implement display_sort_order config option

none, horizontal, or vertical

doc/yabai.1

@@ -2,12 +2,12 @@
 .\"     Title: yabai
 .\"    Author: [see the "AUTHOR(S)" section]
 .\" Generator: Asciidoctor 2.0.10
-.\"      Date: 2020-06-06
+.\"      Date: 2020-06-08
 .\"    Manual: Yabai Manual
 .\"    Source: Yabai
 .\"  Language: English
 .\"
-.TH "YABAI" "1" "2020-06-06" "Yabai" "Yabai Manual"
+.TH "YABAI" "1" "2020-06-08" "Yabai" "Yabai Manual"
 .ie \n(.g .ds Aq \(aq
 .el       .ds Aq '
 .ss \n[.ss] 0
@@ -150,6 +150,17 @@ When focusing a window, put the mouse at its center.
 Automatically focus the window under the mouse.
 .RE
 .sp
+\fBdisplay_sort_order\fP [\fIhorizontal|vertical|none\fP]
+.RS 4
+Specify how displays are ordered.
+.br
+\fIhorizontal\fP|\fIvertical\fP: order by the display\(cqs relative position.
+.br
+\fInone\fP: (default) use the native ordering.
+.br
+The position of a display is determined by its center point.
+.RE
+.sp
 \fBwindow_placement\fP [\fIfirst_child|second_child\fP]
 .RS 4
 Specify whether managed windows should become the first or second leaf\-node.

doc/yabai.asciidoc

@@ -121,6 +121,12 @@ Global Settings
 *focus_follows_mouse* ['autofocus|autoraise|off']::
     Automatically focus the window under the mouse.
 
+*display_sort_order* ['horizontal|vertical|none']::
+    Specify how displays are ordered. +
+    'horizontal'|'vertical': order by the display's relative position. +
+    'none': (default) use the native ordering. +
+    The position of a display is determined by its center point.
+
 *window_placement* ['first_child|second_child']::
     Specify whether managed windows should become the first or second leaf-node.
 

src/display.c

@@ -136,6 +136,21 @@ CGRect display_bounds_constrained(uint32_t did)
     return frame;
 }
 
+static inline float display_frame_center(enum display_sort_order axis, CFStringRef uuid_str) {
+    CFUUIDRef uuid_ref = CFUUIDCreateFromString(NULL, uuid_str);
+    uint32_t did = CGDisplayGetDisplayIDFromUUID(uuid_ref);
+    CGRect frame = CGDisplayBounds(did);
+
+    switch(axis) {
+      case DISPLAY_SORT_HORIZ: return frame.origin.x + (frame.size.width) / 2;
+      case DISPLAY_SORT_VERT: return frame.origin.y + (frame.size.height) / 2;
+
+      // should not get here, but if we do it'll just result in not sorting
+      // (considering every display to be "equal")
+      default: return 0.0;
+    }
+}
+
 CGPoint display_center(uint32_t did)
 {
     CGRect bounds = display_bounds(did);

src/display_manager.c

@@ -81,16 +81,73 @@ uint32_t display_manager_point_display_id(CGPoint point)
     return result;
 }
 
+static inline enum display_sort_order rotate_axis(enum display_sort_order axis) {
+    switch(axis) {
+        case DISPLAY_SORT_NONE: return DISPLAY_SORT_NONE;
+        case DISPLAY_SORT_VERT: return DISPLAY_SORT_HORIZ;
+        case DISPLAY_SORT_HORIZ: return DISPLAY_SORT_VERT;
+    }
+}
+
+static inline float display_sort_lookup(CGPoint point, enum display_sort_order axis) {
+    switch(axis) {
+        case DISPLAY_SORT_NONE: return 0.0;
+        case DISPLAY_SORT_VERT: return point.y;
+        case DISPLAY_SORT_HORIZ: return point.x;
+    }
+}
+
+static enum CFComparisonResult coordinate_comparator(const void *a_p, const void *b_p, void *context_p) {
+    CFStringRef a = (CFStringRef) a_p;
+    CFStringRef b = (CFStringRef) b_p;
+    enum display_sort_order axis = *((enum display_sort_order *) context_p);
+
+    CFUUIDRef uuid_a = CFUUIDCreateFromString(NULL, a);
+    CFUUIDRef uuid_b = CFUUIDCreateFromString(NULL, b);
+
+    uint32_t did_a = CGDisplayGetDisplayIDFromUUID(uuid_a);
+    uint32_t did_b = CGDisplayGetDisplayIDFromUUID(uuid_b);
+
+    CGPoint center_a = display_center(did_a);
+    CGPoint center_b = display_center(did_b);
+
+    float coord_a, coord_b;
+
+    coord_a = display_sort_lookup(center_a, axis);
+    coord_b = display_sort_lookup(center_b, axis);
+    if (coord_a < coord_b) return kCFCompareLessThan;
+    if (coord_a > coord_b) return kCFCompareGreaterThan;
+
+    // if equal, fall back to the other axis
+    axis = rotate_axis(axis);
+
+    coord_a = display_sort_lookup(center_a, axis);
+    coord_b = display_sort_lookup(center_b, axis);
+    if (coord_a < coord_b) return kCFCompareLessThan;
+    if (coord_a > coord_b) return kCFCompareGreaterThan;
+
+    // the screens share a center point, so don't re-order them at all
+    return kCFCompareEqualTo;
+}
+
 CFStringRef display_manager_arrangement_display_uuid(int arrangement)
 {
     CFStringRef result = NULL;
     CFArrayRef displays = SLSCopyManagedDisplays(g_connection);
 
     int count = CFArrayGetCount(displays);
     int index = arrangement - 1;
-
     if (in_range_ie(index, 0, count)) {
-        result = CFRetain(CFArrayGetValueAtIndex(displays, index));
+        if (g_display_manager.sort_order == DISPLAY_SORT_NONE) {
+            result = CFRetain(CFArrayGetValueAtIndex(displays, index));
+        } else {
+            // copy the array to a mutable one, then sort it in place
+            CFRange all = CFRangeMake((long) 0, (long) count);
+            CFMutableArrayRef mut_displays = CFArrayCreateMutableCopy(NULL, count, displays);
+            CFArraySortValues(mut_displays, all, &coordinate_comparator, NULL);
+            result = CFRetain(CFArrayGetValueAtIndex(mut_displays, index));
+            CFRelease(mut_displays);
+        }
     }
 
     CFRelease(displays);
@@ -100,16 +157,15 @@ CFStringRef display_manager_arrangement_display_uuid(int arrangement)
 uint32_t display_manager_arrangement_display_id(int arrangement)
 {
     uint32_t result = 0;
-    CFArrayRef displays = SLSCopyManagedDisplays(g_connection);
-
-    int count = CFArrayGetCount(displays);
-    int index = arrangement - 1;
+    CFStringRef uuid = display_manager_arrangement_display_uuid(arrangement);
+    if (!uuid) return result;
+    CFUUIDRef uuid_ref = CFUUIDCreateFromString(NULL, uuid);
+    CFRelease(uuid);
+    if (!uuid_ref) return result;
 
-    if (in_range_ie(index, 0, count)) {
-        result = display_id(CFArrayGetValueAtIndex(displays, index));
-    }
+    result = CGDisplayGetDisplayIDFromUUID(uuid_ref);
+    CFRelease(uuid_ref);
 
-    CFRelease(displays);
     return result;
 }
 
@@ -328,6 +384,7 @@ bool display_manager_begin(struct display_manager *dm)
     dm->current_display_id = display_manager_active_display_id();
     dm->last_display_id = dm->current_display_id;
     dm->mode = EXTERNAL_BAR_OFF;
+    dm->sort_order = DISPLAY_SORT_NONE;
     dm->top_padding = 0;
     dm->bottom_padding = 0;
     return CGDisplayRegisterReconfigurationCallback(display_handler, NULL) == kCGErrorSuccess;

src/display_manager.h

@@ -14,6 +14,20 @@ extern void CoreDockGetOrientationAndPinning(int *orientation, int *pinning);
 #define DOCK_ORIENTATION_LEFT   3
 #define DOCK_ORIENTATION_RIGHT  4
 
+enum display_sort_order
+{
+  DISPLAY_SORT_NONE,
+  DISPLAY_SORT_HORIZ,
+  DISPLAY_SORT_VERT
+};
+
+static const char *display_sort_order_str[] =
+{
+  "none",
+  "horizontal",
+  "vertical"
+};
+
 enum external_bar_mode
 {
     EXTERNAL_BAR_OFF,
@@ -33,6 +47,8 @@ struct display_manager
     uint32_t current_display_id;
     uint32_t last_display_id;
 
+    enum display_sort_order sort_order;
+
     int top_padding;
     int bottom_padding;
     enum external_bar_mode mode;

src/message.c

@@ -21,6 +21,7 @@ extern bool g_verbose;
 #define COMMAND_CONFIG_MFF                   "mouse_follows_focus"
 #define COMMAND_CONFIG_FFM                   "focus_follows_mouse"
 #define COMMAND_CONFIG_WINDOW_PLACEMENT      "window_placement"
+#define COMMAND_CONFIG_DISPLAY_SORT          "display_sort_order"
 #define COMMAND_CONFIG_TOPMOST               "window_topmost"
 #define COMMAND_CONFIG_OPACITY               "window_opacity"
 #define COMMAND_CONFIG_OPACITY_DURATION      "window_opacity_duration"
@@ -45,6 +46,9 @@ extern bool g_verbose;
 
 #define ARGUMENT_CONFIG_FFM_AUTOFOCUS        "autofocus"
 #define ARGUMENT_CONFIG_FFM_AUTORAISE        "autoraise"
+#define ARGUMENT_CONFIG_DISPLAY_SORT_NONE    "none"
+#define ARGUMENT_CONFIG_DISPLAY_SORT_HORIZ   "horizontal"
+#define ARGUMENT_CONFIG_DISPLAY_SORT_VERT    "vertical"
 #define ARGUMENT_CONFIG_WINDOW_PLACEMENT_FST "first_child"
 #define ARGUMENT_CONFIG_WINDOW_PLACEMENT_SND "second_child"
 #define ARGUMENT_CONFIG_SHADOW_FLT           "float"
@@ -390,6 +394,19 @@ static void handle_domain_config(FILE *rsp, struct token domain, char *message)
         } else {
             daemon_fail(rsp, "unknown value '%.*s' given to command '%.*s' for domain '%.*s'\n", value.length, value.text, command.length, command.text, domain.length, domain.text);
         }
+    } else if (token_equals(command, COMMAND_CONFIG_DISPLAY_SORT)) {
+        struct token value = get_token(&message);
+        if (!token_is_valid(value)) {
+            fprintf(rsp, "%s\n", display_sort_order_str[g_display_manager.sort_order]);
+        } else if (token_equals(value, ARGUMENT_CONFIG_DISPLAY_SORT_NONE)) {
+            g_display_manager.sort_order = DISPLAY_SORT_NONE;
+        } else if (token_equals(value, ARGUMENT_CONFIG_DISPLAY_SORT_HORIZ)) {
+            g_display_manager.sort_order = DISPLAY_SORT_HORIZ;
+        } else if (token_equals(value, ARGUMENT_CONFIG_DISPLAY_SORT_VERT)) {
+            g_display_manager.sort_order = DISPLAY_SORT_VERT;
+        } else {
+            daemon_fail(rsp, "unknown value '%.*s' given to command '%.*s' for domain '%.*s'\n", value.length, value.text, command.length, command.text, domain.length, domain.text);
+        }
     } else if (token_equals(command, COMMAND_CONFIG_WINDOW_PLACEMENT)) {
         struct token value = get_token(&message);
         if (!token_is_valid(value)) {