[feat] 低质量ttf render

2026-06-06 09:00:56 +08:00
parent 3d47667c2f
commit 500d302ea9
15 changed files with 914 additions and 17 deletions
@@ -0,0 +1,93 @@
+#pragma once
+
+#include <efi.h>
+#include <common.h>
+#include "ttf_math.h"
+
+typedef struct ttf_face ttf_face_t;
+
+typedef struct ttf_face {
+    const SUINT8* data;
+    UINTN         size;
+
+    // head
+    SUINT32 units_per_em;
+    SSINT16 index_to_loc_format;  // 0 = short, 1 = long
+
+    // hhea
+    SSINT16 hhea_ascender;
+    SSINT16 hhea_descender;
+    SSINT16 hhea_line_gap;
+    SUINT16 num_long_hor_metrics;
+
+    // maxp
+    SUINT16 num_glyphs;
+    SUINT16 max_points;
+    SUINT16 max_contours;
+
+    // os/2
+    SSINT16 os2_ascender;
+    SSINT16 os2_descender;
+    SSINT16 os2_line_gap;
+
+    // Table directory (sorted by tag at open time)
+    struct {
+        char     tag[4];
+        SUINT32  offset;
+        SUINT32  length;
+    } tables[32];
+    SUINT16 num_tables;
+
+    // Cached pointers into data[]
+    const SUINT8* loca;   // size depends on num_glyphs and format
+    const SUINT8* glyf;
+    SUINT32       glyf_len;
+    const SUINT8* hmtx;
+    SUINT32       hmtx_len;
+    const SUINT8* cmap;
+} ttf_face_t;
+
+// Decomposed glyph: contours in pixel space (26.6 fp) ready to scan.
+typedef struct ttf_outline {
+    f26_6   x[1024];
+    f26_6   y[1024];
+    SUINT8  on_curve[1024];
+    SUINT16 first[64];
+    SUINT16 last[64];
+    SUINT16 num_contours;
+    SUINT16 num_points;
+
+    // Bounding box in pixel space (26.6 fp).
+    SSINT32 xmin, ymin, xmax, ymax;
+
+    // Pen advance in pixel space (26.6 fp).
+    f26_6 advance;
+} ttf_outline_t;
+
+typedef struct ttf_seg {
+    f26_6 x0, y0, x1, y1;  // line / quad end points
+    f26_6 cx, cy;          // quadratic control (set to x0/y0 if is_line)
+    SUINT8 is_line;        // 1 = line, 0 = quad
+} ttf_seg_t;
+
+// Parse the glyf entry for glyph_id. Fills outline already
+// scaled to pixel_size_px. Returns false on composite / parse error.
+bool ttf_load_glyph(ttf_face_t* face, SUINT16 glyph_id,
+    SUINT32 pixel_size_px, ttf_outline_t* out);
+
+// UTF-8 decoder. *p advances past the codepoint. Returns -1 on error.
+SSINT32 ttf_utf8_decode(const char** p);
+
+// cmap lookup — returns glyph_id (0 = notdef).
+SUINT16 ttf_cmap_lookup(ttf_face_t* face, SSINT32 cp);
+
+// Decompose outline into a flat array of line/quadratic segments.
+//   out must have room for 2*num_points + num_contours entries.
+void ttf_outline_to_segments(const ttf_outline_t* outline,
+    ttf_seg_t* segs, SUINT32* num_segs);
+
+// Scanline rasterize segments into per-pixel coverage.
+//   coverage[w*h] gets values in [0, N] where N = supersample count.
+void ttf_rasterize(const ttf_seg_t* segs, SUINT32 num_segs,
+    SSINT32 x0, SSINT32 y0, SUINT32 w, SUINT32 h,
+    SUINT8* coverage, SUINT32 N);