Need help with converting Robot's getPixelColor to use it in Processing

Programming Questions

njitram

Need help with converting Robot's getPixelColor to use it in Processing

in Programming Questions • 8 months ago

I'm trying to readh the RGB from where my mouse is on the screen and this is my code so far.

I know that initializing a class in Ddraw() can't be good but its the only way im not getting errors.

My println(col) is saying "java.awt.Color[r=13,g=12,b=13]"

But dont know how to convert it to an int or something to use in processing?

import java.awt.AWTException;

import java.awt.Robot;
import java.awt.Color;

Robot robot;
Color col;

void setup() {
size(400, 400);
try {
robot = new Robot();
col = new Color();
}
catch (AWTException e) {
e.printStackTrace();
}
robot.mouseMove(displayWidth/2, displayHeight/2);
}

void draw() {
col = robot.getPixelColor(20, 20); //println(frameCount);
println(col.getRed());
background(col.getRed(),col.getGreen(),col.getBlue());
}

Replies(6)

PhiLho

Re: Need help with converting Robot's getPixelColor to use it in Processing

8 months ago

See the reference of Color...
Maybe the What is a color in Processing? can be useful for you too.

njitram

Re: Need help with converting Robot's getPixelColor to use it in Processing

8 months ago

Thanks for the comment PhiLho! I already checked it and there was a previous thread about this and you were also there :D but cant seem to figure it out.

Why doesn't the getPixelColor() update it's value? I initialized it in draw, and then I get the seperate RGB values via getRed() etc...

njitram

Re: Need help with converting Robot's getPixelColor to use it in Processing

8 months ago

import java.awt.AWTException;
import java.awt.Robot;
import java.awt.Color;

Robot robot;
Color col;

void setup() {
size(400, 400);
try {
robot = new Robot();
col = new Color();
}
catch (AWTException e) {
e.printStackTrace();
}
}

void draw() {
col = robot.getPixelColor(mouseX, mouseY); //println(frameCount);
println(col);
background(col.getRed(),col.getGreen(),col.getBlue());

}

If i put it like this, processing says "the constructor color() is undefined"

PhiLho

Re: Need help with converting Robot's getPixelColor to use it in Processing

8 months ago

The message is about Color() constructor, not color(). It was confusing...
Just remove the line:
col = new Color();
it is useless anyway, as this value will be overwritten in draw().

quarks

Re: Need help with converting Robot's getPixelColor to use it in Processing

8 months ago

Why doesn't the getPixelColor() update it's value? I initialized it in draw, and then I get the seperate RGB values via getRed() etc...

The reason is that the first time draw is called you get the color underthe mouse and then use this to set the background after that the getPixelColor will always return the same color because all the pixels are the same color.

PhiLho

Re: Need help with converting Robot's getPixelColor to use it in Processing

8 months ago

Well, colors do change...
The problem in your code, is that you use mouseX, mouseY which are relative to the sketch area.
But getPixelColor() gets an absolute screen position.
So, the colors you see in the sketch are the colors under the mouse relative to the top-left corner of the sketch translated to the top-left corner of the screen...
To fix that, you need to get the absolute position of the mouse on the screen:

import java.awt.AWTException;
import java.awt.Robot;
import java.awt.Color;
import java.awt.Point;
import java.awt.MouseInfo;
Robot robot;
Color col;
void setup() {
size(400, 400);
try {
robot = new Robot();
}
catch (AWTException e) {
e.printStackTrace();
}
}
void draw() {
Point p = MouseInfo.getPointerInfo().getLocation();
col = robot.getPixelColor(p.x, p.y); //println(frameCount);
// println(col);
background(col.getRed(), col.getGreen(), col.getBlue());
}

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