Implement SGR dim

kitty now supports the SGR DIM escape code, which makes text fade into
the background. It works by alpha blending the text color into the
background color. Fixes #446

kitty/cell_fragment.glsl

@@ -19,7 +19,7 @@ in float bg_alpha;
 
 #ifdef NEEDS_FOREGROUND
 uniform sampler2DArray sprites;
-uniform float inactive_text_alpha;
+in float effective_text_alpha;
 in vec3 sprite_pos;
 in vec3 underline_pos;
 in vec3 strike_pos;
@@ -61,7 +61,7 @@ vec4 calculate_foreground() {
     // Since strike and text are the same color, we simply add the alpha values
     float combined_alpha = min(text_alpha + strike_alpha, 1.0f);
     // Underline color might be different, so alpha blend
-    return alpha_blend(decoration_fg, underline_alpha * inactive_text_alpha, fg, combined_alpha * inactive_text_alpha);
+    return alpha_blend(decoration_fg, underline_alpha * effective_text_alpha, fg, combined_alpha * effective_text_alpha);
 }
 #endif
 

kitty/cell_vertex.glsl

@@ -1,6 +1,7 @@
 #version GLSL_VERSION
 #define WHICH_PROGRAM
 #define NOT_TRANSPARENT
+#define SHIFTS
 
 // Inputs {{{
 layout(std140) uniform CellRenderData {
@@ -45,12 +46,14 @@ out float bg_alpha;
 #endif
 
 #ifdef NEEDS_FOREGROUND
+uniform float inactive_text_alpha;
 out vec3 sprite_pos;
 out vec3 underline_pos;
 out vec3 strike_pos;
 out vec3 foreground;
 out vec3 decoration_fg;
 out float colored_sprite;
+out float effective_text_alpha;
 #endif
 
 
@@ -63,9 +66,6 @@ const uint ONE = uint(1);
 const uint TWO = uint(2);
 const uint THREE = uint(3);
 const uint FOUR = uint(4);
-const uint DECORATION_MASK = uint(3);
-const uint STRIKE_MASK = uint(1);
-const uint REVERSE_MASK = uint(1);
 
 vec3 color_to_vec(uint c) {
     uint r, g, b;
@@ -134,7 +134,7 @@ void main() {
     // set cell color indices {{{
     uvec2 default_colors = uvec2(default_fg, default_bg);
     uint text_attrs = sprite_coords[3];
-    uint is_inverted = ((text_attrs >> 6) & REVERSE_MASK) + inverted;
+    uint is_inverted = ((text_attrs >> REVERSE_SHIFT) & ONE) + inverted;
     int fg_index = fg_index_map[is_inverted];
     int bg_index = 1 - fg_index;
     float cursor = is_cursor(c, r);
@@ -151,13 +151,15 @@ void main() {
     // Foreground
     uint resolved_fg = resolve_color(colors[fg_index], default_colors[fg_index]);
     foreground = color_to_vec(resolved_fg);
+    float has_dim = float((text_attrs >> DIM_SHIFT) & ONE);
+    effective_text_alpha = inactive_text_alpha * mix(1.0, 0.75, has_dim);
     // Selection
     foreground = choose_color(float(is_selected & ONE), color_to_vec(highlight_fg), foreground);
     // Underline and strike through (rendered via sprites)
     float in_url = float((is_selected & TWO) >> 1);
     decoration_fg = choose_color(in_url, color_to_vec(url_color), to_color(colors[2], resolved_fg));
-    underline_pos = choose_color(in_url, to_sprite_pos(pos, url_style, ZERO, ZERO), to_sprite_pos(pos, (text_attrs >> 2) & DECORATION_MASK, ZERO, ZERO));
+    underline_pos = choose_color(in_url, to_sprite_pos(pos, url_style, ZERO, ZERO), to_sprite_pos(pos, (text_attrs >> DECORATION_SHIFT) & THREE, ZERO, ZERO));
-    strike_pos = to_sprite_pos(pos, ((text_attrs >> 7) & STRIKE_MASK) * FOUR, ZERO, ZERO);
+    strike_pos = to_sprite_pos(pos, ((text_attrs >> STRIKE_SHIFT) & ONE) * FOUR, ZERO, ZERO);
 
     // Cursor
     foreground = choose_color(cursor, bg, foreground);

kitty/cursor.c

@@ -24,7 +24,7 @@ dealloc(Cursor* self) {
 
 #define EQ(x) (a->x == b->x)
 static int __eq__(Cursor *a, Cursor *b) {
-    return EQ(bold) && EQ(italic) && EQ(strikethrough) && EQ(reverse) && EQ(decoration) && EQ(fg) && EQ(bg) && EQ(decoration_fg) && EQ(x) && EQ(y) && EQ(shape) && EQ(blink);
+    return EQ(bold) && EQ(italic) && EQ(strikethrough) && EQ(dim) && EQ(reverse) && EQ(decoration) && EQ(fg) && EQ(bg) && EQ(decoration_fg) && EQ(x) && EQ(y) && EQ(shape) && EQ(blink);
 }
 
 static const char* cursor_names[NUM_OF_CURSOR_SHAPES] = { "NO_SHAPE", "BLOCK", "BEAM", "UNDERLINE" };
@@ -33,16 +33,16 @@ static const char* cursor_names[NUM_OF_CURSOR_SHAPES] = { "NO_SHAPE", "BLOCK", "
 static PyObject *
 repr(Cursor *self) {
     return PyUnicode_FromFormat(
-        "Cursor(x=%u, y=%u, shape=%s, blink=%R, fg=#%08x, bg=#%08x, bold=%R, italic=%R, reverse=%R, strikethrough=%R, decoration=%d, decoration_fg=#%08x)",
+        "Cursor(x=%u, y=%u, shape=%s, blink=%R, fg=#%08x, bg=#%08x, bold=%R, italic=%R, reverse=%R, strikethrough=%R, dim=%R, decoration=%d, decoration_fg=#%08x)",
         self->x, self->y, (self->shape < NUM_OF_CURSOR_SHAPES ? cursor_names[self->shape] : "INVALID"),
-        BOOL(self->blink), self->fg, self->bg, BOOL(self->bold), BOOL(self->italic), BOOL(self->reverse), BOOL(self->strikethrough), self->decoration, self->decoration_fg
+        BOOL(self->blink), self->fg, self->bg, BOOL(self->bold), BOOL(self->italic), BOOL(self->reverse), BOOL(self->strikethrough), BOOL(self->dim), self->decoration, self->decoration_fg
     );
 }
 
 void
 cursor_reset_display_attrs(Cursor *self) {
     self->bg = 0; self->fg = 0; self->decoration_fg = 0;
-    self->decoration = 0; self->bold = false; self->italic = false; self->reverse = false; self->strikethrough = false;
+    self->decoration = 0; self->bold = false; self->italic = false; self->reverse = false; self->strikethrough = false; self->dim = false;
 }
 
 
@@ -85,6 +85,8 @@ START_ALLOW_CASE_RANGE
                 cursor_reset_display_attrs(self);  break;
             case 1:
                 self->bold = true;  break;
+            case 2:
+                self->dim = true; break;
             case 3:
                 self->italic = true;  break;
             case 4:
@@ -98,7 +100,7 @@ START_ALLOW_CASE_RANGE
             case 21:
                 self->decoration = 2; break;
             case 22:
-                self->bold = false;  break;
+                self->bold = false;  self->dim = false; break;
             case 23:
                 self->italic = false;  break;
             case 24:
@@ -138,6 +140,7 @@ apply_sgr_to_cells(Cell *first_cell, unsigned int cell_count, unsigned int *para
 #define RANGE for(unsigned c = 0; c < cell_count; c++, cell++)
 #define SET(shift) RANGE { cell->attrs |= (1 << shift); } break;
 #define RESET(shift) RANGE { cell->attrs &= ~(1 << shift); } break;
+#define RESET2(shift1, shift2) RANGE { cell->attrs &= ~((1 << shift1) | (1 << shift2)); } break;
 #define SETM(val, mask, shift) { RANGE { cell->attrs &= ~(mask << shift); cell->attrs |= ((val) << shift); } break; }
 #define SET_COLOR(which) { color_type color = 0; parse_color(params, &i, count, &color); if (color) { RANGE { cell->which = color; }} } break;
 #define SIMPLE(which, val) RANGE { cell->which = (val); } break;
@@ -153,6 +156,8 @@ apply_sgr_to_cells(Cell *first_cell, unsigned int cell_count, unsigned int *para
                 break;
             case 1:
                 SET(BOLD_SHIFT);
+            case 2:
+                SET(DIM_SHIFT);
             case 3:
                 SET(ITALIC_SHIFT);
             case 4:
@@ -165,7 +170,7 @@ apply_sgr_to_cells(Cell *first_cell, unsigned int cell_count, unsigned int *para
             case 21:
                 SETM(2, DECORATION_MASK, DECORATION_SHIFT);
             case 22:
-                RESET(BOLD_SHIFT);
+                RESET2(DIM_SHIFT, BOLD_SHIFT);
             case 23:
                 RESET(ITALIC_SHIFT);
             case 24:
@@ -199,6 +204,7 @@ END_ALLOW_CASE_RANGE
         }
     }
 #undef RESET
+#undef RESET2
 #undef SET_COLOR
 #undef SET
 #undef SETM
@@ -237,7 +243,11 @@ cursor_as_sgr(Cursor *self, Cursor *prev) {
 #define SZ sizeof(buf) - (p - buf) - 2
 #define P(fmt, ...) { p += snprintf(p, SZ, fmt ";", __VA_ARGS__); }
     char *p = buf;
-    if (self->bold != prev->bold) P("%d", self->bold ? 1 : 22);
+    bool intensity_differs = self->bold != prev->bold || self->dim != prev->dim;
+    if (intensity_differs) {
+        if (!self->bold || !self->dim) { P("%d", 22); }
+        else P("%d;%d", 1, 2);
+    }
     if (self->italic != prev->italic) P("%d", self->italic ? 3 : 23);
     if (self->reverse != prev->reverse) P("%d", self->reverse ? 7 : 27);
     if (self->strikethrough != prev->strikethrough) P("%d", self->strikethrough ? 9 : 29);
@@ -268,7 +278,7 @@ void cursor_reset(Cursor *self) {
 void cursor_copy_to(Cursor *src, Cursor *dest) {
 #define CCY(x) dest->x = src->x;
     CCY(x); CCY(y); CCY(shape); CCY(blink);
-    CCY(bold); CCY(italic); CCY(strikethrough); CCY(reverse); CCY(decoration); CCY(fg); CCY(bg); CCY(decoration_fg);
+    CCY(bold); CCY(italic); CCY(strikethrough); CCY(dim); CCY(reverse); CCY(decoration); CCY(fg); CCY(bg); CCY(decoration_fg);
 }
 
 static PyObject*
@@ -281,6 +291,7 @@ BOOL_GETSET(Cursor, bold)
 BOOL_GETSET(Cursor, italic)
 BOOL_GETSET(Cursor, reverse)
 BOOL_GETSET(Cursor, strikethrough)
+BOOL_GETSET(Cursor, dim)
 BOOL_GETSET(Cursor, blink)
 
 static PyMemberDef members[] = {
@@ -299,6 +310,7 @@ static PyGetSetDef getseters[] = {
     GETSET(italic)
     GETSET(reverse)
     GETSET(strikethrough)
+    GETSET(dim)
     GETSET(blink)
     {NULL}  /* Sentinel */
 };

kitty/data-types.c

@@ -197,6 +197,7 @@ PyInit_fast_data_types(void) {
         PyModule_AddIntConstant(m, "ITALIC", ITALIC_SHIFT);
         PyModule_AddIntConstant(m, "REVERSE", REVERSE_SHIFT);
         PyModule_AddIntConstant(m, "STRIKETHROUGH", STRIKE_SHIFT);
+        PyModule_AddIntConstant(m, "DIM", DIM_SHIFT);
         PyModule_AddIntConstant(m, "DECORATION", DECORATION_SHIFT);
         PyModule_AddStringMacro(m, ERROR_PREFIX);
 #ifdef KITTY_VCS_REV

kitty/data-types.h

@@ -58,6 +58,7 @@ typedef enum MouseShapes { BEAM, HAND, ARROW } MouseShape;
 #define BI_VAL(attrs) ((attrs >> 4) & 3)
 #define REVERSE_SHIFT 6
 #define STRIKE_SHIFT 7
+#define DIM_SHIFT 8
 #define COL_MASK 0xFFFFFFFF
 #define UTF8_ACCEPT 0
 #define UTF8_REJECT 1
@@ -71,11 +72,12 @@ typedef enum MouseShapes { BEAM, HAND, ARROW } MouseShape;
 
 #define CURSOR_TO_ATTRS(c, w) \
     ((w) | (((c->decoration & 3) << DECORATION_SHIFT) | ((c->bold & 1) << BOLD_SHIFT) | \
-            ((c->italic & 1) << ITALIC_SHIFT) | ((c->reverse & 1) << REVERSE_SHIFT) | ((c->strikethrough & 1) << STRIKE_SHIFT)))
+            ((c->italic & 1) << ITALIC_SHIFT) | ((c->reverse & 1) << REVERSE_SHIFT) | \
+            ((c->strikethrough & 1) << STRIKE_SHIFT) | ((c->dim & 1) << DIM_SHIFT)))
 
 #define ATTRS_TO_CURSOR(a, c) \
     (c)->decoration = (a >> DECORATION_SHIFT) & 3; (c)->bold = (a >> BOLD_SHIFT) & 1; (c)->italic = (a >> ITALIC_SHIFT) & 1; \
-    (c)->reverse = (a >> REVERSE_SHIFT) & 1; (c)->strikethrough = (a >> STRIKE_SHIFT) & 1;
+    (c)->reverse = (a >> REVERSE_SHIFT) & 1; (c)->strikethrough = (a >> STRIKE_SHIFT) & 1; (c)->dim = (a >> DIM_SHIFT) & 1;
 
 #define COPY_CELL(src, s, dest, d) \
     (dest)->cells[d] = (src)->cells[s];
@@ -178,7 +180,7 @@ typedef struct {
 typedef struct {
     PyObject_HEAD
 
-    bool bold, italic, reverse, strikethrough, blink;
+    bool bold, italic, reverse, strikethrough, blink, dim;
     unsigned int x, y;
     uint8_t decoration;
     CursorShape shape;

kitty/line-buf.c

@@ -149,7 +149,7 @@ set_attribute(LineBuf *self, PyObject *args) {
 #define set_attribute_doc "set_attribute(which, val) -> Set the attribute on all cells in the line."
     unsigned int shift, val;
     if (!PyArg_ParseTuple(args, "II", &shift, &val)) return NULL;
-    if (shift < DECORATION_SHIFT || shift > STRIKE_SHIFT) { PyErr_SetString(PyExc_ValueError, "Unknown attribute"); return NULL; }
+    if (shift < DECORATION_SHIFT || shift > DIM_SHIFT) { PyErr_SetString(PyExc_ValueError, "Unknown attribute"); return NULL; }
     linebuf_set_attribute(self, shift, val);
     Py_RETURN_NONE;
 }

kitty/line.c

@@ -515,7 +515,7 @@ set_attribute(Line *self, PyObject *args) {
 #define set_attribute_doc "set_attribute(which, val) -> Set the attribute on all cells in the line."
     unsigned int shift, val;
     if (!PyArg_ParseTuple(args, "II", &shift, &val)) return NULL;
-    if (shift < DECORATION_SHIFT || shift > STRIKE_SHIFT) { PyErr_SetString(PyExc_ValueError, "Unknown attribute"); return NULL; }
+    if (shift < DECORATION_SHIFT || shift > DIM_SHIFT) { PyErr_SetString(PyExc_ValueError, "Unknown attribute"); return NULL; }
     set_attribute_on_line(self->cells, shift, val, self->xnum);
     Py_RETURN_NONE;
 }

kitty/window.py

@@ -15,9 +15,10 @@ from .constants import (
 )
 from .fast_data_types import (
     BLIT_PROGRAM, CELL_BG_PROGRAM, CELL_FG_PROGRAM, CELL_PROGRAM,
-    CELL_SPECIAL_PROGRAM, CSI, CURSOR_PROGRAM, DCS, GRAPHICS_PREMULT_PROGRAM,
+    CELL_SPECIAL_PROGRAM, CSI, CURSOR_PROGRAM, DCS, DECORATION, DIM,
-    GRAPHICS_PROGRAM, OSC, SCROLL_FULL, SCROLL_LINE, SCROLL_PAGE, Screen,
+    GRAPHICS_PREMULT_PROGRAM, GRAPHICS_PROGRAM, OSC, REVERSE, SCROLL_FULL,
-    add_window, compile_program, get_clipboard_string, glfw_post_empty_event,
+    SCROLL_LINE, SCROLL_PAGE, STRIKETHROUGH, Screen, add_window,
+    compile_program, get_clipboard_string, glfw_post_empty_event,
     init_cell_program, init_cursor_program, set_clipboard_string,
     set_titlebar_color, set_window_render_data, update_window_title,
     update_window_visibility, viewport_for_window
@@ -64,6 +65,10 @@ def load_shader_programs(semi_transparent=0):
             'FOREGROUND': CELL_FG_PROGRAM,
     }.items():
         vv, ff = v.replace('WHICH_PROGRAM', which), f.replace('WHICH_PROGRAM', which)
+        shifts = '\n'.join('#define {} {}'.format(name, val) for name, val in (
+            ('DECORATION_SHIFT', DECORATION), ('REVERSE_SHIFT', REVERSE), ('STRIKE_SHIFT', STRIKETHROUGH), ('DIM_SHIFT', DIM),
+        ))
+        vv = vv.replace('#define SHIFTS', shifts)
         if semi_transparent:
             vv = vv.replace('#define NOT_TRANSPARENT', '#define TRANSPARENT')
             ff = ff.replace('#define NOT_TRANSPARENT', '#define TRANSPARENT')

kitty_tests/__init__.py

@@ -52,7 +52,7 @@ def filled_line_buf(ynum=5, xnum=5, cursor=Cursor()):
 
 def filled_cursor():
     ans = Cursor()
-    ans.bold = ans.italic = ans.reverse = ans.strikethrough = True
+    ans.bold = ans.italic = ans.reverse = ans.strikethrough = ans.dim = True
     ans.fg = 0x101
     ans.bg = 0x201
     ans.decoration_fg = 0x301

kitty_tests/datatypes.py

@@ -179,7 +179,7 @@ class TestDataTypes(BaseTest):
         self.assertEqual(str(l0), 'a' + t[1:])
 
         c = C(3, 5)
-        c.bold = c.italic = c.reverse = c.strikethrough = True
+        c.bold = c.italic = c.reverse = c.strikethrough = c.dim = True
         c.fg = c.bg = c.decoration_fg = 0x0101
         self.ae(c, c)
         c2, c3 = c.copy(), c.copy()
@@ -219,7 +219,7 @@ class TestDataTypes(BaseTest):
 
         l3.set_text(t, 0, len(t), C())
         q = C()
-        q.bold = q.italic = q.reverse = q.strikethrough = True
+        q.bold = q.italic = q.reverse = q.strikethrough = c.dim = True
         q.decoration = 2
         c = C()
         c.x = 3
@@ -450,12 +450,12 @@ class TestDataTypes(BaseTest):
         self.ae(a, ['\x1b[0m' + str(lb.line(i)) + '\n' for i in range(lb.ynum)])
         l2 = lb.line(0)
         c = C()
-        c.bold = c.italic = c.reverse = c.strikethrough = True
+        c.bold = c.italic = c.reverse = c.strikethrough = c.dim = True
         c.fg = (4 << 8) | 1
         c.bg = (1 << 24) | (2 << 16) | (3 << 8) | 2
         c.decoration_fg = (5 << 8) | 1
         l2.set_text('1', 0, 1, c)
-        self.ae(l2.as_ansi(), '\x1b[0m\x1b[1;3;7;9;34;48:2:1:2:3;58:5:5m' '1'
+        self.ae(l2.as_ansi(), '\x1b[0m\x1b[1;2;3;7;9;34;48:2:1:2:3;58:5:5m' '1'
                 '\x1b[22;23;27;29;39;49;59m' '0000')
         lb = filled_line_buf()
         for i in range(lb.ynum):

kitty_tests/parser.py

@@ -118,8 +118,8 @@ class TestParser(BaseTest):
         def sgr(params):
             return (('select_graphic_rendition', '{} '.format(x)) for x in params.split())
 
-        pb('\033[1;3;4;7;9;34;44m', *sgr('1 3 4 7 9 34 44'))
+        pb('\033[1;2;3;4;7;9;34;44m', *sgr('1 2 3 4 7 9 34 44'))
-        for attr in 'bold italic reverse strikethrough'.split():
+        for attr in 'bold italic reverse strikethrough dim'.split():
             self.assertTrue(getattr(s.cursor, attr))
         self.ae(s.cursor.decoration, 1)
         self.ae(s.cursor.fg, 4 << 8 | 1)
@@ -202,7 +202,7 @@ class TestParser(BaseTest):
         c.clear()
         pb('\033P$qm\033\\', ('screen_request_capabilities', ord('$'), 'm'))
         self.ae(c.wtcbuf, b'\033P1$rm\033\\')
-        for sgr in '0;34;102;1;3;4 0;38:5:200;58:2:10:11:12'.split():
+        for sgr in '0;34;102;1;2;3;4 0;38:5:200;58:2:10:11:12'.split():
             expected = set(sgr.split(';')) - {'0'}
             c.clear()
             parse_bytes(s, '\033[{}m\033P$qm\033\\'.format(sgr).encode('ascii'))