Draw polygon

graphics/image.cc

@@ -11,6 +11,7 @@
 #include <iostream>
 #include <memory>
 #include <string>
+#include <vector>
 
 #include "cimg/CImg.h"
 
@@ -238,6 +239,31 @@ bool Image::DrawRectangle(int x, int y, int width, int height, int red,
   return true;
 }
 
+bool Image::DrawPolygon(const std::vector<int>& points, int red, int green, int blue) {
+  const int color[] = {red, green, blue};
+  if (!CheckColorInBounds(color)) {
+    return false;
+  }
+  if (points.size() % 2 != 0) {
+    cout << "Invalid vector of vertices. Each vertex should be represented by 2 integers." << endl;
+    return false;
+  }
+  for (int i = 0; i < points.size(); i += 2) {
+    if (!CheckPixelInBounds(points[i], points[i + 1])) {
+      return false;
+    }
+  }
+  CImg<int> c_points(points.size() / 2, 2);
+  int c_point_loc = 0;
+  for (int i = 0; i < points.size(); i += 2) {
+    c_points(c_point_loc, 0) = points[i];
+    c_points(c_point_loc++, 1) = points[i+1];
+  }
+  cimage_->draw_polygon(c_points, color);
+
+  return true;
+}
+
 bool Image::DrawText(int x, int y, const string& text, int font_size, int red,
                      int green, int blue) {
   const int color[] = {red, green, blue};

graphics/image.h

@@ -8,6 +8,7 @@
 #include <memory>
 #include <set>
 #include <string>
+#include <vector>
 
 #include "image_event.h"
 
@@ -277,6 +278,28 @@ class Image {
   bool DrawRectangle(int x, int y, int width, int height, int red, int green,
                      int blue);
 
+  /**
+   * Draws a polygon whose vertices are listed in |points| and colored with
+   * |color|. Each vertex is represented by its x and y coordinate, and are
+   * listed sequentially in the vector. For example, a polygon with three
+   * vertices (0, 0), (0, 2), (2,1) is represented as a vector of integers
+   * {0, 0, 0, 2, 2, 1}. The last vertex will connect with the first vertex in
+   * the list. Returns false if params are out of bounds.
+   */
+  bool DrawPolygon(const std::vector<int>& points, const Color& color) {
+    return DrawPolygon(points, color.Red(), color.Green(), color.Blue());
+  }
+
+  /**
+   * Draws a polygon whose vertices are listed in |points| and colored with
+   * |red|, |green|, |blue|. Each vertex is represented by its x and y
+   * coordinate, and are listed sequentially in the vector. For example, a
+   * polygon with three vertices (0, 0), (0, 2), (2,1) is represented as a
+   * vector of integers {0, 0, 0, 2, 2, 1}. The last vertex will connect with
+   * the first vertex in* the list. Returns false if params are out of bounds.
+   */
+  bool DrawPolygon(const std::vector<int>& points, int red, int green, int blue);
+
   /**
    * Draws the string |text| with position (x,y) at the top left corner,
    * with |font_size| in pixels, colored by |color|. Returns false if the

graphics/test/image_unittest.cc

@@ -109,6 +109,7 @@ TEST(ImageTest, Drawing) {
   graphics::Image image(50, 50);
   graphics::Color white(255, 255, 255);
   graphics::Color blue(0, 0, 255);
+  graphics::Color red(255, 0, 0);
   image.DrawCircle(20, 20, 5, blue);
   // Spot check some pixels.
   EXPECT_EQ(image.GetColor(20, 20), blue);
@@ -123,6 +124,10 @@ TEST(ImageTest, Drawing) {
       EXPECT_EQ(image.GetBlue(i, j), 0);
     }
   }
+  std::vector<int> points = {20, 20, 20, 22, 22, 21};
+  image.DrawPolygon(points, red);
+  EXPECT_EQ(image.GetColor(20, 21), red);
+  EXPECT_EQ(image.GetColor(21, 21), red);  
 
   // Drawing something out of bounds doesn't work.
   image.DrawRectangle(-1, -1, 50, 50, 0, 255, 0);
@@ -131,6 +136,10 @@ TEST(ImageTest, Drawing) {
   image.DrawCircle(40, 50, 100, 0, 255, 0);
   EXPECT_EQ(image.GetColor(0, 0), white);
 
+  std::vector<int> out_points = {-1, 0, 0, 0, -2, 0};
+  image.DrawPolygon(out_points, red);
+  EXPECT_EQ(image.GetColor(0, 0), white);
+
   // Hard to test the line because of anti-aliasing.
   image.DrawLine(0, 0, 40, 40, 255, 0, 0);
   EXPECT_EQ(image.GetGreen(0, 0), 0);