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lazcanvas: Greatly speeds up tlazcanvas.polygonfill

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git-svn-id: trunk@49575 -
This commit is contained in:
sekelsenmat 2015-07-29 13:59:59 +00:00
parent a7f0880392
commit 5ea6418f88
1 changed files with 58 additions and 1 deletions
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59
lcl/lazcanvas.pas
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@ -339,6 +339,9 @@ procedure TLazCanvas.DoPolygonFill(const points: array of TPoint);
var
lBoundingBox: TRect;
x, y, i: integer;
// faster version
nodes, j, swap, polyCorners: Integer;
nodeX: array of Integer;
begin
if Brush.Style = bsClear then Exit;
@ -352,12 +355,66 @@ begin
lBoundingBox.Bottom := Max(Points[i].Y, lBoundingBox.Bottom);
end;
// Now scan all points using IsPointInPolygon
// good but very slow polygon fill function
{// Now scan all points using IsPointInPolygon
for x := lBoundingBox.Left to lBoundingBox.Right do
for y := lBoundingBox.Top to lBoundingBox.Bottom do
begin
if IsPointInPolygon(X, Y, Points) then SetColor(X, Y, Brush.FPColor);
end;
Exit;
}
// Loop through the rows of the image.
polyCorners := Length(points);
for y := lBoundingBox.Top to lBoundingBox.Bottom do
begin
// Build a list of nodes.
nodes := 0;
j := polyCorners-1;
for i := 0 to polyCorners-1 do
begin
if (points[i].Y < y) and (points[j].Y >= y) or
(points[j].Y < y) and (points[i].Y >= Y) then
begin
SetLength(nodeX, nodes+1);
nodeX[nodes] := Round(points[i].X + (y-points[i].Y) / (points[j].Y-points[i].Y) * (points[j].X-points[i].X));
Inc(nodes);
end;
j := i;
end;
// Sort the nodes, via a simple “Bubble” sort.
i := 0;
while (i<nodes-1) do
begin
if (nodeX[i]>nodeX[i+1]) then
begin
swap := nodeX[i];
nodeX[i] := nodeX[i+1];
nodeX[i+1] := swap;
if (i <> 0) then Dec(i);
end
else
Inc(i);
end;
// Fill the pixels between node pairs.
i := 0;
while i<nodes do
begin
if (nodeX[i ] >= lBoundingBox.Right) then break;
if (nodeX[i+1] > lBoundingBox.Left) then
begin
if (nodeX[i ] < lBoundingBox.Left) then nodeX[i] := lBoundingBox.Left;
if (nodeX[i+1] > lBoundingBox.Right) then nodeX[i+1] := lBoundingBox.Right;
for X := nodeX[i] to nodeX[i+1]-1 do
SetColor(X, Y, Brush.FPColor);
end;
i := i + 2;
end;
end;
end;
procedure TLazCanvas.DoLine(x1, y1, x2, y2: integer);