Mouse hit and textlayout
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Shape;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.font.FontRenderContext;
import java.awt.font.TextAttribute;
import java.awt.font.TextHitInfo;
import java.awt.font.TextLayout;
import java.awt.geom.Point2D;
import java.text.AttributedCharacterIterator;
import java.text.AttributedString;
import java.util.Hashtable;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class HitTestSample extends JPanel {
private static final Color STRONG_CARET_COLOR = Color.red;
private static final Color WEAK_CARET_COLOR = Color.black;
private TextLayout textLayout;
private int insertionIndex;
private static final FontRenderContext DEFAULT_FRC = new FontRenderContext(
null, false, false);
private static final Hashtable map = new Hashtable();
static {
map.put(TextAttribute.SIZE, new Float(18.0));
}
private static AttributedString helloWorld = new AttributedString(
"Java Source and Support.", map);
public HitTestSample() {
AttributedCharacterIterator text = helloWorld.getIterator();
// Create a new TextLayout from the given text.
textLayout = new TextLayout(text, DEFAULT_FRC);
// Initilize insertionIndex.
insertionIndex = 0;
addMouseListener(new HitTestMouseListener());
}
public Dimension getPreferredSize() {
return new Dimension(400, 250);
}
private Point2D computeLayoutOrigin() {
Dimension size = getPreferredSize();
Point2D.Float origin = new Point2D.Float();
origin.x = (float) (size.width - textLayout.getAdvance()) / 2;
origin.y = (float) (size.height - textLayout.getDescent() + textLayout
.getAscent()) / 2;
return origin;
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
setBackground(Color.white);
Graphics2D graphics2D = (Graphics2D) g;
Point2D origin = computeLayoutOrigin();
graphics2D.translate(origin.getX(), origin.getY());
// Draw textLayout.
textLayout.draw(graphics2D, 0, 0);
// Retrieve caret Shapes for insertionIndex.
Shape[] carets = textLayout.getCaretShapes(insertionIndex);
graphics2D.setColor(STRONG_CARET_COLOR);
graphics2D.draw(carets[0]);
if (carets[1] != null) {
graphics2D.setColor(WEAK_CARET_COLOR);
graphics2D.draw(carets[1]);
}
}
private class HitTestMouseListener extends MouseAdapter {
public void mouseClicked(MouseEvent e) {
Point2D origin = computeLayoutOrigin();
// Compute the mouse click location relative to
// textLayout's origin.
float clickX = (float) (e.getX() - origin.getX());
float clickY = (float) (e.getY() - origin.getY());
// Get the character position of the mouse click.
TextHitInfo currentHit = textLayout.hitTestChar(clickX, clickY);
insertionIndex = currentHit.getInsertionIndex();
// Repaint the Component so the new caret(s) will be displayed.
repaint();
}
}
public static void main(String[] args) {
JFrame f = new JFrame("HitTestSample");
HitTestSample demo = new HitTestSample();
f.getContentPane().add(demo, "Center");
f.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
f.setSize(new Dimension(400, 250));
f.setVisible(true);
}
}
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