import objectdraw.*;

/*
 * This program shows how to draw cross hairs focussing on 
 * the cursor when the mouse is dragged, as in a drawing program.
 *
 * It illustrates accessor methods on the canvas and points.
 * 
 * This version also illustrates building a string from numbers
 * and using moveTo with an offset from a point by showing
 * the coordinates of the cursor next to it.
 */

public class CrossHairs extends WindowController {    

    // the crosshair lines
    private Line vert, horiz;
    
    // the label next to the cross hairs
    private Text label;

    // displacement from the cursor to the coordinates label
    private static final int LABEL_X_OFFSET = 10;
    private static final int LABEL_Y_OFFSET = 5;
    
    /*
     * Load and display a picture as background
     */
    public void begin() {
        new VisibleImage(getImage("background.jpg"), 0, 0, canvas);
    }

    /*
     * Display the crosshairs as soon as the mouse button is pressed.
     */
    public void onMousePress(Location point) {
        vert = new Line(point.getX(), 0, point.getX(), canvas.getHeight(), canvas);
        horiz = new Line(0, point.getY(), canvas.getWidth(), point.getY(), canvas);
        
        label = new Text(point.getX() + ", " + point.getY(), 
                         point.getX() + LABEL_X_OFFSET, 
                         point.getY() + LABEL_Y_OFFSET, 
                         canvas);
    }
    
    /*
     * Move the crosshairs as the mouse is dragged.
     */
    public void onMouseDrag(Location point) {

        // refocus the lines over the cursor
        vert.setEndPoints(point.getX(), 0, point.getX(), canvas.getHeight());                
        horiz.setEndPoints(0, point.getY(), canvas.getWidth(), point.getY());

        // create the new text for the label, and also move it.
        label.setText(point.getX() + ", " + point.getY());
        label.moveTo(point.getX() + LABEL_X_OFFSET, 
                     point.getY() + LABEL_Y_OFFSET);
    }
    
    /*
     * Remove the crosshairs when the mouse is released.
     */
    public void onMouseRelease(Location point){
        vert.removeFromCanvas();
        horiz.removeFromCanvas();
        label.removeFromCanvas();
    }
}