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gdiplus: Account for blend factors and positions in line gradients.

This commit is contained in:
Vincent Povirk 2009-05-01 14:26:50 -05:00 committed by Alexandre Julliard
parent 47e70af50b
commit a6161307cf
1 changed files with 32 additions and 4 deletions
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36
dlls/gdiplus/graphics.c
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@ -172,15 +172,43 @@ static void transform_and_round_points(GpGraphics *graphics, POINT *pti,
}
}
static ARGB blend_colors(ARGB start, ARGB end, int current, int total)
static ARGB blend_colors(ARGB start, ARGB end, REAL position)
{
ARGB result=0;
ARGB i;
for (i=0xff; i<=0xff0000; i = i << 8)
result |= (((start&i)*(total - current)+(end&i)*(current))/total)&i;
result |= (int)((start&i)*(1.0f - position)+(end&i)*(position))&i;
return result;
}
static ARGB blend_line_gradient(GpLineGradient* brush, REAL position)
{
REAL blendfac;
if (brush->blendcount == 1)
blendfac = position;
else
{
int i=1;
REAL left_blendpos, left_blendfac, right_blendpos, right_blendfac;
REAL range;
/* locate the blend positions surrounding this position */
while (position > brush->blendpos[i])
i++;
/* interpolate between the blend positions */
left_blendpos = brush->blendpos[i-1];
left_blendfac = brush->blendfac[i-1];
right_blendpos = brush->blendpos[i];
right_blendfac = brush->blendfac[i];
range = right_blendpos - left_blendpos;
blendfac = (left_blendfac * (right_blendpos - position) +
right_blendfac * (position - left_blendpos)) / range;
}
return blend_colors(brush->startcolor, brush->endcolor, blendfac);
}
static void brush_fill_path(GpGraphics *graphics, GpBrush* brush)
{
switch (brush->bt)
@ -240,7 +268,7 @@ static void brush_fill_path(GpGraphics *graphics, GpBrush* brush)
for (i=1; i<num_steps; i++)
{
ARGB argb = blend_colors(line->startcolor, line->endcolor, i, num_steps);
ARGB argb = blend_line_gradient(line, i/(REAL)num_steps);
int ofs = width * i / num_steps;
col = ARGB2COLORREF(argb);
hbrush = CreateSolidBrush(col);
@ -296,7 +324,7 @@ static void brush_fill_path(GpGraphics *graphics, GpBrush* brush)
for (i=1; i<num_steps; i++)
{
ARGB argb = blend_colors(line->startcolor, line->endcolor, i, num_steps);
ARGB argb = blend_line_gradient(line, i/(REAL)num_steps);
int ofs = height * i / num_steps;
col = ARGB2COLORREF(argb);
hbrush = CreateSolidBrush(col);