Add imagematch() function

ext/gd/gd.c

@@ -3254,6 +3254,63 @@ PHP_FUNCTION(imagecopyresized)
 }
 /* }}} */
 
+#define GET_TRUECOLOR_PIXEL(px, im, x, y) \
+	if (im->trueColor) { \
+		px = gdImageTrueColorPixel(im, x, y); \
+	} \
+	else { \
+		int c = gdImagePalettePixel(im, x, y); \
+		px = gdTrueColor( \
+			gdImageRed(im, c), \
+			gdImageGreen(im, c), \
+			gdImageBlue(im, c)); \
+	}
+
+/* {{{ Check whether two images are pixel by pixel identical */
+PHP_FUNCTION(imagematch)
+{
+	zval *IM1, *IM2;
+	gdImagePtr im1, im2;
+	int x, y, sx, sy;
+	bool result = true;
+
+	ZEND_PARSE_PARAMETERS_START(2, 2)
+		Z_PARAM_OBJECT_OF_CLASS(IM1, gd_image_ce)
+		Z_PARAM_OBJECT_OF_CLASS(IM2, gd_image_ce)
+	ZEND_PARSE_PARAMETERS_END();
+
+	im1 = php_gd_libgdimageptr_from_zval_p(IM1);
+	im2 = php_gd_libgdimageptr_from_zval_p(IM2);
+
+	sx = im1->sx;
+	if (im1->sx != im2->sx) {
+		RETURN_FALSE;
+	}
+
+	sy = im1->sy;
+	if (im1->sy != im2->sy) {
+		RETURN_FALSE;
+	}
+
+	for (y = 0; y < sy; y++) {
+		for (x = 0; x < sx; x++) {
+			int p1, p2;
+
+			GET_TRUECOLOR_PIXEL(p1, im1, x, y);
+			GET_TRUECOLOR_PIXEL(p2, im2, x, y);
+
+			if (p1 != p2) {
+				result = false;
+			}
+		}
+	}
+
+	RETURN_BOOL(result);
+}
+/* }}} */
+
+#undef GET_TRUECOLOR_PIXEL
+
 /* {{{ Get image width */
 PHP_FUNCTION(imagesx)
 {

ext/gd/gd.stub.php

@@ -713,6 +713,8 @@ function imagecopymergegray(GdImage $dst_image, GdImage $src_image, int $dst_x,
 
 function imagecopyresized(GdImage $dst_image, GdImage $src_image, int $dst_x, int $dst_y, int $src_x, int $src_y, int $dst_width, int $dst_height, int $src_width, int $src_height): bool {}
 
+function imagematch(GdImage $image1, GdImage $image2): bool {}
+
 function imagesx(GdImage $image): int {}
 
 function imagesy(GdImage $image): int {}

ext/gd/tests/imagematch_basic.phpt

@@ -0,0 +1,71 @@
+--TEST--
+imagematch() function test
+--EXTENSIONS--
+gd
+--SKIPIF--
+<?php
+if (!(imagetypes() & IMG_PNG)) die("skip No PNG support");
+?>
+--FILE--
+<?php
+
+/* sample palette image, red/green */
+$palette_1 = imagecreate(2, 1);
+imagesetpixel($palette_1, 0, 0, imagecolorallocate($palette_1, 255, 0, 0));
+imagesetpixel($palette_1, 1, 0, imagecolorallocate($palette_1, 0, 255, 0));
+
+/* same image but with inverted colors allocations */
+$palette_1b = imagecreate(2, 1);
+imagesetpixel($palette_1b, 1, 0, imagecolorallocate($palette_1b, 0, 255, 0));
+imagesetpixel($palette_1b, 0, 0, imagecolorallocate($palette_1b, 255, 0, 0));
+
+/* a different palette image, red/blue */
+$palette_2 = imagecreate(2, 1);
+imagesetpixel($palette_2, 0, 0, imagecolorallocate($palette_2, 255, 0, 0));
+imagesetpixel($palette_2, 1, 0, imagecolorallocate($palette_2, 0, 0, 255));
+
+/* a truecolor image, matching the first one */
+$truecolor_1 = imagecreatetruecolor(2, 1);
+imagesetpixel($truecolor_1, 0, 0, imagecolorallocate($truecolor_1, 255, 0, 0));
+imagesetpixel($truecolor_1, 1, 0, imagecolorallocate($truecolor_1, 0, 255, 0));
+
+/* a truecolor image, identical to the previous one */
+$truecolor_1a = imagecreatetruecolor(2, 1);
+imagesetpixel($truecolor_1a, 0, 0, imagecolorallocate($truecolor_1a, 255, 0, 0));
+imagesetpixel($truecolor_1a, 1, 0, imagecolorallocate($truecolor_1a, 0, 255, 0));
+
+/* a truecolor image, differing only by color */
+$truecolor_2 = imagecreatetruecolor(2, 1);
+imagesetpixel($truecolor_2, 0, 0, imagecolorallocate($truecolor_2, 255, 0, 0));
+imagesetpixel($truecolor_2, 1, 0, imagecolorallocate($truecolor_2, 0, 0, 255));
+
+/* a truecolor image, differing only by alpha */
+$truecolor_3 = imagecreatetruecolor(2, 1);
+imagealphablending($truecolor_3, false);
+imagesetpixel($truecolor_3, 0, 0, imagecolorallocatealpha($truecolor_3, 255, 0, 0, 0));
+imagesetpixel($truecolor_3, 1, 0, imagecolorallocatealpha($truecolor_3, 0, 255, 0, 1));
+
+print   'imagematch($palette_1, $palette_1b) = ';
+var_dump(imagematch($palette_1, $palette_1b));
+
+print   'imagematch($palette_1, $palette_2) = ';
+var_dump(imagematch($palette_1, $palette_2));
+
+print   'imagematch($palette_1, $truecolor_1) = ';
+var_dump(imagematch($palette_1, $truecolor_1));
+
+print   'imagematch($truecolor_1, $truecolor_1a) = ';
+var_dump(imagematch($truecolor_1, $truecolor_1a));
+
+print   'imagematch($truecolor_1, $truecolor_2) = ';
+var_dump(imagematch($truecolor_1, $truecolor_2));
+
+print   'imagematch($truecolor_1, $truecolor_3) = ';
+var_dump(imagematch($truecolor_1, $truecolor_3));
+--EXPECT--
+imagematch($palette_1, $palette_1b) = bool(true)
+imagematch($palette_1, $palette_2) = bool(false)
+imagematch($palette_1, $truecolor_1) = bool(true)
+imagematch($truecolor_1, $truecolor_1a) = bool(true)
+imagematch($truecolor_1, $truecolor_2) = bool(false)
+imagematch($truecolor_1, $truecolor_3) = bool(false)