Option to size window margin (blank area outside window borders)

Defaults to zero

kitty/borders.py

@@ -9,7 +9,7 @@ from threading import Lock
 from .constants import GLfloat, GLint, GLuint, viewport_size
 from .fast_data_types import GL_TRIANGLE_FAN, glMultiDrawArrays, glUniform3fv
 from .shaders import ShaderProgram
-from .utils import get_dpi
+from .utils import pt_to_px
 
 
 def as_color(c):
@@ -63,9 +63,7 @@ class Borders:
         self.is_dirty = False
         self.lock = Lock()
         self.can_render = False
-        dpix, dpiy = get_dpi()['logical']
+        self.border_width = pt_to_px(opts.window_border_width)
-        dpi = (dpix + dpiy) / 2
-        self.border_width = round(opts.window_border_width * dpi / 72)
         self.color_buf = (GLfloat * 9)(
             *as_color(opts.background),
             *as_color(opts.active_border_color),

kitty/config.py

@@ -161,6 +161,7 @@ type_map = {
     'open_url_modifiers': to_open_url_modifiers,
     'repaint_delay': int,
     'window_border_width': float,
+    'window_margin_width': float,
     'wheel_scroll_multiplier': float,
     'visual_bell_duration': float,
     'enable_audio_bell': to_bool,

kitty/kitty.conf

@@ -120,6 +120,9 @@ term xterm-kitty
 # The width (in pts) of window borders. Will be rounded to the nearest number of pixels based on screen resolution.
 window_border_width 1
 
+# The window margin (in pts) (blank area outside the border)
+window_margin_width 0
+
 # The color for the border of the active window
 active_border_color #00ff00
 

kitty/layout.py

@@ -6,25 +6,28 @@ from collections import namedtuple
 from itertools import islice
 
 from .constants import WindowGeometry, viewport_size, cell_size, get_boss
+from .utils import pt_to_px
 
 
 def available_height():
     return viewport_size.height - get_boss().current_tab_bar_height
 
 
-def layout_dimension(length, cell_length, number_of_windows=1, border_length=0, left_align=False):
+def layout_dimension(length, cell_length, number_of_windows=1, border_length=0, margin_length=0, left_align=False):
     number_of_cells = length // cell_length
     space_needed_for_border = number_of_windows * 2 * border_length
+    space_needed_for_padding = number_of_windows * 2 * margin_length
+    space_needed = space_needed_for_padding + space_needed_for_border
     extra = length - number_of_cells * cell_length
-    while extra < space_needed_for_border:
+    while extra < space_needed:
         number_of_cells -= 1
         extra = length - number_of_cells * cell_length
     cells_per_window = number_of_cells // number_of_windows
-    extra -= space_needed_for_border
+    extra -= space_needed
     pos = 0 if left_align else (extra // 2)
-    pos += border_length
+    pos += border_length + margin_length
     inner_length = cells_per_window * cell_length
-    window_length = 2 * border_length + inner_length
+    window_length = 2 * (border_length + margin_length) + inner_length
     extra = number_of_cells - (cells_per_window * number_of_windows)
     while number_of_windows > 0:
         number_of_windows -= 1
@@ -43,6 +46,7 @@ class Layout:
     def __init__(self, opts, border_width, windows):
         self.opts = opts
         self.border_width = border_width
+        self.margin_width = pt_to_px(opts.window_margin_width)
         # A set of rectangles corresponding to the blank spaces at the edges of
         # this layout, i.e. spaces that are not covered by any window
         self.blank_rects = ()
@@ -76,9 +80,9 @@ def window_geometry(xstart, xnum, ystart, ynum):
     return WindowGeometry(left=xstart, top=ystart, xnum=xnum, ynum=ynum, right=xstart + cell_size.width * xnum, bottom=ystart + cell_size.height * ynum)
 
 
-def layout_single_window():
+def layout_single_window(margin_length):
-    xstart, xnum = next(layout_dimension(viewport_size.width, cell_size.width))
+    xstart, xnum = next(layout_dimension(viewport_size.width, cell_size.width, margin_length=margin_length))
-    ystart, ynum = next(layout_dimension(available_height(), cell_size.height))
+    ystart, ynum = next(layout_dimension(available_height(), cell_size.height, margin_length=margin_length))
     return window_geometry(xstart, xnum, ystart, ynum)
 
 
@@ -120,7 +124,7 @@ class Stack(Layout):
 
     def __call__(self, windows, active_window_idx):
         self.blank_rects = []
-        wg = layout_single_window()
+        wg = layout_single_window(self.margin_width)
         for i, w in enumerate(windows):
             w.is_visible_in_layout = i == active_window_idx
             w.set_geometry(wg)
@@ -135,17 +139,17 @@ class Tall(Layout):
     def __call__(self, windows, active_window_idx):
         self.blank_rects = br = []
         if len(windows) == 1:
-            wg = layout_single_window()
+            wg = layout_single_window(self.margin_width)
             windows[0].set_geometry(wg)
             self.blank_rects = blank_rects_for_window(windows[0])
             return
-        xlayout = layout_dimension(viewport_size.width, cell_size.width, 2, self.border_width)
+        xlayout = layout_dimension(viewport_size.width, cell_size.width, 2, self.border_width, margin_length=self.margin_width)
         xstart, xnum = next(xlayout)
-        ystart, ynum = next(layout_dimension(available_height(), cell_size.height, 1, self.border_width, left_align=True))
+        ystart, ynum = next(layout_dimension(available_height(), cell_size.height, 1, self.border_width, left_align=True, margin_length=self.margin_width))
         windows[0].set_geometry(window_geometry(xstart, xnum, ystart, ynum))
         vh = available_height()
         xstart, xnum = next(xlayout)
-        ylayout = layout_dimension(available_height(), cell_size.height, len(windows) - 1, self.border_width, left_align=True)
+        ylayout = layout_dimension(available_height(), cell_size.height, len(windows) - 1, self.border_width, left_align=True, margin_length=self.margin_width)
         for w, (ystart, ynum) in zip(islice(windows, 1, None), ylayout):
             w.set_geometry(window_geometry(xstart, xnum, ystart, ynum))
         left_blank_rect(windows[0], br, vh), top_blank_rect(windows[0], br, vh), right_blank_rect(windows[-1], br, vh)

kitty/utils.py

@@ -37,6 +37,13 @@ def wcwidth(c: str) -> int:
         return wcwidth_impl(ord(c[0]))
 
 
+@lru_cache()
+def pt_to_px(pts):
+    dpix, dpiy = get_dpi()['logical']
+    dpi = (dpix + dpiy) / 2
+    return round(pts * dpi / 72)
+
+
 @contextmanager
 def timeit(name, do_timing=False):
     if do_timing: