如何在调整上传图像大小时保持纵横比

Question

我有一个问题陈述需要保持上传图片的纵横比。

When a photo is uploaded, you will need to create three sizes, a) 310X230 (Thumnail) b) 960X400 (Detail Image) c) Original Size (Full Image) The sizes will be created with exact dimensions. If a photo is not in equal aspect ratio of any of the size, then scale to that size, and crop the extra portion.

我已经实现了使用 php GD 库和下面的代码上传 3 种不同尺寸的图像

    if($_SERVER["REQUEST_METHOD"] == "POST")
 {
    $image =$_FILES["file"]["name"];
    $uploadedfile = $_FILES['file']['tmp_name'];


    if ($image) 
    {

        $filename = stripslashes($_FILES['file']['name']);

        $extension = getExtension($filename);
        $extension = strtolower($extension);


 if (($extension != "jpg") && ($extension != "jpeg") && ($extension != "png") && ($extension != "gif")) 
        {

            $change='<div class="msgdiv">Unknown Image extension </div> ';
            $errors=1;
        }
        else
        {

 $size=filesize($_FILES['file']['tmp_name']);


if ($size > MAX_SIZE*1024)
{
    $change='<div class="msgdiv">You have exceeded the size limit!</div> ';
    $errors=1;
}


if($extension=="jpg" || $extension=="jpeg" )
{
$uploadedfile = $_FILES['file']['tmp_name'];
$src = imagecreatefromjpeg($uploadedfile);

}
else if($extension=="png")
{
$uploadedfile = $_FILES['file']['tmp_name'];
$src = imagecreatefrompng($uploadedfile);

}
else 
{
$src = imagecreatefromgif($uploadedfile);
}

//echo $src;

list($width,$height)=getimagesize($uploadedfile);


$newwidth=$width;
$newheight=($height/$width)*$newwidth;
$tmp=imagecreatetruecolor($newwidth,$newheight);


$newwidth1=310;
$newheight1=230;
$tmp1=imagecreatetruecolor($newwidth1,$newheight1);


$newwidth2=960;
$newheight2=400;
$tmp2=imagecreatetruecolor($newwidth2,$newheight2);

imagecopyresampled($tmp,$src,0,0,0,0,$newwidth,$newheight,$width,$height);

imagecopyresampled($tmp1,$src,0,0,0,0,$newwidth1,$newheight1,$width,$height);

imagecopyresampled($tmp2,$src,0,0,0,0,$newwidth2,$newheight2,$width,$height);

$filename = "images/medium/". $_FILES['file']['name'];

$filename1 = "images/thumbnail/small". $_FILES['file']['name'];

$filename2 = "images/full/". $_FILES['file']['name'];


imagejpeg($tmp,$filename,100);

imagejpeg($tmp1,$filename1,100);

imagejpeg($tmp2,$filename2,100);

imagedestroy($src);
imagedestroy($tmp);
imagedestroy($tmp1);
imagedestroy($tmp2);
}}

}

Answer 1

调整和裁剪多张图片非常复杂，但这里有一个可能适合您的解决方案：

 if($_SERVER["REQUEST_METHOD"] == "POST"){
    $image =$_FILES["file"]["name"];
    $uploadedfile = $_FILES['file']['tmp_name'];

    if($image){
        $filename = stripslashes($_FILES['file']['name']);
        $extension = getExtension($filename);
        $extension = strtolower($extension);

        if(($extension != "jpg") && ($extension != "jpeg") && ($extension != "png") && ($extension != "gif")) {
            $change='<div class="msgdiv">Unknown Image extension </div> ';
            $errors=1;
        } else {
            $size=filesize($_FILES['file']['tmp_name']);

            if($size > MAX_SIZE*1024){
                $change='<div class="msgdiv">You have exceeded the size limit!</div> ';
                $errors=1;
            }

            if($extension=="jpg" || $extension=="jpeg" ) {
                $uploadedfile = $_FILES['file']['tmp_name'];
                $src = imagecreatefromjpeg($uploadedfile);
            } else if($extension=="png"){
                $uploadedfile = $_FILES['file']['tmp_name'];
                $src = imagecreatefrompng($uploadedfile);
            } else {
                $src = imagecreatefromgif($uploadedfile);
            }


        list($width,$height)=getimagesize($uploadedfile);

        /* ORIGINAL ASPECT RATIO */     
        $original_aspect_ratio = $width / $height;

        /* RESIZE AND CROP THUMBNAIL (MEDIUM SIZE) */
        $new_width = 960; // SET DESIRED WIDTH
        $new_height = 400; // SET DESIRED HEIGHT    
        $new_aspect_ratio = $new_width / $new_height;

        if ($original_aspect_ratio > $new_aspect_ratio) {
            /* source image is wider */
            $temp_height = $new_height;
            $temp_width = (int) ($new_height * $original_aspect_ratio);
        } else {
            /* source image is similar or taller */
            $temp_width = $new_width;
            $temp_height = (int) ($new_width / $original_aspect_ratio);
        }

        /* Resize to a temporary GD image */
        $temp = imagecreatetruecolor($temp_width, $temp_height);
        imagecopyresampled($temp,$src,0,0,0,0,$temp_width,$temp_height,$width,$height);

        /* Copy cropped region from temporary image into the desired GD image */
        $x0 = ($temp_width - $new_width) / 2;
        $y0 = ($temp_height - $new_height) / 2;
        $medium = imagecreatetruecolor($new_width, $new_height);
        imagecopy($medium,$temp,0,0,$x0,$y0,$new_width,$new_height);

        /* SAVE TO FILE AND CLEAN UP */
        imagedestroy($temp);// CLEANUP TEMP IMAGE
        $medium_filename = "images/medium/". $_FILES['file']['name'];
        imagejpeg($medium,$medium_filename,100);
        imagedestroy($medium);

        /* RESIZE AND CROP SMALL IMAGES, SAME PROCEDURE AS ABOVE */
        $new_width = 310; // SET DESIRED WIDTH
        $new_height = 230; // SET DESIRED HEIGHT    
        $new_aspect_ratio = $new_width / $new_height;

        if ($original_aspect_ratio > $new_aspect_ratio) {
            $temp_height = $new_height;
            $temp_width = (int) ($new_height * $original_aspect_ratio);
        } else {
            $temp_width = $new_width;
            $temp_height = (int) ($new_width / $original_aspect_ratio);
        }

        $temp = imagecreatetruecolor($temp_width, $temp_height);
        imagecopyresampled($temp,$src,0,0,0,0,$temp_width,$temp_height,$width,$height);

        $x0 = ($temp_width - $new_width) / 2;
        $y0 = ($temp_height - $new_height) / 2;
        $small = imagecreatetruecolor($new_width, $new_height);
        imagecopy($small,$temp,0,0,$x0,$y0,$new_width,$new_height);

        /* SAVE TO FILE AND CLEAN UP */
        imagedestroy($temp);// CLEANUP TEMP IMAGE
        $small_filename = "images/thumbnail/small". $_FILES['file']['name'];
        imagejpeg($small,$small_filename,100);
        imagedestroy($small);


        /* ORIGINAL SIZE. NO RESIZING OR CROPPING... NOT NEEDED? YOU DECIDE... */           
        $full=imagecreatetruecolor($width,$height);
        imagecopyresampled($full,$src,0,0,0,0,$width,$height,$width,$height);

        /* SAVE TO FILE AND CLEAN UP */
        $full_filename = "images/full/". $_FILES['file']['name']; // ORIGINAL
        imagejpeg($full,$full_filename,100);
        imagedestroy($full);

        imagedestroy($src); // CLEAN UP ORIGINAL SOURCE FILE

        }
    }
}

代码未经测试，主要灵感来自这篇博客post：http://salman-w.blogspot.se/2009/04/crop-to-fit-image-using-aspphp.html

我建议的解决方案中有很多重复代码，因为您有多个图像。您可以考虑将一些重复的代码分块为更小的可重用函数，例如计算不同图像的纵横比。

如何在调整上传图像大小时保持纵横比

How to maintain aspect ratio while resizing the uploaded image

php

gd