From df1dadf7ba10a0447dad9808c8501299a3a19f5d Mon Sep 17 00:00:00 2001
From: "Adam D. Ruppe" <destructionator@gmail.com>
Date: Sat, 26 Sep 2015 15:05:21 -0400
Subject: [PATCH] offset function

---
 simpledisplay.d | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/simpledisplay.d b/simpledisplay.d
index 2fb5523..bd39b94 100644
--- a/simpledisplay.d
+++ b/simpledisplay.d
@@ -1917,6 +1917,19 @@ final class Image {
 			} else static assert(0, "fill in this info for other OSes");
 		}
 
+		///
+		int offsetForPixel(int x, int y) {
+			version(X11) {
+				auto offset = (y * width + x) * 4;
+				return offset;
+			} else version(Windows) {
+				auto itemsPerLine = ((cast(int) width * 3 + 3) / 4) * 4;
+				// remember, bmps are upside down
+				auto offset = itemsPerLine * (height - y - 1) + x * 3;
+				return offset;
+			} else static assert(0, "fill in this info for other OSes");
+		}
+
 		///
 		int adjustmentForNextLine() {
 			version(X11) {