Update DPI when changed in resource manager (#1878)

* Update xft_dpi on property change
  * Added fallback calculation when Xft is disabled.
* Removed display_width/height and replaced it with workarea for
  consistency.
* Make DPI work on X11 when Xft is disabled
* Make find_subwindow more specific, rename it

Signed-off-by: Tin Švagelj <tin.svagelj@live.com>

src/display-x11.cc

@@ -49,6 +49,7 @@
 #include <X11/extensions/XInput2.h>
 #undef COUNT
 #endif /* BUILD_XINPUT */
+#include <X11/Xresource.h>
 
 #include <cstdint>
 #include <iostream>
@@ -81,9 +82,7 @@ extern int need_to_update;
 int get_border_total();
 extern conky::range_config_setting<int> maximum_width;
 extern Colour current_color;
-#ifdef BUILD_XFT
+static float screen_dpi = -1;
-static int xft_dpi = -1;
-#endif /* BUILD_XFT */
 
 /* for x_fonts */
 struct x_font_list {
@@ -147,16 +146,36 @@ struct _x11_stuff_s {
 #endif
 } x11_stuff;
 
+void update_dpi() {
+  // Add XRandR support if used
+  // See dunst PR: https://github.com/dunst-project/dunst/pull/608
+
+#ifdef BUILD_XFT
+  if (screen_dpi > 0) return;
+  if (use_xft.get(*state)) {
+    XrmDatabase db = XrmGetDatabase(display);
+    if (db != nullptr) {
+      char *xrmType;
+      XrmValue xrmValue;
+      if (XrmGetResource(db, "Xft.dpi", "Xft.dpi", &xrmType, &xrmValue)) {
+        screen_dpi = strtof(xrmValue.addr, NULL);
+      }
+    } else {
+      auto dpi = XGetDefault(display, "Xft", "dpi");
+      if (dpi) { screen_dpi = strtof(dpi, nullptr); }
+    }
+  }
+#endif /* BUILD_XFT */
+  if (screen_dpi > 0) return;
+  screen_dpi = static_cast<float>(DisplayWidth(display, screen)) * 25.4 /
+               static_cast<float>(DisplayWidthMM(display, screen));
+}
+
 static void X11_create_window() {
   if (!window.window) { return; }
   setup_fonts();
   load_fonts(utf8_mode.get(*state));
-#ifdef BUILD_XFT
+  update_dpi();
-  if (use_xft.get(*state)) {
-    auto dpi = XGetDefault(display, "Xft", "dpi");
-    if (dpi) { xft_dpi = strtol(dpi, nullptr, 10); }
-  }
-#endif                /* BUILD_XFT */
   update_text_area(); /* to position text/window on screen */
 
 #ifdef OWN_WINDOW
@@ -713,19 +732,31 @@ bool handle_event<x_event_handler::PROPERTY_NOTIFY>(
     get_x11_desktop_info(ev.xproperty.display, ev.xproperty.atom);
   }
 
-#ifdef USE_ARGB
+  if (ev.xproperty.atom == 0) return false;
-  if (have_argb_visual) return true;
-#endif
 
-  if (ev.xproperty.atom == ATOM(_XROOTPMAP_ID) ||
+  if (ev.xproperty.atom == XA_RESOURCE_MANAGER) {
-      ev.xproperty.atom == ATOM(_XROOTMAP_ID)) {
+    update_x11_resource_db();
-    if (forced_redraw.get(*state)) {
+    update_x11_workarea();
-      draw_stuff();
+    screen_dpi = -1;
-      next_update_time = get_time();
+    update_dpi();
-      need_to_update = 1;
+    return true;
+  }
+
+  if (!have_argb_visual) {
+    Atom _XROOTPMAP_ID = XInternAtom(display, "_XROOTPMAP_ID", True);
+    Atom _XROOTMAP_ID = XInternAtom(display, "_XROOTMAP_ID", True);
+    if (ev.xproperty.atom == _XROOTPMAP_ID ||
+        ev.xproperty.atom == _XROOTMAP_ID) {
+      if (forced_redraw.get(*state)) {
+        draw_stuff();
+        next_update_time = get_time();
+        need_to_update = 1;
+      }
+      return true;
     }
   }
-  return true;
+
+  return false;
 }
 
 template <>
@@ -947,11 +978,9 @@ void display_output_x11::move_win(int x, int y) {
 
 const float PIXELS_PER_INCH = 96.0;
 float display_output_x11::get_dpi_scale() {
-#ifdef BUILD_XFT
+  if (screen_dpi > 0) {
-  if (use_xft.get(*state) && xft_dpi > 0) {
+    return static_cast<float>(screen_dpi) / PIXELS_PER_INCH;
-    return static_cast<float>(xft_dpi) / PIXELS_PER_INCH;
   }
-#endif /* BUILD_XFT */
   return 1.0;
 }
 

src/gui.cc

@@ -45,8 +45,6 @@
 #endif
 
 /* basic display attributes */
-int display_width;
-int display_height;
 int screen;
 
 /* workarea where window / text is aligned (from _NET_WORKAREA on X11) */

src/gui.h

@@ -168,8 +168,6 @@ inline bool TEST_HINT(uint16_t mask, window_hints hint) {
 #ifdef BUILD_X11
 extern Display *display;
 #endif /* BUILD_X11 */
-extern int display_width;
-extern int display_height;
 extern int screen;
 extern int workarea[4];
 

src/x11.cc

@@ -90,6 +90,7 @@ extern "C" {
 #include <xcb/xcb.h>
 #include <xcb/xcb_errors.h>
 #endif
+#include <X11/Xresource.h>
 }
 
 /* some basic X11 stuff */
@@ -106,9 +107,8 @@ struct conky_x11_window window;
 bool have_argb_visual = false;
 
 /* local prototypes */
-static void update_workarea();
 static Window find_desktop_window(Window *p_root, Window *p_desktop);
-static Window find_subwindow(Window win, int w, int h);
+static Window find_desktop_window_impl(Window win, int w, int h);
 
 /* WARNING, this type not in Xlib spec */
 static int x11_error_handler(Display *d, XErrorEvent *err) {
@@ -260,13 +260,15 @@ void init_x11() {
   info.x11.desktop.name.clear();
 
   screen = DefaultScreen(display);
-  display_width = DisplayWidth(display, screen);
+
-  display_height = DisplayHeight(display, screen);
+  XSetErrorHandler(&x11_error_handler);
+  XSetIOErrorHandler(&x11_ioerror_handler);
+
+  update_x11_resource_db(true);
+  update_x11_workarea();
 
   get_x11_desktop_info(display, 0);
 
-  update_workarea();
-
 #ifdef HAVE_XCB_ERRORS
   auto connection = xcb_connect(NULL, NULL);
   if (!xcb_connection_has_error(connection)) {
@@ -275,11 +277,6 @@ void init_x11() {
     }
   }
 #endif /* HAVE_XCB_ERRORS */
-
-  /* WARNING, this type not in Xlib spec */
-  XSetErrorHandler(&x11_error_handler);
-  XSetIOErrorHandler(&x11_ioerror_handler);
-
   DBGP("leave init_x11()");
 }
 
@@ -291,12 +288,39 @@ void deinit_x11() {
   }
 }
 
-static void update_workarea() {
+// Source: dunst
+// https://github.com/bebehei/dunst/blob/1bc3237a359f37905426012c0cca90d71c4b3b18/src/x11/x.c#L463
+void update_x11_resource_db(bool first_run) {
+  XrmDatabase db;
+  XTextProperty prop;
+  Window root;
+
+  XFlush(display);
+
+  root = RootWindow(display, screen);
+
+  XLockDisplay(display);
+  if (XGetTextProperty(display, root, &prop, XA_RESOURCE_MANAGER)) {
+    if (!first_run) {
+      db = XrmGetDatabase(display);
+      XrmDestroyDatabase(db);
+    }
+
+    db = XrmGetStringDatabase((const char *)prop.value);
+    XrmSetDatabase(display, db);
+  }
+  XUnlockDisplay(display);
+
+  XFlush(display);
+  XSync(display, false);
+}
+
+void update_x11_workarea() {
   /* default work area is display */
   workarea[0] = 0;
   workarea[1] = 0;
-  workarea[2] = display_width;
+  workarea[2] = DisplayWidth(display, screen);
-  workarea[3] = display_height;
+  workarea[3] = DisplayHeight(display, screen);
 
 #ifdef BUILD_XINERAMA
   /* if xinerama is being used, adjust workarea to the head's area */
@@ -344,9 +368,12 @@ static Window find_desktop_window(Window root) {
   Window desktop = root;
 
   /* get subwindows from root */
-  desktop = find_subwindow(root, -1, -1);
+  int display_width = DisplayWidth(display, screen);
-  update_workarea();
+  int display_height = DisplayHeight(display, screen);
-  desktop = find_subwindow(desktop, workarea[2], workarea[3]);
+  desktop = find_desktop_window_impl(root, display_width, display_height);
+  update_x11_workarea();
+  desktop = find_desktop_window_impl(desktop, workarea[2] - workarea[0],
+                                     workarea[3] - workarea[1]);
 
   if (desktop != root) {
     NORM_ERR("desktop window (0x%lx) is subwindow of root window (0x%lx)",
@@ -514,13 +541,11 @@ void x11_init_window(lua::state &l, bool own) {
                                     0,
                                     0};
       flags |= CWBackPixel;
-#ifdef BUILD_ARGB
       if (have_argb_visual) {
         attrs.colormap = window.colourmap;
         flags &= ~CWBackPixel;
         flags |= CWBorderPixel | CWColormap;
       }
-#endif /* BUILD_ARGB */
 
       /* Parent is desktop window (which might be a child of root) */
       window.window =
@@ -557,13 +582,11 @@ void x11_init_window(lua::state &l, bool own) {
       Atom xa;
 
       flags |= CWBackPixel;
-#ifdef BUILD_ARGB
       if (have_argb_visual) {
         attrs.colormap = window.colourmap;
         flags &= ~CWBackPixel;
         flags |= CWBorderPixel | CWColormap;
       }
-#endif /* BUILD_ARGB */
 
       if (own_window_type.get(l) == window_type::DOCK) {
         window.x = window.y = 0;
@@ -868,7 +891,7 @@ void x11_init_window(lua::state &l, bool own) {
   DBGP("leave x11_init_window()");
 }
 
-static Window find_subwindow(Window win, int w, int h) {
+static Window find_desktop_window_impl(Window win, int w, int h) {
   unsigned int i, j;
   Window troot, parent, *children;
   unsigned int n;
@@ -880,13 +903,11 @@ static Window find_subwindow(Window win, int w, int h) {
 
     for (j = 0; j < n; j++) {
       XWindowAttributes attrs;
-
       if (XGetWindowAttributes(display, children[j], &attrs) != 0) {
         /* Window must be mapped and same size as display or
          * work space */
-        if (attrs.map_state != 0 &&
+        if (attrs.map_state == IsViewable && attrs.override_redirect == false &&
-            ((attrs.width == display_width && attrs.height == display_height) ||
+            ((attrs.width == w && attrs.height == h))) {
-             (attrs.width == w && attrs.height == h))) {
           win = children[j];
           break;
         }
@@ -1116,6 +1137,9 @@ void set_struts(alignment align) {
   if (strut != None) {
     long sizes[STRUT_COUNT] = {0};
 
+    int display_width = workarea[2] - workarea[0];
+    int display_height = workarea[3] - workarea[1];
+
     switch (horizontal_alignment(align)) {
       case axis_align::START:
         sizes[*x11_strut::LEFT] =

src/x11.h

@@ -98,6 +98,8 @@ struct conky_x11_window {
 
 extern struct conky_x11_window window;
 
+void update_x11_resource_db(bool first_run = false);
+void update_x11_workarea();
 void init_x11();
 void destroy_window(void);
 void create_gc(void);