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Fix odd-width ellipses not drawing correctly #511

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merged 2 commits into from Aug 30, 2018
Merged

Fix odd-width ellipses not drawing correctly #511

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6091278
Fixes 233, draw odd-width ellipses correctly.
LambdaGoblin Aug 28, 2018
baeadaa
Applied clang-format for minor formatting issues.
LambdaGoblin Aug 28, 2018
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212 changes: 72 additions & 140 deletions src_c/draw.c
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Expand Up @@ -67,9 +67,8 @@ static void
draw_arc(SDL_Surface *dst, int x, int y, int radius1, int radius2,
double angle_start, double angle_stop, Uint32 color);
static void
draw_ellipse(SDL_Surface *dst, int x, int y, int rx, int ry, Uint32 color);
static void
draw_fillellipse(SDL_Surface *dst, int x, int y, int rx, int ry, Uint32 color);
draw_ellipse(SDL_Surface *dst, int x, int y, int width, int height, int solid,
Uint32 color);
static void
draw_fillpoly(SDL_Surface *dst, int *vx, int *vy, int n, Uint32 color);

Expand Down Expand Up @@ -495,15 +494,16 @@ ellipse(PyObject *self, PyObject *arg)
if (!pgSurface_Lock(surfobj))
return NULL;

if (!width)
draw_fillellipse(surf, (Sint16)(rect->x + rect->w / 2),
(Sint16)(rect->y + rect->h / 2),
(Sint16)(rect->w / 2), (Sint16)(rect->h / 2), color);
if (!width) {
draw_ellipse(surf, (Sint16)(rect->x + rect->w / 2),
(Sint16)(rect->y + rect->h / 2), (Sint16)(rect->w),
(Sint16)(rect->h), 1, color);
}
else {
width = MIN(width, MIN(rect->w, rect->h) / 2);
for (loop = 0; loop < width; ++loop) {
draw_ellipse(surf, rect->x + rect->w / 2, rect->y + rect->h / 2,
rect->w / 2 - loop, rect->h / 2 - loop, color);
rect->w - loop, rect->h - loop, 0, color);
}
}

Expand Down Expand Up @@ -554,21 +554,21 @@ circle(PyObject *self, PyObject *arg)
return NULL;

if (!width) {
draw_fillellipse(surf, (Sint16)posx, (Sint16)posy, (Sint16)radius,
(Sint16)radius, color);
draw_ellipse(surf, (Sint16)posx, (Sint16)posy, (Sint16)radius * 2,
(Sint16)radius * 2, 1, color);
}
else {
for (loop = 0; loop < width; ++loop) {
draw_ellipse(surf, posx, posy, radius - loop, radius - loop,
color);
draw_ellipse(surf, posx, posy, 2 * (radius - loop),
2 * (radius - loop), 0, color);
/* To avoid moiré pattern. Don't do an extra one on the outer
ellipse. We draw another ellipse offset by a pixel, over drawing
the missed spots in the filled circle caused by which pixels are
filled.
* ellipse. We draw another ellipse offset by a pixel, over
* drawing the missed spots in the filled circle caused by which
* pixels are filled.
*/
if (width > 1 && loop > 0)
draw_ellipse(surf, posx + 1, posy, radius - loop,
radius - loop, color);
draw_ellipse(surf, posx + 1, posy, 2 * (radius - loop),
2 * (radius - loop), 0, color);
}
}

Expand Down Expand Up @@ -1434,120 +1434,16 @@ draw_arc(SDL_Surface *dst, int x, int y, int radius1, int radius2,
}

static void
draw_ellipse(SDL_Surface *dst, int x, int y, int rx, int ry, Uint32 color)
{
int ix, iy;
int h, i, j, k;
int oh, oi, oj, ok;
int xmh, xph, ypk, ymk;
int xmi, xpi, ymj, ypj;
int xmj, xpj, ymi, ypi;
int xmk, xpk, ymh, yph;

if (rx == 0 && ry == 0) { /* Special case - draw a single pixel */
set_at(dst, x, y, color);
return;
}
if (rx == 0) { /* Special case for rx=0 - draw a vline */
drawvertlineclip(dst, color, x, (Sint16)(y - ry), (Sint16)(y + ry));
return;
}
if (ry == 0) { /* Special case for ry=0 - draw a hline */
drawhorzlineclip(dst, color, (Sint16)(x - rx), y, (Sint16)(x + rx));
return;
}

/* Init vars */
oh = oi = oj = ok = 0xFFFF;
if (rx > ry) {
ix = 0;
iy = rx * 64;
do {
h = (ix + 16) >> 6;
i = (iy + 16) >> 6;
j = (h * ry) / rx;
k = (i * ry) / rx;

if (((ok != k) && (oj != k)) || ((oj != j) && (ok != j)) ||
(k != j)) {
xph = x + h - 1;
xmh = x - h;
if (k > 0) {
ypk = y + k - 1;
ymk = y - k;
if (h > 0) {
set_at(dst, xmh, ypk, color);
set_at(dst, xmh, ymk, color);
}
set_at(dst, xph, ypk, color);
set_at(dst, xph, ymk, color);
}
ok = k;
xpi = x + i - 1;
xmi = x - i;
if (j > 0) {
ypj = y + j - 1;
ymj = y - j;
set_at(dst, xmi, ypj, color);
set_at(dst, xpi, ypj, color);
set_at(dst, xmi, ymj, color);
set_at(dst, xpi, ymj, color);
}
oj = j;
}
ix = ix + iy / rx;
iy = iy - ix / rx;

} while (i > h);
}
else {
ix = 0;
iy = ry * 64;
do {
h = (ix + 32) >> 6;
i = (iy + 32) >> 6;
j = (h * rx) / ry;
k = (i * rx) / ry;

if (((oi != i) && (oh != i)) ||
((oh != h) && (oi != h) && (i != h))) {
xmj = x - j;
xpj = x + j - 1;
if (i > 0) {
ypi = y + i - 1;
ymi = y - i;
if (j > 0) {
set_at(dst, xmj, ypi, color);
set_at(dst, xmj, ymi, color);
}
set_at(dst, xpj, ypi, color);
set_at(dst, xpj, ymi, color);
}
oi = i;
xmk = x - k;
xpk = x + k - 1;
if (h > 0) {
yph = y + h - 1;
ymh = y - h;
set_at(dst, xmk, yph, color);
set_at(dst, xpk, yph, color);
set_at(dst, xmk, ymh, color);
set_at(dst, xpk, ymh, color);
}
oh = h;
}
ix = ix + iy / ry;
iy = iy - ix / ry;
} while (i > h);
}
}

static void
draw_fillellipse(SDL_Surface *dst, int x, int y, int rx, int ry, Uint32 color)
draw_ellipse(SDL_Surface *dst, int x, int y, int width, int height, int solid,
Uint32 color)
{
int ix, iy;
int h, i, j, k;
int oh, oi, oj, ok;
int xoff = (width & 1) ^ 1;
int yoff = (height & 1) ^ 1;
int rx = (width >> 1);
int ry = (height >> 1) - yoff + (solid & 1);

if (rx == 0 && ry == 0) { /* Special case - draw a single pixel */
set_at(dst, x, y, color);
Expand Down Expand Up @@ -1575,14 +1471,32 @@ draw_fillellipse(SDL_Surface *dst, int x, int y, int rx, int ry, Uint32 color)
i = (iy + 8) >> 6;
j = (h * ry) / rx;
k = (i * ry) / rx;
if ((ok != k) && (oj != k) && (k < ry)) {
drawhorzlineclip(dst, color, x - h, y - k - 1, x + h - 1);
drawhorzlineclip(dst, color, x - h, y + k, x + h - 1);
if (((ok != k) && (oj != k) && (k < ry)) || !solid) {
if (solid) {
drawhorzlineclip(dst, color, x - h, y - k - yoff,
x + h - xoff);
drawhorzlineclip(dst, color, x - h, y + k, x + h - xoff);
}
else {
set_at(dst, x - h, y - k - yoff, color);
set_at(dst, x + h - xoff, y - k - yoff, color);
set_at(dst, x - h, y + k, color);
set_at(dst, x + h - xoff, y + k, color);
}
ok = k;
}
if ((oj != j) && (ok != j) && (k != j)) {
drawhorzlineclip(dst, color, x - i, y + j, x + i - 1);
drawhorzlineclip(dst, color, x - i, y - j - 1, x + i - 1);
if (((oj != j) && (ok != j) && (k != j)) || !solid) {
if (solid) {
drawhorzlineclip(dst, color, x - i, y + j, x + i - xoff);
drawhorzlineclip(dst, color, x - i, y - j - yoff,
x + i - xoff);
}
else {
set_at(dst, x - i, y + j, color);
set_at(dst, x + i - xoff, y + j, color);
set_at(dst, x - i, y - j - yoff, color);
set_at(dst, x + i - xoff, y - j - yoff, color);
}
oj = j;
}
ix = ix + iy / rx;
Expand All @@ -1600,14 +1514,32 @@ draw_fillellipse(SDL_Surface *dst, int x, int y, int rx, int ry, Uint32 color)
j = (h * rx) / ry;
k = (i * rx) / ry;

if ((oi != i) && (oh != i) && (i < ry)) {
drawhorzlineclip(dst, color, x - j, y + i, x + j - 1);
drawhorzlineclip(dst, color, x - j, y - i - 1, x + j - 1);
if (((oi != i) && (oh != i) && (i < ry)) || !solid) {
if (solid) {
drawhorzlineclip(dst, color, x - j, y + i, x + j - xoff);
drawhorzlineclip(dst, color, x - j, y - i - yoff,
x + j - xoff);
}
else {
set_at(dst, x - j, y + i, color);
set_at(dst, x + j - xoff, y + i, color);
set_at(dst, x - j, y - i - yoff, color);
set_at(dst, x + j - xoff, y - i - yoff, color);
}
oi = i;
}
if ((oh != h) && (oi != h) && (i != h)) {
drawhorzlineclip(dst, color, x - k, y + h, x + k - 1);
drawhorzlineclip(dst, color, x - k, y - h - 1, x + k - 1);
if (((oh != h) && (oi != h) && (i != h)) || !solid) {
if (solid) {
drawhorzlineclip(dst, color, x - k, y + h, x + k - xoff);
drawhorzlineclip(dst, color, x - k, y - h - yoff,
x + k - xoff);
}
else {
set_at(dst, x - k, y + h, color);
set_at(dst, x + k - xoff, y + h, color);
set_at(dst, x - k, y - h - yoff, color);
set_at(dst, x + k - xoff, y - h - yoff, color);
}
oh = h;
}

Expand Down Expand Up @@ -1756,7 +1688,7 @@ MODINIT_DEFINE(draw)
MODINIT_ERROR;
}

/* create the module */
/* create the module */
#if PY3
return PyModule_Create(&_module);
#else
Expand Down