RFC: Better Text Rendering for cairo / lua

.github/workflows/build-and-test-linux.yaml

@@ -77,6 +77,8 @@ jobs:
             libcurl4-gnutls-dev \
             libcurl4-gnutls-dev \
             libdbus-glib-1-dev \
+            libfreetype6-dev \
+            libstdc++6 \
             libglib2.0-dev \
             libical-dev \
             libimlib2-dev \
@@ -137,6 +139,7 @@ jobs:
             -DBUILD_LUA_CAIRO=ON                 \
             -DBUILD_LUA_IMLIB2=ON                \
             -DBUILD_LUA_RSVG=${RSVG_ENABLED}     \
+            -DBUILD_LUA_TEXT=ON                  \
             -DBUILD_MYSQL=ON                     \
             -DBUILD_NVIDIA=ON                    \
             -DBUILD_PULSEAUDIO=ON                \

.github/workflows/codeql.yml

@@ -38,6 +38,8 @@ jobs:
             libcurl4-gnutls-dev \
             libcurl4-gnutls-dev \
             libdbus-glib-1-dev \
+            libfreetype6-dev \
+            libstdc++6 \
             libglib2.0-dev \
             libical-dev \
             libimlib2-dev \

.github/workflows/publish-appimage.yml

@@ -32,6 +32,8 @@ jobs:
             libcairo2-dev \
             libcurl4-gnutls-dev \
             libdbus-glib-1-dev \
+            libfreetype6-dev \
+            libstdc++6 \
             libfuse2 \
             libglib2.0-dev \
             libical-dev \

AUTHORS

@@ -313,6 +313,9 @@ Mikko Sysikaski <sisu at users dot sourceforge dot net>
 Sceptik <sceptik at users dot sourceforge dot net>
   --quiet patch
 
+Simon Lees <sflees at suse dot de>
+  lua text
+
 Stepan Zastupov <redchrom at gmail dot com>
   WiFi signal level detection support on FreeBSD
 

Dockerfile

@@ -16,6 +16,9 @@ RUN apt-get update \
   libcairo2-dev \
   libcurl4-openssl-dev \
   libdbus-glib-1-dev \
+  libfontconfig-dev \
+  libfreetype-dev \
+  libharfbuzz-dev \
   libical-dev \
   libimlib2-dev \
   libircclient-dev \
@@ -76,6 +79,7 @@ RUN sh -c 'if [ "$X11" = "yes" ] ; then \
   -DBUILD_LUA_CAIRO=ON \
   -DBUILD_LUA_IMLIB2=ON \
   -DBUILD_LUA_RSVG=ON \
+  -DBUILD_LUA_TEXT=ON \
   -DBUILD_MYSQL=ON \
   -DBUILD_NVIDIA=ON \
   -DBUILD_PULSEAUDIO=ON \
@@ -98,6 +102,7 @@ RUN sh -c 'if [ "$X11" = "yes" ] ; then \
   -DBUILD_LUA_CAIRO=ON \
   -DBUILD_LUA_IMLIB2=ON \
   -DBUILD_LUA_RSVG=ON \
+  -DBUILD_LUA_TEXT=ON \
   -DBUILD_MYSQL=ON \
   -DBUILD_PULSEAUDIO=ON \
   -DBUILD_RSS=ON \
@@ -121,6 +126,9 @@ RUN apt-get update \
   libcairo2 \
   libcurl4 \
   libdbus-glib-1-2 \
+  libfontconfig1 \
+  libfreetype6 \
+  libharfbuzz-gobject0 \
   libical3 \
   libimlib2 \
   libircclient1 \

appimage/build.sh

@@ -44,6 +44,7 @@ cmake -G Ninja                         \
   -DBUILD_LUA_CAIRO=ON                 \
   -DBUILD_LUA_IMLIB2=ON                \
   -DBUILD_LUA_RSVG=ON                  \
+  -DBUILD_LUA_TEXT=ON                  \
   -DBUILD_MYSQL=ON                     \
   -DBUILD_NVIDIA=ON                    \
   -DBUILD_PULSEAUDIO=ON                \

cmake/ConkyBuildOptions.cmake

@@ -212,6 +212,7 @@ dependent_option(BUILD_LUA_IMLIB2 "Build Imlib2 bindings for Lua" false
   "BUILD_X11;BUILD_IMLIB2" false
   "Imlib2 Lua bindings require X11 and Imlib2")
 option(BUILD_LUA_RSVG "Build rsvg bindings for Lua" false)
+option(BUILD_LUA_TEXT "Build Fontconfig Freetype and Harfbuzz bindings for Lua" false)
 
 option(BUILD_AUDACIOUS "Build audacious (music player) support" false)
 

cmake/ConkyPlatformChecks.cmake

@@ -517,6 +517,18 @@ if(BUILD_GUI)
     set(luarsvg_libs ${RSVG_LIBRARIES} ${LUA_LIBRARIES})
     set(luarsvg_includes ${RSVG_INCLUDE_DIRS} ${LUA_INCLUDE_DIR})
   endif(BUILD_LUA_RSVG)
+
+  if(BUILD_LUA_TEXT)
+    if(FREETYPE_INCLUDE_DIR_freetype2)
+      set(FREETYPE_FOUND true)
+    else(FREETYPE_INCLUDE_DIR_freetype2)
+      message(FATAL_ERROR "Unable to find freetype library")
+    endif(FREETYPE_INCLUDE_DIR_freetype2)
+    PKG_CHECK_MODULES(FONTCONFIG REQUIRED fontconfig)
+    PKG_CHECK_MODULES(HARFBUZZ REQUIRED harfbuzz)
+    set(luatext_libs ${FREETYPE_LIBRARIES} ${FONTCONFIG_LIBRARIES} ${HARFBUZZ_LIBRARIES} ${LUA_LIBRARIES})
+    set(luatext_includes ${FREETYPE_INCLUDE_DIR_freetype2} ${FONTCONFIG_INCLUDE_DIRS} ${HARFBUZZ_INCLUDE_DIRS} ${LUA_INCLUDE_DIRS})
+  endif(BUILD_LUA_TEXT)
 endif(BUILD_GUI)
 
 if(BUILD_AUDACIOUS)

cmake/config.h.in

@@ -132,6 +132,8 @@
 
 #cmakedefine BUILD_LUA_RSVG 1
 
+#cmakedefine BUILD_LUA_TEXT 1
+
 #cmakedefine BUILD_IBM 1
 
 #cmakedefine BUILD_RSS 1

doc/lua.yaml

@@ -12,8 +12,7 @@
 ---
 desc: |-
   Conky features a Lua Programming API, and also ships with Lua bindings
-  for some useful libraries. Note that the bindings require tolua++, which
-  currently only compiles against Lua 5.1.
+  for some useful libraries. Note that the bindings require tolua++.
 
   To use Lua Conky, you first need to make sure you have a version of
   Conky with Lua support enabled (`conky -v` will report this).
@@ -185,3 +184,44 @@ values:
   - name: RsvgDimensionData:get()
     desc: |-
       Gets the values of an existing RsvgDimensionData.
+  - name: cairo_text_hp_show(cr, x, y, text, font, font_size, alignment, language, script, direction)
+    desc: |-
+      Renders text to a cairo_t using harfbuzz and freetype, this provides significantly
+      better text rendering then using cairo's inbuilt functions.
+
+      | Argument            | Description                                                                          |
+      |---------------------|--------------------------------------------------------------------------------------|
+      | cr                  | The `cairo_t` to render to.                                                          |
+      | x,y                 | Position to render the text.                                                         |
+      | text                | The text to render.                                                                  |
+      | font                | The name of the font to be used, `Fontconfig` is used to search for the font.        |
+      | font_size           | The font size.                                                                       |
+      | alignment           | One of `CAIRO_TEXT_ALIGN_LEFT`, `CAIRO_TEXT_ALIGN_RIGHT`, `CAIRO_TEXT_ALIGN_CENTER`. |
+      |                     | Default value: `CAIRO_TEXT_ALIGN_LEFT`                                               |
+      | language            | A string containing a BCP 47 language tag.                                           |
+      |                     | Default value: `en`                                                                  |
+      | script              | A string containing a ISO 15924 script tag.                                          |
+      |                     | Default value: auto-detect from text                                                 |
+      | direction           | A string representing text direction eg `LTR`, `RTL` or `TTB`                        |
+      |                     | Default value: auto-detect from text otherwise `LTR`                                 |                                                               |
+  - name: width,height:cairo_text_hp_text_size(text, font, font_size, language, script, direction)
+    desc: |-
+      Used to calculate how many pixels will be required to render a string with
+      `cairo_text_hp_show` returns a pair of int's with `width` and `height`.
+
+      | Argument            | Description                                                                          |
+      |---------------------|--------------------------------------------------------------------------------------|
+      | cr                  | The `cairo_t` to render to.                                                          |
+      | text                | The text to render.                                                                  |
+      | font                | The name of the font to be used, `Fontconfig` is used to search for the font.        |
+      | font_size           | The font size.                                                                       |
+      | language            | A string containing a BCP 47 language tag.                                           |
+      |                     | Default value: `en`                                                                  |
+      | script              | A string containing a ISO 15924 script tag.                                          |
+      |                     | Default value: auto-detect from text                                                 |
+      | direction           | A string representing text direction eg `LTR`, `RTL` or `TTB`                        |
+      |                     | Default value: auto-detect from text otherwise `LTR`                                 |
+  - name: cairo_text_hp_delete_fonts()
+    desc: |-
+      `cairo_text_hp_show` and `cairo_text_hp_text_size` both cache internal font details,
+      this function clears those caches.

lua/CMakeLists.txt

@@ -75,6 +75,7 @@ if(BUILD_X11)
     print_target_properties(conky-rsvg)
   endif(BUILD_LUA_RSVG)
 
+
   if(BUILD_LUA_CAIRO AND BUILD_LUA_IMLIB2)
     include_directories(${luacairo_includes} ${luaimlib2_includes}
                         ${CMAKE_CURRENT_SOURCE_DIR})
@@ -90,6 +91,22 @@ if(BUILD_X11)
                           toluapp_lib_static)
     set(lua_libs ${lua_libs} conky-cairo_imlib2_helper)
   endif(BUILD_LUA_CAIRO AND BUILD_LUA_IMLIB2)
+
+  if(BUILD_LUA_CAIRO AND BUILD_LUA_TEXT)
+    include_directories(${luacairo_includes} ${luatext_includes}
+                        ${CMAKE_CURRENT_SOURCE_DIR})
+    wrap_tolua(luacairo_text_helper_src cairo_text_helper.pkg)
+
+    add_library(conky-cairo_text_helper SHARED ${luacairo_text_helper_src})
+    set_target_properties(conky-cairo_text_helper
+                          PROPERTIES OUTPUT_NAME "cairo_text_helper")
+
+    target_link_libraries(conky-cairo_text_helper
+                          ${luacairo_libs}
+                          ${luatext_libs}
+                          toluapp_lib_static)
+    set(lua_libs ${lua_libs} conky-cairo_text_helper)
+  endif(BUILD_LUA_CAIRO AND BUILD_LUA_TEXT)
 endif(BUILD_X11)
 
 install(TARGETS ${lua_libs}

lua/cairo_text_helper.pkg

@@ -0,0 +1,19 @@
+$#include <cairo.h>
+$#include <libcairo_text_helper.h>
+
+typedef enum _cairo_text_alignment {
+  CAIRO_TEXT_ALIGN_LEFT = 0,
+  CAIRO_TEXT_ALIGN_RIGHT,
+  CAIRO_TEXT_ALIGN_CENTER
+} cairo_text_alignment_t;
+
+void cairo_text_hp_show(cairo_t *cr, int x, int y, const char *text, const char *font, int font_size, 
+                        cairo_text_alignment_t alignment = CAIRO_TEXT_ALIGN_LEFT, const char *language = "en",
+                        const char *script = NULL, const char *direction = NULL);
+
+/* This function allows you to get sizing so you can layout multiple sets of text next to each other */
+void cairo_text_hp_text_size(const char *text, const char *font, int font_size, 
+                             const char *language = "en", const char *script = NULL, const char *direction, int *width, int *height);
+
+/* This will clear all currently loaded / cached fonts */
+void cairo_text_hp_delete_fonts();