Use Xlib to read resources (#142)

build.sh

@@ -3,7 +3,7 @@
 cflags+="-Wall -O3 -g -std=gnu11 -fno-strict-aliasing -Isrc -Ilib/font_renderer"
 cflags+=" $(pkg-config --cflags lua5.2) $(sdl2-config --cflags)"
 lflags="-static-libgcc -static-libstdc++"
-for package in libagg freetype2 lua5.2; do
+for package in libagg freetype2 lua5.2 x11; do
   lflags+=" $(pkg-config --libs $package)"
 done
 lflags+=" $(sdl2-config --libs) -lm"

meson.build

@@ -3,6 +3,7 @@ project('lite', 'c', 'cpp', default_options : ['c_std=gnu11', 'cpp_std=c++03'])
 cc = meson.get_compiler('c')
 libm = cc.find_library('m', required : false)
 libdl = cc.find_library('dl', required : false)
+libx11 = dependency('x11', required : false)
 lua_dep = dependency('lua5.2', required : false)
 
 if not lua_dep.found()

src/main.c

@@ -7,7 +7,10 @@
   #include <windows.h>
 #elif __linux__
   #include <unistd.h>
-  #include "xrdb_parse.h"
+  #include <SDL_syswm.h>
+  #include <X11/Xlib.h>
+  #include <X11/Xatom.h>
+  #include <X11/Xresource.h>
 #elif __APPLE__
   #include <mach-o/dyld.h>
 #endif
@@ -16,16 +19,32 @@
 SDL_Window *window;
 
 static double get_scale(void) {
-#if _WIN32
+#ifdef _WIN32
   float dpi;
   SDL_GetDisplayDPI(0, NULL, &dpi, NULL);
   return dpi / 96.0;
-#elif __unix__
-  int xft_dpi = xrdb_find_dpi();
-  if (xft_dpi > 0) {
-    return xft_dpi / 96.0;
-  }
-  return 1.0;
+#elif __linux__
+  SDL_SysWMinfo info;
+  XrmDatabase db;
+  XrmValue value;
+  char *type = NULL;
+
+  SDL_VERSION(&info.version);
+  if (!SDL_GetWindowWMInfo(window, &info)
+      || info.subsystem != SDL_SYSWM_X11)
+    return 1.0;
+
+  char *resource = XResourceManagerString(info.info.x11.display);
+  if (resource == NULL)
+    return 1.0;
+  
+  XrmInitialize();
+  db = XrmGetStringDatabase(resource);
+  if (XrmGetResource(db, "Xft.dpi", "String", &type, &value) == False
+      || value.addr == NULL)
+    return 1.0;
+
+  return atof(value.addr) / 96.0;
 #else
   return 1.0;
 #endif

src/meson.build

@@ -6,14 +6,13 @@ lite_sources = [
     'api/system.c',
     'renderer.c',
     'rencache.c',
-    'xrdb_parse.c',
     'main.c',
 ]
 
 executable('lite',
     lite_sources + lite_rc,
     include_directories: [lite_include, font_renderer_include],
-    dependencies: [lua_dep, sdl_dep, libm, libdl],
+    dependencies: [lua_dep, sdl_dep, libm, libdl, libx11],
     c_args: lite_cargs,
     link_with: libfontrenderer,
     link_args: lite_link_args,

src/xrdb_parse.c

@@ -1,139 +0,0 @@
-#ifdef __unix__
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <sys/wait.h>
-#include <unistd.h>
-#include "xrdb_parse.h"
-
-extern char **environ;
-
-static int join_path(char buf[], int buf_size, const char *path, const char *name) {
-  const char *path_delim = strchr(path, ':');
-  if (!path_delim) {
-    path_delim = path + strlen(path);
-  }
-  const int path_len = path_delim - path, name_len = strlen(name);
-  if (buf_size < path_len + 1 + name_len + 1) return -1;
-  memcpy(buf, path, path_len);
-  buf[path_len] = '/';
-  memcpy(buf + path_len + 1, name, name_len + 1);
-  return 0;
-}
-
-
-static int xrdb_popen (int *pid_ptr) {
-  int fd[2];
-
-  if (pipe(fd) != 0) return -1;
-  int read_fd = fd[0];
-  int write_fd = fd[1];
-
-  int pid = fork();
-  if (pid == 0) {
-    close(read_fd);
-    dup2(write_fd, STDOUT_FILENO);
-    close(write_fd);
-    char *path = getenv("PATH");
-    char xrdb_filename[256];
-    while (path) {
-      char *xrgb_argv[3] = {"xrdb", "-query", NULL};
-      if (join_path(xrdb_filename, 256, path, "xrdb") == 0) {
-        execve(xrdb_filename, xrgb_argv, environ);
-      }
-      path = strchr(path, ':');
-      if (path) {
-        path++;
-      }
-    }
-  } else {
-    *pid_ptr = pid;
-    close(write_fd);
-    return read_fd;
-  }
-  return -1;
-}
-
-
-static int xrdb_try_dpi_match(const char *line, int len) {
-  if (len >= 8 && strncmp(line, "Xft.dpi:", 8) == 0) {
-    for (line += 8; *line && (*line == '\t' || *line == ' '); line++) { }
-    int dpi = 0;
-    for ( ; *line >= '0' && *line <= '9'; line++) {
-      dpi = dpi * 10 + ((int) (*line) - (int) '0');
-    }
-    return dpi;
-  }
-  return -1;
-}
-
-static void xrdb_complete_reading(int read_fd, char *buf, size_t buf_size) {
-  while (1) {
-    int nr = read(read_fd, buf, buf_size);
-    if (nr <= 0) return;
-  }
-}
-
-#define XRDB_READ_BUF_SIZE 256
-static int xrdb_parse_for_dpi(int read_fd) {
-  char buf[XRDB_READ_BUF_SIZE];
-  char buf_remaining = 0;
-  while (1) {
-    int nr = read(read_fd, buf + buf_remaining, XRDB_READ_BUF_SIZE - buf_remaining);
-    if (nr > 0) {
-      const char * const buf_limit = buf + nr + buf_remaining;
-      char *line_start = buf;
-      while (line_start < buf_limit) {
-        char *nlptr = line_start;
-        while (nlptr < buf_limit && *nlptr != '\n') {
-          nlptr++;
-        }
-        if (nlptr < buf_limit) {
-          int dpi_read = xrdb_try_dpi_match(line_start, nlptr - line_start);
-          if (dpi_read > 0) {
-            xrdb_complete_reading(read_fd, buf, XRDB_READ_BUF_SIZE);
-            return dpi_read;
-          }
-          /* doesn't match: position after newline to search again */
-          line_start = nlptr + 1;
-        } else {
-          /* No newline found: copy the remaining part at the beginning of buf
-             and read again from file descriptor. */
-          buf_remaining = buf_limit - line_start;
-          if (buf_remaining >= XRDB_READ_BUF_SIZE) {
-            /* Line is too long for the buffer: skip. */
-            buf_remaining = 0;
-          } else {
-            memmove(buf, line_start, buf_remaining);
-          }
-          break;
-        }
-      }
-    } else {
-      if (nr == 0 && buf_remaining > 0) {
-        int dpi_read = xrdb_try_dpi_match(buf, buf_remaining);
-        if (dpi_read > 0) {
-          return dpi_read;
-        }
-      }
-      break;
-    }
-  }
-  return -1;
-}
-
-int xrdb_find_dpi() {
-  int xrdb_pid;
-  int read_fd = xrdb_popen(&xrdb_pid);
-  if (read_fd >= 0) {
-    int dpi_read = xrdb_parse_for_dpi(read_fd);
-    int child_status;
-    waitpid(xrdb_pid, &child_status, 0);
-    close(read_fd);
-    return dpi_read;
-  }
-  return -1;
-}
-
-#endif

src/xrdb_parse.h

@@ -1,6 +0,0 @@
-#ifndef XRDB_PARSE_H
-#define XRDB_PARSE_H
-
-extern int xrdb_find_dpi();
-
-#endif