I have created two buttons to enable the speed of the movement to be altered.

However, only the increase speed button is working and it only works when it the mouse is held down on it. Ideally, I would like to increase the speed by a small amount each time the button was clicked. And similarly, decrease the speed with each click.

Any help would be very much appreciated thank you!

Here is my code:

2. PImage panorama, image2;
3. int dimension, loc1, loc2;
4. int speed;
5. 
   
6. 
   
7. void setup() {
8. 
   
9.   panorama = loadImage ("Panorama.jpg");
10.   dimension = (panorama.width*panorama.height);
11. 
    
12.   size (panorama.width, panorama.height+200);
13. 
    
14.   image (panorama, 0, 0);
15. 
    
16.   image2 = createImage (panorama.width, panorama.height, RGB);
17. }
18. 
    
19. void draw() {
20.   {
21. 
    
22.     background (255);
23.     speed= 1;
24. 
    
25.     if (dist(panorama.width/2+100, panorama.height+50, mouseX, mouseY) < 75/2) {
26.       if (mousePressed) { 
27. 
    
28.         speed= speed +10;
29.       }
30. 
    
31. 
    
32.       if (dist(panorama.width/2-100, panorama.height+50, mouseX, mouseY) < 75/2) {
33.         if (mousePressed) { 
34.           if (speed >0) {
35.             speed= speed -1;
36.           }
37.         }
38.       }
39.     }
40. 
    
41.     panorama.loadPixels();
42.     image2.loadPixels();
43.     for (int y=0; y < panorama.height; y++) {
44.       for (int x = 0; x < panorama.width; x++) {
45. 
    
46.         //define the locations (1 pixel shift) 
47.         loc1 = x + y*panorama.width;
48.         loc2 = (x-speed) +y*panorama.width;
49. 
    
50. 
    
51.         //if loc2 is inside the range (0-dim), go on!
52.         if ((loc2 > 0)&(loc2 < dimension)) {
53.           //copy panorama to image 2, moved over one pixel
54.           image2.pixels[loc2]=panorama.pixels[loc1];
55.         }
56.         //else skip this line 
57.         else {
58.         }
59. 
    
60. 
    
61.         //end of for loop
62.       }
63.     }
64.     panorama.updatePixels();
65.     image2.updatePixels();
66.     panorama= image2;  
67.     image (panorama, 0, 0);
68. 
    
69. 
    
70.     if (dist(panorama.width/2-100, panorama.height+50, mouseX, mouseY) < 75/2) {
71.       stroke(0);
72.       cursor(HAND);
73.       if (mousePressed) { 
74.         strokeWeight(3);
75.       }
76.     }
77. 
    
78.     else {
79.       cursor(ARROW);
80.       noStroke();
81.       strokeWeight(1);
82.     }
83. 
    
84. 
    
85.     rectMode(CENTER); 
86.     //draw two squares
87.     fill(255);
88.     rect(panorama.width/2-100, panorama.height+50, 75, 75);
89. 
    
90.     fill(0);
91.     rect(panorama.width/2-100, panorama.height+50, 50, 10);
92. 
    
93. 
    
94. 
    
95.     if (dist(panorama.width/2+100, panorama.height+50, mouseX, mouseY) < 75/2) {
96.       stroke(0);
97.       cursor(HAND);
98.       if (mousePressed) { 
99.         strokeWeight(3);
100.       }
101.     }
102. 
     
103.     else {
104.       cursor(ARROW);
105.       noStroke();
106.       strokeWeight(1);
107.     }
108. 
     
109.     fill(255);
110.     rect(panorama.width/2+100, panorama.height+50, 75, 75); 
111. 
     
112.     //plus sign
113. 
     
114.     fill(0);
115. 
     
116.     rect(panorama.width/2+100, panorama.height+50, 50, 10);
117. 
     
118.     rect(panorama.width/2+100, panorama.height+50, 10, 50);
119.   }
120. }

I am trying to make a wrap around image with 2 buttons which enable the speed of the picture to change.

The error is 'java.lang.NullPointerException'

Any help would be very much appreciated thank you!!

Here is the code: