Meson: Change png/jpeg/tiff options from boolean to feature

png/jpeg are essential and have a fallback subproject so they are
enabled by default. tiff is not required by GTK and does not have a
subproject so it's set to 'auto' by default.

This fixes the case where tiff option was set to true by default but
meson setup was not aborting if the dependency was not found. Instead it
was failing at build time.

1 files changed, 50 insertions, 31 deletions

diff --git a/meson.build b/meson.build
index fde0e9ade..8dc3ea68b 100644
--- a/meson.build
+++ b/meson.build
@@ -253,7 +253,8 @@ endif
 enabled_loaders = []
 loaders_deps = []
 
-if get_option('png')
+png_opt = get_option('png')
+if not png_opt.disabled()
   png_dep = dependency('libpng', required: false)
 
   if not png_dep.found() and cc.has_header('png.h')
@@ -283,11 +284,16 @@ if get_option('png')
   # that will bypass --wrap-mode and cause issues for distro packagers.
   # See: https://mesonbuild.com/Reference-manual.html#dependency
   if not png_dep.found()
-    png_dep = dependency('libpng', fallback: ['libpng', 'png_dep'])
+    png_dep = dependency('libpng',
+      fallback: ['libpng', 'png_dep'],
+      required: png_opt,
+    )
   endif
 
-  enabled_loaders += 'png'
-  loaders_deps += png_dep
+  if png_dep.found()
+    enabled_loaders += 'png'
+    loaders_deps += png_dep
+  endif
 endif
 
 # On Windows, check whether we are building the native Windows loaders
@@ -307,7 +313,8 @@ if native_windows_loaders
 endif
 
 # Don't check and build the jpeg loader if native_windows_loaders is true
-if get_option('jpeg') and not native_windows_loaders
+jpeg_opt = get_option('jpeg')
+if not jpeg_opt.disabled() and not native_windows_loaders
   jpeg_dep = dependency('libjpeg', required: false)
 
   if not jpeg_dep.found() and cc.has_header('jpeglib.h')
@@ -321,43 +328,55 @@ if get_option('jpeg') and not native_windows_loaders
 
   # Finally, look for the dependency in a fallback
   if not jpeg_dep.found()
-    jpeg_dep = dependency('libjpeg', fallback: ['libjpeg-turbo', 'jpeg_dep'])
+    jpeg_dep = dependency('libjpeg',
+      fallback: ['libjpeg-turbo', 'jpeg_dep'],
+      required: jpeg_opt,
+    )
   endif
 
-  enabled_loaders += 'jpeg'
-  loaders_deps += jpeg_dep
+  if jpeg_dep.found()
+    enabled_loaders += 'jpeg'
+    loaders_deps += jpeg_dep
 
-  if jpeg_dep.type_name() == 'internal'
-    has_destroy_decompress = true
-    has_simple_progression = true
-  else
-    has_destroy_decompress = cc.has_function('jpeg_destroy_decompress', dependencies: jpeg_dep)
-    has_simple_progression = cc.has_function('jpeg_simple_progression', dependencies: jpeg_dep)
-  endif
+    if jpeg_dep.type_name() == 'internal'
+      has_destroy_decompress = true
+      has_simple_progression = true
+    else
+      has_destroy_decompress = cc.has_function('jpeg_destroy_decompress', dependencies: jpeg_dep)
+      has_simple_progression = cc.has_function('jpeg_simple_progression', dependencies: jpeg_dep)
+    endif
 
-  if has_destroy_decompress and has_simple_progression
-    gdk_pixbuf_conf.set('HAVE_PROGRESSIVE_JPEG', has_simple_progression)
+    if has_destroy_decompress and has_simple_progression
+      gdk_pixbuf_conf.set('HAVE_PROGRESSIVE_JPEG', has_simple_progression)
+    endif
   endif
 endif
 
 # Don't check and build the tiff loader if native_windows_loaders is true
-if get_option('tiff') and not native_windows_loaders
+tiff_opt = get_option('tiff')
+if not tiff_opt.disabled() and not native_windows_loaders
   tiff_dep = dependency('libtiff-4', required: false)
-  if not tiff_dep.found()
-    # Fallback when no pkg-config file is found for libtiff on MSVC, which is quite normal
-    if cc.get_id() == 'msvc' and cc.has_header('tiff.h')
-      # First look for the DLL builds of libtiff, then the static builds
-      tiff_dep = cc.find_library('libtiff_i', required: false)
-
-      if not tiff_dep.found()
-        # For the static lib, zlib and libjpeg .lib's have been looked for first, and
-        # they are optional for libtiff
-        tiff_dep = cc.find_library('libtiff')
-      endif
+  if not tiff_dep.found() and cc.has_header('tiff.h')
+    # First look for the DLL builds of libtiff, then the static builds
+    tiff_dep = cc.find_library('libtiff_i', required: false)
+
+    if not tiff_dep.found()
+      # For the static lib, zlib and libjpeg .lib's have been looked for first, and
+      # they are optional for libtiff
+      tiff_dep = cc.find_library('libtiff', required: false)
     endif
   endif
-  enabled_loaders += 'tiff'
-  loaders_deps += tiff_dep
+
+  # We currently don't have a fallback subproject, but this handles error
+  # reporting if tiff_opt is enabled.
+  if not tiff_dep.found()
+    tiff_dep = dependency('libtiff-4', required: tiff_opt)
+  endif
+
+  if tiff_dep.found()
+    enabled_loaders += 'tiff'
+    loaders_deps += tiff_dep
+  endif
 endif
 
 # Determine whether we enable application bundle relocation support, and we use