private ActiveEdge CreateActiveEdge(Edge edge, int offX, float startPoint)
{
var z = new ActiveEdge(); // TODO: make a pool of these!!!
float dxdy = (edge.x1 - edge.x0) / (edge.y1 - edge.y0);
//STBTT_assert(e->y0 <= start_point);
// round dx down to avoid going too far
if (dxdy < 0)
{
z.dx = -(int)Math.Floor(FIX * -dxdy);
}
else
{
z.dx = (int)Math.Floor(FIX * dxdy);
}
z.x = (int)Math.Floor(FIX * (edge.x0 + dxdy * (startPoint - edge.y0)));
z.x -= offX * FIX;
z.ey = edge.y1;
z.next = null;
if (edge.invert)
{
z.valid = 1;
}
else
{
z.valid = -1;
}
return(z);
}
// note: this routine clips fills that extend off the edges...
// ideally this wouldn't happen, but it could happen if the truetype glyph bounding boxes are wrong, or if the user supplies a too-small bitmap
private void FillActiveEdges(byte[] scanline, int len, ActiveEdge e, int max_weight)
{
// non-zero winding fill
int x0 = 0;
int w = 0;
int x1;
while (e != null)
{
if (w == 0)
{
// if we're currently at zero, we need to record the edge start point
x0 = e.x;
w += e.valid;
}
else
{
x1 = e.x;
w += e.valid;
// if we went to zero, we need to draw
if (w == 0)
{
int i = x0 >> FIXSHIFT;
int j = x1 >> FIXSHIFT;
if (i < len && j >= 0)
{
if (i == j)
{
// x0,x1 are the same pixel, so compute combined coverage
scanline[i] = (byte)(scanline[i] + (byte)(((x1 - x0) * max_weight) >> FIXSHIFT));
}
else
{
if (i >= 0)// add antialiasing for x0
{
scanline[i] = (byte)(scanline[i] + (byte)(((FIX - (x0 & FIXMASK)) * max_weight) >> FIXSHIFT));
}
else
{
i = -1; // clip
}
if (j < len) // add antialiasing for x1
{
scanline[j] = (byte)(scanline[j] + (byte)(((x1 & FIXMASK) * max_weight) >> FIXSHIFT));
}
else
{
j = len; // clip
}
i++;
while (i < j) // fill pixels between x0 and x1
{
scanline[i] = (byte)(scanline[i] + (byte)max_weight);
i++;
}
}
}
}
}
e = e.next;
}
}
private void RasterizeSortedEdges(GlyphBitmap bitmap, List <Edge> e, int vSubSamples, int offX, int off_y)
{
int eIndex = 0;
ActiveEdge active = null;
int max_weight = 255 / vSubSamples; // weight per vertical scanline
int y = off_y * vSubSamples;
int n = e.Count - 1;
var tempEdge = e[n];
tempEdge.y0 = (off_y + bitmap.Height) * vSubSamples + 1;
e[n] = tempEdge;
var scanline = new byte[bitmap.Width];
float scanY = 0;
int j = 0;
while (j < bitmap.Height)
{
for (int iii = 0; iii < bitmap.Width; iii++)
{
scanline[iii] = 0;
}
for (int s = 0; s < vSubSamples; s++)
{
// find center of pixel for this scanline
scanY = y + 0.5f;
// update all active edges;
// remove all active edges that terminate before the center of this scanline
var curr = active;
ActiveEdge prev = null;
while (curr != null)
{
if (curr.ey <= scanY)
{
// delete from list
if (prev != null)
{
prev.next = curr.next;
}
else
{
active = curr.next;
}
curr = curr.next;
}
else
{
curr.x += curr.dx; // advance to position for current scanline
prev = curr;
curr = curr.next; // advance through list
}
}
// resort the list if needed
bool changed;
do
{
changed = false;
curr = active;
prev = null;
while (curr != null && curr.next != null)
{
var prox = curr.next;
if (curr.x > prox.x)
{
if (prev == null)
{
active = prox;
}
else
{
prev.next = prox;
}
curr.next = prox.next;
prox.next = curr;
Console.WriteLine("Sorted " + curr.ey + " with " + prox.ey);
changed = true;
}
prev = curr;
curr = curr.next; // advance through list
}
} while (changed);
// insert all edges that start before the center of this scanline -- omit ones that also end on this scanline
while (e[eIndex].y0 <= scanY)
{
if (e[eIndex].y1 > scanY)
{
var z = CreateActiveEdge(e[eIndex], offX, scanY);
// find insertion point
if (active == null)
{
active = z;
}
else
if (z.x < active.x) // insert at front
{
z.next = active;
active = z;
}
else
{
// find thing to insert AFTER
var p = active;
while (p.next != null && p.next.x < z.x)
{
p = p.next;
}
// at this point, p->next->x is NOT < z->x
z.next = p.next;
p.next = z;
}
}
eIndex++;
}
// now process all active edges in XOR fashion
if (active != null)
{
FillActiveEdges(scanline, bitmap.Width, active, max_weight);
}
y++;
}
for (int iii = 0; iii < bitmap.Width; iii++)
{
if (scanline[iii] > 0) // OPTIMIZATION?
{
int ofs = iii + j * bitmap.Width;
bitmap.Pixels[ofs] = scanline[iii];
}
}
j++;
}
}