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Optimize glyph set bitmap rectangles by trimming empty regions

This commit is contained in:
Francesco Abbate 2020-06-02 18:46:44 +02:00
parent d46cf80226
commit e01ba599ba
1 changed files with 54 additions and 0 deletions
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54
src/font_renderer.cpp
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@ -51,6 +51,57 @@ int FontRendererGetFontHeight(FontRenderer *font_renderer, float size) {
return int((ascender - descender) * face_height * scale + 0.5);
}
static void glyph_trim_rect(agg::rendering_buffer& ren_buf, GlyphBitmapInfo *gli) {
const int height = ren_buf.height();
int x0 = gli->x0, y0 = gli->y0, x1 = gli->x1, y1 = gli->y1;
for (int y = gli->y0; y < gli->y1; y++) {
uint8_t *row = ren_buf.row_ptr(height - 1 - y);
unsigned int row_bitsum = 0;
for (int x = x0; x < x1; x++) {
row_bitsum |= row[x];
}
if (row_bitsum == 0) {
y0++;
} else {
break;
}
}
for (int y = gli->y1 - 1; y >= gli->y0; y--) {
uint8_t *row = ren_buf.row_ptr(height - 1 - y);
unsigned int row_bitsum = 0;
for (int x = x0; x < x1; x++) {
row_bitsum |= row[x];
}
if (row_bitsum == 0) {
y1--;
} else {
break;
}
}
int xtriml = x0, xtrimr = x1;
for (int y = y0; y < y1; y++) {
uint8_t *row = ren_buf.row_ptr(height - 1 - y);
for (int x = x0; x < x1; x++) {
if (row[x]) {
if (x < xtriml) xtriml = x;
break;
}
}
for (int x = x1 - 1; x >= x0; x--) {
if (row[x]) {
if (x > xtrimr) xtrimr = x + 1;
break;
}
}
}
gli->xoff += (xtriml - x0);
gli->yoff += (y0 - gli->y0);
gli->x0 = xtriml;
gli->y0 = y0;
gli->x1 = xtrimr;
gli->y1 = y1;
}
int FontRendererBakeFontBitmap(FontRenderer *font_renderer, int font_height,
void *pixels, int pixels_width, int pixels_height,
int first_char, int num_chars, GlyphBitmapInfo *glyphs)
@ -99,10 +150,13 @@ int FontRendererBakeFontBitmap(FontRenderer *font_renderer, int font_height,
glyph_info.y0 = pixels_height - (y_baseline + ascender_px + pad_y);
glyph_info.x1 = x_next_i;
glyph_info.y1 = pixels_height - (y_baseline + descender_px - pad_y);
glyph_info.xoff = 0;
glyph_info.yoff = -pad_y;
glyph_info.xadvance = x_next - x;
glyph_trim_rect(ren_buf, &glyph_info);
x = x_next_i + pad_x;
#ifdef FONT_RENDERER_DEBUG