我正在 PHP 中制作上传表单。虽然我希望表单上传一个精确的缩略图，比如说，100px 高和 100px 宽。表单必须在不拉伸图像的情况下重新缩放缩略图，而是从图像中删除一部分。我更喜欢用 100% php 和最简单的脚本来做这件事。我已经制作了上传表单，我只想知道如何用我的缩略图制作这个自动裁剪系统。
我真的希望你能帮助我，我想提前感谢你。
我的脚本已经上传了带有缩略图的图像：
if( $imgtype == 'image/jpeg' ){ $filetype= '.jpg'; }else{ $filetype= str_replace ( 'image/', '', $imgtype ); }
$path= 'images/' . md5( rand( 0, 1000 ) . rand( 0, 1000 ) . rand( 0, 1000 ) . rand( 0, 1000 ) ) . '.jpg';
$thumb_path= 'images/thumb_' . md5( rand( 0, 1000 ) . rand( 0, 1000 ) . rand( 0, 1000 ) . rand( 0, 1000 ) ) . '.jpg';
$imgsize2= getimagesize( $imgtemp );
$width= $imgsize2[0];
$height= $imgsize2[1];
$maxwidth= 1281;
$maxheight= 721;
$allowed= array( 'image/png', 'image/jpeg', 'image/gif', );
if( in_array( $imgtype, $allowed ) ){
if( $width < $maxwidth && $height < $maxheight ){
if( $imgsize < 5242880 ){
if( $width == $height ){ $case=1; }
if( $width > $height ){ $case=2; }
if( $width < $height ){ $case=3; }
switch( $case ){
case 1:
$newwidth= 100;
$newheight= 100;
break;
case 2:
$newheight= 100;
$ratio= $newheight / $height;
$newwidth= round( $width * $ratio );
break;
case 3:
$newwidth= 100;
$ratio= $newwidth / $width;
$newheight= $height * $ratio;
break;
}
switch( $imgtype ){
case 'image/jpeg';
$img= imagecreatefromjpeg( $imgtemp );
$thumb= imagecreatetruecolor( $newwidth, $newheight );
imagecopyresized( $thumb, $img, 0,0,0,0, $newwidth, $newheight, $width, $height );
imagejpeg( $thumb, $thumb_path );
break;
case 'image/png';
$img= imagecreatefrompng( $imgtemp );
$thumb= imagecreatetruecolor( $newwidth, $newheight );
imagecopyresized( $thumb, $img, 0,0,0,0, $newwidth, $newheight, $width, $height );
imagepng( $thumb, $thumb_path );
break;
case 'image/gif';
$img= imagecreatefromgif( $imgtemp );
$thumb= imagecreatetruecolor( $newwidth, $newheight );
imagecopyresized( $thumb, $img, 0,0,0,0, $newwidth, $newheight, $width, $height );
imagegif( $thumb, $thumb_path );
break;
} if(empty($errors)) {
move_uploaded_file( $imgtemp, $path );
$upimage = "Image is successfully uploaded.";
}
} else{
$errors[9] = "The image you just uploaded does not meet the requirements. Your picture is too large. ";
}
} else{
$errors[10] = "The image you just uploaded does not meet the requirements. It is a forbidden extension.";
}
} else{
$errors[11] = "The image you just uploaded does not meet the requirements. It is a forbidden extension. Type: $imgtype, $image, $imgsize, $imgtemp, $name";
}
if(empty($errors)) {
move_uploaded_file( $imgtemp, $path );
}
}