Change 0 to null to properly encode image to BMP if the first pixel is black

Ref #22288

Signed-off-by: Morris Jobke <hey@morrisjobke.de>

diff --git a/lib/private/legacy/OC_Image.php b/lib/private/legacy/OC_Image.php
index 1e2791f62c917e17fab4ef2b3953861cf686d57d..3e9812c99f2e69fda3290e8e6687765721e2d02f 100644 (file)
--- a/lib/private/legacy/OC_Image.php
+++ b/lib/private/legacy/OC_Image.php
@@ -1211,7 +1211,7 @@ if (!function_exists('imagebmp')) {
                        } // RLE8
                        elseif ($compression == 1 && $bit == 8) {
                                for ($j = $height - 1; $j >= 0; $j--) {
-                                       $lastIndex = 0;
+                                       $lastIndex = null;
                                        $sameNum = 0;
                                        for ($i = 0; $i <= $width; $i++) {
                                                $index = imagecolorat($im, $i, $j);