Файл: qa-include/qa-util-image.php
Строк: 202
<?php
/*
Question2Answer (c) Gideon Greenspan
http://www.question2answer.org/
File: qa-include/qa-util-image.php
Version: See define()s at top of qa-include/qa-base.php
Description: Some useful image-related functions (using GD)
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
More about this license: http://www.question2answer.org/license.php
*/
if (!defined('QA_VERSION')) { // don't allow this page to be requested directly from browser
header('Location: ../');
exit;
}
function qa_has_gd_image()
/*
Return true if PHP has the GD extension installed and it appears to be usable
*/
{
return extension_loaded('gd') && function_exists('imagecreatefromstring') && function_exists('imagejpeg');
}
function qa_image_file_too_big($imagefile, $size=null)
/*
Check if the image in $imagefile will be too big for PHP/GD to process given memory usage and limits
Pass the width and height limit beyond which the image will require scaling in $size (if any)
Returns false if the image will fit fine, otherwise a safe estimate of the factor the image should be sized by
*/
{
if (function_exists('memory_get_usage')) {
$gotbytes=trim(@ini_get('memory_limit'));
switch (strtolower(substr($gotbytes, -1))) {
case 'g':
$gotbytes*=1024;
case 'm':
$gotbytes*=1024;
case 'k':
$gotbytes*=1024;
}
if ($gotbytes>0) { // otherwise we clearly don't know our limit
$gotbytes=($gotbytes-memory_get_usage())*0.9; // safety margin of 10%
$needbytes=filesize($imagefile); // memory to store file contents
$imagesize=@getimagesize($imagefile);
if (is_array($imagesize)) { // if image can't be parsed, don't worry about anything else
$width=$imagesize[0];
$height=$imagesize[1];
$bits=isset($imagesize['bits']) ? $imagesize['bits'] : 8; // these elements can be missing (PHP bug) so assume this as default
$channels=isset($imagesize['channels']) ? $imagesize['channels'] : 3; // for more info: http://gynvael.coldwind.pl/?id=223
$needbytes+=$width*$height*$bits*$channels/8*2; // memory to load original image
if (isset($size) && qa_image_constrain($width, $height, $size)) // memory for constrained image
$needbytes+=$width*$height*3*2; // *2 here and above based on empirical tests
}
if ($needbytes>$gotbytes)
return sqrt($gotbytes/($needbytes*1.5)); // additional 50% safety margin since JPEG quality may change
}
}
return false;
}
function qa_image_constrain_data($imagedata, &$width, &$height, $size)
/*
Given $imagedata containing JPEG/GIF/PNG data, constrain it proportionally to fit in $size (square)
Return the new image data (will be a JPEG), and set the $width and $height variables
*/
{
$inimage=@imagecreatefromstring($imagedata);
if (is_resource($inimage)) {
$width=imagesx($inimage);
$height=imagesy($inimage);
// always call qa_gd_image_resize(), even if the size is the same, to take care of possible PNG transparency
qa_image_constrain($width, $height, $size);
qa_gd_image_resize($inimage, $width, $height);
}
if (is_resource($inimage)) {
$imagedata=qa_gd_image_jpeg($inimage);
imagedestroy($inimage);
return $imagedata;
}
return null;
}
function qa_image_constrain(&$width, &$height, $size)
/*
Given and $width and $height, return true if those need to be contrained to fit in $size (square)
If so, also set $width and $height to the new proportionally constrained values
*/
{
if (($width>$size) || ($height>$size)) {
$multiplier=min($size/$width, $size/$height);
$width=floor($width*$multiplier);
$height=floor($height*$multiplier);
return true;
}
return false;
}
function qa_gd_image_resize(&$image, $width, $height)
/*
Resize the GD $image to $width and $height, setting it to null if the resize failed
*/
{
$oldimage=$image;
$image=null;
$newimage=imagecreatetruecolor($width, $height);
$white=imagecolorallocate($newimage, 255, 255, 255); // fill with white first in case we have a transparent PNG
imagefill($newimage, 0, 0, $white);
if (is_resource($newimage)) {
if (imagecopyresampled($newimage, $oldimage, 0, 0, 0, 0, $width, $height, imagesx($oldimage), imagesy($oldimage)))
$image=$newimage;
else
imagedestroy($newimage);
}
imagedestroy($oldimage);
}
function qa_gd_image_jpeg($image, $output=false)
/*
Return the JPEG data for GD $image, also echoing it to browser if $output is true
*/
{
ob_start();
imagejpeg($image, null, 90);
return $output ? ob_get_flush() : ob_get_clean();
}
function qa_gd_image_formats()
/*
Return an array of strings listing the image formats that are supported
*/
{
$imagetypebits=imagetypes();
$bitstrings=array(
IMG_GIF => 'GIF',
IMG_JPG => 'JPG',
IMG_PNG => 'PNG',
);
foreach (array_keys($bitstrings) as $bit)
if (!($imagetypebits&$bit))
unset($bitstrings[$bit]);
return $bitstrings;
}
/*
Omit PHP closing tag to help avoid accidental output
*/