好的，所以我尝试使用php调整图像大小。我无法在我目前使用的服务器上安装插件。
$originalimage是我要调整大小的实际原始图片。
$width是定义$original_width的另一个参数。 $height和$original_height也可以这样说。
$original_width = imagesx($originalimage);
$original_height = imagesy($originalimage);
$max_width = $thumbwidth;
$max_height = $thumbheight;
$width = $original_width;
$height = $original_height;
使用上面的预设置，我在这里开始处理这个。这有效但无法设置最大高度。例如，我将最大宽度传递为$thumbwidth，最大高度传递为$thumbheight，这将按照需要运行，直到我尝试继续使用比宽度更高的图像。 （纵向图像。）它没有完全失败，但是它无法强制执行最大高度，渲染的图像可能非常高。
if ($width > $height) {
$newwidth = $thumbwidth;
$divisor = $width / $thumbwidth;
$newheight = floor( $height / $divisor);
} else {
$newheight = $thumbheight;
$divisor = $height / $thumbheight;
$newwidth = floor( $width / $divisor );
}
$image = imagecreatetruecolor( $newwidth, $newheight );
imagecopyresampled( $image, $originalimage, 0, 0, 0, 0, $newwidth, $newheight, $original_width, $original_height );
在尝试理解这个并在几个小时后失败后，我想出了我从php.net获得的代码。正如您所看到的，有一个原因我在代码的预设置部分设置了两组彼此相等的变量。主要是因为我无法理解在第二个代码段中将$max_width称为$thumbwidth。
下面的内容也适用，直到您传入的参数大于$originalimage的宽度或高度。
# taller
if ($height > $max_height) {
$width = ($max_height / $height) * $width;
$height = $max_height;
}
# wider
if ($width > $max_width) {
$height = ($max_width / $width) * $height;
$width = $max_width;
}
$image = imagecreatetruecolor( $width, $height );
imagecopyresampled( $image, $originalimage, 0, 0, 0, 0, $width, $height, $original_width, $original_height );
对不起，我无法自己找到办法。至于这是一个重复的问题，大多数类似的问题最终都是＆＃34; [在这里插入插件名称]更好地使用它。＆＃34;我特意要求一个不使用其他插件或javascript的答案。 （除了我的服务器上预装的GD。）
在结束这个问题之前，我会说我正在使用imagejpeg($image);，因此完全禁止使用HTML或CSS。
答案 0 :(得分：1)
这是我为我所参与的课程掀起的课程。也许它会对你有帮助吗？
<?php
class ImageHelper
{
/**
* @static
* @param $source string Path for source image
* @param $destination string Path for destination image to be placed
* @param $targetWidth int Width of the new image (in pixels)
* @param $targetHeight int Height of the new image (in pixels)
* @param $strict bool
*/
public static function createImage($source, $destination, $targetWidth, $targetHeight, $strict = false){
$dir = dirname($destination);
if(!is_dir($dir)){
mkdir($dir, 0770, true);
}
$fileContents = file_get_contents($source);
$image = imagecreatefromstring($fileContents);
$thumbnail = ImageHelper::resizeImage($image, $targetWidth, $targetHeight, $strict);
imagejpeg($thumbnail, $destination, 100);
imagedestroy($thumbnail);
imagedestroy($image);
}
/**
* Resize an image to the specified dimensions
* @param string $original Path to the original image
* @param int $targetWidth Width of the new image (in pixels)
* @param int $targetHeight Height of the new image (in pixels)
* @param bool $strict True to crop the picture to the specified dimensions, false for best fit
* @return bool|resource Returns the new image resource or false if the image was not resized.
*/
public static function resizeImage($original, $targetWidth, $targetHeight, $strict = false)
{
$originalWidth = imagesx($original);
$originalHeight = imagesy($original);
$widthRatio = $targetWidth / $originalWidth;
$heightRatio = $targetHeight / $originalHeight;
if(($widthRatio > 1 || $heightRatio > 1) && !$strict){
// don't scale up an image if either targets are greater than the original sizes and we aren't using a strict parameter
$dstHeight = $originalHeight;
$dstWidth = $originalWidth;
$srcHeight = $originalHeight;
$srcWidth = $originalWidth;
$srcX = 0;
$srcY = 0;
}elseif ($widthRatio > $heightRatio) {
// width is the constraining factor
if ($strict) {
$dstHeight = $targetHeight;
$dstWidth = $targetWidth;
$srcHeight = $originalHeight;
$srcWidth = $heightRatio * $targetWidth;
$srcX = floor(($originalWidth - $srcWidth) / 2);
$srcY = 0;
} else {
$dstHeight = ($originalHeight * $targetWidth) / $originalWidth;
$dstWidth = $targetWidth;
$srcHeight = $originalHeight;
$srcWidth = $originalWidth;
$srcX = 0;
$srcY = 0;
}
} else {
// height is the constraining factor
if ($strict) {
$dstHeight = $targetHeight;
$dstWidth = $targetWidth;
$srcHeight = $widthRatio * $targetHeight;
$srcWidth = $originalWidth;
$srcY = floor(($originalHeight - $srcHeight) / 2);
$srcX = 0;
} else {
$dstHeight = $targetHeight;
$dstWidth = ($originalWidth * $targetHeight) / $originalHeight;
$srcHeight = $originalHeight;
$srcWidth = $originalWidth;
$srcX = 0;
$srcY = 0;
}
}
$new = imagecreatetruecolor($dstWidth, $dstHeight);
if ($new === false) {
return false;
}
imagecopyresampled($new, $original, 0, 0, $srcX, $srcY, $dstWidth, $dstHeight, $srcWidth, $srcHeight);
return $new;
}
}
答案 1 :(得分：0)
您可以尝试此功能，如下所示。
<?php
function makeThumbnail($sourcefile,$max_width, $max_height, $endfile, $type){
// Takes the sourcefile (path/to/image.jpg) and makes a thumbnail from it
// and places it at endfile (path/to/thumb.jpg).
// Load image and get image size.
//
switch($type){
case'image/png':
$img = imagecreatefrompng($sourcefile);
break;
case'image/jpeg':
$img = imagecreatefromjpeg($sourcefile);
break;
case'image/gif':
$img = imagecreatefromgif($sourcefile);
break;
default :
return 'Un supported format';
}
$width = imagesx( $img );
$height = imagesy( $img );
if ($width > $height) {
if($width < $max_width)
$newwidth = $width;
else
$newwidth = $max_width;
$divisor = $width / $newwidth;
$newheight = floor( $height / $divisor);
}
else {
if($height < $max_height)
$newheight = $height;
else
$newheight = $max_height;
$divisor = $height / $newheight;
$newwidth = floor( $width / $divisor );
}
// Create a new temporary image.
$tmpimg = imagecreatetruecolor( $newwidth, $newheight );
imagealphablending($tmpimg, false);
imagesavealpha($tmpimg, true);
// Copy and resize old image into new image.
imagecopyresampled( $tmpimg, $img, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
// Save thumbnail into a file.
//compressing the file
switch($type){
case'image/png':
imagepng($tmpimg, $endfile, 0);
break;
case'image/jpeg':
imagejpeg($tmpimg, $endfile, 100);
break;
case'image/gif':
imagegif($tmpimg, $endfile, 0);
break;
}
// release the memory
imagedestroy($tmpimg);
imagedestroy($img);
}
?>
该功能有五个参数。
> $sourcefile - Specicifies the temporary location of your image file
> $max_width - Specifies the possible maximum width
> $max_height - Specifies the possible maximum width
> $endfile - Specifies the directory to save the image
> $type - Specifies the image file type
下载演示代码here
答案 2 :(得分：0)
我在构建图库页面的缩略图时遇到了非常相似的问题。我在上面尝试了Daniel Nyamasyo解决方案，但无法通过“ $ img = imagecreatefromjpeg（$ sourcefile）;”行，而不会收到“警告：imagecreatefromjpeg无法打开流：HTTP请求失败！HTTP / 1.1 400错误请求”，无论我用什么$ sourcefile喂它。 我想出了这种肮脏的方法。
<?php
// Some variables
$thumb_width = 162; // The maximum values you want
$thumb_height = 122;
$thumb_pointer = 'thumbs'; // Put your output folder here which must exist
$img = imagecreatefromjpeg( $image_name);
$width = imagesx( $img );
$height = imagesy( $img );
if ($width>=$height)
{
// Now calculate thumbnail size
$new_width = $thumb_width;
$new_height = floor( $height * ($thumb_width / $width));
// The 'dirty' bit I found was needed for square or near square images
while ($new_height > $thumb_height)
{
$new_width = floor($new_width * 0.99);
$new_height = floor($new_height * 0.99);
}
}
else
{
$new_height = $thumb_height;
$new_width = floor($width * ($thumb_height / $height));
}
// Create a new temporary image
$tmp_img = imagecreatetruecolor( $new_width, $new_height );
// Copy and resize old image into new image
imagecopyresized( $tmp_img, $img, 0, 0, 0, 0, $new_width, $new_height, $width, $height );
// Save the thumbnail into a file
imagejpeg( $tmp_img, $thumb_pointer.'/'.$image_name);
?>