Develop Reference

Swing drawing sometimes works

I'm trying to draw functions using Java Swing and AWT. The problem is not always all of the 300 points of the graph are drawn. When I loop over the first points of the graph in debug mode, there is much more change the graph is drawn completely. I use the following code to create a JFrame and set the graphics object to the class member g.
jFrame = new JFrame();
jFrame.setSize(WIDTH, HEIGHT);
jFrame.setVisible(true);
g = jFrame.getContentPane().getGraphics();
Then I call this method for every function I want to draw.
private void drawGraph(IGraph graph, Bounds bounds, Ratios ratios) {
//contains visual information about the graph
GraphVisuals visuals = graph.getVisuals();
g.setColor(visuals.color);
//the previous point is remembered, to be able to draw a line from one point to the next
int previousXi = 0;
int previousYi = 0;
//a loop over every point of the graph. The graph object contains two arrays: the x values and the y values
for (int i = 0; i < graph.getSize(); ++i) {
//calculate the x value using the ratio between the graph's size on the x-axis and the window size and the starting point on the x-axis
int xi = (int) (ratios.xRatio * (graph.getX(i) - bounds.xMin) + 0.5);
//analogous for the y axis
int yi = HEIGHT - (int) (ratios.yRatio * (graph.getY(i) - bounds.yMin) + 0.5);
//draw
if (visuals.hasBullets) {
g.fillOval(xi, yi, visuals.bulletSize, visuals.bulletSize);
}
if (visuals.hasLine) {
if (i != 0) {
g.drawLine(previousXi, previousYi, xi, yi);
}
}
previousXi = xi;
previousYi = yi;
}
}

Splitting an Image Object into a 2D Array in Java

The aim of this little project is to break down an image (in this case a flag) into pieces like a jigsaw and store each piece in part of a 2D array. I then want to be able to view each piece individually so that I know it has worked.
I have created an object class which loads and stores the image. I created the object in my main class and then pass it to my splitImage method which divides the image into chunks and stores in the array. I would like to be able to view a section of the array to check that the splitImage method has worked correctly. Long term however I do need to view the array as I will be determining the colour of the pixel in each image piece and counting how many of each colour is in the image. When I run the current code I get the following in the console,
Exception in thread "main" java.lang.ClassCastException: sun.awt.image.ToolkitImage cannot be cast to java.awt.image.BufferedImage
at sample.ImageFrame.splitImage(ImageFrame.java:28)
at sample.ImageFrame.main(ImageFrame.java:59)
28 is the line - BufferedImage image = (BufferedImage)((Image) icon.getImage());
59 is - ImageFrame.splitImage(imageSwing.label);
I have played around with these for some time, changing the position trying other options and have been unsuccessful. Help on this is much appreciated.
Code is below and thanks in advance.
public class ImageSwing extends JFrame
{
public JLabel label;
public ImageSwing()
{
super("Test Image Array");
setLayout(new FlowLayout());
Icon flag = new ImageIcon(getClass().getResource("Italy_flag.jpg"));
label = new JLabel(flag);
label.setToolTipText("Italian Flag");
add(label);
}//main
}//class
public class ImageFrame
{
//public ImageSwing imageSwing = new ImageSwing();
//ImageSwing imageSwing = new ImageSwing();
public static BufferedImage splitImage(JLabel i) throws IOException
{
//Holds the dimensions of image
int rows = 4;
int cols = 4;
ImageIcon icon = (ImageIcon)i.getIcon();
BufferedImage image = (BufferedImage)((Image) icon.getImage());
int chunks = rows * cols; //Total amount of image pieces
int partWidth = i.getWidth() / cols; // determines the piece width
int partHeight = i.getHeight() / rows; //determines the piece height
int count = 0;
BufferedImage[][] flagArray = new BufferedImage[rows][cols]; //2D Array to hold each image piece
for (int x = 0; x < rows; x++)
{
for (int y = 0; y < cols; y++)
{
//Initialize the image array with image chunks
flagArray[x][y] = new BufferedImage(partWidth, partHeight, image.getType());
// draws the image chunk
Graphics2D gr = flagArray[x][y].createGraphics();
gr.drawImage(image, 0, 0, partWidth, partHeight, partWidth * y, partHeight * x, partWidth * y + partWidth, partHeight * x + partHeight, null);
gr.dispose();
}
}
return flagArray[rows][cols];
}
public static void main(String[] args)
{
ImageSwing imageSwing = new ImageSwing();
try
{
ImageFrame.splitImage(imageSwing.label);
} catch (IOException e)
{
e.printStackTrace();
}
imageSwing.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
imageSwing.setSize(260,180);
imageSwing.setVisible(true);
}//main
}//class

Take a look at Java converting Image to BufferedImage
It provides a way to convert from Image to BufferedImage, which seems to be the problem.

How do I initiate particles to grow from anywhere on stage upon mouseClick?

I want to be able to create new particles from wherever I click on stage. I'm just stuck on adding the mouse portion and I've tried to add/pass parameters and I always get errors while I try setting the parameters. Any suggestions?
This is my current code:
float parSpeed = 1; //speed of particles
int nParticles = 1000; //# of particles
Particle[] particles;
void setup() {
size(700,700); //size of image (8.5 x 11 # 300px) is 3300,2550)
frameRate(60); //framerate of stage
background(0); //color of background
particles = new Particle[nParticles];
//start particle array
for(int i=0; i<nParticles; i++) {
particles[i] = new Particle();
}
}
void draw() {
fill(0,0,0,5); //5 is Alpha
rect(0,0,width,height); //color of rectangle on top?
translate(width/2, height/2); //starting point of particles
//start particle array
for(int i=0; i<nParticles; i++) {
particles[i].update();
particles[i].show();
}
}
//Particle Class
class Particle {
PVector pos; //position
float angle; //angle
float dRange; //diameter range
float dAngle; //beginning angle?
color c; //color
Particle() {
pos = new PVector(0,0);//new position for the particles.
angle = 1; //controls randomization of direction in position when multiplied
dRange = 0.01; // how big of a circle shold the particles rotate on
dAngle = 0.15; // -- maximum angle when starting
c = color(0,0,random(100, 255)); //set color to random blue
}
void update() {
float cor = .25*dRange*atan(angle)/PI;
float randNum = (random(2)-1)*dRange-cor; //Random number from (-dRange, dRange)
dAngle+=randNum; //We don't change the angle directly
//but its differential - source of the smoothness!
angle+=dAngle; //new angle is angle+dAngle -- change angle each frame
pos.x+=parSpeed*cos(angle);//random direction for X axis multiplied by speed
pos.y+=parSpeed*sin(angle);//rabdin durectuib for y axis multiplied by speed
}
void show() {
fill(c); //fill in the random color
noStroke(); //no stroke
ellipse(pos.x,pos.y,10,10); //make the shape
smooth(); //smooth out the animation
}
}
void keyPressed() {
print("pressed " + int(key) + " " + keyCode);
if (key == 's' || key == 'S'){
saveFrame("image-##.png");
}
}
void mouseReleased() {
print("mouse has been clicked!");
}

Overwrite the mouseReleased() method:
In there you'll need to:
capture the position of the mouse
create the new particle
update the position of the newly created particle.
add it to the array (the particle system)
This may look simple but you'll have to keep in mind an array cannot change sizes. I would advise that you create a ParticleSystem class that takes care of adding and removing particles from the system.
Edit: You might want to consider using an ArrayList instead of an Array of Particles. Have a look at this
In pseudo code this would look like this:
void mouseReleased() {
int particleX = mouseX;
int particleY = mouseY;
Particle P = new Particle();
P.setPos ( new PVector ( particleX, particleY ) ); // this needs to be implemented
ParticleSystem.add ( P ); // this needs to be implemented
}
I hope this will be a good start.
AH

Android: drawing an arraylist of Bitmaps results in a black background

it's my first time asking a question here so I'll try to stay on-topic. I'm trying to randomly generate a background by creating an appropriately-sized ArrayList of Bitmap objects, and drawing them in order. This implementation works fine loading a single Bitmap, by the way; it's just stumbling with a list.
Before I get to the code, I'd like to point out that Ideally I would make a single Bitmap by adding the individual pixels or tiles, and indeed have tried a few variations of that, but they all result in black screens; I'm starting to think it might be a problem with how I draw to the Canvas. Anyways, here's what I have:
First, I generate the random ArrayList, only using 3 colors right now. I'd make it return the list, but it's just a private method inside the thread referencing one of the thread's variables so it doesn't matter much.
private void genMap(Resources res)
{
// Load basic tiles.
Bitmap green = BitmapFactory.decodeResource(res, R.drawable.green);
Bitmap red = BitmapFactory.decodeResource(res, R.drawable.red);
Bitmap blue = BitmapFactory.decodeResource(res, R.drawable.blue);
// All tiles must be the same size.
int tile_width = green.getWidth();
int tile_height = green.getHeight();
int num_x = mCanvasWidth / tile_width;
int num_y = mCanvasHeight / tile_height;
for (int j = 0; j < num_y; j++)
{
for (int i = 0; i < num_x; i++)
{
double r = Math.random();
Bitmap tile;
if (r <= 1/3) {tile = green;}
else if (r <= 2/3) {tile = red;}
else {tile = blue;}
// Create a new Bitmap in order to avoid referencing the old value.
mBackgroundImages.add(Bitmap.createBitmap(tile));
}
}
}
So, that's how the random values are mapped to a pattern. The method is called in the thread's constructor, which is in turn called every time onCreate is called; for now, I'm just clearing the list and making a new random pattern each time:
...
Resources res = context.getResources();
mBackgroundImages = new ArrayList<Bitmap>();
genMap(res);
...
And finally, the draw method; it works fine loading a single Bitmap via BitmapFactory.decodeResources, but shows a black screen when doing this:
private void doDraw(Canvas canvas)
{
/* Draw the bg.
* Remember, Canvas objects accumulate.
* So drawn first = most in the background. */
if (canvas != null)
{
if (mBackgroundImages.size() > 0)
{
int tile_width = mBackgroundImages.get(0).getWidth();
int tile_height = mBackgroundImages.get(0).getHeight();
for (int y = 0; y < mCanvasHeight / tile_height; y++)
{
for(int x = 0; x < mCanvasWidth / tile_width; x++)
{
// Draw the Bitmap at the correct position in the list; Y * XWIDTH + X, at pos X * XWIDTH, Y * YWIDTH.
canvas.drawBitmap(mBackgroundImages.get((x + y * (mCanvasWidth/tile_width))), x * tile_width, y * tile_height, null);
}
}
}
}
}
Any help would be appreciated, thanks.

Have you double-checked the order of precedence of the following line?
((x + y * (mCanvasWidth/tile_width)))
Interesting question though: are you drawing solid colors? I would also see if this is actually making a Bitmap:
mBackgroundImages.add(Bitmap.createBitmap(tile));
You might actually be able to just keep references instead of creating a lot of bitmaps, but that can come later

if/then with pixel finding and looping, all of which is above me at the moment

I want to take a screenshot, and if the pixel is the correct value RGB then take another screenshot and find next pixel or else repeat.
this is the code to get the pixel and it works like a charm!
{
BufferedImage image = robot.createScreenCapture(rectangle);
search: for(int x = 0; x < rectangle.getWidth(); x++)
{
for(int y = 0; y < rectangle.getHeight(); y++)
{
if(image.getRGB(x, y) == color3.getRGB())
{
break search;
}
}
}
}
what i want to know i guess is how would i go about asking it to repeat this segment of code until the pixel equals the true color. the color i am looking for is:
Color color3 = new Color(114, 46, 33);
Ok context, i am building a program that goes through steps, one opens the given puzzle, i have that down because i can use simple pixel data, then it needs to center the mouse on the center pixel. The problem is i cant just use a second get pixel image because it takes a while for the game to open the relevant jpanel so i need my program to wait until it can find a pixel indicating the game is open before it starts to look for the pixel to center the mouse.

You can probably separate the screenshot code into a method and call it until you get the desired result:
public boolean checkColor(Color inputColor) {
BufferedImage image = robot.createScreenCapture(rectangle);
for(int x = 0; x < rectangle.getWidth(); x++) {
for (int y = 0; y < rectangle.getHeight(); y++) {
if (image.getRGB(x, y) == inputColor.getRGB()) {
return true;
}
}
}
return false;
}
This method will return true if it can find the given inputColor in the screenshot. You might then use it in a loop as follows:
Color newColor = ...;
while (!checkColor(newColor)) {
new Color = new Color(114, 46, 33);
// Or change color in here for every iteration
}
This loop will terminate if it can't match the screenshot to newColor.