Computer Science 252
Problem Solving with Java
Spring 2014, The College of Saint Rose
MovingFlags Demo
A working demo of MovingFlags will appear below. Click inside the applet to interact with it.
MovingFlags BlueJ Project
Click here to download a BlueJ project for MovingFlags.
MovingFlags Source Code
The Java source code for MovingFlags is below. Click on a file name to download it.
/*
*
* Example FlagMaker: draw some flags at click points.
*
* Jim Teresco, Siena College, CSIS 120, Spring 2011
* Based on example from CSCI 134, Williams College
*
* $Id: MovingFlags.java 2218 2013-10-18 14:06:39Z terescoj $
*/
import java.awt.*;
import objectdraw.*;
import java.util.ArrayList;
public class MovingFlags extends WindowController {
private ArrayList<Flag> flags;
private boolean dragging;
private Flag selectedFlag;
private Location lastMouse;
public void begin() {
flags = new ArrayList<Flag>();
new Text("Click to draw a flag", 10, 10,canvas);
}
public void onMousePress(Location point) {
dragging = false;
// if point is on a flag, start dragging it
for (int flagNum = 0; flagNum < flags.size(); flagNum++) {
if (flags.get(flagNum).contains(point)) {
dragging = true;
selectedFlag = flags.get(flagNum);
lastMouse = point;
}
}
// if not, create a new flag
if (!dragging) {
flags.add(new Flag(point, canvas));
}
}
public void onMouseDrag(Location point) {
if (dragging) {
selectedFlag.move(point.getX() - lastMouse.getX(),
point.getY() - lastMouse.getY());
lastMouse = point;
}
}
}
/*
*
* Example FlagMaker: draw a 48-star flag using while loops
* and private helper methods.
*
* Jim Teresco, Siena College, CSIS 120, Spring 2011
* Based on example from CSCI 134, Williams College
*
* $Id: Flag.java 2218 2013-10-18 14:06:39Z terescoj $
*/
import java.awt.*;
import objectdraw.*;
import java.util.ArrayList;
public class Flag {
// number of stars per row and column
private static final int NUM_ROWS_STARS = 6;
private static final int NUM_COLS_STARS = 8;
// size of stars (really circles!)
private static final int STAR_DIAM = 6;
// space btn start of successive stars
private static final int STAR_JUMP = 8;
// space btn edge of star field and first star
private static final int OFFSET = 1;
// dimensions of star field
private static final int STAR_FIELD_WIDTH =
NUM_COLS_STARS * STAR_JUMP+OFFSET;
private static final int STAR_FIELD_HT =
NUM_ROWS_STARS * STAR_JUMP+OFFSET;
// dimensions of flag
private static final double FLAG_WIDTH =
2.5 * STAR_FIELD_WIDTH;
private static final int FLAG_HT = STAR_FIELD_HT*13/7;
// dimensions of stripes
private static final double SHORT_STRIPE_WIDTH =
FLAG_WIDTH - STAR_FIELD_WIDTH;
private static final int STRIPE_HT = STAR_FIELD_HT/7;
// number of red stripes of each sort in flag
private static final int NUM_SHORT_STRIPES = 4;
private static final int NUM_LONG_STRIPES = 3;
// instance variables for all parts of the flag
private ArrayList<FilledOval> stars;
private ArrayList<FilledRect> stripes;
private FilledRect background;
private FilledRect starBackground;
private FramedRect starBorder;
private FramedRect flagBorder;
public Flag(Location point, DrawingCanvas canvas) {
stars = new ArrayList<FilledOval>();
stripes = new ArrayList<FilledRect>();
// white rectangle so the flag is opaque
background = new FilledRect(point, FLAG_WIDTH, FLAG_HT, canvas);
background.setColor(Color.white);
// draw short stripes
drawStripes(point.getX() + STAR_FIELD_WIDTH,
point.getY(),
SHORT_STRIPE_WIDTH,
NUM_SHORT_STRIPES, canvas);
// draw long stripes
drawStripes(point.getX(),
point.getY()+2 * NUM_SHORT_STRIPES * STRIPE_HT,
FLAG_WIDTH+1,
NUM_LONG_STRIPES, canvas);
// draw field of stars
drawStars(point, canvas);
// outline of the flag
flagBorder = new FramedRect(point.getX()-1,
point.getY()-1,
FLAG_WIDTH+1,
FLAG_HT+1,
canvas);
}
// Draw numStripes red stripes starting at (x,y)
// which are "width" pixels wide.
private void drawStripes(double x, double y,
double width, int numStripes,
DrawingCanvas canvas) {
int stripeNum = 0;
while (stripeNum < numStripes)
{
FilledRect stripe =
new FilledRect(x, y, width, STRIPE_HT, canvas);
stripe.setColor(Color.red);
stripes.add(stripe);
stripeNum++;
y = y + 2 * STRIPE_HT;
}
}
// Draw blue background and stars, framed in black,
// starting at point.
private void drawStars(Location point, DrawingCanvas canvas) {
// Draw and frame background
starBackground = new FilledRect(point, STAR_FIELD_WIDTH,
STAR_FIELD_HT, canvas);
starBackground.setColor(Color.blue);
starBorder = new FramedRect(point.getX()-1,
point.getY()-1,
STAR_FIELD_WIDTH+1,
STAR_FIELD_HT+1,
canvas);
int row = 0;
int col;
double x;
double y = point.getY()+OFFSET;
// draw stars
while (row < NUM_ROWS_STARS) {
col = 0;
x = point.getX()+OFFSET;
while (col < NUM_COLS_STARS) {
FilledOval star = new FilledOval(x,y,STAR_DIAM,
STAR_DIAM,canvas);
star.setColor(Color.white);
stars.add(star);
col++;
x = x + STAR_JUMP;
}
y = y + STAR_JUMP;
row++;
}
}
public void move(double dx, double dy) {
for (int starNum = 0; starNum < stars.size(); starNum++) {
stars.get(starNum).move(dx, dy);
}
for (int stripeNum = 0; stripeNum < stripes.size(); stripeNum++) {
stripes.get(stripeNum).move(dx, dy);
}
background.move(dx, dy);
starBackground.move(dx, dy);
starBorder.move(dx, dy);
flagBorder.move(dx, dy);
}
public boolean contains(Location point) {
return flagBorder.contains(point);
}
}