1 files changed, 38 insertions, 0 deletions
diff --git a/src/symbols.h b/src/symbols.h
new file mode 100644
index 0000000..da33e34
--- /dev/null
+++ b/src/symbols.h
@@ -0,0 +1,38 @@
+#ifndef VEGA_SYMBOLS_H
+#define VEGA_SYMBOLS_H
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+/* Symbols: glyphs and icons as quadratic curves in one file, verified once
+ * and then read where it lies (docs/design/002-symbol-format.md). */
+enum { VEGA_SYMBOLS_HEADER = 28, VEGA_SYMBOL_BYTES = 24, VEGA_CURVE_BYTES = 12 };
+typedef struct { int16_t x0, y0, x1, y1, x2, y2; } VegaCurve;
+typedef struct {
+    uint32_t code, first, count;          /* its curves: [first, first + count) */
+    int16_t left, bottom, right, top;     /* bounds, in units, y up */
+    int16_t advance;
+} VegaSymbol;
+typedef struct {
+    const unsigned char *bytes;
+    size_t size;
+    uint16_t units; /* per em */
+    uint32_t symbols, curves;
+} VegaSymbols;
+
+/* Verify bytes as a symbol file (kept, not copied); false with why. What
+ * reading needs is checked, per symbol: after this no read leaves the file.
+ * The curves themselves are not: one outside its symbol's bounds draws wrong. */
+bool vega_symbols_open(VegaSymbols *, const unsigned char *bytes, size_t size, char *error, size_t error_size);
+/* The symbol of code (a binary search), or false. */
+bool vega_symbol(const VegaSymbols *, uint32_t code, VegaSymbol *out);
+VegaSymbol vega_symbol_at(const VegaSymbols *, uint32_t index);
+VegaCurve vega_curve(const VegaSymbols *, uint32_t index);
+/* The coverage (0 to 1) of the pixel whose center is (x, y) in units, at
+ * scale pixels per unit: as a GPU would compute it per pixel. */
+double vega_symbol_coverage(const VegaSymbols *, const VegaSymbol *, double scale, double x, double y);
+/* width x height 8-bit coverage, rows top first; pixel (i, j) has its center
+ * at (left + (i + 0.5) / scale, top - (j + 0.5) / scale) in units. */
+void vega_symbol_raster(const VegaSymbols *, const VegaSymbol *, double scale, double left, double top, int width,
+                        int height, unsigned char *out);
+#endif