PHP implementation supports transparent PNG image scaling

This article mainly introduced PHP implementation of the PNG image scaling method (support transparent background), PHP for PNG image to achieve the zoom function, and support transparent background, with a certain reference value. We hope to help you.

The implementation method is as follows:

function Smart_resize_image ($file, $width = 0, $height = 0, $proportional = false, $output = ' file ', $delete _original = t    Rue, $use _linux_commands = False) {if ($height <= 0 && $width <= 0) {return false;    } $info = getimagesize ($file);    $image = ";    $final _width = 0;    $final _height = 0;    List ($width _old, $height _old) = $info;      if ($proportional) {if ($width = = 0) $factor = $height/$height _old;      ElseIf ($height = = 0) $factor = $width/$width _old;       else $factor = min ($width/$width _old, $height/$height _old);      $final _width = Round ($width _old * $factor);    $final _height = Round ($height _old * $factor);      } else {$final _width = ($width <= 0)? $width _old: $width; $final _height = ($height <= 0)?    $height _old: $height;      } switch ($info [2]) {case imagetype_gif: $image = Imagecreatefromgif ($file);      Break Case Imagetype_jpeg: $image = Imagecreatefromjpeg ($file);      Break      Case Imagetype_png: $image = Imagecreatefrompng ($file);      Break    Default:return false;    } $image _resized = Imagecreatetruecolor ($final _width, $final _height); if (($info [2] = = Imagetype_gif) | | ($info [2] = = Imagetype_png))      {$trnprt _indx = imagecolortransparent ($image);  If we have a specific transparent color if ($trnprt _indx >= 0) {//Get the original image ' s transparent        Color ' s RGB values $trnprt _color = Imagecolorsforindex ($image, $trnprt _indx); Allocate the same color in the new image resource $trnprt _indx = imagecolorallocate ($image _resized, $trnprt _col        or[' Red '], $trnprt _color[' green '), $trnprt _color[' Blue ');        Completely fill the background of the new image with allocated color.        Imagefill ($image _resized, 0, 0, $trnprt _indx);      Set the background color for new image to Transparent imagecolortransparent ($image _resized, $trnprt _indx);     } Always make a transparent background color for PNGs that don ' t has one allocated already elseif ($info [2] = = IMA        Getype_png) {//Turn off transparency blending (temporarily) imagealphablending ($image _resized, false);        Create a new transparent color for image $color = Imagecolorallocatealpha ($image _resized, 0, 0, 0, 127);        Completely fill the background of the new image with allocated color.        Imagefill ($image _resized, 0, 0, $color);      Restore Transparency Blending Imagesavealpha ($image _resized, true);    }} imagecopyresampled ($image _resized, $image, 0, 0, 0, 0, $final _width, $final _height, $width _old, $height _old);      if ($delete _original) {if ($use _linux_commands) exec (' rm '. $file);    else @unlink ($file);        } switch (Strtolower ($output)) {case ' browser ': $mime = Image_type_to_mime_type ($info [2]);        Header ("Content-type: $mime");      $output = NULL; BReak;      Case ' file ': $output = $file;      Break      Case ' return ': Return $image _resized;      Break    Default:break;      } switch ($info [2]) {case imagetype_gif:imagegif ($image _resized, $output);      Break      Case Imagetype_jpeg:imagejpeg ($image _resized, $output);      Break      Case Imagetype_png:imagepng ($image _resized, $output);      Break    Default:return false; } return true;

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