Hi there,

I'm teaching myself to program in Processing after a 10-year absence from coding. My current project is supposed to parse a manually downloaded XML file of delicious tags and display them as a simple bar graph.

Here is the code:

Code:

import processing.xml.*;

int plotX1;
int plotY1;
int plotX2;
int plotY2;

int dataMax;
int totalTags;
XMLElement[] tags;

void setup() {
  size(640, 400);
  
  // Initialize variables;
  plotX1 = 0;
  plotX2 = 620;
  plotY1 = 0;
  plotY2 = 390;
  
  //load the XML
  XMLElement xml = new XMLElement(this, "myTags.xml");
  
  //how many elements?
  totalTags = xml.getChildCount();
  
  //load the array
  tags = xml.getChildren();
  
  //find the largest no. of tags used
  dataMax = 0;
  for (int i = 0; i < totalTags; i++) {
    int now = tags[i].getIntAttribute("count");
    String name = tags[i].getStringAttribute("tag");
    println(name);
    if (now > dataMax) {
      dataMax = now;
    }
  }
  println(dataMax);
}
  
void draw() {
  float x = plotX1;
  float y = plotY2;
  float wide = abs(plotX1 - plotX2)/tags.length;
  for (int i = 0; i < tags.length; i++) {
    // Map value from 0 to datamax, to y2 to y1
    float high = map (tags[i].getIntAttribute("count"), 0, dataMax, plotY2, plotY1);
    fill(0);
    // Draw the rectangle.
    rect(x, y, wide, high);
    x = x + wide;
  }
} 

The println command tells me that I really am getting the data out of the XML file, but the display is just a blank rectangle. What am I missing?

I noticed that I didn't call the draw() method in setup; I'm not actually clear if I'm supposed do. draw() gets called every frame refresh, right?

I added the background(255) but with no effect. Hm. I'm remembering there's this thing called "debugging" which I'm going to start reading up on...