Image Resizing: Poor jpeg quality and black PNG backgrounds
- by azz0r
Hello,
I have two issues with my class, basically the quality of the jpeg images is quite poor, but I'm not sure if thats down to my ratio resizing. Ideally I'd like this class to be strict with image sizes and crop into them, but I cant get my head around it.
My main issue is that pngs always have a black bg, does anyone have experience with this happening?
<?php
class OpenSource_ImageResize {
function __construct($theFile, $toWhere, $mime, $extension, $newWidth, $newHeight) {
if ($mime == NULL) {
$mime = getimagesize($theFile);
$mime = $mime['mime'];
}
if ($mime == 'image/jpeg') {
$size = getimagesize($theFile);
if ($size[0] > $newWidth || $size[1] > $newHeight) {
$sourceImage = imagecreatefromjpeg($theFile);
} else {
return copy($theFile, $toWhere);
throw new exception('Could not create jpeg');
return false;
}
} else if ($mime == 'image/png') {
$size = getimagesize($theFile);
if ($size[0] > $newWidth || $size[1] > $newHeight) {
$sourceImage = imagecreatefrompng($theFile);
} else {
return copy($theFile, $toWhere);
//throw new exception('Could not create png');
return false;
}
} else if ($mime == 'image/gif') {
$size = getimagesize($theFile);
if ($size[0] > $newWidth || $size[1] > $newHeight) {
$sourceImage = imagecreatefromgif ($theFile);
} else {
return copy($theFile, $toWhere);
//throw new exception('Could not create gif');
return false;
}
} else {
throw new exception('Not a valid mime type');
return false;
}
$oldX = imageSX($sourceImage);
$oldY = imageSY($sourceImage);
if ($newWidth == NULL) {
$thumbHeight = $newHeight;
$thumbWidth = round($newHeight/($oldY/$oldX));
} else
if ($oldX > $oldY) {
$thumbWidth = $newWidth;
$thumbHeight = $oldY * ($newHeight/$oldX);
}
if ($oldX < $oldY) {
$thumbWidth = round($newHeight/($oldY/$oldX));
$thumbHeight = $newHeight;
}
if ($oldX == $oldY) {
$thumbWidth = $newWidth;
$thumbHeight = $newHeight;
}
if (!gd_info()) {
$dstImage = ImageCreate($thumbWidth, $thumbHeight);
imagecopyresized($dstImage, $sourceImage, 0, 0, 0, 0, $thumbWidth, $thumbHeight, $oldX, $oldY);
} else {
$dstImage = ImageCreateTrueColor($thumbWidth, $thumbHeight);
imagecopyresampled($dstImage, $sourceImage, 0, 0, 0, 0, $thumbWidth, $thumbHeight, $oldX, $oldY);
}
if ($mime == 'image/png') {
$xparent = imagecolorresolvealpha($dstImage, 255,2,240, 0) ;
imagecolortransparent($dstImage,$xparent);
imagealphablending($dstImage,true);
imagepng($dstImage, $toWhere);
} else if ($mime == 'image/jpeg') {
imagejpeg($dstImage, $toWhere);
} else if ($mime == 'image/gif') {
imagegif ($dstImage, $toWhere);
}
imagedestroy($dstImage);
imagedestroy($sourceImage);
return true;
}
}
