Scale multicell box char line thickness

kitty/decorations.c

@@ -229,6 +229,7 @@ typedef struct Canvas {
     uint8_t *mask;
     uint width, height, supersample_factor;
     struct { double x, y; } dpi;
+    double scale;  // used to scale line thickness with font size for multicell rendering
     Range *holes; uint holes_count, holes_capacity;
     Limit *y_limits; uint y_limits_count, y_limits_capacity;
 } Canvas;
@@ -255,7 +256,7 @@ thickness(Canvas *self, uint level, bool horizontal) {
     level = min(level, arraysz(OPT(box_drawing_scale)));
     double pts = OPT(box_drawing_scale)[level];
     double dpi = horizontal ? self->dpi.x : self->dpi.y;
-    return self->supersample_factor * (uint)ceil(pts * dpi / 72.0);
+    return (uint)ceil(self->supersample_factor * self->scale * pts * dpi / 72.0);
 }
 
 static uint
@@ -1338,8 +1339,8 @@ sextant(Canvas *self, uint which) {
 }
 
 void
-render_box_char(char_type ch, uint8_t *buf, unsigned width, unsigned height, double dpi_x, double dpi_y) {
-    Canvas canvas = {.mask=buf, .width = width, .height = height, .dpi={.x=dpi_x, .y=dpi_y}, .supersample_factor=1u}, ss = canvas;
+render_box_char(char_type ch, uint8_t *buf, unsigned width, unsigned height, double dpi_x, double dpi_y, double scale) {
+    Canvas canvas = {.mask=buf, .width = width, .height = height, .dpi={.x=dpi_x, .y=dpi_y}, .supersample_factor=1u, .scale=scale}, ss = canvas;
     ss.mask = buf + width*height; ss.supersample_factor = SUPERSAMPLE_FACTOR; ss.width *= SUPERSAMPLE_FACTOR; ss.height *= SUPERSAMPLE_FACTOR;
     fill_canvas(&canvas, 0);
     Canvas *c = &canvas;

kitty/decorations.h

@@ -23,5 +23,5 @@ DecorationGeometry add_missing_glyph(uint8_t *buf, FontCellMetrics fcm);
 DecorationGeometry add_beam_cursor(uint8_t *buf, FontCellMetrics fcm, double dpi_x);
 DecorationGeometry add_underline_cursor(uint8_t *buf, FontCellMetrics fcm, double dpi_y);
 DecorationGeometry add_hollow_cursor(uint8_t *buf, FontCellMetrics fcm, double dpi_x, double dpi_y);
-void render_box_char(char_type ch, uint8_t *buf, unsigned width, unsigned height, double dpi_x, double dpi_y);
+void render_box_char(char_type ch, uint8_t *buf, unsigned width, unsigned height, double dpi_x, double dpi_y, double scale);
 #define SUPERSAMPLE_FACTOR 4u

kitty/fast_data_types.pyi

@@ -1717,7 +1717,7 @@ def glfw_get_system_color_theme(query_if_unintialized: bool = True) -> Literal['
 def set_redirect_keys_to_overlay(os_window_id: int, tab_id: int, window_id: int, overlay_window_id: int) -> None: ...
 def buffer_keys_in_window(os_window_id: int, tab_id: int, window_id: int, enabled: bool = True) -> bool: ...
 def sprite_idx_to_pos(idx: int, xnum: int, ynum: int) -> tuple[int, int, int]: ...
-def render_box_char(ch: int, width: int, height: int, dpi_x: float = 96.0, dpi_y: float = 96.0) -> bytes: ...
+def render_box_char(ch: int, width: int, height: int, scale: float = 1.0, dpi_x: float = 96.0, dpi_y: float = 96.0) -> bytes: ...
 
 class MousePosition(TypedDict):
     cell_x: int

kitty/fonts.c

@@ -1041,15 +1041,15 @@ render_box_cell(FontGroup *fg, RunFont rf, CPUCell *cpu_cell, GPUCell *gpu_cell,
     uint8_t *alpha_mask = NULL;
     ensure_canvas_can_fit(fg, num_glyphs + 1, rf.scale);
     if (num_glyphs == 1) {
-        render_box_char(ch, fg->canvas.alpha_mask, width, height, fg->logical_dpi_x, fg->logical_dpi_y);
+        render_box_char(ch, fg->canvas.alpha_mask, width, height, fg->logical_dpi_x, fg->logical_dpi_y, scale);
         alpha_mask = fg->canvas.alpha_mask;
     } else {
         alpha_mask = ((uint8_t*)fg->canvas.buf) + fg->canvas.size_in_bytes - (num_glyphs * width * height);
         unsigned cnum = 0;
         for (unsigned i = 0; i < num_glyphs; i++) {
             unsigned int ch = global_glyph_render_scratch.lc->chars[cnum++];
             while (!ch) ch = global_glyph_render_scratch.lc->chars[cnum++];
-            render_box_char(ch, fg->canvas.alpha_mask, width, height, fg->logical_dpi_x, fg->logical_dpi_y);
+            render_box_char(ch, fg->canvas.alpha_mask, width, height, fg->logical_dpi_x, fg->logical_dpi_y, scale);
             uint8_t *src = fg->canvas.alpha_mask;
             for (unsigned y = 0; y < height; y++) {
                 uint8_t *dest_row = alpha_mask + y*num_glyphs*width + i*width;
@@ -2303,11 +2303,11 @@ sprite_idx_to_pos(PyObject *self UNUSED, PyObject *args) {
 static PyObject*
 pyrender_box_char(PyObject *self UNUSED, PyObject *args) {
     unsigned int ch;
-    unsigned long width, height; double dpi_x = 96., dpi_y = 96.;
-    if (!PyArg_ParseTuple(args, "Ikk|dd", &ch, &width, &height, &dpi_x, &dpi_y)) return NULL;
+    unsigned long width, height; double dpi_x = 96., dpi_y = 96., scale = 1.;
+    if (!PyArg_ParseTuple(args, "Ikk|ddd", &ch, &width, &height, &scale, &dpi_x, &dpi_y)) return NULL;
     RAII_PyObject(ans, PyBytes_FromStringAndSize(NULL, width*16 * height*16));
     if (!ans) return NULL;
-    render_box_char(ch, (uint8_t*)PyBytes_AS_STRING(ans), width, height, dpi_x, dpi_y);
+    render_box_char(ch, (uint8_t*)PyBytes_AS_STRING(ans), width, height, dpi_x, dpi_y, scale);
     if (_PyBytes_Resize(&ans, width * height) != 0) return NULL;
     return Py_NewRef(ans);
 }