Add determine_icon_destination() function

Author: probonopd

build.sh

@@ -144,7 +144,7 @@ fi
 rm -f a.out
 
 # appimaged, an optional component
-cc -std=gnu99 -D_FILE_OFFSET_BITS=64 -DHAVE_LIBARCHIVE3=$have_libarchive3 -DVERSION_NUMBER=\"$(git describe --tags --always --abbrev=7)\" ../getsection.c ../notify.c -Wl,-Bdynamic ../elf.c ../appimaged.c ../squashfuse/.libs/libsquashfuse.a ../squashfuse/.libs/libfuseprivate.a -I../squashfuse/ -Wl,-Bstatic -linotifytools -Wl,-Bdynamic -larchive${archive_n} $(pkg-config --cflags --libs glib-2.0) $(pkg-config --cflags gio-2.0) $(pkg-config --libs gio-2.0) -ldl -lpthread -lz -Wl,-Bstatic -llzma -Wl,-Bdynamic -o appimaged # liblz4
+cc -std=gnu99 -D_FILE_OFFSET_BITS=64 -DHAVE_LIBARCHIVE3=$have_libarchive3 -DVERSION_NUMBER=\"$(git describe --tags --always --abbrev=7)\" ../getsection.c ../notify.c -Wl,-Bdynamic ../elf.c ../appimaged.c ../squashfuse/.libs/libsquashfuse.a ../squashfuse/.libs/libfuseprivate.a -I../squashfuse/ -Wl,-Bstatic -linotifytools -Wl,-Bdynamic -larchive${archive_n} $(pkg-config --cflags --libs glib-2.0) $(pkg-config --cflags --libs gio-2.0) $(pkg-config --libs --cflags cairo) -ldl -lpthread -lz -Wl,-Bstatic -llzma -Wl,-Bdynamic -o appimaged # liblz4
 
 cd ..
 

shared.c

@@ -56,6 +56,8 @@
 
 #include <regex.h>
 
+#include <cairo.h> // To get the size of icons, determine_icon_destination()
+
 #define FNM_FILE_NAME 2
 
 #define URI_MAX (FILE_MAX * 3 + 8)
@@ -125,6 +127,56 @@ char * get_thumbnail_path(char *path, char *thumbnail_size, gboolean verbose)
     return thumbnail_path;
 }
 
+/* Return the path where a given icon can be installed in $HOME.
+ * This is needed because png and xpm icons cannot be installed in a generic
+ * location but are only picked up in directories that have the size of 
+ * the icon as part of their directory name, as specified in the theme.index
+ * See https://github.com/probonopd/AppImageKit/issues/258
+ */
+
+gchar* determine_icon_destination(gchar *icon_path)
+{
+    gchar *dest_dir;
+    
+    if((g_str_has_suffix (icon_path, ".svg")) || (g_str_has_suffix (icon_path, ".svgz"))) {
+        dest_dir = g_build_path("/", g_get_user_data_dir(), "/icons/hicolor/scalable", NULL);
+    }
+ 
+    if((g_str_has_suffix (icon_path, ".png")) || (g_str_has_suffix (icon_path, ".xpm"))) {
+        
+        cairo_surface_t *image;
+ 
+        if(g_str_has_suffix (icon_path, ".xpm")) {
+            // TODO: GdkPixbuf has a convenient way to load XPM data. Then you can call
+            // gdk_cairo_set_source_pixbuf() to transfer the data to a Cairo surface.
+            fprintf(stderr, "XPM size parsing not yet implemented\n");
+            return NULL;
+        }
+
+        if(g_str_has_suffix (icon_path, ".png")) {
+            image = cairo_image_surface_create_from_png(icon_path);
+        }
+        
+        int w = cairo_image_surface_get_width (image);
+        int h = cairo_image_surface_get_height (image);
+        
+        // FIXME: The following sizes are taken from the hicolor icon theme. 
+        // Probably the right thing to do would be to figure out at runtime which icon sizes are allowable.
+        // Or could we put our own index.theme into .local/share/icons/ and have it observed?
+        if((w != h) || ((w != 16) && (w != 24) && (w != 32) && (w != 36) && (w != 48) && (w != 64) && (w != 72) && (w != 96) && (w != 128) && (w != 192) && (w != 256) && (w != 512))){
+            fprintf(stderr, "%s has nonstandard size w = %i, h = %i; please fix it\n", icon_path, w, h);
+            return NULL;
+        }
+
+        cairo_surface_destroy (image);
+        
+        dest_dir = g_build_path("/", g_get_user_data_dir(), "/icons/hicolor/", g_strdup_printf("%ix%i", w, h), NULL);
+    }
+        
+    return(dest_dir);
+
+}
+
 /* Check if a file is an AppImage. Returns the image type if it is, or -1 if it isn't */
 int check_appimage_type(char *path, gboolean verbose)
 {