今天改寫了之前寫得縮圖程式,之前寫的縮圖程式會將小於特定寬度的圖片重新取樣成特定尺寸,這樣的做法會導致小圖片的失真,所以我改寫了這個過程,將小於特定尺寸的圖片透過補色,變成一張符合特定尺寸的圖:
public function resizeImg($img, $width = 300, $height = 300, $newFilename = '', $maxImgWidth = 800, $maxImgHeight=800, $bgColor=null) {
$bgColor = $bgColor === null || !is_array($bgColor) ? array('r'=>255, 'g'=>255, 'b'=>255) : $bgColor;
switch (strtolower($img['type'])) {
case 'image/jpg':
case 'image/jpeg':
case 'image/pjpeg':
$image = imagecreatefromjpeg($img['tmp_name']);
break;
case 'image/png':
$image = imagecreatefrompng($img['tmp_name']);
break;
case 'image/gif':
$image = imagecreatefromgif($img['tmp_name']);
break;
default:
throw new Exception('Unsupported type: ' . $img['type']);
}
// Target dimensions
$max_width = $width;
$max_height = $height;
// Get current dimensions
$old_width = imagesx($image);
$old_height = imagesy($image);
// Calculate the scaling we need to do to fit the image inside our frame
$scale = min($max_width / $old_width, $max_height / $old_height);
$new_width = ceil($scale * $old_width);
$new_height = ceil($scale * $old_height);
// Create new empty image
$new = imagecreatetruecolor($new_width, $new_height);
// Get the new dimensions
if($old_width >= $maxImgWidth){
imagecopyresampled($new, $image, 0, 0, 0, 0, $new_width, $new_height, $old_width, $old_height);
}else{
$new_width = $maxImgWidth;
$new_height = ($maxImgHeight >= $old_height ? $maxImgHeight : $old_height);
$new = imagecreatetruecolor($new_width, $new_height);
$backgroundColor = imagecolorallocate($new, $bgColor['r'], $bgColor['g'], $bgColor['b']);
imagefill($new, 0, 0, $backgroundColor);
$centerX = (($new_width - $old_width) / 2);
$centerY = (($new_height - $old_height) / 2);
$centerY = $centerY + $old_height >= $new_height ? 0 : $centerY;
imagecopy($new, $image, $centerX, $centerY, 0, 0, $old_width, $old_height);
}
switch (strtolower($img['type'])) {
case 'image/jpg':
case 'image/jpeg':
case 'image/pjpeg':
$optImg = imagejpeg($new, $newFilename, 100);
break;
case 'image/png':
$optImg = imagepng($new, $newFilename, 0, PNG_ALL_FILTERS);
break;
case 'image/gif':
$optImg = imagegif($new, $newFilename);
break;
}
imagedestroy($image);
imagedestroy($new);
}