IAT 265 Images in Processing PImage

Jun 27, 2014IAT 2652 Outline  Programming concepts –Classes –PImage –PFont

Jun 27, 2014IAT 2653 Loading Images  Loading Images –Give your project a name and save. –Place the image file in: /sketchbook/ /data/ –Use this code: PImage img = loadImage(“ ”);

Jun 27, 2014IAT 2654 Displaying Images  image( PImage img, int x, int y); shows your image. image(img, 0, 0) will display your image from the last slide at the top left of the window.

Jun 27, 2014IAT 2655 Accessing Pixels  The PImage class allows you to access the RGB values of each individual pixel of the image, with the pixels[] array.  You can get the width and height of the image file using the width and height fields of PImage.

Jun 27, 2014IAT 2656 Accessing Pixels  How do we know which pixel to look for in the array?

Jun 27, 2014IAT 2657 Accessing Pixels  How do we know which pixel to look for in the array?

Jun 27, 2014IAT 2658 Accessing Pixels  How do we know which pixel to look for in the array?

Jun 27, 2014IAT 2659 Accessing Pixels  How do we know which pixel to look for in the array?

Jun 27, 2014IAT Accessing Pixels  Array Index –x + y*width (4, 0) = 4 + 0*5 = 4 (3, 2) = 3 + 2*5 = 13

Jun 27, 2014IAT Accessing Pixels  What would a piece of code look like that got a color from a pixel?  Let’s look at some applications of this. PImage im = loadImage(“test1.jpg”); color c1 = im.pixels[3 + 2*im.width];// get color at (3, 2) stroke(c1); // set our line color

Jun 27, 2014IAT Window vs. Image  The drawing window also has a pixels[] array. –You must call loadPixels(); to get the image from the screen –You don’t need a PImage object. loadPixels(); color c2 = pixels[3 + 2*width]; // gives us the color at (3, 2) in the window.

Jun 27, 2014IAT Window vs. Image  When would we want to use both of these? –Use the Window’s pixels if you want to draw more things based on the image that’s already on the screen. –Use the Image’s pixels if you want to manipulate the pixels of the image before you draw them.

Jun 27, 2014IAT D Arrays  Java lets us make Arrays of Arrays, otherwise called 2D Arrays. These are very useful for accessing arrays of pixels like the ones we’ve been working with. int[][] bob = new int[3][4]; color[][] pixels2d = new color[200][200];

Jun 27, 2014IAT D Arrays  Processing doesn’t provide us with a 2D array of pixels to use, so let’s develop a class that will make manipulating pixels easier.

Jun 27, 2014IAT D Arrays  Interestingly, 2D Arrays are just covering up a 1D array much like the pixels[] array. color[][] pixels2d = new color[20][20]; color c2 = pixels2d[3][2]; color[] pixels1d = new color[400]; color c1 = pixels1d[3 + 2*20]; Underneath, these two pieces of code do the same thing. The 2D array convention just makes it easier for us to access the array based on things like our x and y values.

Jun 27, 2014IAT PFont  PFont is the Processing class for manipulating fonts –Like PImage for images  Use PFont with –PFont loadFont() – loads a font –textFont(PFont font, int size) – sets the current font –text(String str, int x, int y) – draws a string in the current font at the current location

Jun 27, 2014IAT Simple example // the fonts must be located in the data directory PFont engravers = loadFont("EngraversMT-48.vlw"); PFont cour = loadFont("Courier-32.vlw"); textFont(engravers, 44); text("word", 10, 30); textFont(cour, 44); text("word", 10, 60);

Jun 27, 2014IAT Use fill() to change the color of text // the fonts must be located in the data directory PFont engravers = loadFont("EngraversMT-48.vlw"); PFont cour = loadFont("Courier-32.vlw"); fill( 0, 255, 0 ); textFont(engravers, 44); text("word", 10, 30); fill( 255, 0, 0 ); textFont(cour, 44); text("word", 10, 60);

Jun 27, 2014IAT textMode sets the alignment  textAlign( LEFT ); –x, y is the upper left hand corner of the text  textAlign( RIGHT ); –x, y is the upper right hand corner of the text  textAlign( CENTER ); –x, y is the upper center of the text

Jun 27, 2014IAT Producing text effects  All the transform methods apply to drawing text –That means you can translate, rotate, and scale text  Combined with draw(), this means you can move text around the screen in real time –Remember, the movement of the rocket and asteroids in our asteroids example was just translation and rotation  So you can make textual machines where text moves around the screen!

Jun 27, 2014IAT Processing example PImage im ; PFont engrvr ; PFont courier ; void setup() { size( 600, 600 ); im = loadImage( "cdshaw.96.jpg" ); for( int i = 600 ; i >= 0 ; i -= 50 ) image( im, i, i ); engrvr = loadFont( "EngraversMT-48.vlw" ); courier = loadFont( "Courier-32.vlw" ); textFont( engrvr ); } void draw( ) { image( im, mouseX-370, mouseY-210 ); color c1 = im.pixels[ * im.width ] ; loadPixels(); c1 = pixels[ * width ] ; stroke( c1 ); fill( c1 ); textAlign( LEFT ); ellipse( mouseX, mouseY, 20, 10 ); textFont( engrvr, 44 ); text( "Yo!", mouseX + 20, mouseY + 20 ); fill( 255, 0, 0); pushMatrix(); textAlign( RIGHT ); rotate( 0.2); textFont( courier, 44 ); text( "Yo?", mouseX, mouseY ); popMatrix(); }

Review  Graphics: image( img, x, y )  PImage is also a class. –Each actual image is an object Jun 27, 2014IAT 26523

Review  Object Oriented Programming –Class-- a type you define –Instance-- one variable of a class –Fields-- variables within a class –Methods-- functions that act within a class –Constructor-- create an instance of a class Jun 27, 2014IAT 26524