From ba035ac532a65457d55ec77b06273642d5191909 Mon Sep 17 00:00:00 2001
From: Cameron Cawley
Date: Sat, 16 Nov 2019 15:27:55 +0000
Subject: GRAPHICS: Add a function to vertically flip surfaces

---
 graphics/surface.cpp | 14 ++++++++++++++
 graphics/surface.h   |  7 +++++++
 2 files changed, 21 insertions(+)

diff --git a/graphics/surface.cpp b/graphics/surface.cpp
index 265249e72f..26d40b8922 100644
--- a/graphics/surface.cpp
+++ b/graphics/surface.cpp
@@ -354,6 +354,20 @@ void Surface::move(int dx, int dy, int height) {
 	}
 }
 
+void Surface::flipVertical(const Common::Rect &r) {
+	const int width = r.width() * format.bytesPerPixel;
+	byte *temp = new byte[width];
+	for (int y = r.top; y < r.bottom / 2; y++) {
+		byte *row1 = (byte *)getBasePtr(r.left, y);
+		byte *row2 = (byte *)getBasePtr(r.left, r.bottom - y - 1);
+
+		memcpy(temp, row1, width);
+		memcpy(row1, row2, width);
+		memcpy(row2, temp, width);
+	}
+	delete[] temp;
+}
+
 void Surface::convertToInPlace(const PixelFormat &dstFormat, const byte *palette) {
 	// Do not convert to the same format and ignore empty surfaces.
 	if (format == dstFormat || pixels == 0) {
diff --git a/graphics/surface.h b/graphics/surface.h
index 19107b8bab..8728106273 100644
--- a/graphics/surface.h
+++ b/graphics/surface.h
@@ -327,6 +327,13 @@ public:
 
 	// See comment in graphics/surface.cpp about it
 	void move(int dx, int dy, int height);
+
+	/**
+	 * Flip the specified rect vertically.
+	 *
+	 * @param r Rect to flip
+	 */
+	void flipVertical(const Common::Rect &r);
 };
 
 /**
-- 
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