I'm developing a Java Swing app for an award winning password protection system, and I need a large custom cursor [ 80 x 80 ], you might ask why so large, there is an online web demo you may look at to learn why it needs to be so large : http://gatecybertech.net
That large cursor is used on the login page in the above link. Of course you need to create a test password first before you can try the login process.
But anyway, in my Swing app, I hit a limit of 32 x 32 for the largest possible custom cursor, my code looks like the following :
Image cursorImage = toolkit.getImage("Cursor_Crosshair.PNG");
Tabular_Panel.setCursor(Toolkit.getDefaultToolkit().createCustomCursor(cursorImage,new Point(0,0),"custom cursor"));
The image size of Cursor_Crosshair.PNG is : 80 x 80
But what shows up in the screen is a shrinked version of it at : 32 x 32
So my question is : how can I bypass the size limit on customer cursor image, and make the cursor to show up at the size of 80 x 80 ?
I know the OS might be the reason for the limit, is there a way to overcome it ?
Here's my take on the glass pane painting approach. This is set up to behave pretty much like setting a custom cursor. The default "arrow" cursor is hidden while the custom cursor is shown, and the custom cursor is hidden when a component has some other cursor set, such as a text box.
Unfortunately, it ended up seeming to require quite a bit of Swing black magic, so I don't like it very much, but it does seem to work correctly. I've done a cursor like this before, but it was for something simpler, so I didn't run in to these issues.
Some of the problems I ran in to are:
The glass pane intercepts cursor changes (described e.g. on SO here). The only solution I've been able to find is to override Component.contains(int,int) to return false (described here, shown here), but why that works and doesn't seem to break anything else is mysterious.
Mouse exit events sometimes return a location inside the bounds of the component, so I don't think there's a reliable way to know when the mouse leaves the window except to use a timer.
package mcve;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import javax.imageio.*;
import java.net.*;
import java.io.*;
public class LargeCursor {
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> {
JFrame frame = new JFrame();
JPanel glass = new CustomGlassPane();
glass.add(new CursorPanel(), BorderLayout.CENTER);
frame.setGlassPane(glass);
// This next call is necessary because JFrame.setGlassPane delegates to the root pane:
// - https://docs.oracle.com/javase/9/docs/api/javax/swing/RootPaneContainer.html#setGlassPane-java.awt.Component-
// - http://hg.openjdk.java.net/jdk8/jdk8/jdk/file/687fd7c7986d/src/share/classes/javax/swing/JFrame.java#l738
// And JRootPane.setGlassPane may call setVisible(false):
// - https://docs.oracle.com/javase/9/docs/api/javax/swing/JRootPane.html#setGlassPane-java.awt.Component-
// - http://hg.openjdk.java.net/jdk8/jdk8/jdk/file/687fd7c7986d/src/share/classes/javax/swing/JRootPane.java#l663
glass.setVisible(true);
JPanel content = createTestPanel();
content.setCursor(BlankCursor.INSTANCE);
frame.setContentPane(content);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
});
}
static class CustomGlassPane extends JPanel {
CustomGlassPane() {
super(new BorderLayout());
super.setOpaque(false);
}
@Override
public boolean contains(int x, int y) {
return false;
}
}
static class CursorPanel extends JPanel {
final BufferedImage cursorImage;
Point mouseLocation;
CursorPanel() {
try {
cursorImage = createTransparentImage(
ImageIO.read(new URL("https://i.sstatic.net/9h2oI.png")));
} catch (IOException x) {
throw new UncheckedIOException(x);
}
setOpaque(false);
long mask = AWTEvent.MOUSE_EVENT_MASK | AWTEvent.MOUSE_MOTION_EVENT_MASK;
Toolkit.getDefaultToolkit().addAWTEventListener((AWTEvent e) -> {
switch (e.getID()) {
case MouseEvent.MOUSE_ENTERED:
case MouseEvent.MOUSE_EXITED:
case MouseEvent.MOUSE_MOVED:
case MouseEvent.MOUSE_DRAGGED:
capturePoint((MouseEvent) e);
break;
}
}, mask);
// This turned out to be necessary, because
// the 'mouse exit' events don't always have
// a Point location which is outside the pane.
Timer timer = new Timer(100, (ActionEvent e) -> {
if (mouseLocation != null) {
Point p = MouseInfo.getPointerInfo().getLocation();
SwingUtilities.convertPointFromScreen(p, this);
if (!contains(p)) {
setMouseLocation(null);
}
}
});
timer.setRepeats(true);
timer.start();
}
void capturePoint(MouseEvent e) {
Component comp = e.getComponent();
Point onThis = SwingUtilities.convertPoint(comp, e.getPoint(), this);
boolean drawCursor = contains(onThis);
if (drawCursor) {
Window window = SwingUtilities.windowForComponent(this);
if (window instanceof JFrame) {
Container content = ((JFrame) window).getContentPane();
Point onContent = SwingUtilities.convertPoint(comp, e.getPoint(), content);
Component deepest = SwingUtilities.getDeepestComponentAt(content, onContent.x, onContent.y);
if (deepest != null) {
if (deepest.getCursor() != BlankCursor.INSTANCE) {
drawCursor = false;
}
}
}
}
setMouseLocation(drawCursor ? onThis : null);
}
void setMouseLocation(Point mouseLocation) {
this.mouseLocation = mouseLocation;
repaint();
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (mouseLocation != null) {
int x = mouseLocation.x - (cursorImage.getWidth() / 2);
int y = mouseLocation.y - (cursorImage.getHeight() / 2);
g.drawImage(cursorImage, x, y, this);
}
}
}
static final class BlankCursor {
static final Cursor INSTANCE =
Toolkit.getDefaultToolkit().createCustomCursor(
new BufferedImage(1, 1, BufferedImage.TYPE_INT_ARGB),
new Point(),
"BLANK");
}
static JPanel createTestPanel() {
JPanel panel = new JPanel(new GridLayout(3, 3));
panel.setBorder(BorderFactory.createEmptyBorder(100, 100, 100, 100));
for (int i = 0; i < 9; ++i) {
if ((i % 2) == 0) {
JTextField field = new JTextField("Text Field");
field.setHorizontalAlignment(JTextField.CENTER);
panel.add(field);
} else {
panel.add(new JButton("Button"));
}
}
return panel;
}
static BufferedImage createTransparentImage(BufferedImage img) {
BufferedImage copy =
GraphicsEnvironment.getLocalGraphicsEnvironment()
.getDefaultScreenDevice()
.getDefaultConfiguration()
.createCompatibleImage(img.getWidth(),
img.getHeight(),
Transparency.TRANSLUCENT);
for (int x = 0; x < img.getWidth(); ++x) {
for (int y = 0; y < img.getHeight(); ++y) {
int rgb = img.getRGB(x, y) & 0x00FFFFFF;
int bright = (((rgb >> 16) & 0xFF) + ((rgb >> 8) & 0xFF) + (rgb & 0xFF)) / 3;
int alpha = 255 - bright;
copy.setRGB(x, y, (alpha << 24) | rgb);
}
}
return copy;
}
}