[python] merge '6fcab395' and fix a bug in fill_polygon()

kandinsky/src/context_polygon.cpp

@@ -0,0 +1,67 @@
+#include <kandinsky/context.h>
+#include <assert.h>
+#include <math.h>
+
+void KDContext::fillPolygon(KDCoordinate pointsX[], KDCoordinate pointsY[], int numberOfPoints, KDColor color)
+{
+  //The used algorithm is the scan-line algorithm
+
+  KDCoordinate top = KDCOORDINATE_MAX;
+  KDCoordinate bottom = KDCOORDINATE_MIN;
+  KDCoordinate right = m_clippingRect.width();
+  KDCoordinate left = 0;
+
+  for (int i = 0; i < numberOfPoints; i++) {
+    if (pointsY[i] < top) {
+      top = pointsY[i];
+    }
+    if (pointsY[i] > bottom) {
+      bottom = pointsY[i];
+    }
+  }
+
+  if (top < 0) {
+    top = 0;
+  }
+  if (bottom > m_clippingRect.height()) {
+    bottom = m_clippingRect.height();
+  }
+
+
+  for (int y=top; y<=bottom; y++) {
+
+    int switches=0;
+    KDCoordinate switchesX[KDContext::k_polygonMaxNumberOfPoints];
+    int lastPointIndex = numberOfPoints-1;
+
+    for (int i=0; i<numberOfPoints; i++) {
+      if (((pointsY[i]<=y && pointsY[lastPointIndex]>=y) || (pointsY[lastPointIndex]<= y && pointsY[i]>=y)) && pointsY[i] != pointsY[lastPointIndex]) {
+        switchesX[switches++] = (int) round(pointsX[i]+1.0*(y-pointsY[i])/(pointsY[lastPointIndex]-pointsY[i])*(pointsX[lastPointIndex]-pointsX[i])); 
+      }
+      lastPointIndex=i; 
+    }
+
+    //Sorting switches by a bubble sort
+    int i=0;
+    while (i<switches-1) {
+      if (switchesX[i]>switchesX[i+1]) {
+        KDCoordinate temp = switchesX[i]; 
+        switchesX[i]=switchesX[i+1]; 
+        switchesX[i+1]=temp; 
+        if (i) i--; 
+      }
+      else {
+        i++; 
+      }
+    }
+
+    for (i=0; i<switches; i+=2) {
+      if (switchesX[i]>=right) {
+        break;
+      }
+      if (switchesX[i+1]>left) {
+          fillRect( KDRect( switchesX[ i ] , y, switchesX[ i+1 ] - switchesX[ i ], 1 ), color ) ;
+      }
+    }
+  }
+}