Learning Processing: A Beginner's Guide to Programming Images ...

400 Learning Processing
// Draw some stuff!
background(255);
fill(175);
stroke(0);
ellipse(width/2,height/2,160,160);
// Very important, required for the PDF to render properly
exit();
If you run this example, you will notice that no window appears. Once you have set the Processing
rendering mode to PDF, the sketch window will no longer appear. Th is is because one often uses PDF
mode to create extremely high-resolution, complex images that cannot easily be displayed onscreen.
However, it is possible to see the Processing sketch window while rendering a PDF using the functions
beginRecord( ) and endRecord( ) . Th is runs slower than the fi rst example, but allows you to see what is
being saved.
Example 21-2: PDF using beginRecord( )
import processing.pdf.*;
void setup() {
size(400, 400);
beginRecord(PDF, " filename.pdf " );
}
void draw() {
// Draw some stuff!
smooth();
background(100);
fill(0);
stroke(255);
ellipse(width/2,height/2,160,160);
endRecord();
noLoop();
}
endRecord( ) does not have to be called on the fi rst frame rendered, and therefore this mode can be used
to generate a PDF compiled from multiple cycles through draw( ) . Th e following example takes the
“ Scribbler ” program from Chapter 16 and renders the result to a PDF. Here the colors are not taken from
a video stream, but are picked based on a counter variable. See Figure 21.3 for a sample output.
Example 21-3: Multiple frames into one PDF
import processing.pdf.*;
float x � 0;
float y � 0;
beginRecord( ) starts the process.
The fi rst argument should read PDF
and the second is the fi lename.
endRecord( ) is called to fi nish
the PDF.
There’s no reason to loop any more
since the PDF is fi nished.