如何在调整上传图像大小时保持纵横比

Question

我有一个问题声明，需要保持上传图片的纵横比。

上传照片时，您需要创建三种尺寸，a) 310X230（缩略图）b) 960X400（细节图像）c) 原稿尺寸（全尺寸） 图像）将创建具有精确尺寸的尺寸。如果一张照片是 不在任何大小的相等纵横比中，然后缩放到该大小， 并裁剪多余的部分。

我已经实现了使用php GD库上传3种不同尺寸的图片，代码如下

    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

调整多个图像的大小和裁剪多个图像都相当复杂，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文：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成更小的可重用函数，例如计算不同图像的纵横比。