並且適用於任何Component
。 有效性檢查只是代表某種程度的驗證采樣顏色是否具有正確的值。
注意:這些測試不是 Swing/線程安全的,但會表明如果您正確使用它們會帶來什么性能(例如在事件調度線程上執行采樣)。
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.