I'm having a problem scaling Pgraphics on event.  For example, when you press the 'a' key I want the Pgraphic to zoom in; simple enough but I am unable to get the Pgraphic to scale.  I am using Matt Patey's example.  I think it might be how I order the image and Pgraphic.  

See below. 

Thanks for any help....

j

2. /**
3.  * Pan Demo
4.  *
5.  * Processing sketch illustrates how an off-screen buffer can be
6.  * used to create a panning tool to view an image larger than the
7.  * base canvas. Use the arrow keys to scroll to the limits of
8.  * the displayed image.
9.  *
10.  * @author Matt Patey
11.  */
12.  
13. PImage bufSlice;
14. PGraphics buf;
15. int copyOffsetX;
16. int copyOffsetY;
17. int copyWidth;
18. int copyHeight;
19. 
    
20. float scaler = 1.0;
21.  
22. void setup() {
23.   size(400, 400, P3D);
24.  
25.   // Create an off-screen buffer that will contain the entire image.
26.   buf = createGraphics(800, 800, JAVA2D);
27.   buf.beginDraw();
28.   buf.smooth();
29.   buf.scale(scaler);
30.   buf.background(255);
31.   for (int i = 0; i < buf.width; i+=10) {
32.     buf.line(i, 0, i + 50, buf.height);
33.     buf.line(0, i, buf.height, i + 30);
34.   }
35.   buf.endDraw();
36.  
37.   copyOffsetX = 0;
38.   copyOffsetY = 0;
39.   copyWidth = width;
40.   copyHeight = height;
41. }
42.  
43. void draw() {
44.   background(0);
45.   image(getBufSlice(), 0, 0);
46. }
47.  
48. /**
49.  * Updates the copied version of the off-screen buffer.
50.  */
51. PImage getBufSlice() {
52.   buf.scale(scaler);
53.   return buf.get(copyOffsetX, copyOffsetY, copyWidth, copyHeight);
54. }
55.  
56. /**
57.  * Handle key presses.
58.  */
59. void keyPressed() {
60.   
61.   if(key == 'a'){
62.     scaler += 0.1;
63.   }
64.   
65.   
66.   switch(keyCode) {
67.   case LEFT:
68.     if(copyOffsetX < buf.width - width) {
69.       copyOffsetX++;
70.     }
71.     break;
72.  
73.   case RIGHT:
74.     if(copyOffsetX > 0) {
75.       copyOffsetX--;
76.     }
77.     break;
78.  
79.   case UP:
80.     if(copyOffsetY < buf.height - height) {
81.       copyOffsetY++;
82.     }
83.     break;
84.  
85.   case DOWN:
86.     if(copyOffsetY > 0) {
87.       copyOffsetY--;
88.     }
89.     break;
90.   }
91. }