所以，一切都很好。我已经调整了源PNG的大小，并正确地定位在创建的背景上，但PNG以外的其他区域变成黑色。我已经通过imagecolortransparent让它变得透明，但这会使png边缘锯齿状。
这是我现在在PNG周围制作的黑条。请记住，我这里只处理PNG图像。
// TARGET IMAGE
$target = imagecreatetruecolor($this->request['width'], $this->request['height']);
imagealphablending($target, false);
imagesavealpha($target, true);
// SOURCE IMAGE
$source = imagecreatefrompng($this->src_image);
// RESAMPLING
imagecopyresampled($target, $source, $offsetX, $offsetY, 0, 0, $tnWidth, $tnHeight, $this->src_width, $this->src_height);
// FINAL IMAGE
imagepng($target, $source, $quality);
// MEMORY CLEAN UP
imagedestroy($source);
imagedestroy($target);
// PRODUCES SOMETHING LIKE THIS
+--------------------------------+
| BLACK AREA |
+--------------------------------+
| |
| RESIZED PNG |
| WITH TRANSPARENCY |
| |
+--------------------------------+
| BLACK AREA |
+--------------------------------+
// WHERE IT SHOULD HAVE THE BLACK AREAS TRANSPARENT AS WELL
+--------------------------------+
| TRANSPARENT |
+--------------------------------+
| |
| RESIZED PNG |
| WITH TRANSPARENCY |
| |
+--------------------------------+
| TRANSPARENT |
+--------------------------------+
希望有人有这方面的经验，因为我在网上找到的所有例子都是关于在透明BG上调整PNG大小的，这很容易。
TIA
好吧，花了好几个小时才弄明白。所以我希望这对别人有帮助。
// SOURCE PNG
$src = imagecreatefrompng($this->src_image);
// DESTINATION CANVAS
$dst = imagecreatetruecolor($canvasW, $canvasH);
imagealphablending($dst, false);
$color = imagecolorallocatealpha($dst, 0, 0, 0, 127);
imagefill($dst, 0, 0, $color);
imagesavealpha($dst, true);
// RESAMPLE/RESIZE SOURCE AND TARGET TOGETHER
imagecopyresampled($dst, $src, $offsetX, $offsetY, 0, 0, $tnWidth, $tnHeight, $this->src_width, $this->src_height);
// WRITE FILE
imagepng($dst, $resized, $quality);
// MEMORY CLEAN UP
imagedestroy($src);
imagedestroy($dst);