GLfloat QueryXOffsets(
const CodePoint* cps,
GLsizei size,
std::vector<GLfloat>& x_offsets
) const
{
if(size <= 0) return 0.0f;
x_offsets.resize(size);
float scale = _tt_font.ScaleForPixelHeight(_font_resolution);
scale /= _font_resolution;
aux::STBTTFontGlyph g = _tt_font.GetGlyph(cps[0]);
GLfloat sum = g.LeftBearing()*scale;
x_offsets[0] = sum;
GLsizei i = 0;
while(++i != size)
{
sum += g.Width()*scale;
aux::STBTTFontGlyph pg = g;
g = _tt_font.GetGlyph(cps[i]);
sum += KernAdvance(pg, g)*scale;
x_offsets[i] = sum;
}
return sum + g.Width()*scale;
}
OGLPLUS_LIB_FUNC
float STBTTFont2D::Width(
std::size_t size_in_pixels,
const Layout& layout
) const
{
float scale = ScaleForPixelHeight(float(size_in_pixels));
float width = 0.0f;
for(auto i=layout.begin(), p=i, e=layout.end(); i!=e; p = i, ++i)
{
if(p != i) width += KernAdvance(*p, *i);
width += i->Width();
}
return width*scale;
}
OGLPLUS_LIB_FUNC
void STBTTFont2D::Render(
std::size_t size_in_pixels,
const STBTTFont2D::Layout& layout,
unsigned char* buffer_start,
const std::size_t buffer_width,
const std::size_t buffer_height,
const int xposition,
const int yposition
) const
{
if(int(buffer_height) < yposition) return;
if(int(size_in_pixels) <= -yposition) return;
std::vector<unsigned char> tmp_buffer;
int tmp_height = int(size_in_pixels);
int tmp_width = 0;
float scale = ScaleForPixelHeight(float(size_in_pixels));
float xoffset = 0.0f;
for(auto i=layout.begin(), p=i, e=layout.end(); i!=e; ++i)
{
const int xo = int(std::floor(xoffset))+xposition;
const float advance = i->Width()*scale;
int width_in_pixels = int(std::ceil(advance));
if(xo >= int(buffer_width))
{
break;
}
if(xo+width_in_pixels < 0)
{
xoffset += advance;
continue;
}
if(tmp_width < width_in_pixels)
{
tmp_width = width_in_pixels;
tmp_buffer.resize(tmp_width*tmp_height);
}
std::fill(tmp_buffer.begin(), tmp_buffer.end(), 0x00);
if(p != i) xoffset += KernAdvance(*p, *i)*scale;
const float xshift = xoffset - std::floor(xoffset);
int x0, y0, x1, y1;
i->GetBitmapBoxSubpixel(
scale, scale,
xshift, 0,
x0, y0,
x1, y1
);
const float yshift = std::floor((i->Ascent()*scale+y0));
::stbtt_MakeGlyphBitmapSubpixel(
&_font,
tmp_buffer.data(),
tmp_width,
tmp_height,
tmp_width,
scale,
scale,
xshift,
yshift,
i->_index
);
const int yo = yposition;
int gb = xo<0?-xo:0;
int gw = int(gb+1+(x1-x0));
if(gw > tmp_width) gw = tmp_width;
if(gw > int(buffer_width-xo)) gw = int(buffer_width-xo);
int gy = (std::floor(yshift));
if(gy < -yo) gy = -yo;
int gh = tmp_height;
if(gh > int(buffer_height-yo)) gh = int(buffer_height-yo);
while(gy < gh)
{
int gx = gb;
while(gx < gw)
{
int si = gy*tmp_width+gx;
unsigned src = tmp_buffer[si];
if(src != 0)
{
int di = (gy+yo)*buffer_width+gx+xo+x0;
unsigned dst = buffer_start[di]+src;
if(dst > 0xFF) dst = 0xFF;
buffer_start[di] = dst & 0xFF;
}
++gx;
}
++gy;
}
p = i;
xoffset += advance;
}
}
