import java.awt.*; import javax.swing.*; public class Rule extends JComponent { public static final int INCH = Toolkit.getDefaultToolkit(). getScreenResolution(); public static final int HORIZONTAL = 0; public static final int VERTICAL = 1; public static final int SIZE = 35; public int orientation; public boolean isMetric; private int increment; private int units; public Rule(int o, boolean m) { orientation = o; isMetric = m; setIncrementAndUnits(); } public void setIsMetric(boolean isMetric) { this.isMetric = isMetric; setIncrementAndUnits(); repaint(); } private void setIncrementAndUnits() { if (isMetric) { units = (int)((double)INCH / (double)2.54); // dots per centimeter increment = units; } else { units = INCH; increment = units / 2; } } public boolean isMetric() { return this.isMetric; } public int getIncrement() { return increment; } public void setPreferredHeight(int ph) { setPreferredSize(new Dimension(SIZE, ph)); } public void setPreferredWidth(int pw) { setPreferredSize(new Dimension(pw, SIZE)); } public void paintComponent(Graphics g) { Rectangle drawHere = g.getClipBounds(); // Fill clipping area with dirty brown/orange. g.setColor(new Color(230, 163, 4)); g.fillRect(drawHere.x, drawHere.y, drawHere.width, drawHere.height); // Do the ruler labels in a small font that's black. g.setFont(new Font("SansSerif", Font.PLAIN, 10)); g.setColor(Color.black); // Some vars we need. int end = 0; int start = 0; int tickLength = 0; String text = null; // Use clipping bounds to calculate first tick and last tick location. if (orientation == HORIZONTAL) { start = (drawHere.x / increment) * increment; end = (((drawHere.x + drawHere.width) / increment) + 1) * increment; } else { start = (drawHere.y / increment) * increment; end = (((drawHere.y + drawHere.height) / increment) + 1) * increment; } // Make a special case of 0 to display the number // within the rule and draw a units label. if (start == 0) { text = Integer.toString(0) + (isMetric ? " cm" : " in"); tickLength = 10; if (orientation == HORIZONTAL) { g.drawLine(0, SIZE-1, 0, SIZE-tickLength-1); g.drawString(text, 2, 21); } else { g.drawLine(SIZE-1, 0, SIZE-tickLength-1, 0); g.drawString(text, 9, 10); } text = null; start = increment; } // ticks and labels for (int i = start; i < end; i += increment) { if (i % units == 0) { tickLength = 10; text = Integer.toString(i/units); } else { tickLength = 7; text = null; } if (tickLength != 0) { if (orientation == HORIZONTAL) { g.drawLine(i, SIZE-1, i, SIZE-tickLength-1); if (text != null) g.drawString(text, i-3, 21); } else { g.drawLine(SIZE-1, i, SIZE-tickLength-1, i); if (text != null) g.drawString(text, 9, i+3); } } } } }