Magical bresenham

exercise2/src/bresenham_line_tool.cpp

@@ -7,15 +7,19 @@
 #include <algorithm>
 #include <math.h>
 
+#include <iostream>
+
 // Initialize the tool and store a reference of a canvas_buffer
-bresenham_line_tool::bresenham_line_tool(canvas_buffer& canvas): tool_base(canvas)
+bresenham_line_tool::bresenham_line_tool(canvas_buffer &canvas) : tool_base(canvas)
 {
 	// This tool draws lines!
 	shape = TS_LINE;
 }
 
-
-
+void print_point(int x, int y)
+{
+	std::cout << "point (" << x << ", " << y << ")" << std::endl;
+}
 
 // Draw a line from (x0, y0) to (x1, y1)
 void bresenham_line_tool::draw(int x0, int y0, int x1, int y1)
@@ -35,14 +39,93 @@ void bresenham_line_tool::draw(int x0, int y0, int x1, int y1)
 				   den Standardfall her. Falls Sie den Wert zweier Variablen vertauschen
 				   muessen koennen Sie dafür die Methode "std::swap(a, b)" verwenden.
    	*************/
+
+	std::cout << "first: " << std::endl;
+	print_point(x0, y0);
+	print_point(x1, y1);
+
+	if (x0 > x1)
+	{
+		std::swap(x0, x1);
+		std::swap(y0, y1);
+	}
+
+	std::cout << "second: " << std::endl;
+	print_point(x0, y0);
+	print_point(x1, y1);
+	std::cout << std::endl;
+
+	bool swap_y = false;
+
+	if (y0 > y1)
+	{
+		swap_y = true;
+		std::swap(y0, y1);
+	}
+
+	int x = x0;
+	int y = y0;
+
+	float dx = static_cast<float>(abs(x1 - x0));
+	float dy = static_cast<float>(abs(y1 - y0));
+
+	int sR;
+	float f;
+
+	if (dx > dy)
+	{
+		sR = 0;
+		f = dx / 2.0f;
+	}
+	else
+	{
+		sR = 1;
+		f = dy / 2.0f;
+	}
+
+	int p = (2 * dy) - dx;
+
+	while (x < x1 || y < y1)
+	{
+		if (sR == 0)
+		{
+			x++;
+			f -= dy;
+		}
+		else
+		{
+			y++;
+			f -= dx;
+		}
+
+		if (f < 0.0f)
+		{
+			if (sR == 0)
+			{
+				y++;
+				f += dx;
+			}
+			else
+			{
+				x++;
+				f += dy;
+			}
+		}
+
+		int x_res = x;
+
+		if (swap_y)
+		{
+			x_res = x1 - (x - x0);
+		}
+
+		canvas.set_pixel(x_res, y);
+	}
 }
 
-
-
-
 // Put debug output into the stream "stream" to be displayed in the
 // main window
-void bresenham_line_tool::set_text(std::stringstream& stream)
+void bresenham_line_tool::set_text(std::stringstream &stream)
 {
-	stream<<"Tool: Bresenham-Line (click and drag mouse to draw)";
+	stream << "Tool: Bresenham-Line (click and drag mouse to draw)";
 }