From e835673c5e8499bd67f0f5ac0e52d9c77f5bfb88 Mon Sep 17 00:00:00 2001
From: sfan5 <sfan5@live.de>
Date: Fri, 20 Jun 2025 12:57:28 +0200
Subject: [PATCH] Extract bitmap class

---
 src/client/imagefilters.cpp | 46 +-----------------
 src/util/bitmap.h           | 93 +++++++++++++++++++++++++++++++++++++
 2 files changed, 95 insertions(+), 44 deletions(-)
 create mode 100644 src/util/bitmap.h

diff --git a/src/client/imagefilters.cpp b/src/client/imagefilters.cpp
index 8b38e9ad9..c51743765 100644
--- a/src/client/imagefilters.cpp
+++ b/src/client/imagefilters.cpp
@@ -4,54 +4,12 @@
 
 #include "imagefilters.h"
 #include "util/numeric.h"
+#include "util/bitmap.h"
 #include <cmath>
 #include <cassert>
-#include <vector>
 #include <algorithm>
 #include <IVideoDriver.h>
 
-// Simple 2D bitmap class with just the functionality needed here
-class Bitmap {
-	u32 linesize, lines;
-	std::vector<u8> data;
-
-	static inline u32 bytepos(u32 index) { return index >> 3; }
-	static inline u8 bitpos(u32 index) { return index & 7; }
-
-public:
-	Bitmap(u32 width, u32 height) :  linesize(width), lines(height),
-		data(bytepos(width * height) + 1) {}
-
-	inline bool get(u32 x, u32 y) const {
-		u32 index = y * linesize + x;
-		return data[bytepos(index)] & (1 << bitpos(index));
-	}
-
-	inline void set(u32 x, u32 y) {
-		u32 index = y * linesize + x;
-		data[bytepos(index)] |= 1 << bitpos(index);
-	}
-
-	inline bool all() const {
-		for (u32 i = 0; i < data.size() - 1; i++) {
-			if (data[i] != 0xff)
-				return false;
-		}
-		// last byte not entirely filled
-		for (u8 i = 0; i < bitpos(linesize * lines); i++) {
-			bool value_of_bit = data.back() & (1 << i);
-			if (!value_of_bit)
-				return false;
-		}
-		return true;
-	}
-
-	inline void copy(Bitmap &to) const {
-		assert(to.linesize == linesize && to.lines == lines);
-		to.data = data;
-	}
-};
-
 template <bool IS_A8R8G8B8>
 static void imageCleanTransparentWithInlining(video::IImage *src, u32 threshold)
 {
@@ -143,7 +101,7 @@ static void imageCleanTransparentWithInlining(video::IImage *src, u32 threshold)
 
 	// Apply changes to bitmap for next run. This is done so we don't introduce
 	// a bias in color propagation in the direction pixels are processed.
-	newmap.copy(bitmap);
+	bitmap = newmap;
 
 	}
 }
diff --git a/src/util/bitmap.h b/src/util/bitmap.h
new file mode 100644
index 000000000..39e114c8e
--- /dev/null
+++ b/src/util/bitmap.h
@@ -0,0 +1,93 @@
+// Luanti
+// SPDX-License-Identifier: LGPL-2.1-or-later
+// Copyright (C) 2021-2025 sfan5
+
+#include "irrlichttypes.h"
+#include <vector>
+#include <algorithm>
+#include <cassert>
+
+/**
+ * Rudimentary header-only 2D bitmap class.
+ * @warning not thread-safe
+ */
+class Bitmap {
+	u32 linesize, lines;
+	std::vector<u8> data;
+
+	static inline u32 bytepos(u32 index) { return index >> 3; }
+	static inline u8 bitpos(u32 index) { return index & 7; }
+
+	template<bool set, bool toggle, bool clear>
+	bool modify_(u32 x, u32 y)
+	{
+		u32 index = y * linesize + x;
+		u8 mask = 1 << bitpos(index);
+		u8 byte = data[bytepos(index)];
+		if constexpr (set)
+			byte |= mask;
+		else if constexpr (toggle)
+			byte ^= mask;
+		else if constexpr (clear)
+			byte &= ~mask;
+		data[bytepos(index)] = byte;
+		return byte & mask;
+	}
+
+public:
+	/// @brief Create an empty bitmap
+	Bitmap() : linesize(0), lines(0) {}
+
+	/// @brief Create a new zero-filled bitmap
+	Bitmap(u32 width, u32 height)
+	{
+		resize(width, height);
+	}
+
+	inline u32 width() const { return linesize; }
+	inline u32 height() const { return lines; }
+
+	inline void resize(u32 width, u32 height, bool initial_value=false)
+	{
+		assert(width <= 65534 && height <= 65534); // index would overflow
+		linesize = width;
+		lines = height;
+		data.clear(); // make sure to discard all data
+		if (width && height)
+			data.resize(bytepos(width * height) + 1, static_cast<u8>(initial_value ? 0xff : 0));
+	}
+
+	inline void reset(bool value)
+	{
+		std::fill(data.begin(), data.end(), value ? 0xff : 0);
+	}
+
+	inline bool get(u32 x, u32 y) const
+	{
+		u32 index = y * linesize + x;
+		return data[bytepos(index)] & (1 << bitpos(index));
+	}
+
+	inline void set(u32 x, u32 y)   { modify_<1, 0, 0>(x, y); }
+	inline void unset(u32 x, u32 y) { modify_<0, 0, 1>(x, y); }
+	inline bool toggle(u32 x, u32 y) { return modify_<0, 1, 0>(x, y); }
+
+	/// @brief Returns true if all bits in the bitmap are set
+	inline bool all() const
+	{
+		if (!linesize || !lines)
+			return (assert(0), true);
+		for (u32 i = 0; i < data.size() - 1; i++) {
+			if (data[i] != 0xff)
+				return false;
+		}
+		u8 last_byte = data.back(); // not used entirely
+		for (u8 i = 0; i < bitpos(linesize * lines); i++) {
+			if (!(last_byte & (1 << i)))
+				return false;
+		}
+		return true;
+	}
+};
+
+// Note: a 3D class could be written based on the 2D one. Or maybe the other way?