Add an option :opt:cursor_text_color to render text under the cursor in a fixed color.

See #126

docs/changelog.rst

@@ -3,6 +3,12 @@ Changelog
 
 |kitty| is a feature full, cross-platform, *fast*, GPU based terminal emulator.
 
+0.12.0 [future]
+------------------------------
+
+- Add an option :opt:`cursor_text_color` to render text under the cursor in a
+  fixed color. (:iss:`126`)
+
 0.11.3 [2018-07-10]
 ------------------------------
 

kitty/cell_vertex.glsl

@@ -5,6 +5,7 @@
 #define REVERSE_SHIFT {REVERSE_SHIFT}
 #define STRIKE_SHIFT {STRIKE_SHIFT}
 #define DIM_SHIFT {DIM_SHIFT}
+#define CURSOR_TEXT_COLOR {CURSOR_TEXT_COLOR}
 
 // Inputs {{{
 layout(std140) uniform CellRenderData {
@@ -166,8 +167,8 @@ void main() {
     strike_pos = to_sprite_pos(pos, ((text_attrs >> STRIKE_SHIFT) & ONE) * FOUR, ZERO, ZERO);
 
     // Cursor
-    foreground = choose_color(cursor, bg, foreground);
-    decoration_fg = choose_color(cursor, bg, decoration_fg);
+    foreground = choose_color(cursor, CURSOR_TEXT_COLOR, foreground);
+    decoration_fg = choose_color(cursor, CURSOR_TEXT_COLOR, decoration_fg);
 #endif
     // }}}
 

kitty/config_data.py

@@ -266,7 +266,17 @@ def to_cursor_shape(x):
         )
 
 
+def cursor_text_color(x):
+    if x.lower() == 'background':
+        return
+    return to_color(x)
+
+
 o('cursor', '#cccccc', _('Default cursor color'), option_type=to_color)
+o('cursor_text_color', 'background', option_type=cursor_text_color, long_text=_('''
+Choose the color of text under the cursor. By default, text under the cursor is
+rendered using the background color. If, instead you want it rendered using a
+fixed color, you can specify that color here.'''))
 o('cursor_shape', 'block', option_type=to_cursor_shape, long_text=_(
     'The cursor shape can be one of (block, beam, underline)'))
 o('cursor_blink_interval', 0.5, option_type=positive_float, long_text=_('''

kitty/main.py

@@ -82,10 +82,13 @@ def talk_to_instance(args):
 
 
 def load_all_shaders(semi_transparent=0):
-    load_shader_programs(semi_transparent)
+    load_shader_programs(semi_transparent, load_all_shaders.cursor_text_color)
     load_borders_program()
 
 
+load_all_shaders.cursor_text_color = None
+
+
 def init_glfw(debug_keyboard=False):
     glfw_module = 'cocoa' if is_macos else ('wayland' if is_wayland else 'x11')
     if not glfw_init(glfw_path(glfw_module), debug_keyboard):
@@ -118,6 +121,7 @@ def _run_app(opts, args):
     new_os_window_trigger = get_new_os_window_trigger(opts)
     if is_macos:
         set_custom_ibeam_cursor()
+    load_all_shaders.cursor_text_color = opts.cursor_text_color
     with cached_values_for(run_app.cached_values_name) as cached_values:
         with startup_notification_handler(extra_callback=run_app.first_window_callback) as pre_show_callback:
             window_id = create_os_window(

kitty/window.py

@@ -56,9 +56,14 @@ def calculate_gl_geometry(window_geometry, viewport_width, viewport_height, cell
     return ScreenGeometry(xstart, ystart, window_geometry.xnum, window_geometry.ynum, dx, dy)
 
 
-def load_shader_programs(semi_transparent=0):
+def load_shader_programs(semi_transparent=0, cursor_text_color=None):
     compile_program(BLIT_PROGRAM, *load_shaders('blit'))
     v, f = load_shaders('cell')
+
+    def color_as_vec3(x):
+        return 'vec3({}, {}, {})'.format(x.red / 255, x.green / 255, x.blue / 255)
+
+    cursor_text_color = color_as_vec3(cursor_text_color) if cursor_text_color else 'bg'
     for which, p in {
             'SIMPLE': CELL_PROGRAM,
             'BACKGROUND': CELL_BG_PROGRAM,
@@ -66,7 +71,13 @@ def load_shader_programs(semi_transparent=0):
             'FOREGROUND': CELL_FG_PROGRAM,
     }.items():
         vv, ff = v.replace('WHICH_PROGRAM', which), f.replace('WHICH_PROGRAM', which)
-        for gln, pyn in {'REVERSE_SHIFT': REVERSE, 'STRIKE_SHIFT': STRIKETHROUGH, 'DIM_SHIFT': DIM, 'DECORATION_SHIFT': DECORATION}.items():
+        for gln, pyn in {
+                'REVERSE_SHIFT': REVERSE,
+                'STRIKE_SHIFT': STRIKETHROUGH,
+                'DIM_SHIFT': DIM,
+                'DECORATION_SHIFT': DECORATION,
+                'CURSOR_TEXT_COLOR': cursor_text_color,
+        }.items():
             vv = vv.replace('{{{}}}'.format(gln), str(pyn), 1)
         if semi_transparent:
             vv = vv.replace('#define NOT_TRANSPARENT', '#define TRANSPARENT')