Allow reverse video for the mouse selection

Fixes #646

docs/changelog.rst

@@ -19,6 +19,9 @@ To update |kitty|, :doc:`follow the instructions <binary>`.
 - Allow rendering the cursor with a *reverse video* effect. See :opt:`cursor`
   for details (:iss:`126`)
 
+- Allow rendering the mouse selection with a *reverse video* effect. See
+  :opt:`selection_foreground` (:iss:`646`)
+
 - A new option :opt:`tab_bar_align` to draw the tab bar centered or right
   aligned (:iss:`3946`)
 

kitty/cell_vertex.glsl

@@ -12,7 +12,7 @@
 
 // Inputs {{{
 layout(std140) uniform CellRenderData {
-    float xstart, ystart, dx, dy, sprite_dx, sprite_dy, background_opacity, use_fg_for_selection;
+    float xstart, ystart, dx, dy, sprite_dx, sprite_dy, background_opacity, use_cell_for_selection_fg, use_cell_for_selection_bg;
 
     uint default_fg, default_bg, highlight_fg, highlight_bg, cursor_fg, cursor_bg, url_color, url_style, inverted;
 
@@ -170,6 +170,7 @@ void main() {
     uint bg_as_uint = resolve_color(colors[bg_index], default_colors[bg_index]);
     bg_as_uint = has_mark * color_table[NUM_COLORS + mark] + (ONE - has_mark) * bg_as_uint;
     vec3 bg = color_to_vec(bg_as_uint);
+    uint fg_as_uint = resolve_color(colors[fg_index], default_colors[fg_index]);
     // }}}
 
     // Foreground {{{
@@ -180,7 +181,6 @@ void main() {
     colored_sprite = float((sprite_coords.z & COLOR_MASK) >> 14);
 
     // Foreground
-    uint fg_as_uint = resolve_color(colors[fg_index], default_colors[fg_index]);
     fg_as_uint = has_mark * color_table[NUM_COLORS + MARK_MASK + 1 + mark] + (ONE - has_mark) * fg_as_uint;
     foreground = color_to_vec(fg_as_uint);
     float has_dim = float((text_attrs >> DIM_SHIFT) & ONE);
@@ -189,7 +189,7 @@ void main() {
     decoration_fg = choose_color(in_url, color_to_vec(url_color), to_color(colors[2], fg_as_uint));
 #ifdef USE_SELECTION_FG
     // Selection
-    vec3 selection_color = choose_color(use_fg_for_selection, foreground, color_to_vec(highlight_fg));
+    vec3 selection_color = choose_color(use_cell_for_selection_fg, bg, color_to_vec(highlight_fg));
     foreground = choose_color(float(is_selected & ONE), selection_color, foreground);
     decoration_fg = choose_color(float(is_selected & ONE), selection_color, decoration_fg);
 #endif
@@ -236,7 +236,7 @@ void main() {
 
 #if defined(SPECIAL) || defined(SIMPLE)
     // Selection and cursor
-    bg = choose_color(float(is_selected & ONE), color_to_vec(highlight_bg), bg);
+    bg = choose_color(float(is_selected & ONE), choose_color(use_cell_for_selection_bg, color_to_vec(fg_as_uint), color_to_vec(highlight_bg)), bg);
     background = choose_color(cell_has_block_cursor, color_to_vec(cursor_bg), bg);
 #if !defined(TRANSPARENT) && defined(SPECIAL)
     float is_special_cell = cell_has_block_cursor + float(is_selected & ONE);

kitty/options/definition.py

@@ -1146,15 +1146,13 @@ and zero means fully dimmed (i.e. invisible).
 opt('selection_foreground', '#000000',
     option_type='to_color_or_none',
     long_text='''
-The foreground for text selected with the mouse. A value of none means to leave
-the color unchanged.
-'''
-    )
+The foreground and background colors for text selected with the mouse. Setting both of
+these to :code:`none` will cause a "reverse video" effect for selections, where the
+selection will be the cell text color and the text will become the cell background color.
+Note that these colors can be overridden by the program running in the terminal.
+''')
 
-opt('selection_background', '#fffacd',
-    option_type='to_color',
-    long_text='The background for text selected with the mouse.'
-    )
+opt('selection_background', '#fffacd', option_type='to_color_or_none',)
 
 
 # colors.table {{{

kitty/options/parse.py

@@ -1125,7 +1125,7 @@ class Parser:
         ans['select_by_word_characters'] = str(val)
 
     def selection_background(self, val: str, ans: typing.Dict[str, typing.Any]) -> None:
-        ans['selection_background'] = to_color(val)
+        ans['selection_background'] = to_color_or_none(val)
 
     def selection_foreground(self, val: str, ans: typing.Dict[str, typing.Any]) -> None:
         ans['selection_foreground'] = to_color_or_none(val)

kitty/options/types.py

@@ -537,7 +537,7 @@ class Options:
     scrollback_pager: typing.List[str] = ['less', '--chop-long-lines', '--RAW-CONTROL-CHARS', '+INPUT_LINE_NUMBER']
     scrollback_pager_history_size: int = 0
     select_by_word_characters: str = '@-./_~?&=%+#'
-    selection_background: Color = Color(255, 250, 205)
+    selection_background: typing.Optional[kitty.fast_data_types.Color] = Color(255, 250, 205)
     selection_foreground: typing.Optional[kitty.fast_data_types.Color] = Color(0, 0, 0)
     shell: str = '.'
     shell_integration: str = 'enabled'

kitty/rc/set_colors.py

@@ -17,7 +17,10 @@ if TYPE_CHECKING:
     from kitty.cli_stub import SetColorsRCOptions as CLIOptions
 
 
-nullable_colors = ('cursor', 'cursor_text_color', 'tab_bar_background', 'tab_bar_margin_color', 'selection_foreground', 'active_border_color')
+nullable_colors = (
+    'cursor', 'cursor_text_color', 'tab_bar_background', 'tab_bar_margin_color',
+    'selection_foreground', 'selection_background', 'active_border_color'
+)
 
 
 def parse_colors(args: Iterable[str]) -> Dict[str, Optional[int]]:

kitty/shaders.c

@@ -276,7 +276,7 @@ pick_cursor_color(Line *line, ColorProfile *color_profile, color_type cell_fg, c
 static void
 cell_update_uniform_block(ssize_t vao_idx, Screen *screen, int uniform_buffer, GLfloat xstart, GLfloat ystart, GLfloat dx, GLfloat dy, CursorRenderInfo *cursor, bool inverted, OSWindow *os_window) {
     struct CellRenderData {
-        GLfloat xstart, ystart, dx, dy, sprite_dx, sprite_dy, background_opacity, use_fg_for_selection;
+        GLfloat xstart, ystart, dx, dy, sprite_dx, sprite_dy, background_opacity, use_cell_for_selection_fg, use_cell_for_selection_bg;
 
         GLuint default_fg, default_bg, highlight_fg, highlight_bg, cursor_fg, cursor_bg, url_color, url_style, inverted;
 
@@ -295,7 +295,8 @@ cell_update_uniform_block(ssize_t vao_idx, Screen *screen, int uniform_buffer, G
     rd->default_fg = COLOR(default_fg); rd->default_bg = COLOR(default_bg);
     rd->highlight_fg = COLOR(highlight_fg); rd->highlight_bg = COLOR(highlight_bg);
     // selection
-    rd->use_fg_for_selection = IS_SPECIAL_COLOR(highlight_fg) ? 1. : 0.;
+    rd->use_cell_for_selection_fg = IS_SPECIAL_COLOR(highlight_fg) ? 1. : 0.;
+    rd->use_cell_for_selection_bg = IS_SPECIAL_COLOR(highlight_bg) ? 1. : 0.;
     // Cursor position
     enum { BLOCK_IDX = 0, BEAM_IDX = 6, UNDERLINE_IDX = 7, UNFOCUSED_IDX = 8 };
     if (cursor->is_visible) {