import javax.swing.*; import java.awt.*; import java.awt.font.FontRenderContext; import java.awt.font.TextHitInfo; import java.awt.font.TextLayout; import java.awt.geom.Point2D; import java.awt.event.MouseAdapter; import java.awt.event.MouseEvent; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; import java.text.AttributedCharacterIterator; import java.text.AttributedCharacterIterator; import java.text.AttributedString; import java.awt.font.TextAttribute; import java.util.Hashtable; import java.util.Enumeration; /** * This class demonstrates how to hit-test a TextLayout. Hit-testing * is the mapping of a graphical location to a character position within * text. * * This class constructs a TextLayout from an AttributedCharacterIterator * and displays the TextLayout. When the mouse is clicked inside this * Component, the mouse position is mapped to a character position, and the * carets for this character position are displayed. */ public class HitTestSample extends JApplet { // Colors to use for the strong and weak carets. private static final Color STRONG_CARET_COLOR = Color.red; private static final Color WEAK_CARET_COLOR = Color.black; // The TextLayout to draw and hit-test. private TextLayout textLayout; // The insertion index of the most recent mouse click. 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)); } // text to use in samples: private static AttributedString helloWorld = new AttributedString("Hello World", map); Dimension preferredSize = new Dimension(400, 250); HitPane hitPane; public void init() { AttributedCharacterIterator text = helloWorld.getIterator(); buildUI(getContentPane(), text); } public void buildUI(Container container, AttributedCharacterIterator text){ // Create a new TextLayout from the given text. textLayout = new TextLayout(text, DEFAULT_FRC); // Initilize insertionIndex. insertionIndex = 0; hitPane = new HitPane(); container.add(hitPane, BorderLayout.CENTER); hitPane.addMouseListener(new HitTestMouseListener()); } public Dimension getPreferredSize() { return preferredSize; } /** * Compute a location within this Component for textLayout's origin, * such that textLayout is centered horizontally and vertically. * * Note that this location is unknown to textLayout; it is used only * by this Component for positioning. */ 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; } class HitPane extends JPanel { public void HitPane() {} /** * Draw textLayout and the carets corresponding to the most recent * mouse click (if any). */ public void paintComponent(Graphics g) { super.paintComponent(g); setBackground(Color.white); Graphics2D graphics2D = (Graphics2D) g; Point2D origin = computeLayoutOrigin(); // Since the caret Shapes are relative to the origin // of textLayout, we'll translate the graphics so that // the origin of the graphics is where we want textLayout // to appear. graphics2D.translate(origin.getX(), origin.getY()); // Draw textLayout. textLayout.draw(graphics2D, 0, 0); // Retrieve caret Shapes for insertionIndex. Shape[] carets = textLayout.getCaretShapes(insertionIndex); // Draw the carets. carets[0] is the strong caret, and // is never null. carets[1], if it is not null, is the // weak caret. 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 { /** * Compute the character position of the mouse click. */ 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. hitPane.repaint(); } } public static void main(String[] args) { JFrame sampleFrame = new JFrame("HitTestSample"); AttributedCharacterIterator text = helloWorld.getIterator(); final HitTestSample controller = new HitTestSample(); controller.buildUI(sampleFrame.getContentPane(), text); sampleFrame.addWindowListener(new WindowAdapter(){ public void windowClosing(WindowEvent e) { System.exit(0); } }); sampleFrame.setSize(new Dimension(400, 250)); sampleFrame.setVisible(true); } }