fix: Support negative struts

Fixed #2642

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [Unreleased]
 ### Fixed
 - `format-offset` being ignored ([`#2643`](https://github.com/polybar/polybar/pull/2643))
+- Negative struts (`margin-bottom`, `margin-top`) being ignored ([`#2642`](https://github.com/polybar/polybar/issues/2642), [`#2644`](https://github.com/polybar/polybar/pull/2644))
 
 ## [3.6.1] - 2022-03-05
 ### Build

include/components/types.hpp

@@ -59,6 +59,11 @@ static inline mousebtn mousebtn_get_double(mousebtn btn) {
   }
 }
 
+/**
+ * Order of values for _NET_WM_STRUT_PARTIAL
+ *
+ * https://specifications.freedesktop.org/wm-spec/wm-spec-latest.html#idm45381391268672
+ */
 enum class strut {
   LEFT = 0,
   RIGHT,
@@ -132,13 +137,6 @@ struct percentage_with_offset {
   extent_val offset{ZERO_PX_EXTENT};
 };
 
-struct edge_values {
-  unsigned int left{0U};
-  unsigned int right{0U};
-  unsigned int top{0U};
-  unsigned int bottom{0U};
-};
-
 struct radius {
   double top_left{0.0};
   double top_right{0.0};
@@ -173,7 +171,7 @@ struct bar_settings {
   monitor_t monitor{};
   bool monitor_strict{false};
   bool monitor_exact{true};
-  edge origin{edge::TOP};
+  bool bottom{false};
   struct size size {
     1U, 1U
   };
@@ -185,7 +183,10 @@ struct bar_settings {
   position offset{0, 0};
   side_values padding{ZERO_SPACE, ZERO_SPACE};
   side_values module_margin{ZERO_SPACE, ZERO_SPACE};
-  edge_values strut{0U, 0U, 0U, 0U};
+  struct {
+    int top;
+    int bottom;
+  } strut{0, 0};
 
   rgba background{0xFF000000};
   rgba foreground{0xFFFFFFFF};

include/x11/window.hpp

@@ -2,6 +2,7 @@
 
 #include <xcb/xcb.h>
 #include <xcb/xcb_aux.h>
+
 #include <xpp/window.hpp>
 
 #include "common.hpp"
@@ -17,7 +18,7 @@ class window : public xpp::window<connection&> {
 
   window reconfigure_geom(unsigned short int w, unsigned short int h, short int x = 0, short int y = 0);
   window reconfigure_pos(short int x, short int y);
-  window reconfigure_struts(unsigned short int w, unsigned short int h, short int x, bool bottom = false);
+  window reconfigure_struts(uint32_t w, uint32_t strut, uint32_t x, bool bottom = false);
 };
 
 POLYBAR_NS_END

src/components/bar.cpp

@@ -191,7 +191,7 @@ bar::bar(connection& conn, signal_emitter& emitter, const config& config, const
 
   // Load configuration values
 
-  m_opts.origin = m_conf.get(bs, "bottom", false) ? edge::BOTTOM : edge::TOP;
+  m_opts.bottom = m_conf.get(bs, "bottom", m_opts.bottom);
   m_opts.spacing = m_conf.get(bs, "spacing", m_opts.spacing);
   m_opts.separator = drawtypes::load_optional_label(m_conf, bs, "separator", "");
   m_opts.locale = m_conf.get(bs, "locale", ""s);
@@ -221,10 +221,8 @@ bar::bar(connection& conn, signal_emitter& emitter, const config& config, const
   // Load values used to adjust the struts atom
   auto margin_top = m_conf.get("global/wm", "margin-top", percentage_with_offset{});
   auto margin_bottom = m_conf.get("global/wm", "margin-bottom", percentage_with_offset{});
-  m_opts.strut.top =
+  m_opts.strut.top = units_utils::percentage_with_offset_to_pixel(margin_top, m_opts.monitor->h, m_opts.dpi_y);
-      units_utils::percentage_with_offset_to_pixel_nonnegative(margin_top, m_opts.monitor->h, m_opts.dpi_y);
+  m_opts.strut.bottom = units_utils::percentage_with_offset_to_pixel(margin_bottom, m_opts.monitor->h, m_opts.dpi_y);
-  m_opts.strut.bottom =
-      units_utils::percentage_with_offset_to_pixel_nonnegative(margin_bottom, m_opts.monitor->h, m_opts.dpi_y);
 
   // Load commands used for fallback click handlers
   vector<action> actions;
@@ -329,7 +327,7 @@ bar::bar(connection& conn, signal_emitter& emitter, const config& config, const
   m_opts.size.h += m_opts.borders[edge::TOP].size;
   m_opts.size.h += m_opts.borders[edge::BOTTOM].size;
 
-  if (m_opts.origin == edge::BOTTOM) {
+  if (m_opts.bottom) {
     m_opts.pos.y = m_opts.monitor->y + m_opts.monitor->h - m_opts.size.h - m_opts.offset.y;
   }
 
@@ -556,23 +554,41 @@ void bar::reconfigure_pos() {
  */
 void bar::reconfigure_struts() {
   auto geom = m_connection.get_geometry(m_screen->root());
-  auto w = m_opts.size.w + m_opts.offset.x;
+  int h = m_opts.size.h + m_opts.offset.y;
-  auto h = m_opts.size.h + m_opts.offset.y;
 
-  if (m_opts.origin == edge::BOTTOM) {
+  // Apply user-defined margins
+  if (m_opts.bottom) {
     h += m_opts.strut.top;
   } else {
     h += m_opts.strut.bottom;
   }
 
-  if (m_opts.origin == edge::BOTTOM && m_opts.monitor->y + m_opts.monitor->h < geom->height) {
+  h = std::max(h, 0);
-    h += geom->height - (m_opts.monitor->y + m_opts.monitor->h);
+
-  } else if (m_opts.origin != edge::BOTTOM) {
+  int correction = 0;
-    h += m_opts.monitor->y;
+
+  // Only apply correction if any space is requested
+  if (h > 0) {
+    /*
+     * Strut coordinates have to be relative to root window and not any monitor.
+     * If any monitor is not aligned at the top or bottom
+     */
+    if (m_opts.bottom) {
+      /*
+       * For bottom-algined bars, the correction is the number of pixels between
+       * the root window's bottom edge and the monitor's bottom edge
+       */
+      correction = geom->height - (m_opts.monitor->y + m_opts.monitor->h);
+    } else {
+      // For top-aligned bars, we simply add the monitor's y-position
+      correction = m_opts.monitor->y;
+    }
+
+    correction = std::max(correction, 0);
   }
 
   window win{m_connection, m_opts.window};
-  win.reconfigure_struts(w, h, m_opts.pos.x, m_opts.origin == edge::BOTTOM);
+  win.reconfigure_struts(m_opts.size.w, h + correction, m_opts.pos.x, m_opts.bottom);
 }
 
 /**

src/x11/window.cpp

@@ -1,9 +1,10 @@
+#include "x11/window.hpp"
+
 #include "components/types.hpp"
 #include "utils/memory.hpp"
 #include "x11/atoms.hpp"
 #include "x11/connection.hpp"
 #include "x11/extensions/randr.hpp"
-#include "x11/window.hpp"
 
 POLYBAR_NS
 
@@ -45,24 +46,31 @@ window window::reconfigure_pos(short int x, short int y) {
 
 /**
  * Reconfigure the windows ewmh strut
+ *
+ * Ref: https://specifications.freedesktop.org/wm-spec/wm-spec-latest.html#idm45381391268672
+ *
+ * @param w Width of the bar window
+ * @param strut Size of the reserved space. Height of the window, corrected for unaligned monitors
+ * @param x The absolute x-position of the bar window (top-left corner)
+ * @param bottom Whether the bar is at the bottom of the screen
  */
-window window::reconfigure_struts(unsigned short int w, unsigned short int h, short int x, bool bottom) {
+window window::reconfigure_struts(uint32_t w, uint32_t strut, uint32_t x, bool bottom) {
-  unsigned int none{0};
+  std::array<uint32_t, 12> values{};
-  unsigned int values[12]{none};
 
   if (bottom) {
-    values[static_cast<int>(strut::BOTTOM)] = h;
+    values[to_integral(strut::BOTTOM)] = strut;
-    values[static_cast<int>(strut::BOTTOM_START_X)] = x;
+    values[to_integral(strut::BOTTOM_START_X)] = x;
-    values[static_cast<int>(strut::BOTTOM_END_X)] = x + w - 1;
+    values[to_integral(strut::BOTTOM_END_X)] = x + w - 1;
   } else {
-    values[static_cast<int>(strut::TOP)] = h;
+    values[to_integral(strut::TOP)] = strut;
-    values[static_cast<int>(strut::TOP_START_X)] = x;
+    values[to_integral(strut::TOP_START_X)] = x;
-    values[static_cast<int>(strut::TOP_END_X)] = x + w - 1;
+    values[to_integral(strut::TOP_END_X)] = x + w - 1;
   }
 
-  connection().change_property_checked(XCB_PROP_MODE_REPLACE, *this, _NET_WM_STRUT, XCB_ATOM_CARDINAL, 32, 4, values);
   connection().change_property_checked(
-      XCB_PROP_MODE_REPLACE, *this, _NET_WM_STRUT_PARTIAL, XCB_ATOM_CARDINAL, 32, 12, values);
+      XCB_PROP_MODE_REPLACE, *this, _NET_WM_STRUT, XCB_ATOM_CARDINAL, 32, 4, values.data());
+  connection().change_property_checked(
+      XCB_PROP_MODE_REPLACE, *this, _NET_WM_STRUT_PARTIAL, XCB_ATOM_CARDINAL, 32, 12, values.data());
 
   return *this;
 }