How to detect laser movement like, moving from top to bottom

I am done with tracking the laser and moving the mouse pointer to the centroid of the laser.Now I want to recognize the laser gesture/movement like, top to bottom and from bottom to top. if the event is from top to bottom do scroll down by calling java.awt.event function cursor.mouseWheel(+1). I have used some other methods,but not working properly.

clc;
clear all;
close all;

greenThresh = 0.04; % Threshold for green detection

x1=[];
y1=[];

count=0;

vidDevice = imaq.VideoDevice('winvideo', 1, 'YUY2_640x480', ... 
                    'ROI', [1 1 640 480], ...
                    'ReturnedColorSpace', 'rgb');

%set(vidDevice.DeviceProperties, 'Brightness', 0); 

set(vidDevice.DeviceProperties, 'Exposure', -8); 

set(vidDevice.DeviceProperties, 'FrameRate', '30.0000');

set(vidDevice.DeviceProperties, 'Sharpness', 100); 

set(vidDevice.DeviceProperties, 'Zoom',1);

vidInfo = imaqhwinfo(vidDevice);

hblob = vision.BlobAnalysis('AreaOutputPort', false, ... 
                                'CentroidOutputPort', true, ... 
                                'BoundingBoxOutputPort', true', ...
                                'MinimumBlobArea', 600, ...
                                'MaximumBlobArea', 3000, ...
                                'MaximumCount', 10);

   hshapeinsBox = vision.ShapeInserter('BorderColorSource', 'Input port', ... % box handling
                                           'Fill', true, ...
                                           'FillColorSource', 'Input port', ...
                                           'Opacity', 0.2);

htextinsCent = vision.TextInserter('Text', '+ X:%d,Y:%d', ... % text for centroid
                                    'LocationSource', 'Input port', ...
                                    'Color', [1 1 1], ... 
                                    'Font', 'Courier New', ...
                                    'FontSize', 15);

hVideoIn = vision.VideoPlayer('Name', 'Final Video', ... % video player
                                'Position', [400 100 vidInfo.MaxWidth+20 vidInfo.MaxHeight+30]);

%nFrame = 0;

import java.awt.Robot;
import java.awt.event.*;

cursor = Robot;

while(1)

      rgbFrame = step(vidDevice); 

      diffFrameGreen = imsubtract(rgbFrame(:,:,2), rgb2gray(rgbFrame)); % Get green component of the image

      diffFrameGreen = medfilt2(diffFrameGreen, [3 3]); % Filter out the noise by using median filter

      binFrameGreen = im2bw(diffFrameGreen, greenThresh); % Convert the image into binary image with the green objects as white
     binFrameGreen = bwareaopen(binFrameGreen,1000);

     [centroidGreen, bboxGreen] = step(hblob, binFrameGreen); % Get the centroids and bounding boxes of the green blobs
    centroidGreen = uint16(centroidGreen); % Convert the centroids into Integer for further steps  

     vidIn = step(hshapeinsBox, rgbFrame, bboxGreen, single([0 1 0])); % Insert the green box

     for object = 1:1:length(bboxGreen(:,1)) % Write the corresponding centroids for green

          centXGreen = centroidGreen(object,1);
          centYGreen = centroidGreen(object,2);

          x1=cat(1,x1,centXGreen);
          y1=cat(1,y1,centYGreen);

          vidIn = step(htextinsCent, vidIn, [centXGreen centYGreen], [centXGreen-6 centYGreen-9]); 

          cursor.mouseMove(2.14*centXGreen,1.6*centYGreen);

          end

%        if(centYGreen>300)
%             if(y1>250)
%                display('Scroll up');
%                
%                %cursor.mouseWheel(-1);
%             end  
 %      end 

%     if(x==1)    
%         
%         if(centXGreen>580&&centYGreen>420)
%            
%             count=count+1;
%             
%             if(count>20)
%             
%                 display('Scroll down');
%                 cursor.mouseWheel(+1);
%                 pause(1);
%             count=0;
%             end
%             
%         end 
%        
%         if(centXGreen>580&&centYGreen<50)
%             
%             count=count+1;
%             
%             if(count>20)
%             
%                 display('Scroll up');
%                 cursor.mouseWheel(-1);
%                 pause(1);
%              count=0;
%             end
%            
%         end
%         
%         
%     else
%         
%         count=count+1;
%         

%         if (count>50)
%            
%                    %FlagClick=0; 
%                    display('double click');
%                    cursor.mousePress(InputEvent.BUTTON1_MASK);
%                    %cursor.delay(0.1);
%                    cursor.mouseRelease(InputEvent.BUTTON1_MASK);
%                    %cursor.delay(0.5);
%                    cursor.mousePress(InputEvent.BUTTON1_MASK);
%                    %cursor.delay(0.1);
%                    cursor.mouseRelease(InputEvent.BUTTON1_MASK);
%        count=0;
%         
%         end 

                  %cursor.mouseWheel(+1);
              %end  
         % end   
  %             if(y1>250)
  %                 display('Scroll down');
  %                
  %                 %cursor.mouseWheel(+1);
  %             end  
  %         end      

step(hVideoIn, vidIn); % Output video stream

      %nFrame = nFrame+1;

end    

release(hVideoIn);
release(vidDevice);