Switch to libgd anti-aliased drawing API

Instead of rolling our own in the bundled libgd, we use libgd's anti-aliased
drawing API. This way imageantialias() is also available, when built against
a system libgd.

UPGRADING

@@ -96,10 +96,11 @@ PHP 7.2 UPGRADE NOTES
      Samsung, DJI, Panasonic, Sony, Pentax, Minolta & Sigma/Foveon.
 
 - GD:
-    . Removed --enable-gd-native-ttf configuration option which was unused as
-      of PHP 5.5.0 anyway.
-    . imagegd() stores truecolor images as real truecolor images. Formerly, they
-      have been converted to palette.
+  . Removed --enable-gd-native-ttf configuration option which was unused as
+    of PHP 5.5.0 anyway.
+  . imagegd() stores truecolor images as real truecolor images. Formerly, they
+    have been converted to palette.
+  . imageantialias() is now also available if compiled with a system libgd.
 
 - Mbstring
   . mb_check_encoding() accepts array parameter. Both key and value

ext/gd/gd.c

@@ -786,12 +786,10 @@ ZEND_BEGIN_ARG_INFO(arginfo_imageflip, 0)
 	ZEND_ARG_INFO(0, mode)
 ZEND_END_ARG_INFO()
 
-#ifdef HAVE_GD_BUNDLED
 ZEND_BEGIN_ARG_INFO(arginfo_imageantialias, 0)
 	ZEND_ARG_INFO(0, im)
 	ZEND_ARG_INFO(0, on)
 ZEND_END_ARG_INFO()
-#endif
 
 ZEND_BEGIN_ARG_INFO(arginfo_imagecrop, 0)
 	ZEND_ARG_INFO(0, im)
@@ -884,9 +882,7 @@ const zend_function_entry gd_functions[] = {
 	PHP_FE(imagerotate,     						arginfo_imagerotate)
 	PHP_FE(imageflip,								arginfo_imageflip)
 
-#ifdef HAVE_GD_BUNDLED
 	PHP_FE(imageantialias,							arginfo_imageantialias)
-#endif
 	PHP_FE(imagecrop,								arginfo_imagecrop)
 	PHP_FE(imagecropauto,							arginfo_imagecropauto)
 	PHP_FE(imagescale,								arginfo_imagescale)
@@ -3111,14 +3107,11 @@ PHP_FUNCTION(imageline)
 		RETURN_FALSE;
 	}
 
-#ifdef HAVE_GD_BUNDLED
-	if (im->antialias) {
-		gdImageAALine(im, x1, y1, x2, y2, col);
-	} else
-#endif
-	{
-		gdImageLine(im, x1, y1, x2, y2, col);
+	if (im->AA) {
+		gdImageSetAntiAliased(im, col);
+		col = gdAntiAliased;
 	}
+	gdImageLine(im, x1, y1, x2, y2, col);
 	RETURN_TRUE;
 }
 /* }}} */
@@ -3398,6 +3391,10 @@ static void php_imagepolygon(INTERNAL_FUNCTION_PARAMETERS, int filled)
 		}
 	}
 
+	if (im->AA) {
+		gdImageSetAntiAliased(im, col);
+		col = gdAntiAliased;
+	}
 	if (filled) {
 		gdImageFilledPolygon(im, points, npoints, col);
 	} else {
@@ -4601,7 +4598,6 @@ PHP_FUNCTION(imageflip)
 }
 /* }}} */
 
-#ifdef HAVE_GD_BUNDLED
 /* {{{ proto bool imageantialias(resource im, bool on)
    Should antialiased functions used or not*/
 PHP_FUNCTION(imageantialias)
@@ -4617,11 +4613,10 @@ PHP_FUNCTION(imageantialias)
 	if ((im = (gdImagePtr)zend_fetch_resource(Z_RES_P(IM), "Image", le_gd)) == NULL) {
 		RETURN_FALSE;
 	}
-	gdImageAntialias(im, alias);
+	gdImageSetAntiAliased(im, 0);
 	RETURN_TRUE;
 }
 /* }}} */
-#endif
 
 /* {{{ proto void imagecrop(resource im, array rect)
    Crop an image using the given coordinates and size, x, y, width and height. */

ext/gd/libgd/gd.c

@@ -2608,24 +2608,17 @@ void gdImagePolygon (gdImagePtr im, gdPointPtr p, int n, int c)
 {
 	int i;
 	int lx, ly;
-	typedef void (*image_line)(gdImagePtr im, int x1, int y1, int x2, int y2, int color);
-	image_line draw_line;
 
 	if (n <= 0) {
 		return;
 	}
 
-	if ( im->antialias) {
-		draw_line = gdImageAALine;
-	} else {
-		draw_line = gdImageLine;
-	}
 	lx = p->x;
 	ly = p->y;
-	draw_line(im, lx, ly, p[n - 1].x, p[n - 1].y, c);
+	gdImageLine(im, lx, ly, p[n - 1].x, p[n - 1].y, c);
 	for (i = 1; i < n; i++) {
 		p++;
-		draw_line(im, lx, ly, p->x, p->y, c);
+		gdImageLine(im, lx, ly, p->x, p->y, c);
 		lx = p->x;
 		ly = p->y;
 	}
@@ -2953,13 +2946,6 @@ void gdImageAlphaBlending (gdImagePtr im, int alphaBlendingArg)
 	im->alphaBlendingFlag = alphaBlendingArg;
 }
 
-void gdImageAntialias (gdImagePtr im, int antialias)
-{
-	if (im->trueColor){
-		im->antialias = antialias;
-	}
-}
-
 void gdImageSaveAlpha (gdImagePtr im, int saveAlphaArg)
 {
 	im->saveAlphaFlag = saveAlphaArg;

ext/gd/libgd/gd.h

@@ -222,8 +222,6 @@ typedef struct gdImageStruct {
 		To do that, build your image as a truecolor image,
 		then quantize down to 8 bits. */
 	int alphaBlendingFlag;
-	/* Should antialias functions be used */
-	int antialias;
 	/* Should the alpha channel of the image be saved? This affects
 		PNG at the moment; other future formats may also
 		have that capability. JPEG doesn't. */

ext/gd/php_gd.h

@@ -123,9 +123,7 @@ PHP_FUNCTION(imagerotate);
 
 PHP_FUNCTION(imageflip);
 
-#ifdef HAVE_GD_BUNDLED
 PHP_FUNCTION(imageantialias);
-#endif
 
 PHP_FUNCTION(imagecrop);
 PHP_FUNCTION(imagecropauto);

ext/gd/tests/bug28147.phpt

@@ -3,7 +3,6 @@ Bug #28147 (Crash with anti-aliased line)
 --SKIPIF--
 <?php
 	if (!extension_loaded('gd')) die("skip gd extension not available\n");
-	if (!function_exists("imageantialias")) die("skip requires bundled GD library\n");
 ?>
 --FILE--
 <?php

ext/gd/tests/bug42434.phpt

@@ -5,7 +5,6 @@ Bug #42434 (ImageLine w/ antialias = 1px shorter)
 if (!extension_loaded('gd')) {
 	die('skip gd extension not available');
 }
-if (!GD_BUNDLED) die("skip requires bundled GD library\n");
 ?>
 --FILE--
 <?php

ext/gd/tests/imageantialias_error1.phpt

@@ -6,7 +6,6 @@ Guilherme Blanco <guilhermeblanco [at] hotmail [dot] com>
 --SKIPIF--
 <?php 
 if (!extension_loaded("gd")) die("skip GD not present");
-if (!GD_BUNDLED) die("skip requires bundled GD library\n");
 ?>
 --FILE--
 <?php

ext/gd/tests/imageantialias_error2.phpt

@@ -6,7 +6,6 @@ Guilherme Blanco <guilhermeblanco [at] hotmail [dot] com>
 --SKIPIF--
 <?php 
 if (!extension_loaded("gd")) die("skip GD not present");
-if (!GD_BUNDLED) die("skip requires bundled GD library\n");
 ?>
 --FILE--
 <?php