如何在 php 中调整图像的大小以使其适合自定义大小的框并保留其纵横比？答案

【问题标题】：How to resize a image in php to fit it into a box of custom size preserving its aspect ratio?如何在 php 中调整图像的大小以使其适合自定义大小的框并保留其纵横比？
【发布时间】：2011-06-17 10:55:47
【问题描述】：

我有一张 400 x 350 像素的图像。我必须把它装进一个 90 x 80 像素的盒子里。每当我使用此代码调整它的大小时：

****************** Create Thumbnails *************************************/
$imageEditor = new ImageEditor($image_name, $path);
$imageEditor->resize(90, 80);
$imageEditor->outputFile($image_name, $paththumbnail);
$imageEditor->outputFile();
**************************************************************************/

在保持纵横比的情况下，输出图像在高度的情况下较小。如何获得准确的图像调整大小？

【问题讨论】：

你的问题对我来说不是很清楚。你想让你的缩略图正好有 90 x 80 像素吗？这意味着您将不得不在左右剪掉大约 1 像素（80/350*400 = 91.4 > 90）。这就是你想要的吗？

标签： php

【解决方案1】：

$thumb_width = 90;
$thumb_max_height = 80;

$imageEditor = new ImageEditor($image_name, $path);

// get the size of the image
list($width_orig, $height_orig, $image_type) = getimagesize($path . $image_name);

// calculate the aspect ratio
$aspect_ratio = (float) $height_orig / $width_orig;

// calculate new height
$thumb_height = round($thumb_width * $aspect_ratio);

while($thumb_height>$thumb_max_height)
{
    $thumb_width -= 10;
    $thumb_height = round($thumb_width * $aspect_ratio);
}

// resize
$imageEditor->resize($thumb_width, $thumb_height);

$imageEditor->outputFile($image_name, $paththumbnail);
$imageEditor->outputFile();

【讨论】：

【解决方案2】：

这是在 php 中调整图像大小的简单函数。只需传递所需的图像大小即可。

    /***********************************************************
    *       Custom Image Resize and cropping function
    ***********************************************************/
    function custom_resize($url, $width, $height = null, $crop = null, $single = true) {
        //echo '<br>Width :'.$width.'  Height'.$height;
        //validate inputs
        if (!$url OR !$width)
        return false;

        //define upload path & dir
        $upload_info = wp_upload_dir();
        $upload_dir = $upload_info['basedir'];
        $upload_url = $upload_info['baseurl'];

        //check if $img_url is local
        if (strpos($url, $upload_url) === false)
            return false;

        //define path of image
        $rel_path = str_replace($upload_url, '', $url);
        $img_path = $upload_dir . $rel_path;

        //check if img path exists, and is an image indeed
        if (!file_exists($img_path) OR !getimagesize($img_path))
        return false;

        //get image info
        $info = pathinfo($img_path);
        $ext = $info['extension'];
        list($orig_w, $orig_h) = getimagesize($img_path);

        //get image size after cropping
        $dims = image_resize_dimensions($orig_w, $orig_h, $width, $height, $crop);
        $dst_w = $dims[4];
        $dst_h = $dims[5];

        //use this to check if cropped image already exists, so we can return that instead
        $suffix = "{$dst_w}x{$dst_h}";
        $dst_rel_path = str_replace('.' . $ext, '', $rel_path);
        $destfilename = "{$upload_dir}{$dst_rel_path}-{$suffix}.{$ext}";

        if (!$dst_h) {
        //can't resize, so return original url
        //echo '<br>Width :'.$width.'  Height'.$height;
        $img_url = $url;
        $dst_w = $orig_w;
        $dst_h = $orig_h;
        }
        //else check if cache exists
        elseif (file_exists($destfilename) && getimagesize($destfilename)) {
        //echo '<br>Width :'.$width.'  Height'.$height;
        $img_url = "{$upload_url}{$dst_rel_path}-{$suffix}.{$ext}";
        }
        //else, we resize the image and return the new resized image url
        else {

        // Note: pre-3.5 fallback check 
        if (function_exists('wp_get_image_editor')) {

            $editor = wp_get_image_editor($img_path);

            if (is_wp_error($editor) || is_wp_error($editor->resize($width, $height, $crop)))
                return false;

            $resized_file = $editor->save();

            if (!is_wp_error($resized_file)) {
                $resized_rel_path = str_replace($upload_dir, '', $resized_file['path']);
                $img_url = $upload_url . $resized_rel_path;
            } else {
                return false;
            }
            } else {

                $resized_img_path = image_resize($img_path, $width, $height, $crop);
                if (!is_wp_error($resized_img_path)) {
                    $resized_rel_path = str_replace($upload_dir, '', $resized_img_path);
                    $img_url = $upload_url . $resized_rel_path;
                } else {
                    return false;
                }
            }
        }

        //return the output
        if ($single) {
        //str return
            $image = $img_url;
        } else {
        //array return
            $image = array(
                0 => $img_url,
                1 => $dst_w,
                2 => $dst_h
            );
        }
        return $image;
    }

 // ****************  Use of these function *********************

 <img src="<?php echo custom_resize($img_url,270,270,true); ?>" />

【讨论】：