Fixed bezier drawing, improved performance

QT/bezier_1/mywindow.cpp

@@ -106,27 +106,8 @@ void MyWindow::on_cleanButton_clicked()
 // obszaru rysowania
 void MyWindow::czysc()
 {
-    // Wskaznik za pomoca, ktorego bedziemy modyfikowac obraz
-    unsigned char *ptr;
-
-    // Funkcja "bits()" zwraca wskaznik do pierwszego piksela danych
-    ptr = img->bits();
-
-    int i,j;
-
-    // Przechodzimy po wszystkich wierszach obrazu
-    for(i=0; i<wys; i++)
-    {
-        // Przechodzimy po pikselach danego wiersza
-        // W kazdym wierszu jest "szer" pikseli (tzn. 4 * "szer" bajtow)
-        for(j=0; j<szer; j++)
-        {
-            ptr[szer*4*i + 4*j]=0; // Skladowa BLUE
-            ptr[szer*4*i + 4*j + 1] = 0; // Skladowa GREEN
-            ptr[szer*4*i + 4*j + 2] = 0; // Skladowa RED
-            ptr[szer*4*i + 4*j + 3] = 255; // Skladowa RED
-        }
-    }
+    bezier_points.clear();
+    DrawBezier();
 }
 
 
@@ -152,7 +133,6 @@ void MyWindow::mousePressEvent(QMouseEvent *event)
 
 //    draw_finished = false;
 
-//    mode = event->button() == Qt::LeftButton ? Add : event->button() == Qt::RightButton ? Move : Move;
     int id = -1;
     switch(event->button()){
         case Qt::LeftButton:
@@ -239,7 +219,7 @@ int MyWindow::FindPoint(int x, int y, float radius){
     float min_dist = FLT_MAX;
     int min_id = -1;
     for(int i = 0; i < bezier_points.size(); i++){
-        float dist = src_point - (Point)(bezier_points[i]);
+        float dist = (src_point - (Point)(bezier_points[i])).length();
         if(dist < min_dist && dist < radius){
             min_id = i;
             min_dist = dist;
@@ -309,9 +289,6 @@ void MyWindow::DrawCircle(int x1, int y1, int x2, int y2){
 
     UpdateTempImage();
 
-    unsigned char *ptr;
-    ptr = img_tmp->bits();
-
     float R = sqrt(pow(x2 - x1, 2) + pow(y2 - y1, 2));
     int q_last_x = R / sqrt(2) + 1;
 
@@ -370,21 +347,41 @@ void MyWindow::DrawBezier(){
         DrawPixel(img, bezier_points[i].x, bezier_points[i].y);
     }
     for(int i = 1; i < bezier_points.size(); i+=3){
-        if(i + 3 <= bezier_points.size()){
-            for(int j = i; j < i + 3; j++){
-                Point p1 = bezier_points[j-1];
-                Point p2 = bezier_points[j];
+        if(i + 2 >= bezier_points.size())
+            break;
+        Point p0 = bezier_points[i - 1];
+        Point p1 = bezier_points[i];
+        Point p2 = bezier_points[i + 1];
+        Point p3 = bezier_points[i + 2];
 
-                DrawLine(p1.x, p1.y, p2.x, p2.y, img);
-            }
+
+        Point last_point = p0;
+        for(int i = 1; i <= segment_count; i++){
+            float t = (float(i) / segment_count);
+
+            Point P =
+                    p0 * (float)pow(1.0f - t, 3)
+                    + p1 * 3.0f * (float)pow(1.0f - t, 2) * t
+                    + p2 * 3.0f * (1.0f - t) * (float)pow(t, 2)
+                    + p3 * (float)pow(t, 3);
+
+            DrawLine(last_point.x, last_point.y, P.x, P.y, img);
+
+            last_point = P;
         }
     }
 }
 
 void MyWindow::ClearImage(QImage *img){
+    unsigned char* empty_val = (unsigned char*)malloc(4);
+    empty_val[0] = 0;
+    empty_val[1] = 0;
+    empty_val[2] = 0;
+    empty_val[3] = 255;
+    unsigned char* ptr = img->bits();
     for(int i = 0; i < img->width(); i++){
         for(int j = 0; j < img->height(); j++){
-            DrawPixel(img, i, j, QColor(0,0,0));
+            memcpy(ptr + 4 * (i + j * img->width()), empty_val, 4);
         }
     }
 }

QT/bezier_1/mywindow.h

@@ -45,12 +45,26 @@ struct Point{
         this->y=y;
     }
 
-    float operator-(const Point& other){
-        float x = other.x - this->x;
-        float y = other.y - this->y;
+    float length(){
         float mag = std::sqrt(std::pow(x, 2) + std::pow(y, 2));
         return mag;
     }
+
+    Point operator-(const Point& other){
+        return Point(this->x - other.x, this->y - other.y);
+//        float x = other.x - this->x;
+//        float y = other.y - this->y;
+//        float mag = std::sqrt(std::pow(x, 2) + std::pow(y, 2));
+//        return mag;
+    }
+
+    Point operator*(const float mul){
+        return Point(this->x * mul, this->y * mul);
+    }
+
+    Point operator+(const Point& other){
+        return Point(this->x + other.x, this->y + other.y);
+    }
 };
 
 // MyWindow jest podklasa klasy QMainWindow.