patterns: Add Windows animated cursor (#242)

* patterns: Add Windows animated cursor

* Added readme entry

* Added mime type to readme

---------

Co-authored-by: Nik <werwolv98@gmail.com>

patterns/ani.hexpat

@@ -0,0 +1,66 @@
+#pragma description Windows animated cursor
+#pragma MIME application/x-navi-animation
+#pragma endian little
+
+import std.io;
+import std.mem;
+
+bitfield HeaderFlags {
+    icon : 1;
+    sequence : 1;
+    padding: 30;
+};
+
+struct anih {
+    u32 struct_size;
+    u32 stored_frames;
+    u32 animation_steps;
+    u32 w;
+    u32 h;
+    u32 bits;
+    u32 planes;
+    u32 default_jiffies;
+    HeaderFlags flags;
+};
+
+struct rate {
+    u32 jiffies[parent.size / 4];
+};
+
+struct seq {
+    u32 index[parent.size / 4];
+};
+
+struct RiffChunk {
+    char signature[4];
+    u32 size;
+    if (signature == "RIFF" || signature == "LIST") {
+        char type[4];
+        RiffChunk chunks[while($ - addressof(type) < size)];
+    } else if (signature[0] == 'I' && parent.type == "INFO") {
+        char info[size];
+    } else if (signature == "anih") {
+        anih anih [[inline]];
+    } else if (signature == "rate") {
+        rate rate [[inline]];
+    } else if (signature == "seq ") {
+        seq seq [[inline]];
+    } else {
+        std::mem::Bytes<size> data;
+    }
+    padding[size % 2];
+} [[format_read("read_chunk")]];
+
+fn read_chunk(RiffChunk chunk) {
+    if (chunk.signature == "RIFF" || chunk.signature == "LIST") {
+        return std::format("{}<{}> ({})", chunk.signature, chunk.type, chunk.size);
+    } else {
+        str ret = std::format("{} ({})", chunk.signature, chunk.size);
+        try {
+            ret += std::format(" \"{}\"", chunk.info);
+        } catch {}
+        return ret;
+    }
+};
+
+RiffChunk riff @ 0;