initial commit

Code lifted from sectr prototype

Still quite a bit todo before its considered "done"

shaped_text.odin

@@ -0,0 +1,132 @@
+package VEFontCache
+
+import "core:math"
+
+ShapedText :: struct {
+	glyphs         : [dynamic]Glyph,
+	positions      : [dynamic]Vec2,
+	end_cursor_pos : Vec2,
+}
+
+ShapedTextCache :: struct {
+	storage       : [dynamic]ShapedText,
+	state         : LRU_Cache,
+	next_cache_id : i32,
+}
+
+shape_text_cached :: proc( ctx : ^Context, font : FontID, text_utf8 : string, entry : ^Entry ) -> ^ShapedText
+{
+	// profile(#procedure)
+	@static buffer : [64 * Kilobyte]byte
+
+	font            := font
+	text_size       := len(text_utf8)
+	sice_end_offset := size_of(FontID) + len(text_utf8)
+
+	buffer_slice := buffer[:]
+	font_bytes   := slice_ptr( transmute(^byte) & font, size_of(FontID) )
+	copy( buffer_slice, font_bytes )
+
+	text_bytes             := transmute( []byte) text_utf8
+	buffer_slice_post_font := buffer[ size_of(FontID) : sice_end_offset ]
+	copy( buffer_slice_post_font, text_bytes )
+
+	hash := shape_lru_hash( transmute(string) buffer[: sice_end_offset ] )
+
+	shape_cache := & ctx.shape_cache
+	state       := & ctx.shape_cache.state
+
+	shape_cache_idx := LRU_get( state, hash )
+	if shape_cache_idx == -1
+	{
+		if shape_cache.next_cache_id < i32(state.capacity) {
+			shape_cache_idx            = shape_cache.next_cache_id
+			shape_cache.next_cache_id += 1
+			evicted := LRU_put( state, hash, shape_cache_idx )
+			assert( evicted == hash )
+		}
+		else
+		{
+			next_evict_idx := LRU_get_next_evicted( state )
+			assert( next_evict_idx != 0xFFFFFFFFFFFFFFFF )
+
+			shape_cache_idx = LRU_peek( state, next_evict_idx, must_find = true )
+			assert( shape_cache_idx != - 1 )
+
+			LRU_put( state, hash, shape_cache_idx )
+		}
+
+		shape_text_uncached( ctx, font, text_utf8, entry, & shape_cache.storage[ shape_cache_idx ] )
+	}
+
+	return & shape_cache.storage[ shape_cache_idx ]
+}
+
+// TODO(Ed): Make position rounding an option
+shape_text_uncached :: proc( ctx : ^Context, font : FontID, text_utf8 : string, entry : ^Entry, output : ^ShapedText )
+{
+	// profile(#procedure)
+	assert( ctx != nil )
+	assert( font >= 0 && int(font) < len(ctx.entries) )
+
+	use_full_text_shape := ctx.text_shape_adv
+
+	clear( & output.glyphs )
+	clear( & output.positions )
+
+	ascent, descent, line_gap := parser_get_font_vertical_metrics( & entry.parser_info )
+
+	if use_full_text_shape
+	{
+		// assert( entry.shaper_info != nil )
+		shaper_shape_from_text( & ctx.shaper_ctx, & entry.shaper_info, output, text_utf8, ascent, descent, line_gap, entry.size, entry.size_scale )
+		return
+	}
+	else
+	{
+		// Note(Original Author):
+		// We use our own fallback dumbass text shaping.
+		// WARNING: PLEASE USE HARFBUZZ. GOOD TEXT SHAPING IS IMPORTANT FOR INTERNATIONALISATION.
+		ascent   := f32(ascent)
+		descent  := f32(descent)
+		line_gap := f32(line_gap)
+
+		position           : Vec2
+		advance            : i32 = 0
+		to_left_side_glyph : i32 = 0
+
+		prev_codepoint : rune
+		for codepoint in text_utf8
+		{
+			if prev_codepoint > 0 {
+				kern       := parser_get_codepoint_kern_advance( & entry.parser_info, prev_codepoint, codepoint )
+				position.x += f32(kern) * entry.size_scale
+			}
+			if codepoint == '\n'
+			{
+				position.x  = 0.0
+				position.y -= (ascent - descent + line_gap) * entry.size_scale
+				position.y  = ceil(position.y)
+				prev_codepoint = rune(0)
+				continue
+			}
+			if abs( entry.size ) <= Advance_Snap_Smallfont_Size {
+				position.x = math.ceil( position.x )
+			}
+
+			append( & output.glyphs, parser_find_glyph_index( & entry.parser_info, codepoint ))
+			advance, to_left_side_glyph = parser_get_codepoint_horizontal_metrics( & entry.parser_info, codepoint )
+
+			append( & output.positions, Vec2 {
+				ceil(position.x),
+				position.y
+			})
+			// append( & output.positions, position )
+
+			position.x    += f32(advance) * entry.size_scale
+			prev_codepoint = codepoint
+		}
+
+		output.end_cursor_pos = position
+	}
+}