Remove harfbuzz as it's not capable of running on micro memory systems

Harfbuzz's FreeType integration is written to load the entire font into
memory. I wanted Harfbuzz as a drop-in solution for substitution of
emoji sequences, which are stored in the 9MB NotoColorEmoji font
currently. This won't work without significant modification to Harfbuzz,
so I'll need a different solution to achieve ZWJ sequences.

Looks like we'll need to look up the GSUB table on our own to do this 🕶

firmware/CMakeLists.txt

@@ -26,7 +26,6 @@ set(FETCHCONTENT_QUIET FALSE)
 
 # Source dependencies
 FetchContent_Declare(freetype URL https://download.savannah.gnu.org/releases/freetype/freetype-2.12.1.tar.gz)
-FetchContent_Declare(harfbuzz URL https://github.com/harfbuzz/harfbuzz/releases/download/3.4.0/harfbuzz-3.4.0.tar.xz)
 FetchContent_Declare(libpng URL https://cytranet.dl.sourceforge.net/project/libpng/libpng16/1.6.37/libpng-1.6.37.tar.xz)
 FetchContent_Declare(unicode_blocks URL https://unicode.org/Public/UNIDATA/Blocks.txt DOWNLOAD_NO_EXTRACT TRUE)
 FetchContent_Declare(unicode_codepoints URL https://unicode.org/Public/UNIDATA/UnicodeData.txt DOWNLOAD_NO_EXTRACT TRUE)
@@ -96,18 +95,6 @@ set(PNG_INCLUDE_DIRS ${libpng_SOURCE_DIR} ${libpng_BINARY_DIR} CACHE INTERNAL ""
 add_subdirectory(${freetype_SOURCE_DIR} ${freetype_BINARY_DIR} EXCLUDE_FROM_ALL)
 
 
-# harfbuzz
-FetchContent_GetProperties(harfbuzz)
-if(NOT harfbuzz_POPULATED)
-	FetchContent_Populate(harfbuzz)
-endif()
-
-set(CMAKE_DISABLE_FIND_PACKAGE_Threads TRUE CACHE INTERNAL "Prevent Harfbuzz from looking for a threading library")
-
-add_subdirectory(${harfbuzz_SOURCE_DIR} ${harfbuzz_BINARY_DIR} EXCLUDE_FROM_ALL)
-target_compile_options(harfbuzz PUBLIC -DHB_TINY -Wno-format)
-
-
 #
 # Support embedding resources in the binary (GCC-specific)
 # Based on https://stackoverflow.com/a/56006001/1470907
@@ -181,7 +168,6 @@ set(DEVICE_SOURCES
 
 set(FIRMWARE_LIBS
 	freetype
-	harfbuzz
 	pico_stdlib
 	png_static
 	zlibstatic
@@ -227,16 +213,14 @@ endif()
 # Explicitly select targets to build from libpng and zlib (since we're EXCLUDE_FROM_ALL)
 add_dependencies(png_static zlibstatic)
 add_dependencies(freetype png_static zlibstatic)
-add_dependencies(harfbuzz freetype)
-add_dependencies(firmware png_static zlibstatic freetype harfbuzz)
+add_dependencies(firmware png_static zlibstatic freetype)
 
 target_include_directories(firmware PRIVATE
     ${libpng_SOURCE_DIR}
     ${libpng_BINARY_DIR}
     ${zlib_SOURCE_DIR}
     ${zlib_BINARY_DIR}
     ${FREETYPE_INCLUDE_DIRS}
-    ${harfbuzz_SOURCE_DIR}/src # not ideal, but the harfbuzz public headers aren't exposed anywhere
 )
 
 target_link_libraries(firmware ${FIRMWARE_LIBS})

firmware/font.cpp

@@ -6,10 +6,6 @@
 #include <freetype/ftoutln.h>
 #include <freetype/internal/ftobjs.h>
 
-// Harfbuzz
-#include <hb.h>
-#include <hb-ft.h>
-
 // C++
 #include <algorithm>
 #include <cmath>
@@ -136,46 +132,6 @@ bool FontStore::drawGlyph(uint32_t codepoint, int adjust_y)
         return false;
     }
 
-    // {
-    //     hb_buffer_t *buf;
-    //     buf = hb_buffer_create();
-    //     // hb_buffer_add_utf8(buf, "\U0001f3c3\u200d\U0001f3fe", -1, 0, -1);
-    //     // hb_buffer_add_utf8(buf, "\u2764\uFE0F\u200D\U0001F525", -1, 0, -1);
-    //     hb_buffer_add_utf8(buf, "\U0001F3F4\u200D\u2620\uFE0F", -1, 0, -1);
-
-    //     hb_buffer_set_direction(buf, HB_DIRECTION_LTR);
-    //     hb_buffer_set_script(buf, HB_SCRIPT_COMMON);
-    //     hb_buffer_set_language(buf, hb_language_get_default());
-
-    //     hb_font_t *font = hb_ft_font_create(m_face, noop_destroy_func);
-
-    //     hb_shape(font, buf, NULL, 0);
-
-    //     unsigned int glyph_count;
-    //     hb_glyph_info_t *glyph_info    = hb_buffer_get_glyph_infos(buf, &glyph_count);
-    //     hb_glyph_position_t *glyph_pos = hb_buffer_get_glyph_positions(buf, &glyph_count);
-
-    //     hb_position_t cursor_x = 0;
-    //     hb_position_t cursor_y = 0;
-    //     for (unsigned int i = 0; i < glyph_count; i++) {
-    //         hb_codepoint_t glyphid  = glyph_info[i].codepoint;
-    //         hb_position_t x_offset  = glyph_pos[i].x_offset;
-    //         hb_position_t y_offset  = glyph_pos[i].y_offset;
-    //         hb_position_t x_advance = glyph_pos[i].x_advance;
-    //         hb_position_t y_advance = glyph_pos[i].y_advance;
-
-    //         /* draw_glyph(glyphid, cursor_x + x_offset, cursor_y + y_offset); */
-
-    //         // printf(" glyph: %d\n", glyphid);
-
-    //         cursor_x += x_advance;
-    //         cursor_y += y_advance;
-    //     }
-
-    //     hb_buffer_destroy(buf);
-    //     hb_font_destroy(font);
-    // }
-
     FT_Error error;
     int width = 0;
     int height = 0;