690 Midterm: derive display parameters for centering an image in a display area.

CenterImage.java

/*
 * CenterImage 
 *
 * Derive display parameters for centering an image within an arbitrary display area
 *
 * @build Processing sketch app
 * @fileType .pde
 * @description no physical image used, the image is defined by its dimensions (w, h) and position (x, y)
 */

int winW, winH, displayAreaW, displayAreaH, displayAreaX, displayAreaY, imgW, imgH, imgX, imgY;

void setup ()
{
  // window dimensions
  winW = 800;
  winH = 600;
  
  // draw window
  background(255);
  size(winW, winH);
  
  // displayArea dimensions
  displayAreaW = 600;
  displayAreaH = 450;
  
  // arbitrary displayArea position (x, y)
  displayAreaX = 40; // center displayArea => x = winW / 2 - displayAreaW / 2 
  displayAreaY = 40; // center displayArea => y = winH / 2 - displayAreaH / 2;
  
  // draw displayArea
  fill(220);
  stroke(220);
  rect(displayAreaX, displayAreaY, displayAreaW, displayAreaH);
  
  // image dimensions
  imgW = 400;
  imgH = 200;
  
  // centered image position (x, y)
  imgX = (displayAreaW / 2) - (imgW / 2) + displayAreaX;
  imgY = (displayAreaH / 2) - (imgH / 2) + displayAreaY;
  
  // draw image
  fill(100, 200, 200);
  stroke(100, 200, 200);
  rect(imgX, imgY, imgW, imgH);
}

void draw ()
{
  // stuff
}