lib: Use XDG_DATA_DIRS to query themes (#58)

* lib: use XDG_DATA_DIRS to search themes

* lib: fix some stylistic errors

* lib: more stylistic errors fixed

libhyprcursor/hyprcursor.cpp

@@ -2,6 +2,7 @@
 #include "internalSharedTypes.hpp"
 #include "internalDefines.hpp"
 #include <array>
+#include <cstdio>
 #include <filesystem>
 #include <zip.h>
 #include <cstring>
@@ -15,11 +16,25 @@
 
 using namespace Hyprcursor;
 
-// directories for lookup
-constexpr const std::array<const char*, 1> systemThemeDirs = {"/usr/share/icons"};
+static std::vector<std::string> getSystemThemeDirs() {
+    const auto               envXdgData = std::getenv("XDG_DATA_DIRS");
+    std::vector<std::string> result;
+    if (envXdgData) {
+        std::stringstream envXdgStream(envXdgData);
+        std::string       tmpStr;
+        while (getline(envXdgStream, tmpStr, ':'))
+            result.push_back((tmpStr + "/icons"));
+    } else
+        result = {"/usr/share/icons"};
+
+    return result;
+}
+
+const std::vector<std::string>             systemThemeDirs = getSystemThemeDirs();
 constexpr const std::array<const char*, 2> userThemeDirs   = {"/.local/share/icons", "/.icons"};
 
 //
+
 static std::string themeNameFromEnv(PHYPRCURSORLOGFUNC logfn) {
     const auto ENV = getenv("HYPRCURSOR_THEME");
     if (!ENV) {

nix/default.nix

@@ -15,11 +15,6 @@ stdenv.mkDerivation {
   inherit version;
   src = ../.;
 
-  patches = [
-    # adds /run/current-system/sw/share/icons to the icon lookup directories
-    ./dirs.patch
-  ];
-
   nativeBuildInputs = [
     cmake
     pkg-config

nix/dirs.patch

@@ -1,13 +0,0 @@
-diff --git a/libhyprcursor/hyprcursor.cpp b/libhyprcursor/hyprcursor.cpp
-index 304ab9f..1f7e95d 100644
---- a/libhyprcursor/hyprcursor.cpp
-+++ b/libhyprcursor/hyprcursor.cpp
-@@ -14,7 +14,7 @@
- using namespace Hyprcursor;
- 
- // directories for lookup
--constexpr const std::array<const char*, 1> systemThemeDirs = {"/usr/share/icons"};
-+constexpr const std::array<const char*, 2> systemThemeDirs = {"/usr/share/icons", "/run/current-system/sw/share/icons"};
- constexpr const std::array<const char*, 2> userThemeDirs   = {"/.local/share/icons", "/.icons"};
- 
- //