WindowServer: Rewrite damaged region tracking

Instead of immediately doing rerender of client data and syncing 60 Hz,
we now only keep track of the damaged regions and also do the rerender
step 60 Hz.

userspace/programs/WindowServer/Utils.h

@@ -74,6 +74,69 @@ struct Rectangle
 		};
 	}
 
+	size_t split_along_edges_of(const Rectangle& other, Rectangle out[9]) const
+	{
+		out[0] = *this;
+
+		size_t vertical = 1;
+
+		if (min_x < other.min_x && other.min_x < max_x)
+		{
+			auto& rect1 = out[vertical - 1];
+			auto& rect2 = out[vertical - 0];
+			rect2 = rect1;
+
+			rect1.max_x = other.min_x;
+			rect2.min_x = other.min_x;
+
+			vertical++;
+		}
+
+		if (min_x < other.max_x && other.max_x < max_x)
+		{
+			auto& rect1 = out[vertical - 1];
+			auto& rect2 = out[vertical - 0];
+			rect2 = rect1;
+
+			rect1.max_x = other.max_x;
+			rect2.min_x = other.max_x;
+
+			vertical++;
+		}
+
+		size_t horizontal = 1;
+
+		if (min_y < other.min_y && other.min_y < max_y)
+		{
+			for (size_t i = 0; i < vertical; i++)
+			{
+				auto& rect1 = out[vertical * (horizontal - 1) + i];
+				auto& rect2 = out[vertical * (horizontal - 0) + i];
+				rect2 = rect1;
+
+				rect1.max_y = other.min_y;
+				rect2.min_y = other.min_y;
+			}
+			horizontal++;
+		}
+
+		if (min_y < other.max_y && other.max_y < max_y)
+		{
+			for (size_t i = 0; i < vertical; i++)
+			{
+				auto& rect1 = out[vertical * (horizontal - 1) + i];
+				auto& rect2 = out[vertical * (horizontal - 0) + i];
+				rect2 = rect1;
+
+				rect1.max_y = other.max_y;
+				rect2.min_y = other.max_y;
+			}
+			horizontal++;
+		}
+
+		return vertical * horizontal;
+	}
+
 	bool operator==(const Rectangle& other) const
 	{
 		return min_x == other.min_x && min_y == other.min_y && max_x == other.max_x && max_y == other.max_y;
@@ -95,32 +158,3 @@ struct Circle
 	}
 
 };
-
-struct Range
-{
-	uint32_t start { 0 };
-	uint32_t count { 0 };
-
-	bool is_continuous_with(const Range& range) const
-	{
-		return start <= range.start + range.count && range.start <= start + count;
-	}
-
-	uint32_t distance_between(const Range& range) const
-	{
-		if (is_continuous_with(range))
-			return 0;
-		if (start < range.start)
-			return range.start - (start + count);
-		return start - (range.start + range.count);
-	}
-
-	void merge_with(const Range& range)
-	{
-		const uint32_t new_start = BAN::Math::min(start, range.start);
-		const uint32_t new_end   = BAN::Math::max(start + count, range.start + range.count);
-
-		start = new_start;
-		count = new_end - new_start;
-	}
-};