Add initial support for LCD_V rendering (requires rewrite as height = rows/3 in this case)

Author: nightuser

kitty/config_data.py

@@ -939,12 +939,23 @@ def macos_option_as_alt(x):
 Enable/disable custom mouse cursor for macOS that is easier to see on both
 light and dark backgrounds. WARNING: this might make your mouse cursor
 invisible on dual GPU machines.'''))
-# }}}
 
-o('use_subpixel_rendering', False, long_text=_('''
+
+def to_subpixel_options(x):
+    x = x.lower()
+    if x == 'lcd':
+        return 1
+    if x == 'lcd_v':
+        return 2
+    return 0
+
+
+o('subpixel_rendering', 'none', option_type=to_subpixel_options, long_text=_('''
 Use subpixel rendering instead of grayscale in freetype. Impacts performance,
-but may look better on low DPI screens.
+but may look better on low DPI screens. Possible values are :code:`none`,
+:code:`lcd`, and :code:`lcd_v`.
 '''))
+# }}}
 
 g('shortcuts')  # {{{
 

kitty/freetype.c

@@ -329,7 +329,7 @@ trim_borders(ProcessedBitmap *ans, size_t extra) {
     // Trim empty columns from the right side of the bitmap
     for (ssize_t x = ans->width - 1; !column_has_text && x > -1 && extra > 0; x--) {
         for (size_t y = 0; y < ans->rows && !column_has_text; y++) {
-            if (ans->buf[x + y * ans->stride] > 200) column_has_text = true;
+            if (ans->buf[x + y * ans->stride] > 200) column_has_text = true; // TODO
         }
         if (!column_has_text) { ans->width--; extra--; }
     }
@@ -357,8 +357,17 @@ populate_processed_bitmap(FT_GlyphSlotRec *slot, FT_Bitmap *bitmap, ProcessedBit
 static inline bool
 render_bitmap(Face *self, int glyph_id, ProcessedBitmap *ans, unsigned int cell_width, unsigned int cell_height, unsigned int num_cells, bool bold, bool italic, bool rescale, FONTS_DATA_HANDLE fg) {
     int flags = FT_LOAD_RENDER;
-    if (OPT(use_subpixel_rendering))
-      flags |= FT_LOAD_TARGET_LCD;
+    switch (OPT(subpixel_rendering)) {
+        case SUBPIXEL_LCD:
+            flags |= FT_LOAD_TARGET_LCD;
+            break;
+        case SUBPIXEL_LCD_V:
+            flags |= FT_LOAD_TARGET_LCD_V;
+            break;
+        case SUBPIXEL_NONE:
+        default:
+            break;
+    }
     if (!load_glyph(self, glyph_id, flags)) return false;
     unsigned int max_width = cell_width * num_cells;
 
@@ -383,6 +392,9 @@ render_bitmap(Face *self, int glyph_id, ProcessedBitmap *ans, unsigned int cell_
     } else if (self->face->glyph->bitmap.pixel_mode == FT_PIXEL_MODE_LCD) {
         populate_processed_bitmap(self->face->glyph, &self->face->glyph->bitmap, ans, false);
         ans->width /= 3;
+    } else if (self->face->glyph->bitmap.pixel_mode == FT_PIXEL_MODE_LCD_V) {
+        populate_processed_bitmap(self->face->glyph, &self->face->glyph->bitmap, ans, false);
+        // TODO: tune ans->rows, as it's 3 times biger than the actual height
     } else {
         populate_processed_bitmap(self->face->glyph, &self->face->glyph->bitmap, ans, false);
     }
@@ -547,6 +559,9 @@ place_bitmap_in_canvas(pixel *cell, ProcessedBitmap *bm, size_t cell_width, size
         copy_color_bitmap(bm->buf, cell, &src, &dest, bm->stride, cell_width);
     } else if (bm->pixel_mode == FT_PIXEL_MODE_LCD) {
         copy_lcd_bitmap(bm->buf, cell, &src, &dest, bm->stride, cell_width, bgr);
+    } else if (bm->pixel_mode == FT_PIXEL_MODE_LCD_V) {
+        // copy_lcd_v_bitmap(bm->buf, cell, &src, &dest, bm->stride, cell_width, bgr);
+        // TODO: implement it
     } else render_alpha_mask(bm->buf, cell, &src, &dest, bm->stride, cell_width);
 }
 
@@ -570,7 +585,7 @@ render_glyphs_in_cells(PyObject *f, bool bold, bool italic, hb_glyph_info_t *inf
         } else {
             if (!render_bitmap(self, info[i].codepoint, &bm, cell_width, cell_height, num_cells, bold, italic, true, fg)) return false;
         }
-        *was_subpixel = (bm.pixel_mode == FT_PIXEL_MODE_LCD);
+        *was_subpixel = (bm.pixel_mode == FT_PIXEL_MODE_LCD || bm.pixel_mode = FT_PIXEL_MODE_LCD_V);
         x_offset = x + (float)positions[i].x_offset / 64.0f;
         y = (float)positions[i].y_offset / 64.0f;
         if ((*was_colored || self->face->glyph->metrics.width > 0) && bm.width > 0) {
@@ -623,10 +638,18 @@ render_simple_text_impl(PyObject *s, const char *text, unsigned int baseline) {
         int error = FT_Load_Glyph(self->face, glyph_index, FT_LOAD_DEFAULT);
         if (error) continue;
         int flags = 0;
-        if (OPT(use_subpixel_rendering))
-          flags |= FT_RENDER_MODE_LCD;
-        else
-          flags |= FT_RENDER_MODE_NORMAL;
+        switch (OPT(subpixel_rendering)) {
+            case SUBPIXEL_LCD:
+                flags |= FT_RENDER_MODE_LCD;
+                break;
+            case SUBPIXEL_LCD_V:
+                flags |= FT_RENDER_MODE_LCD_V;
+                break;
+            case SUBPIXEL_NONE:
+            default:
+                flags |= FT_RENDER_MODE_NORMAL;
+                break;
+        }
         error = FT_Render_Glyph(self->face->glyph, flags);
         if (error) continue;
         FT_Bitmap *bitmap = &self->face->glyph->bitmap;

kitty/glfw.c

@@ -567,7 +567,7 @@ create_os_window(PyObject UNUSED *self, PyObject *args) {
     // blank the window once so that there is no initial flash of color
     // changing, in case the background color is not black
     blank_canvas(is_semi_transparent ? OPT(background_opacity) : 1.0f);
-    bool is_subpixel_enabled = OPT(use_subpixel_rendering);
+    bool is_subpixel_enabled = (OPT(subpixel_rendering) == SUBPIXEL_LCD || OPT(subpixel_rendering) == SUBPIXEL_LCD_V);
 #ifndef __APPLE__
     if (is_first_window) glfwSwapInterval(OPT(sync_to_monitor) && !global_state.is_wayland ? 1 : 0);
 #endif

kitty/state.c

@@ -408,7 +408,7 @@ PYWRAP1(set_options) {
     S(macos_window_resizable, PyObject_IsTrue);
     S(macos_hide_from_tasks, PyObject_IsTrue);
     S(macos_thicken_font, PyFloat_AsDouble);
-    S(use_subpixel_rendering, PyObject_IsTrue);
+    S(subpixel_rendering, PyLong_AsLong);
     S(tab_bar_min_tabs, PyLong_AsUnsignedLong);
     S(disable_ligatures, PyLong_AsLong);
 

kitty/state.h

@@ -12,6 +12,8 @@
 
 typedef enum { LEFT_EDGE, TOP_EDGE, RIGHT_EDGE, BOTTOM_EDGE } Edge;
 
+typedef enum { SUBPIXEL_NONE, SUBPIXEL_LCD, SUBPIXEL_LCD_V } SubpixelRendering;
+
 typedef struct {
     double visual_bell_duration, cursor_blink_interval, cursor_stop_blinking_after, mouse_hide_wait, click_interval, wheel_scroll_multiplier, touch_scroll_multiplier;
     bool enable_audio_bell;
@@ -25,7 +27,7 @@ typedef struct {
     double repaint_delay, input_delay;
     bool focus_follows_mouse, hide_window_decorations;
     bool macos_hide_from_tasks, macos_quit_when_last_window_closed, macos_window_resizable, macos_traditional_fullscreen, macos_show_window_title_in_menubar;
-    bool use_subpixel_rendering;
+    SubpixelRendering subpixel_rendering;
     unsigned int macos_option_as_alt;
     float macos_thicken_font;
     int adjust_line_height_px, adjust_column_width_px;