DrawingBox is a frame upon which many of the
* java.awt.Graphics operations can be performed. As a
* frame, it exists as a separate window, and the operations on it may be
* performed from anywhere -- not just from within a paint
* method (as is normal with a frame's Graphics object).
* (However, to be used effectively as a teaching aid, operations on a
* DrawingBox should be performed from within
* a single method, which later can be converted to a paint
* method.)
*
* Care must be taken that when this frame is obscured, that
* subsequently it can repaint itself. An off-screen Graphics
* context keeps an up-to-date copy of this frame's Graphics
* at all times. The origin of the coordinate system is translated so that
* it is in the upper left of the drawable portion of the
* frame. Consequently, DrawingBox behaves more like a
* Canvas object that occupies the drawable portion of a frame.
*
* In order to distinguish the Frame from its drawable portion,
* methods getDrawableWidth and getDrawableHeight
* are provided.
*
* DrawingBox uses inner classes DBMouseAdapter
* (extending java.awt.event.MouseAdapter) to implement mouse
* listeners, and DBMouseMotionAdapter (extending
* java.awt.event.MouseMotionAdapter) to implement mouse
* motion listeners.
*
* @see ClosableFrame
* @see java.awt.Graphics
*
* @author M. Dennis Mickunas
*
*/
public class DrawingBox extends ClosableFrame {
/**
* the Graphics object affiliated with this Frame
*/
private Graphics g;
/**
* the size of the user's screen
*/
Dimension screenSize;
/**
* an off-screen image of everything that is done to g
*/
private Image buffer;
/**
* the Graphics affiliated with the off-screen image
*/
private Graphics gContext;
/**
* Constructs a DrawingBox with the default title.
*/
public DrawingBox () {
this ("DrawingBox");
}
/**
* Constructs a DrawingBox with a specific title.
*
* @param title the string to use as this DrawingBox title.
*
* @see java.awt.Graphics#translate(int, int)
* @see java.awt.Container#getInsets()
*/
public DrawingBox (String title) {
super(title);
screenSize = Toolkit.getDefaultToolkit().getScreenSize();
setBackground(Color.white);
// By default, set size to 3/4 screen wide by 3/4 screen high.
setSize(screenSize.width*3/4, screenSize.height*3/4);
setVisible(true);
g = getGraphics();
validate();
setFont(new Font("Courier", Font.PLAIN, 12));
// Create an off-screen image, and get its Graphics object
buffer = createImage(screenSize.width, screenSize.height);
gContext = buffer.getGraphics();
gContext.setColor(Color.white);
gContext.fillRect(0, 0, screenSize.width, screenSize.height);
gContext.setColor(Color.black);
// Translate the origin to the upper-left corner of the drawable area.
g.translate(getInsets().left, getInsets().top);
addMouseListener(new DBMouseAdapter());
addMouseMotionListener(new DBMouseMotionAdapter());
}
/**
* DBMouseAdapter is an inner class that implements
* the Mouse listener for DrawingBox. It does this
* by extending the Java convenience wrapper MouseAdapter.
*
* Each MouseEvent must be translated to correspond
* to the translated coordinate system of the DrawingBox.
* This translation remains in effect for any downstream mouse
* listeners.
*
* @see java.awt.event.MouseAdapter
* @see java.awt.event.MouseEvent#translatePoint(int int)
* @see java.awt.Container#getInsets()
*/
public class DBMouseAdapter extends MouseAdapter {
public void mouseClicked(MouseEvent e) {
e.translatePoint(-getInsets().left, -getInsets().top);
}
public void mouseEntered(MouseEvent e) {
e.translatePoint(-getInsets().left, -getInsets().top);
}
public void mouseExited(MouseEvent e) {
e.translatePoint(-getInsets().left, -getInsets().top);
}
public void mousePressed(MouseEvent e) {
e.translatePoint(-getInsets().left, -getInsets().top);
}
public void mouseReleased(MouseEvent e) {
e.translatePoint(-getInsets().left, -getInsets().top);
}
}
/**
* DBMouseMotionAdapter is an inner class that implements
* the Mouse motion listener for DrawingBox. It does this
* by extending the Java convenience wrapper
* MouseMotionAdapter.
*
* Each MouseEvent must be translated to correspond to the
* translated coordinate system of the DrawingBox. This
* translation remains in effect for any downstream mouse motion listeners.
*
* @see java.awt.event.MouseMotionAdapter
* @see java.awt.event.MouseEvent#translatePoint(int int)
* @see java.awt.Container#getInsets()
*/
public class DBMouseMotionAdapter extends MouseMotionAdapter {
public void mouseDragged(MouseEvent e) {
e.translatePoint(-getInsets().left, -getInsets().top);
}
public void mouseMoved(MouseEvent e) {
e.translatePoint(-getInsets().left, -getInsets().top);
}
}
/**
* Paints the drawing box. This will be called when the drawing box must
* be restored. The off-screen image in buffer has a true
* copy of what was drawn in the drawing box.
*
* @see java.awt.Container#getInsets()
*/
public void paint (Graphics g) {
// Restore the DrawingBox from the offscreen cache,
// making sure that the insets are avoided.
if (buffer!=null)
g.drawImage(buffer, getInsets().left, getInsets().top, this);
}
/** Returns the current drawable width (less insets) of this drawing box.
*
* @see java.awt.Container#getInsets()
*
* @return the current drawable width of this drawing box.
*/
public int getDrawableWidth () {
return getSize().width-getInsets().left-getInsets().right;
}
/** Returns the current drawable height (less insets) of this drawing box.
*
* @see java.awt.Container#getInsets()
*
* @return the current drawable height of this drawing box.
*/
public int getDrawableHeight () {
return getSize().height-getInsets().top-getInsets().bottom;
}
/**
* Sets the drawable size of this drawing box by setting a smaller size,
* then increasing it by the amount of the insets.
*
* @see java.awt.Container#getInsets()
*
* @param width the desired drawable width
* @param height the desired drawable height
*/
public void setDrawableSize (int width, int height) {
super.setSize(width, height);
super.setSize(width+getInsets().left+getInsets().right,
height+getInsets().top+getInsets().bottom);
}
/**
* Gets this drawing box's current color.
*
* @return this drawing box's current color.
*
* @see java.awt.Color
* @see java.awt.Graphics#getColor
*/
public Color getColor () { return g.getColor(); }
/**
* Sets this drawing box's color.
*
* @param c the desired drawing box's color.
*
* @see java.awt.Color
* @see java.awt.Graphics#setColor
*/
public void setColor (Color c) {
g.setColor(c);
gContext.setColor(c);
}
/**
* Draws a line, using the current color, between the points
* (x1,y1) and (x2,y2)
* in this drawing box's coordinate system.
*
* @param x1 the first point's x coordinate.
* @param y1 the first point's y coordinate.
* @param x2 the second point's x coordinate.
* @param y2 the second point's y coordinate.
*
* @see java.awt.Graphics#drawLine
*/
public void drawLine (int x1, int x2, int y1, int y2) {
gContext.drawLine (x1, x2, y1, y2);
g.drawLine (x1, x2, y1, y2);
}
/**
* Draws the outline of the specified rectangle.
* The left and right edges of the rectangle are at
* x and x+width.
* The top and bottom edges are at
* y and y+height.
* The rectangle is drawn using this drawing box's current color.
*
* @param x the x coordinate
* of the rectangle to be drawn.
* @param y the y coordinate
* of the rectangle to be drawn.
* @param width the width of the rectangle to be drawn.
* @param height the height of the rectangle to be drawn.
*
* @see java.awt.Graphics#drawRect
*/
public void drawRect (int x, int y, int width, int height) {
gContext.drawRect (x, y, width, height);
g.drawRect (x, y, width, height);
}
/**
* Fills the specified rectangle.
* The left and right edges of the rectangle are at
* x and x+width-1.
* The top and bottom edges are at
* y and y+height-1.
* The resulting rectangle covers an area
* width pixels wide by
* height pixels tall.
* The rectangle is filled using this drawing box's current color.
*
* @param x the x coordinate
* of the rectangle to be filled.
* @param y the y coordinate
* of the rectangle to be filled.
* @param width the width of the rectangle to be filled.
* @param height the height of the rectangle to be filled.
*
* @see java.awt.Graphics#fillRect
*/
public void fillRect (int x, int y, int width, int height) {
gContext.fillRect (x, y, width, height);
g.fillRect (x, y, width, height);
}
/**
* Draws the outline of a circle.
* The result is a circle with center at (x,y)
* and a given radius.
*
* @param x the x coordinate of the center
* of the circle to be drawn.
* @param y the y coordinate of the center
* of the circle to be drawn.
* @param radius the radius of the circle to be drawn.
*
* @see java.awt.Graphics#drawOval
*/
public void drawCircle (int x, int y, int radius) {
gContext.drawOval (x-radius, y-radius, 2*radius, 2*radius);
g.drawOval (x-radius, y-radius, 2*radius, 2*radius);
}
/**
* Draws the outline of a circle.
* The result is a circle with center at p
* and a given radius.
*
* @param p the point giving the center of the
* circle to be drawn.
* @param radius the radius of the circle to be drawn.
*
* @see CSLib#drawCircle(int, int, int)
*/
public void drawCircle (Point p, int radius) {
drawCircle (p.x, p.y, radius);
}
/**
* Fills a circle with center at (x,y)
* and with a given radius using this drawing box's current color.
*
* @param x the x coordinate of the center
* of the circle to be filled.
* @param y the y coordinate of the center
* of the circle to be filled.
* @param radius the radius of the circle to be filled.
*
* @see java.awt.Graphics#fillOval
*/
public void fillCircle (int x, int y, int radius) {
gContext.fillOval (x-radius, y-radius, 2*radius, 2*radius);
g.fillOval (x-radius, y-radius, 2*radius, 2*radius);
}
/**
* Fills a circle with center at point p
* and with a given radius, using this drawing box's current color.
*
* @param p the point giving the center of the
* circle to be filled.
* @param radius the radius of the circle to be filled.
*
* @see CSLib#fillCircle(int, int, int)
*/
public void fillCircle (Point p, int radius) {
fillCircle(p.x, p.y, radius);
}
/**
* Draws the text given by the specified string, using this
* drawing box's current font and color. The baseline of the
* leftmost character is at position (x,y) in this
* drawing box's translated coordinate system.
*
* @param str the string to be drawn.
* @param x the x coordinate.
* @param y the y coordinate.
*
* @see java.awt.Graphics#drawString
*/
public void drawString (String str, int x, int y) {
gContext.drawString (str, x, y);
g.drawString (str, x, y);
}
/**
* Fills an oval bounded by the specified rectangle with this
* drawing box's current color.
*
* @param x the x coordinate of the upper left corner
* of the oval to be filled.
* @param y the y coordinate of the upper left corner
* of the oval to be filled.
* @param width the width of the oval to be filled.
* @param height the height of the oval to be filled.
*
* @see java.awt.Graphics#fillOval
*/
public void fillOval (int x1, int y1, int width, int height) {
gContext.fillOval (x1, y1, width, height);
g.fillOval (x1, y1, width, height);
}
/**
* Draws the outline of an oval.
* The result is an ellipse that fits within the rectangle
* specified by the x, y,
* width, and height arguments.
*
* @param x the x coordinate of the upper left
* corner of the oval to be drawn.
* @param y the y coordinate of the upper left
* corner of the oval to be drawn.
* @param width the width of the oval to be drawn.
* @param height the height of the oval to be drawn.
*
* @see java.awt.Graphics#drawOval
*/
public void drawOval (int x1, int y1, int width, int height) {
gContext.drawOval (x1, y1, width, height);
g.drawOval (x1, y1, width, height);
}
/**
* Clears the specified rectangle by filling it with the background
* color of the current drawing box.
*
* @param x the x coordinate of the rectangle to clear.
* @param y the y coordinate of the rectangle to clear.
* @param width the width of the rectangle to clear.
* @param height the height of the rectangle to clear.
*
* @see java.awt.Graphics#setColor
* @see java.awt.Graphics#fillRect
* @see java.awt.Graphics#clearRect
*/
public void clearRect (int x, int y, int width, int height) {
gContext.setColor(Color.white);
gContext.fillRect (x, y, width, height);
gContext.setColor(g.getColor());
g.clearRect (x, y, width, height);
}
/**
* Clears the entire drawing box.
*
* @see java.awt.Graphics#setColor
* @see java.awt.Graphics#fillRect
* @see java.awt.Graphics#clearRect
*/
public void clear() {
gContext.setColor(Color.white);
gContext.fillRect (0, 0, screenSize.width, screenSize.height);
gContext.setColor(g.getColor());
g.clearRect(0, 0, getDrawableWidth(), getDrawableHeight());
}
/**
* Draws the specified image with its top-left corner at
* (x,y) in this drawing box's coordinate system.
*
* This method waits for the image to be fully loaded. * * @param img the specified image to be drawn. * @param x the x coordinate. * @param y the y coordinate. * * @see java.awt.Graphics#drawImage * @see java.awt.Image * @see java.awt.MediaTracker */ public void drawImage (Image img, int x, int y) { // Wait for the image to be fully loaded. MediaTracker checker = new MediaTracker(this); checker.addImage(img, 0); try { checker.waitForID(0);} catch (InterruptedException e){}; // Now draw it. gContext.drawImage(img, x, y, this); g.drawImage(img, x, y, this); } }