From 9c3cceef31cd65da5d7e0a598026ce9d6f51da06 Mon Sep 17 00:00:00 2001
From: Jan Philipp Timme <jan.philipp@timme.it>
Date: Fri, 18 Dec 2015 14:30:38 +0100
Subject: [PATCH] [TASK] Begin implementing basic gradiant parts for canny
 edge.

---
 canny_edge_machine.cpp | 43 ++++++++++++++++++++++++++++++++++++------
 1 file changed, 37 insertions(+), 6 deletions(-)

diff --git a/canny_edge_machine.cpp b/canny_edge_machine.cpp
index 7192919..d58863a 100644
--- a/canny_edge_machine.cpp
+++ b/canny_edge_machine.cpp
@@ -77,7 +77,7 @@ class CannyEdgeMachine {
 	  filter[i*filter_width + j] = pow(2, i) * pow(2, j);
 	  sum_weights += filter[i*filter_width + j];
 	}
-      }      
+      }
       // apply gauss filter
       int filter_offset = (filter_width+1)/2;
       for(int x=(0+filter_offset); x<(this->width-filter_offset); x++) {
@@ -105,14 +105,45 @@ class CannyEdgeMachine {
       free(filter);
     };
     
+    void doGradiants(void) {
+      // build the gradiant vector
+      int gradiant_size = 3;
+      double* gradiant_vector = (double*) malloc(sizeof(double) * gradiant_size);
+      gradiant_vector[0] = -0.5;
+      gradiant_vector[1] = 0;
+      gradiant_vector[2] = 0.5;
+      int gradiant_offset = gradiant_size;
+      // calculate gradiants
+      for(int x=(0+gradiant_offset); x<(this->width-gradiant_offset); x++) {
+        for(int y=(0+gradiant_offset); y<(this->height-gradiant_offset); y++) {
+	  int h, s, l;
+	  // x gradiant
+          double sum_intensity = 0;
+	  for(int i=0; i<gradiant_size; i++) {
+	    int dx = i - gradiant_size/2;
+	    QColor color = QColor::fromRgb(this->original->getPixel(x+dx, y, LazyImage::DEFAULT));
+	    color.getHsl(&h, &s, &l);
+	    sum_intensity += l * gradiant_vector[i];
+	  }
+	  this->gradient_x[y*width + x] = sum_intensity;
+	  // y gradiant
+          double sum_intensity = 0;
+	  for(int i=0; i<gradiant_size; i++) {
+	    int dy = i - gradiant_size/2;
+	    QColor color = QColor::fromRgb(this->original->getPixel(x, y+dy, LazyImage::DEFAULT));
+	    color.getHsl(&h, &s, &l);
+	    sum_intensity += l * gradiant_vector[i];
+	  }
+	  this->gradient_y[y*width + x] = sum_intensity;
+        }
+      }
+      free(gradiant_vector);
+    };
+    
     void work() {
       this->reset();
       this->doGaussBlur();
-      /*for(int x=0; x<this->width; x++) {
-	for(int y=0; y<this->height; y++) {
-	  //this->gradient_magnitude = sqrt(...)
-	}
-      }*/
+      this->doGradiants();
       
     };