move stb to src/stb, add stb_image for png decoding

src/font/face/freetype.zig

@@ -8,7 +8,7 @@ const std = @import("std");
 const builtin = @import("builtin");
 const freetype = @import("freetype");
 const harfbuzz = @import("harfbuzz");
-const resize = @import("stb_image_resize");
+const stb = @import("../../stb/main.zig");
 const assert = std.debug.assert;
 const testing = std.testing;
 const Allocator = std.mem.Allocator;
@@ -204,7 +204,7 @@ pub const Face = struct {
             result.buffer = buf.ptr;
             errdefer alloc.free(buf);
 
-            if (resize.stbir_resize_uint8(
+            if (stb.stbir_resize_uint8(
                 bm.buffer,
                 @intCast(bm.width),
                 @intCast(bm.rows),

src/stb/main.zig

@@ -0,0 +1,4 @@
+pub usingnamespace @cImport({
+    @cInclude("stb_image.h");
+    @cInclude("stb_image_resize.h");
+});

src/stb/stb.c

@@ -0,0 +1,13 @@
+// For STBI we only need PNG because the only use case we have right now
+// is the Kitty Graphics protocol which only supports PNG as a format
+// besides raw RGB/RGBA buffers.
+#define STBI_ONLY_PNG
+
+// We don't want to support super large images.
+#define STBI_MAX_DIMENSIONS 131072
+
+#define STB_IMAGE_IMPLEMENTATION
+#include <stb_image.h>
+
+#define STB_IMAGE_RESIZE_IMPLEMENTATION
+#include <stb_image_resize.h>