* meson.build, meson_option.txt: Handle new HVF driver.

(hvf): New option.

meson.build

@@ -401,6 +401,35 @@ if brotli_dep.found()
   ft2_deps += [brotli_dep]
 endif
 
+# HVF support (Apple platforms only).
+hvf_dep = disabler()
+hvf_found = false
+
+if not get_option('hvf').disabled()
+  if host_machine.system() == 'darwin'
+    # Check for HVF header availability.
+    if cc.has_header('hvf/Scaler.h')
+      # Find the HVF library.
+      hvf_dep = cc.find_library('hvf', required: get_option('hvf'))
+
+      if hvf_dep.found()
+        hvf_found = true
+        ftoption_command += ['--enable=FT_CONFIG_OPTION_HVF']
+        ft2_deps += [hvf_dep]
+
+        # Check for Clang compiler for runtime availability support.
+        if cc.get_id() == 'clang'
+          ft2_defines += ['-DHVF_RUNTIME_AVAILABLE=1']
+        endif
+      endif
+    elif get_option('hvf').enabled()
+      error('HVF support was enabled but hvf/Scaler.h header was not found')
+    endif
+  elif get_option('hvf').enabled()
+    error('HVF support is only available on Apple platforms (macOS/iOS)')
+  endif
+endif
+
 if get_option('error_strings')
   ftoption_command += ['--enable=FT_CONFIG_OPTION_ERROR_STRINGS']
 endif
@@ -524,6 +553,7 @@ summary({'Zlib': zlib_option,
          'Png': libpng_dep.found(),
          'HarfBuzz': harfbuzz_opt,
          'Brotli': brotli_dep.found(),
+         'HVF': hvf_found,
         }, bool_yn: true, section: 'Used Libraries')
 
 # EOF

meson_options.txt

@@ -53,6 +53,12 @@ option('zlib',
              'disabled', 'enabled' ],
   description: 'Support reading gzip-compressed font files')
 
+option('hvf',
+  type: 'feature',
+  value: 'auto',
+  description: 'Support Apple Hierarchical Variable Font (HVF) format'
+               + ' on Apple platforms')
+
 option('error_strings',
   type: 'boolean',
   value: false,