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gdiplus: Properly draw points outside of line gradients. 

Theoretically, a line gradient covers the area enclosed by the
starting and ending gradient lines, which intersect the start and end
points respectively and are perpendicular to a line joining the start
and end points.
This commit is contained in:
Vincent Povirk 2009-05-01 15:23:02 -05:00 committed by Alexandre Julliard
parent a6161307cf
commit 966fd5ec09
1 changed files with 55 additions and 60 deletions
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115
dlls/gdiplus/graphics.c
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@ -185,6 +185,19 @@ static ARGB blend_line_gradient(GpLineGradient* brush, REAL position)
{
REAL blendfac;
/* clamp to between 0.0 and 1.0, using the wrap mode */
if (brush->wrap == WrapModeTile)
{
position = fmodf(position, 1.0f);
if (position < 0.0f) position += 1.0f;
}
else /* WrapModeFlip* */
{
position = fmodf(position, 2.0f);
if (position < 0.0f) position += 2.0f;
if (position > 1.0f) position = 2.0f - position;
}
if (brush->blendcount == 1)
blendfac = position;
else
@ -217,7 +230,6 @@ static void brush_fill_path(GpGraphics *graphics, GpBrush* brush)
{
GpLineGradient *line = (GpLineGradient*)brush;
RECT rc;
int num_steps = 255;
SelectClipPath(graphics->hdc, RGN_AND);
if (GetClipBox(graphics->hdc, &rc) != NULLREGION)
@ -228,9 +240,6 @@ static void brush_fill_path(GpGraphics *graphics, GpBrush* brush)
SelectObject(graphics->hdc, GetStockObject(NULL_PEN));
/* fill with starting color */
FillRect(graphics->hdc, &rc, brush->gdibrush);
endpointsf[0] = line->startpoint;
endpointsf[1] = line->endpoint;
transform_and_round_points(graphics, endpointsi, endpointsf, 2);
@ -238,114 +247,100 @@ static void brush_fill_path(GpGraphics *graphics, GpBrush* brush)
if (abs(endpointsi[0].x-endpointsi[1].x) > abs(endpointsi[0].y-endpointsi[1].y))
{
/* vertical-ish gradient */
int endborderx; /* vertical rectangle boundary near endpoint */
int startx, endx; /* x co-ordinates of endpoints shifted to intersect the top of the visible rectangle */
int startbottomx, endbottomx; /* x co-ordinate of endpoints shifted to intersect the bottom of the visible rectangle */
int startbottomx; /* x co-ordinate of start point shifted to intersect the bottom of the visible rectangle */
int width;
COLORREF col;
HBRUSH hbrush, hprevbrush;
int i;
if (endpointsi[1].x > endpointsi[0].x)
endborderx = rc.right;
else
endborderx = rc.left;
int leftx, rightx; /* x co-ordinates where the leftmost and rightmost gradient lines hit the top of the visible rectangle */
int x;
int tilt; /* horizontal distance covered by a gradient line */
startx = roundr((rc.top - endpointsf[0].Y) * (endpointsf[1].Y - endpointsf[0].Y) / (endpointsf[0].X - endpointsf[1].X) + endpointsf[0].X);
endx = roundr((rc.top - endpointsf[1].Y) * (endpointsf[1].Y - endpointsf[0].Y) / (endpointsf[0].X - endpointsf[1].X) + endpointsf[1].X);
width = endx - startx;
startbottomx = roundr((rc.bottom - endpointsf[0].Y) * (endpointsf[1].Y - endpointsf[0].Y) / (endpointsf[0].X - endpointsf[1].X) + endpointsf[0].X);
endbottomx = startbottomx+width;
tilt = startx - startbottomx;
if (num_steps > abs(width)) num_steps = abs(width);
if (startx >= startbottomx)
{
leftx = rc.left;
rightx = rc.right + tilt;
}
else
{
leftx = rc.left + tilt;
rightx = rc.right;
}
poly[0].x = endborderx;
poly[0].x = rc.right;
poly[0].y = rc.bottom;
poly[1].x = endborderx;
poly[1].x = rc.right;
poly[1].y = rc.top;
poly[2].y = rc.top;
poly[3].y = rc.bottom;
for (i=1; i<num_steps; i++)
for (x=leftx; x<=rightx; x++)
{
ARGB argb = blend_line_gradient(line, i/(REAL)num_steps);
int ofs = width * i / num_steps;
ARGB argb = blend_line_gradient(line, (x-startx)/(REAL)width);
col = ARGB2COLORREF(argb);
hbrush = CreateSolidBrush(col);
hprevbrush = SelectObject(graphics->hdc, hbrush);
poly[2].x = startx + ofs;
poly[3].x = startbottomx + ofs;
poly[2].x = x;
poly[3].x = x - tilt;
Polygon(graphics->hdc, poly, 4);
SelectObject(graphics->hdc, hprevbrush);
DeleteObject(hbrush);
}
poly[2].x = endx;
poly[3].x = endbottomx;
/* draw the ending color */
col = ARGB2COLORREF(line->endcolor);
hbrush = CreateSolidBrush(col);
hprevbrush = SelectObject(graphics->hdc, hbrush);
Polygon(graphics->hdc, poly, 4);
SelectObject(graphics->hdc, hprevbrush);
DeleteObject(hbrush);
}
else if (endpointsi[0].y != endpointsi[1].y)
{
/* horizontal-ish gradient */
int endbordery; /* horizontal rectangle boundary near endpoint */
int starty, endy; /* y co-ordinates of endpoints shifted to intersect the left of the visible rectangle */
int startrighty, endrighty; /* y co-ordinate of endpoints shifted to intersect the right of the visible rectangle */
int startrighty; /* y co-ordinate of start point shifted to intersect the right of the visible rectangle */
int height;
COLORREF col;
HBRUSH hbrush, hprevbrush;
int i;
if (endpointsi[1].y > endpointsi[0].y)
endbordery = rc.bottom;
else
endbordery = rc.top;
int topy, bottomy; /* y co-ordinates where the topmost and bottommost gradient lines hit the left of the visible rectangle */
int y;
int tilt; /* vertical distance covered by a gradient line */
starty = roundr((rc.left - endpointsf[0].X) * (endpointsf[0].X - endpointsf[1].X) / (endpointsf[1].Y - endpointsf[0].Y) + endpointsf[0].Y);
endy = roundr((rc.left - endpointsf[1].X) * (endpointsf[0].X - endpointsf[1].X) / (endpointsf[1].Y - endpointsf[0].Y) + endpointsf[1].Y);
height = endy - starty;
startrighty = roundr((rc.right - endpointsf[0].X) * (endpointsf[0].X - endpointsf[1].X) / (endpointsf[1].Y - endpointsf[0].Y) + endpointsf[0].Y);
endrighty = startrighty+height;
tilt = starty - startrighty;
if (num_steps > abs(height)) num_steps = abs(height);
if (starty >= startrighty)
{
topy = rc.top;
bottomy = rc.bottom + tilt;
}
else
{
topy = rc.top + tilt;
bottomy = rc.bottom;
}
poly[0].x = rc.right;
poly[0].y = endbordery;
poly[0].y = rc.bottom;
poly[1].x = rc.left;
poly[1].y = endbordery;
poly[1].y = rc.bottom;
poly[2].x = rc.left;
poly[3].x = rc.right;
for (i=1; i<num_steps; i++)
for (y=topy; y<=bottomy; y++)
{
ARGB argb = blend_line_gradient(line, i/(REAL)num_steps);
int ofs = height * i / num_steps;
ARGB argb = blend_line_gradient(line, (y-starty)/(REAL)height);
col = ARGB2COLORREF(argb);
hbrush = CreateSolidBrush(col);
hprevbrush = SelectObject(graphics->hdc, hbrush);
poly[2].y = starty + ofs;
poly[3].y = startrighty + ofs;
poly[2].y = y;
poly[3].y = y - tilt;
Polygon(graphics->hdc, poly, 4);
SelectObject(graphics->hdc, hprevbrush);
DeleteObject(hbrush);
}
poly[2].y = endy;
poly[3].y = endrighty;
/* draw the ending color */
col = ARGB2COLORREF(line->endcolor);
hbrush = CreateSolidBrush(col);
hprevbrush = SelectObject(graphics->hdc, hbrush);
Polygon(graphics->hdc, poly, 4);
SelectObject(graphics->hdc, hprevbrush);
DeleteObject(hbrush);
}
/* else startpoint == endpoint */
}