Make the $num_points parameter of php_imagepolygon optional

That parameter is mostly useless in practise, and likely has been
directly ported from the underlying `gdImagePolygon()` and friends,
which require that parameter since the number of elements of the point
array would otherwise be unknown.  Typical usages of `imagepolygon()`,
`imageopenpolygon()` and `imagefilledpolygon()` pass `count($points)/2`
or hard-code this value as literal.  Since explicitly specifying this
parameter is annoying and error-prone, we offer the possibility to omit
it, in which case the `$points` array must have an even number of
elements, and the number of points is calculated as `count($points)/2`.

NEWS

@@ -19,6 +19,7 @@ PHP                                                                        NEWS
 - GD:
   . Fixed bug #55005 (imagepolygon num_points requirement). (cmb)
   . Replaced gd resources with objects. (Mark Randall)
+  . Made the $num_points parameter of php_imagepolygon optional. (cmb)
   . Removed deprecated image2wbmp(). (cmb)
   . Removed deprecated png2wbmp() and jpeg2wbmp(). (cmb)
 

UPGRADING

@@ -355,6 +355,12 @@ PHP 8.0 UPGRADE NOTES
 9. Other Changes to Extensions
 ========================================
 
+- GD:
+  . The $num_points parameter of imagepolygon(), imageopenpolygon() and
+    imagefilledpolygon() is now optional, i.e. these functions may be called
+    with either 3 or 4 arguments. If the arguments is omitted, it is calculated
+    as count($points)/2.
+
 ========================================
 10. New Global Constants
 ========================================

ext/gd/gd.c

@@ -2735,9 +2735,18 @@ static void php_imagepolygon(INTERNAL_FUNCTION_PARAMETERS, int filled)
 	gdPointPtr points;
 	int npoints, col, nelem, i;
 
-	if (zend_parse_parameters(ZEND_NUM_ARGS(), "Oall", &IM, gd_image_ce, &POINTS, &NPOINTS, &COL) == FAILURE) {
+	if (zend_parse_parameters(ZEND_NUM_ARGS(), "Oal|l", &IM, gd_image_ce, &POINTS, &NPOINTS, &COL) == FAILURE) {
 		return;
 	}
+	if (ZEND_NUM_ARGS() == 3) {
+		COL = NPOINTS;
+		NPOINTS = zend_hash_num_elements(Z_ARRVAL_P(POINTS));
+		if (NPOINTS % 2 != 0) {
+			zend_value_error("Points array must have an even number of elements");
+			return;
+		}
+		NPOINTS /= 2;
+	}
 
 	im = php_gd_libgdimageptr_from_zval_p(IM);
 

ext/gd/gd.stub.php

@@ -186,11 +186,11 @@ function imagecolortransparent(GdImage $im, int $col = UNKNOWN): ?int {}
 
 function imageinterlace(GdImage $im, int $interlace = UNKNOWN): ?int {}
 
-function imagepolygon(GdImage $im, array $points, int $num_pos, int $col): bool {}
+function imagepolygon(GdImage $im, array $points, int $num_points_or_col, int $col = UNKNOWN): bool {}
 
-function imageopenpolygon(GdImage $im, array $points, int $num_pos, int $col): bool {}
+function imageopenpolygon(GdImage $im, array $points, int $num_points_or_col, int $col = UNKNOWN): bool {}
 
-function imagefilledpolygon(GdImage $im, array $points, int $num_pos, int $col): bool {}
+function imagefilledpolygon(GdImage $im, array $points, int $num_points_or_col, int $col = UNKNOWN): bool {}
 
 function imagefontwidth(int $font): int {}
 

ext/gd/gd_arginfo.h

@@ -367,10 +367,10 @@ ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO_EX(arginfo_imageinterlace, 0, 1, IS_LONG, 1
 	ZEND_ARG_TYPE_INFO(0, interlace, IS_LONG, 0)
 ZEND_END_ARG_INFO()
 
-ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO_EX(arginfo_imagepolygon, 0, 4, _IS_BOOL, 0)
+ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO_EX(arginfo_imagepolygon, 0, 3, _IS_BOOL, 0)
 	ZEND_ARG_OBJ_INFO(0, im, GdImage, 0)
 	ZEND_ARG_TYPE_INFO(0, points, IS_ARRAY, 0)
-	ZEND_ARG_TYPE_INFO(0, num_pos, IS_LONG, 0)
+	ZEND_ARG_TYPE_INFO(0, num_points_or_col, IS_LONG, 0)
 	ZEND_ARG_TYPE_INFO(0, col, IS_LONG, 0)
 ZEND_END_ARG_INFO()
 

ext/gd/tests/bug43073.phpt

@@ -38,7 +38,7 @@ $cos_t = cos(deg2rad($delta_t));
 $sin_t = sin(deg2rad($delta_t));
 for ($angle = 0.0, $i = 0; $angle < 360.0; $angle += $delta_t, $i++) {
   $bbox = imagettftext($g, 24, $angle, 400+$x, 400+$y, $black, $font, 'ABCDEF');
-  imagepolygon($g, $bbox, 4, $red);
+  imagepolygon($g, $bbox, $red);
   printf("%2d: ", $i);
   for ($j = 0; $j < 8; $j++) {
 	if ($bbox[$j] >= $exp[$i][$j] - 1 && $bbox[$j] <= $exp[$i][$j] + 1) {

ext/gd/tests/bug53504.phpt

@@ -72,7 +72,7 @@ foreach ($tests as $testnum => $test) {
     }
 
     // draw bounding box:
-    imagepolygon($g, $bboxDrawn, 4, $red);
+    imagepolygon($g, $bboxDrawn, $red);
 
     // draw baseline:
     $width = sqrt(pow($bboxDrawn[2] - $bboxDrawn[0], 2) + pow($bboxDrawn[3] - $bboxDrawn[1], 2));

ext/gd/tests/bug55005.phpt

@@ -16,6 +16,6 @@ trycatch_dump(
     fn () => imagepolygon($g, array(200,10, 200,100, 280,100), 2, $fgnd)
 );
 ?>
---EXPECT--
+--EXPECTF--
 !! [ValueError] Polygon must have at least 3 points
 !! [ValueError] Polygon must have at least 3 points

ext/gd/tests/bug64641.phpt

@@ -18,14 +18,14 @@ $points = array(
 	100, 200,
 	100, 300
 );
-imagefilledpolygon($im, $points, 3, 0xFFFF00);
+imagefilledpolygon($im, $points, 0xFFFF00);
 
 $points = array(
 	300, 200,
 	400, 200,
 	500, 200
 );
-imagefilledpolygon($im, $points, 3, 0xFFFF00);
+imagefilledpolygon($im, $points, 0xFFFF00);
 
 $ex = imagecreatefrompng(__DIR__ . '/bug64641.png');
 if (($diss = calc_image_dissimilarity($ex, $im)) < 1e-5) {

ext/gd/tests/imagefilledpolygon_basic.phpt

@@ -36,7 +36,7 @@ $bg = imagecolorallocate($image, 0, 0, 0);
 $col_poly = imagecolorallocate($image, 0, 255, 0);
 
 // draw the polygon
-imagefilledpolygon($image, $points, count($points)/2, $col_poly);
+imagefilledpolygon($image, $points, $col_poly);
 
 // output the picture to a file
 imagepng($image, $dest);

ext/gd/tests/imageopenpolygon_basic.phpt

@@ -16,10 +16,10 @@ $green = imagecolorallocate($im, 0, 128, 0);
 $blue = imagecolorallocate($im, 0, 0, 255);
 imagefilledrectangle($im, 0,0, 99,99, $white);
 
-imageopenpolygon($im, [10,10, 49,89, 89,10], 3, $black);
-imageopenpolygon($im, [10,89, 35,10, 60,89, 85,10], 4, $red);
-imageopenpolygon($im, [10,49, 30,89, 50,10, 70,89, 90,10], 5, $green);
-imageopenpolygon($im, [10,50, 25,10, 40,89, 55,10, 80,89, 90,50], 6, $blue);
+imageopenpolygon($im, [10,10, 49,89, 89,10], $black);
+imageopenpolygon($im, [10,89, 35,10, 60,89, 85,10], $red);
+imageopenpolygon($im, [10,49, 30,89, 50,10, 70,89, 90,10], $green);
+imageopenpolygon($im, [10,50, 25,10, 40,89, 55,10, 80,89, 90,50], $blue);
 
 test_image_equals_file(__DIR__ . DIRECTORY_SEPARATOR . 'imageopenpolygon.png', $im);
 ?>

ext/gd/tests/imagepolygon_aa.phpt

@@ -14,7 +14,7 @@ $black = imagecolorallocate($im, 0, 0, 0);
 imagefilledrectangle($im, 0,0, 99,99, $white);
 imageantialias($im, true);
 
-imagepolygon($im, [10,10, 49,89, 89,49], 3, $black);
+imagepolygon($im, [10,10, 49,89, 89,49], $black);
 
 test_image_equals_file(__DIR__ . DIRECTORY_SEPARATOR . 'imagepolygon_aa.png', $im);
 ?>

ext/gd/tests/imagepolygon_basic.phpt

@@ -33,7 +33,6 @@ imagepolygon($image, array (
         100, 200,
         300, 200
     ),
-    3,
     $col_poly);
 
 // output the picture to a file

ext/gd/tests/libgd00100.phpt

@@ -33,7 +33,7 @@ $points = array(
   $x+$d,   ($top+$bot)/2,
   $x,      $bot
 );
-imagefilledpolygon($im, $points, 5, $yellow);
+imagefilledpolygon($im, $points, $yellow);
 
 // left-facing M not on baseline
 $top = 40;
@@ -47,7 +47,7 @@ $points = array(
   $left,  $bot,
   ($left+$right)/2, ($top+$bot)/2
 );
-imagefilledpolygon($im, $points, 5, $purple);
+imagefilledpolygon($im, $points, $purple);
 
 // left-facing M on baseline
 $top = 240;
@@ -61,7 +61,7 @@ $points = array(
   $left,  $bot,
   ($left+$right)/2, ($top+$bot)/2
 );
-imagefilledpolygon($im, $points, 5, $magenta);
+imagefilledpolygon($im, $points, $magenta);
 
 // left-facing M on ceiling
 $top = -15;
@@ -75,23 +75,23 @@ $points = array(
   $left,  $bot,
   ($left+$right)/2, ($top+$bot)/2
 );
-imagefilledpolygon($im, $points, 5, $blue);
+imagefilledpolygon($im, $points, $blue);
 
 $d = 30;
 $x = 150;
 $y = 150;
 $diamond = array($x-$d, $y, $x, $y+$d, $x+$d, $y, $x, $y-$d);
-imagefilledpolygon($im, $diamond, 4, $green);
+imagefilledpolygon($im, $diamond, $green);
 
 $x = 180;
 $y = 225;
 $diamond = array($x-$d, $y, $x, $y+$d, $x+$d, $y, $x, $y-$d);
-imagefilledpolygon($im, $diamond, 4, $red);
+imagefilledpolygon($im, $diamond, $red);
 
 $x = 225;
 $y = 255;
 $diamond = array($x-$d, $y, $x, $y+$d, $x+$d, $y, $x, $y-$d);
-imagefilledpolygon($im, $diamond, 4, $cyan);
+imagefilledpolygon($im, $diamond, $cyan);
 
 // M (bridge) not touching bottom boundary
 $top = 100;
@@ -104,7 +104,7 @@ $points = array(
   $x+$d,   ($top+$bot)/2,
   $x,      $bot
 );
-imagefilledpolygon($im, $points, 5, $black);
+imagefilledpolygon($im, $points, $black);
 
 include_once __DIR__ . '/func.inc';
 test_image_equals_file(__DIR__ . '/libgd00100.png', $im);