Basic implementation, and write function

Exec/main.cpp

@@ -1,9 +1,26 @@
 #include <BMP.h>
+#include <iostream>
+#include <BmpHeader.h>
 
 using namespace Leonetienne::BmpPP;
 
 int main() {
-    BMP bmp({800, 600});
+
+    BMP bmp({800, 600}, Colormode::RGB);
+
+    for (int x = 0; x < 800; x++)
+    for (int y = 0; y < 600; y++) {
+
+        bmp.SetPixel({x, y},
+            (std::uint8_t)(       ((double)x / 800.0) * 255.0),
+            (std::uint8_t)((1.0 - ((double)x / 800.0)) * 255.0),
+            (std::uint8_t)((1.0 - ((double)y / 800.0)) * 255.0),
+            255
+        );
+    }
+
+    if (!bmp.Write("test.bmp"))
+        std::cerr << "What the hell" << std::endl;
 
     return 0;
 }