在php中裁剪和调整图像大小

Question

我正在尝试裁剪和调整图像的大小。当图像移动到resized_images文件夹时，所有图像都变为黑色，但图像的大小会调整(535* 313)。这是我到目前为止已经尝试过的代码。你能建议我做这件事的正确方法吗？谢谢你

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<form action="" method="POST" enctype="multipart/form-data">
 <input id="input-6" name="slideshow_images[]" type="file" multiple class="file-loading">
 <input type="submit" name="sub" >
 </form>
<?php 
if(isset($_POST['sub']))
{
$pic =  $_FILES["slideshow_images"]["name"];	 
foreach($pic as $pic_src)
{  	
 
$image = imagecreatefromjpeg($pic_src);
$filename =  'resized_images/'.$pic_src.'cropped_whatever.jpeg';

$thumb_width = 535;

$thumb_height = 313;

$width = imagesx($image);
$height = imagesy($image);
 	
$original_aspect = $width / $height;
$thumb_aspect = $thumb_width / $thumb_height;
 
if ( $original_aspect >= $thumb_aspect )
{
   // If image is wider than thumbnail (in aspect ratio sense)
   $new_height = $thumb_height;
   $new_width = $width / ($height / $thumb_height);
}
else
{
   // If the thumbnail is wider than the image
   $new_width = $thumb_width;
   	
   $new_height = $height / ($width / $thumb_width);

    
   
 }

$thumb = imagecreatetruecolor( $thumb_width, $thumb_height );

// Resize and crop
imagecopyresampled($thumb,
                   $image,
                   0 - ($new_width - $thumb_width) / 2, // Center the image horizontally
                   0 - ($new_height - $thumb_height) / 2, // Center the image vertically
                   0, 0,
                   $new_width, $new_height,
                   $width, $height);
imagejpeg($thumb, $filename, 80);
}

}
  ?>

​

Answer 1

将代码行更改为：

$pic =  $_FILES["slideshow_images"]["tmp_name"];

$image = imagecreatefromstring(file_get_contents(($pic_src)));

因为name只有123.jpg，所以它不是object。

最好的方法是：

<form action="" method="POST" enctype="multipart/form-data">
 <input id="input-6" name="slideshow_images[]" type="file" multiple class="file-loading">
 <input type="submit" name="sub" >
 </form>
<?php 
if(isset($_POST['sub'])){
  if(isset($_FILES['slideshow_images'])){
    foreach ($_FILES["slideshow_images"]["error"] as $key => $error) {
      if ($error == UPLOAD_ERR_OK) {
        $tmp_name = $_FILES["slideshow_images"]["tmp_name"][$key];
        $name = $_FILES["slideshow_images"]["name"][$key];
          $image = imagecreatefromstring(file_get_contents(($tmp_name)));
          $filename = 'images/'.$name.'cropped_whatever.jpg';
          $thumb_width = 535;

          $thumb_height = 313;

          $width = imagesx($image);
          $height = imagesy($image);

          $original_aspect = $width / $height;
          $thumb_aspect = $thumb_width / $thumb_height;

          if ( $original_aspect >= $thumb_aspect )
          {
             // If image is wider than thumbnail (in aspect ratio sense)
             $new_height = $thumb_height;
             $new_width = $width / ($height / $thumb_height);
          }
          else
          {
             // If the thumbnail is wider than the image
             $new_width = $thumb_width;

             $new_height = $height / ($width / $thumb_width);



           }

          $thumb = imagecreatetruecolor( $thumb_width, $thumb_height );

          // Resize and crop
          imagecopyresampled($thumb,
                             $image,
                             0 - ($new_width - $thumb_width) / 2, // Center the image horizontally
                             0 - ($new_height - $thumb_height) / 2, // Center the image vertically
                             0, 0,
                             $new_width, $new_height,
                             $width, $height);
          imagejpeg($thumb, $filename, 80);
      }
    }
  }
}
  ?>

此外，如果您不想在文件名中添加".jpg“，请将$filename行替换为：

$filename = 'images/'.preg_replace('/\.[^.]*$/', '', $name).'cropped_whatever.jpg';

Answer 2

我刚刚遇到了这个问题。问题是背景颜色是黑色的，而且完全透明。你要做的就是分配一个真实的颜色(如白色)给alpha，并使alpha完全不透明。然后，只需先在新区域上做一个填充矩形，然后您的图像就会显示出来。:-)

以下内容直接摘自php文档中关于imagecopy的内容：

// create new image with padding
$img = imagecreatetruecolor($right-$left+$padding*2,$bottom-$top+$padding*2);
// Allocate background color
$white = imagecolorallocatealpha( $img, 255, 255, 255, 0 );
// fill the background
imagefill($img, 0, 0, $white);
// or use
imagefilledrectangle( $img, 0,0,$width,$height, $white );
// copy
imagecopy($img, $image, $padding, $padding, $left, $top, $right-$left, $bottom-$top);

请注意，在实际复制新图像之前，他们使用背景颜色进行了imagefill。对于imagecopyresample也是如此。

和以前不同的是，这一次我没有得到黑色的图像。因此，根据以下内容检查您所做的工作:实际上，下载以下内容并运行它(以及test.jpg映像)。看看它对你是否有效。请注意，这篇文章直接来自于imagecopyresample的PHP文档网站。

<?php
// The file
$filename = './test.jpg';
$percent = 0.5;

// Content type
header('Content-Type: image/jpeg');

// Get new dimensions
list($width, $height) = getimagesize($filename);
$new_width = $width * $percent;
$new_height = $height * $percent;

// Resample
$image_p = imagecreatetruecolor($new_width, $new_height);
$image = imagecreatefromjpeg($filename);
imagecopyresampled($image_p, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height);

// Output
imagejpeg($image_p, "new.jpg", 100);
?>

下面是图片：

​

​

下面是输出：

​