Fix #53154: Zero-height rectangle has whiskers

To avoid drawing the corner pixels twice, gdImageRectangle() draws the vertical
lines 2 points shorter than the actual side of the rectangle. However, this
causes "whiskers" for rectangles with height 0. This patch fixes this issue and
at the same time optimizes the algorithm by drawing only a single line for zero
height and zero width rectangles.

2 files changed, 31 insertions, 6 deletions

diff --git a/ext/gd/libgd/gd.c b/ext/gd/libgd/gd.c
index d73f0943af..c75c985c4e 100644
--- a/ext/gd/libgd/gd.c
+++ b/ext/gd/libgd/gd.c
@@ -2095,12 +2095,16 @@ void gdImageRectangle (gdImagePtr im, int x1, int y1, int x2, int y2, int color)
 
 		return;
 	} else {
-		y1v = y1h + 1;
-		y2v = y2h - 1;
-		gdImageLine(im, x1h, y1h, x2h, y1h, color);
-		gdImageLine(im, x1h, y2h, x2h, y2h, color);
-		gdImageLine(im, x1v, y1v, x1v, y2v, color);
-		gdImageLine(im, x2v, y1v, x2v, y2v, color);
+		if (x1 == x2 || y1 == y2) {
+			gdImageLine(im, x1, y1, x2, y2, color);
+		} else {
+			y1v = y1h + 1;
+			y2v = y2h - 1;
+			gdImageLine(im, x1h, y1h, x2h, y1h, color);
+			gdImageLine(im, x1h, y2h, x2h, y2h, color);
+			gdImageLine(im, x1v, y1v, x1v, y2v, color);
+			gdImageLine(im, x2v, y1v, x2v, y2v, color);
+		}
 	}
 }
 
diff --git a/ext/gd/tests/bug53154.phpt b/ext/gd/tests/bug53154.phpt
new file mode 100644
index 0000000000..6cbae2016c
--- /dev/null
+++ b/ext/gd/tests/bug53154.phpt
@@ -0,0 +1,21 @@
+--TEST--
+Bug #53154 (Zero-height rectangle has whiskers)
+--SKIPIF--
+<?php
+if (!extension_loaded('gd')) die('skip gd extension not available');
+?>
+--FILE--
+<?php
+$im = imagecreatetruecolor(100, 10);
+$red = imagecolorallocate($im, 255, 0, 0);
+imagerectangle($im, 5, 5, 95, 5, $red);
+var_dump(imagecolorat($im, 5, 4) !== $red);
+var_dump(imagecolorat($im, 5, 6) !== $red);
+var_dump(imagecolorat($im, 95, 4) !== $red);
+var_dump(imagecolorat($im, 95, 6) !== $red);
+?>
+--EXPECT--
+bool(true)
+bool(true)
+bool(true)
+bool(true)