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FreeType code to render a simple string

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This commit is contained in:
Kovid Goyal 2019-03-01 11:02:02 +05:30
parent 4a5a9b2888
commit bb97c589c1
No known key found for this signature in database
GPG Key ID: 06BC317B515ACE7C
3 changed files with 63 additions and 5 deletions
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8
kitty/fonts.c
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@ -1073,6 +1073,14 @@ render_line(FONTS_DATA_HANDLE fg_, Line *line) {
#undef RENDER
}
StringCanvas
render_simple_text(FONTS_DATA_HANDLE fg_, const char *text) {
FontGroup *fg = (FontGroup*)fg_;
if (fg->fonts_count) return render_simple_text_impl(fg->fonts[0].face, text);
StringCanvas ans = {0};
return ans;
}
static inline void
clear_symbol_maps() {
if (symbol_maps) { free(symbol_maps); symbol_maps = NULL; num_symbol_maps = 0; }

5
kitty/fonts.h
View File

@ -13,6 +13,10 @@
#include <hb.h>
#pragma GCC diagnostic pop
typedef struct {
uint8_t *canvas;
size_t width, height;
} StringCanvas;
// API that font backends need to implement
typedef uint16_t glyph_index;
@ -33,6 +37,7 @@ void render_alpha_mask(uint8_t *alpha_mask, pixel* dest, Region *src_rect, Regio
void render_line(FONTS_DATA_HANDLE, Line *line);
void sprite_tracker_set_limits(size_t max_texture_size, size_t max_array_len);
typedef void (*free_extra_data_func)(void*);
StringCanvas render_simple_text_impl(PyObject *s, const char *text);
static inline void
right_shift_canvas(pixel *canvas, size_t width, size_t height, size_t amt) {

55
kitty/freetype.c
View File

@ -75,13 +75,18 @@ set_freetype_error(const char* prefix, int err_code) {
static FT_Library library;
#define CALC_CELL_HEIGHT(self) font_units_to_pixels(self, self->height)
#define CALC_CELL_HEIGHT(self) font_units_to_pixels_y(self, self->height)
static inline int
font_units_to_pixels(Face *self, int x) {
font_units_to_pixels_y(Face *self, int x) {
return ceil((double)FT_MulFix(x, self->face->size->metrics.y_scale) / 64.0);
}
static inline int
font_units_to_pixels_x(Face *self, int x) {
return ceil((double)FT_MulFix(x, self->face->size->metrics.x_scale) / 64.0);
}
static inline bool
set_font_size(Face *self, FT_F26Dot6 char_width, FT_F26Dot6 char_height, FT_UInt xdpi, FT_UInt ydpi, unsigned int desired_height, unsigned int cell_height) {
int error = FT_Set_Char_Size(self->face, 0, char_height, xdpi, ydpi);
@ -256,9 +261,9 @@ cell_metrics(PyObject *s, unsigned int* cell_width, unsigned int* cell_height, u
Face *self = (Face*)s;
*cell_width = calc_cell_width(self);
*cell_height = CALC_CELL_HEIGHT(self);
*baseline = font_units_to_pixels(self, self->ascender);
*underline_position = MIN(*cell_height - 1, (unsigned int)font_units_to_pixels(self, MAX(0, self->ascender - self->underline_position)));
*underline_thickness = MAX(1, font_units_to_pixels(self, self->underline_thickness));
*baseline = font_units_to_pixels_y(self, self->ascender);
*underline_position = MIN(*cell_height - 1, (unsigned int)font_units_to_pixels_y(self, MAX(0, self->ascender - self->underline_position)));
*underline_thickness = MAX(1, font_units_to_pixels_y(self, self->underline_thickness));
}
unsigned int
@ -569,6 +574,46 @@ extra_data(PyObject *self, PyObject *a UNUSED) {
return PyLong_FromVoidPtr(((Face*)self)->extra_data);
}
StringCanvas
render_simple_text_impl(PyObject *s, const char *text) {
Face *self = (Face*)s;
StringCanvas ans = {0};
size_t num_chars = strnlen(text, 20);
int max_char_width = font_units_to_pixels_x(self, self->face->max_advance_width);
size_t canvas_width = max_char_width * (num_chars*2);
size_t canvas_height = font_units_to_pixels_y(self, self->face->height) + 8;
unsigned char *canvas = calloc(1, canvas_width * canvas_height);
if (!canvas) return ans;
size_t pen_x = 0;
for (size_t n = 0; n < num_chars; n++ ) {
FT_UInt glyph_index = FT_Get_Char_Index(self->face, text[n]);
int error = FT_Load_Glyph(self->face, glyph_index, FT_LOAD_DEFAULT);
if (error) continue;
error = FT_Render_Glyph(self->face->glyph, FT_RENDER_MODE_NORMAL);
if (error) continue;
FT_Bitmap *bitmap = &self->face->glyph->bitmap;
const unsigned char *rowp = bitmap->buffer;
for (size_t row = 0; row < MIN(bitmap->rows, canvas_height); row++) {
rowp += bitmap->pitch;
unsigned char *canvasp = canvas + ((row * canvas_width) + pen_x);
memcpy(canvasp, rowp, MIN(bitmap->width, canvas_width - pen_x));
}
pen_x += self->face->glyph->advance.x >> 6;
}
ans.width = pen_x; ans.height = canvas_height;
ans.canvas = malloc(ans.width * ans.height);
if (ans.canvas) {
for (size_t row = 0; row < ans.height; row++) {
unsigned char *destp = ans.canvas + (ans.width * row);
unsigned char *srcp = canvas + (canvas_width * row);
memcpy(destp, srcp, ans.width);
}
}
free(canvas);
return ans;
}
// Boilerplate {{{
static PyMemberDef members[] = {