我在使用自适应图像时遇到了问题。( http://adaptive-images.com )
我已经让 AI 在本地和在线运行了好几个月，完全没有遇到任何问题。就在这个周末，我尝试用与原始图像相同目录中的新 png 图像替换页面上的图像，之前的图像是 jpg。新图像根本不会在本地版本上加载（它适用于在线版本），控制台显示：
加载资源失败：服务器响应状态为 500（内部服务器错误）
这些是我试图解决这个问题的步骤（所有这些都没有奏效）：
- 检查并再次检查，文件的路径。如前所述，唯一的区别是这是一个 png 而不是 jpg 文件。
- 再次添加了相同的 png 文件，但名称不同。
- 从 Photoshop 创建了一个完全不同的 png 来使用。
- 检查是否在 ai-cache 文件夹中创建了 png - 它不是。
- 创建了一个未通过任何优化软件（如 imageAlpha 或 imageOptim）的全新 png 文件 - 认为这里的某些东西损坏了文件。
- 在不同的浏览器中查看。
- 重新启动 MAMP 服务器。
- 重新启动 Mac。
- 重新安装 MAMP。
- 喊道。
这是我尝试过的有效的方法：
- 用原始和新的 jpg 替换图像。图像加载正常，并在 ai-cache 中创建了一个版本。
- 使用 .htaccess 文件禁用自适应图像 — png 文件都按预期加载，但当然 AI 不再运行。
- 使用 jpg - 不理想，因为图像需要透明度。
- 编辑：使用 8 位 png 有效，但我更喜欢 24 位仍然没有运气。
这是我发现的一件有趣的事情。我使用了一个不是用 Photoshop CC 创建的 png 文件（标准截图）。在本地安装上，图像显示正常。但是，在 ai-cache 中不会创建较小的版本。使用与在线设置相同的屏幕截图文件，图像也显示良好，并且还在 ai-cache 中创建了一个版本。
还值得指出的是，我从 Photoshop CC 创建的所有 png 文件在直接打开时也可以在浏览器中很好地查看。我也有以前用 Photoshop CC 制作的 png 文件，这些文件仍然显示良好，并且在 ai-cache 中有版本。
我有点不知道下一步该往哪里看，我似乎唯一推断出的就是 Photoshop 的 png 文件中一定有一些东西不能正确读取。但我不明白的是，据我所知，在过去的几天里，安装/文件（MAMP、Photoshop、自适应图像、htaccess）都没有被更改/更新。
任何帮助或建议将不胜感激，谢谢！
如果需要，下面是我.htaccess文件中的自适应图像代码：
<IfModule mod_rewrite.c>
Options +FollowSymlinks
RewriteEngine On
# Adaptive-Images -----------------------------------------------------------------------------------
# Add any directories you wish to omit from the Adaptive-Images process on a new line, as follows:
# RewriteCond %{REQUEST_URI} !some-directory
# RewriteCond %{REQUEST_URI} !another-directory
RewriteCond %{REQUEST_URI} !assets
# Send any GIF, JPG, or PNG request that IS NOT stored inside one of the above directories
# to adaptive-images.php so we can select appropriately sized versions
RewriteRule \.(?:jpe?g|gif|png)$ _inc/plugins/adaptive-images/adaptive-images.php
# END Adaptive-Images -------------------------------------------------------------------------------
</IfModule>
我正在使用自适应图像的标准安装，但如果您还没有看到其中包含的 php 文件，则如下所示：
<?php
/* PROJECT INFO --------------------------------------------------------------------------------------------------------
Version: 1.5.2
Changelog: http://adaptive-images.com/changelog.txt
Homepage: http://adaptive-images.com
GitHub: https://github.com/MattWilcox/Adaptive-Images
Twitter: @responsiveimg
LEGAL:
Adaptive Images by Matt Wilcox is licensed under a Creative Commons Attribution 3.0 Unported License.
/* CONFIG ----------------------------------------------------------------------------------------------------------- */
$resolutions = array(3840, 2880, 1920, 1600, 768); // the resolution break-points to use (screen widths, in pixels)
$cache_path = "_inc/images/ai-cache"; // where to store the generated re-sized images. Specify from your document root!
$jpg_quality = 100; // the quality of any generated JPGs on a scale of 0 to 100
$sharpen = TRUE; // Shrinking images can blur details, perform a sharpen on re-scaled images?
$watch_cache = TRUE; // check that the adapted image isn't stale (ensures updated source images are re-cached)
$browser_cache = 60*60*24*7; // How long the BROWSER cache should last (seconds, minutes, hours, days. 7days by default)
/* END CONFIG ----------------------------------------------------------------------------------------------------------
------------------------ Don't edit anything after this line unless you know what you're doing -------------------------
--------------------------------------------------------------------------------------------------------------------- */
/* get all of the required data from the HTTP request */
$document_root = $_SERVER['DOCUMENT_ROOT'];
$requested_uri = parse_url(urldecode($_SERVER['REQUEST_URI']), PHP_URL_PATH);
$requested_file = basename($requested_uri);
$source_file = $document_root.$requested_uri;
$resolution = FALSE;
/* Mobile detection
NOTE: only used in the event a cookie isn't available. */
function is_mobile() {
$userAgent = strtolower($_SERVER['HTTP_USER_AGENT']);
return strpos($userAgent, 'mobile');
}
/* Does the UA string indicate this is a mobile? */
if(!is_mobile()){
$is_mobile = FALSE;
} else {
$is_mobile = TRUE;
}
// does the $cache_path directory exist already?
if (!is_dir("$document_root/$cache_path")) { // no
if (!mkdir("$document_root/$cache_path", 0755, true)) { // so make it
if (!is_dir("$document_root/$cache_path")) { // check again to protect against race conditions
// uh-oh, failed to make that directory
sendErrorImage("Failed to create cache directory at: $document_root/$cache_path");
}
}
}
/* helper function: Send headers and returns an image. */
function sendImage($filename, $browser_cache) {
$extension = strtolower(pathinfo($filename, PATHINFO_EXTENSION));
if (in_array($extension, array('png', 'gif', 'jpeg'))) {
header("Content-Type: image/".$extension);
} else {
header("Content-Type: image/jpeg");
}
header("Cache-Control: private, max-age=".$browser_cache);
header('Expires: '.gmdate('D, d M Y H:i:s', time()+$browser_cache).' GMT');
header('Content-Length: '.filesize($filename));
readfile($filename);
exit();
}
/* helper function: Create and send an image with an error message. */
function sendErrorImage($message) {
/* get all of the required data from the HTTP request */
$document_root = $_SERVER['DOCUMENT_ROOT'];
$requested_uri = parse_url(urldecode($_SERVER['REQUEST_URI']), PHP_URL_PATH);
$requested_file = basename($requested_uri);
$source_file = $document_root.$requested_uri;
if(!is_mobile()){
$is_mobile = "FALSE";
} else {
$is_mobile = "TRUE";
}
$im = ImageCreateTrueColor(800, 300);
$text_color = ImageColorAllocate($im, 233, 14, 91);
$message_color = ImageColorAllocate($im, 91, 112, 233);
ImageString($im, 5, 5, 5, "Adaptive Images encountered a problem:", $text_color);
ImageString($im, 3, 5, 25, $message, $message_color);
ImageString($im, 5, 5, 85, "Potentially useful information:", $text_color);
ImageString($im, 3, 5, 105, "DOCUMENT ROOT IS: $document_root", $text_color);
ImageString($im, 3, 5, 125, "REQUESTED URI WAS: $requested_uri", $text_color);
ImageString($im, 3, 5, 145, "REQUESTED FILE WAS: $requested_file", $text_color);
ImageString($im, 3, 5, 165, "SOURCE FILE IS: $source_file", $text_color);
ImageString($im, 3, 5, 185, "DEVICE IS MOBILE? $is_mobile", $text_color);
header("Cache-Control: no-store");
header('Expires: '.gmdate('D, d M Y H:i:s', time()-1000).' GMT');
header('Content-Type: image/jpeg');
ImageJpeg($im);
ImageDestroy($im);
exit();
}
/* sharpen images function */
function findSharp($intOrig, $intFinal) {
$intFinal = $intFinal * (750.0 / $intOrig);
$intA = 52;
$intB = -0.27810650887573124;
$intC = .00047337278106508946;
$intRes = $intA + $intB * $intFinal + $intC * $intFinal * $intFinal;
return max(round($intRes), 0);
}
/* refreshes the cached image if it's outdated */
function refreshCache($source_file, $cache_file, $resolution) {
if (file_exists($cache_file)) {
// not modified
if (filemtime($cache_file) >= filemtime($source_file)) {
return $cache_file;
}
// modified, clear it
unlink($cache_file);
}
return generateImage($source_file, $cache_file, $resolution);
}
/* generates the given cache file for the given source file with the given resolution */
function generateImage($source_file, $cache_file, $resolution) {
global $sharpen, $jpg_quality;
$extension = strtolower(pathinfo($source_file, PATHINFO_EXTENSION));
// Check the image dimensions
$dimensions = GetImageSize($source_file);
$width = $dimensions[0];
$height = $dimensions[1];
// Do we need to downscale the image?
if ($width <= $resolution) { // no, because the width of the source image is already less than the client width
return $source_file;
}
// We need to resize the source image to the width of the resolution breakpoint we're working with
$ratio = $height/$width;
$new_width = $resolution;
$new_height = ceil($new_width * $ratio);
$dst = ImageCreateTrueColor($new_width, $new_height); // re-sized image
switch ($extension) {
case 'png':
$src = @ImageCreateFromPng($source_file); // original image
break;
case 'gif':
$src = @ImageCreateFromGif($source_file); // original image
break;
default:
$src = @ImageCreateFromJpeg($source_file); // original image
ImageInterlace($dst, true); // Enable interlancing (progressive JPG, smaller size file)
break;
}
if($extension=='png'){
imagealphablending($dst, false);
imagesavealpha($dst,true);
$transparent = imagecolorallocatealpha($dst, 255, 255, 255, 127);
imagefilledrectangle($dst, 0, 0, $new_width, $new_height, $transparent);
}
ImageCopyResampled($dst, $src, 0, 0, 0, 0, $new_width, $new_height, $width, $height); // do the resize in memory
ImageDestroy($src);
// sharpen the image?
// NOTE: requires PHP compiled with the bundled version of GD (see http://php.net/manual/en/function.imageconvolution.php)
if($sharpen == TRUE && function_exists('imageconvolution')) {
$intSharpness = findSharp($width, $new_width);
$arrMatrix = array(
array(-1, -2, -1),
array(-2, $intSharpness + 12, -2),
array(-1, -2, -1)
);
imageconvolution($dst, $arrMatrix, $intSharpness, 0);
}
$cache_dir = dirname($cache_file);
// does the directory exist already?
if (!is_dir($cache_dir)) {
if (!mkdir($cache_dir, 0755, true)) {
// check again if it really doesn't exist to protect against race conditions
if (!is_dir($cache_dir)) {
// uh-oh, failed to make that directory
ImageDestroy($dst);
sendErrorImage("Failed to create cache directory: $cache_dir");
}
}
}
if (!is_writable($cache_dir)) {
sendErrorImage("The cache directory is not writable: $cache_dir");
}
// save the new file in the appropriate path, and send a version to the browser
switch ($extension) {
case 'png':
$gotSaved = ImagePng($dst, $cache_file);
break;
case 'gif':
$gotSaved = ImageGif($dst, $cache_file);
break;
default:
$gotSaved = ImageJpeg($dst, $cache_file, $jpg_quality);
break;
}
ImageDestroy($dst);
if (!$gotSaved && !file_exists($cache_file)) {
sendErrorImage("Failed to create image: $cache_file");
}
return $cache_file;
}
// check if the file exists at all
if (!file_exists($source_file)) {
header("Status: 404 Not Found");
exit();
}
/* check that PHP has the GD library available to use for image re-sizing */
if (!extension_loaded('gd')) { // it's not loaded
if (!function_exists('dl') || !dl('gd.so')) { // and we can't load it either
// no GD available, so deliver the image straight up
trigger_error('You must enable the GD extension to make use of Adaptive Images', E_USER_WARNING);
sendImage($source_file, $browser_cache);
}
}
/* Check to see if a valid cookie exists */
if (isset($_COOKIE['resolution'])) {
$cookie_value = $_COOKIE['resolution'];
// does the cookie look valid? [whole number, comma, potential floating number]
if (! preg_match("/^[0-9]+[,]*[0-9\.]+$/", "$cookie_value")) { // no it doesn't look valid
setcookie("resolution", "$cookie_value", time()-100); // delete the mangled cookie
}
else { // the cookie is valid, do stuff with it
$cookie_data = explode(",", $_COOKIE['resolution']);
$client_width = (int) $cookie_data[0]; // the base resolution (CSS pixels)
$total_width = $client_width;
$pixel_density = 1; // set a default, used for non-retina style JS snippet
if (@$cookie_data[1]) { // the device's pixel density factor (physical pixels per CSS pixel)
$pixel_density = $cookie_data[1];
}
rsort($resolutions); // make sure the supplied break-points are in reverse size order
$resolution = $resolutions[0]; // by default use the largest supported break-point
// if pixel density is not 1, then we need to be smart about adapting and fitting into the defined breakpoints
if($pixel_density != 1) {
$total_width = $client_width * $pixel_density; // required physical pixel width of the image
// the required image width is bigger than any existing value in $resolutions
if($total_width > $resolutions[0]){
// firstly, fit the CSS size into a break point ignoring the multiplier
foreach ($resolutions as $break_point) { // filter down
if ($total_width <= $break_point) {
$resolution = $break_point;
}
}
// now apply the multiplier
$resolution = $resolution * $pixel_density;
}
// the required image fits into the existing breakpoints in $resolutions
else {
foreach ($resolutions as $break_point) { // filter down
if ($total_width <= $break_point) {
$resolution = $break_point;
}
}
}
}
else { // pixel density is 1, just fit it into one of the breakpoints
foreach ($resolutions as $break_point) { // filter down
if ($total_width <= $break_point) {
$resolution = $break_point;
}
}
}
}
}
/* No resolution was found (no cookie or invalid cookie) */
if (!$resolution) {
// We send the lowest resolution for mobile-first approach, and highest otherwise
$resolution = $is_mobile ? min($resolutions) : max($resolutions);
}
/* if the requested URL starts with a slash, remove the slash */
if(substr($requested_uri, 0,1) == "/") {
$requested_uri = substr($requested_uri, 1);
}
/* whew might the cache file be? */
$cache_file = $document_root."/$cache_path/$resolution/".$requested_uri;
/* Use the resolution value as a path variable and check to see if an image of the same name exists at that path */
if (file_exists($cache_file)) { // it exists cached at that size
if ($watch_cache) { // if cache watching is enabled, compare cache and source modified dates to ensure the cache isn't stale
$cache_file = refreshCache($source_file, $cache_file, $resolution);
}
sendImage($cache_file, $browser_cache);
}
/* It exists as a source file, and it doesn't exist cached - lets make one: */
$file = generateImage($source_file, $cache_file, $resolution);
sendImage($file, $browser_cache);