Data commit

Task/Bitmap-Write-a-PPM-file/Common-Lisp/bitmap-write-a-ppm-file.lisp

@@ -0,0 +1,28 @@
+(defun write-rgb-buffer-to-ppm-file (filename buffer)
+  (with-open-file (stream filename
+			  :element-type '(unsigned-byte 8)
+			  :direction :output
+			  :if-does-not-exist :create
+			  :if-exists :supersede)
+    (let* ((dimensions (array-dimensions buffer))
+	   (width (first dimensions))
+	   (height (second dimensions))
+	   (header (format nil "P6~A~D ~D~A255~A"
+			   #\newline
+			   width height #\newline
+			   #\newline)))
+      (loop
+	 :for char :across header
+	 :do (write-byte (char-code char) stream)) #| Assumes char-codes match ASCII |#
+
+      (loop
+	 :for x :upfrom 0 :below width
+	 :do (loop :for y :upfrom 0 :below height
+		:do (let ((pixel (rgb-pixel buffer x y)))
+		      (let ((red (rgb-pixel-red pixel))
+			    (green (rgb-pixel-green pixel))
+			    (blue (rgb-pixel-blue pixel)))
+			(write-byte red stream)
+			(write-byte green stream)
+			(write-byte blue stream)))))))
+  filename)