PROCESSING
LESSON 04 – THE MOUSE

LESSON NOTE/GUIDE

Note: For your mouse events to work, your program needs to have a draw method in it (even if it is empty). Otherwise, since there is no looping, the program stops after executing once.

PROGRAM 1 – MOUSE CLICK

· This program displays a message in the console when the mouse is clicked inside the window.

THE CODE

public void setup()

{}

public void draw()

{}

public void mouseClicked()

{

System.out.println("Mouse was clicked");

}

RESULT

A small window appears. When clicked on, a message appears in the console.

EXPLANATION

The function mouseClicked() is automatically executed on frames when the mouse has been clicked. This is very easy to do!

PROGRAM 2 – MOUSE LOCATION

· This program makes use of mouseX and mouseY to get the location of the mouse.

THE CODE

public void setup()

{

size(500,500);

surface.setTitle("Click Location");

}

public void draw()

{}

public void mouseClicked()

{

System.out.println("Mouse was clicked at (" + mouseX + "," + mouseY + ")");

}

RESULT

EXPLANATION

The mouseX and mouseY variables can be used at any time to get the location of the mouse.

PROGRAM 3 – ADDING RECTANGLES AT CLICK LOCATIONS

· This program makes use of mouseX and mouseY to get the location of the mouse.

THE CODE

public void setup()

{

size(500,500);

surface.setTitle("Click To Add Rectangles");

}

public void draw()

{}

public void mouseClicked()

{

rect(mouseX, mouseY, 10, 10);

}

RESULT

A rectangle (actually a square) appears wherever the mouse is clicked.

EXPLANATION

The code is very simple. When the mouse is clicked, we draw a rectangle with top left corner at point (mouseX, mouseY).

MORE

Instead of mouseClicked(), we can also use other built-in functions such as:

mousePressed()

mouseReleased()

mouseDragged()

mouseMoved()