Doubt in assigning pixel values in MemoryImageSource

[atiprashant]

Hello everyone....!!!

I am having problem in understanding the following piece of code...

int alpha = (rgb >> 24) & 0xff;

I am not able to get what value will be assigned to alpha here..

Please help

Thanks in advance...:):):)

[Norm]

What does this have to do with Java Applets?
You're in the wrong part of this forum.

[atiprashant]

It is used in MemoryImageSource part of JAVA applets.

[DarrylBurke]

What does this have to do with Java Applets?
You're in the wrong part of this forum.

Agreed. Moved to Java2D

db

[DarrylBurke]

int alpha = (rgb >> 24) & 0xff;

I am not able to get what value will be assigned to alpha here..

Bitwise and Bit Shift Operators (The Java™ Tutorials > Learning the Java Language > Language Basics)

db

[atiprashant]

I have a doubt in this piece of code


int w = 100;
int h = 100;
int pix[] = new int[w * h];
int index = 0;
for (int y = 0; y < h; y++) {
int red = (y * 255) / (h - 1);
for (int x = 0; x < w; x++) {
int blue = (x * 255) / (w - 1);
pix[index++] = (255 << 24) | (red << 16) | blue;
}
}
Image img = createImage(new MemoryImageSource(w, h, pix, 0, w));

int pixels[];
MemoryImageSource source;

public void init() {
int width = 50;
int height = 50;
int size = width * height;
pixels = new int[size];

int value = getBackground().getRGB();
for (int i = 0; i < size; i++) {
pixels[i] = value;
}

source = new MemoryImageSource(width, height, pixels, 0, width);
source.setAnimated(true);
image = createImage(source);
}

public void run() {
Thread me = Thread.currentThread( );
me.setPriority(Thread.MIN_PRIORITY);

while (true) {
try {
thread.sleep(10);
} catch( InterruptedException e ) {
return;
}

// Modify the values in the pixels array at (x, y, w, h)

// Send the new data to the interested ImageConsumers
source.newPixels(x, y, w, h);
}
}

In this code you can find a highlighted , bold line...

Can anyone please explain me how that assignment goes. I mean how values to pixels are assigned...

Thanks...:) :)

[Norm]

Try writing a simple one line program that prints out the results of different shifts and ORs.
Use Integer.toHexString() to display the results.
Keep trying different combinations until you get what you want.

[DarrylBurke]

atiprashant , please use one thread per question. I've merged your two threads which are about the same problem.

db

[atiprashant]

Thanks...:) :)