php - 从中心裁剪并在 PHP 中调整大小（函数）

Question

我想要一个功能，可以在不丢失纵横比的情况下调整图像的特定高度和重量。所以首先我想裁剪它然后调整它的大小。

这是我到目前为止得到的：

function image_resize($src, $dst, $width, $height, $crop=1){

  if(!list($w, $h) = getimagesize($src)) return "Unsupported picture type!";

  $type = strtolower(substr(strrchr($src,"."),1));
  if($type == 'jpeg') $type = 'jpg';
  switch($type){
    case 'bmp': $img = imagecreatefromwbmp($src); break;
    case 'gif': $img = imagecreatefromgif($src); break;
    case 'jpg': $img = imagecreatefromjpeg($src); break;
    case 'png': $img = imagecreatefrompng($src); break;
    default : return "Unsupported picture type!";
  }

  // resize
    $originalW = $w;
    $originalH = $h;

  if($crop){
    if($w < $width or $h < $height) return "Picture is too small!";
    $ratio = max($width/$w, $height/$h);
    $h = $height / $ratio;
    $x = ($w - $width / $ratio) / 2;
    $w = $width / $ratio;
  }
  else{
    if($w < $width and $h < $height) return "Picture is too small!";
    $ratio = min($width/$w, $height/$h);
    $width = $w * $ratio;
    $height = $h * $ratio;
    $x = 0;
  }

  $new = imagecreatetruecolor($width, $height);

  // preserve transparency
  if($type == "gif" or $type == "png"){
    imagecolortransparent($new, imagecolorallocatealpha($new, 0, 0, 0, 127));
    imagealphablending($new, false);
    imagesavealpha($new, true);
  }

  imagecopyresampled($new, $img, 0, 0, ($originalW - $width)/2, ($originalH - $height)/2, $width, $height, $w, $h);


  switch($type){
    case 'bmp': imagewbmp($new, $dst); break;
    case 'gif': imagegif($new, $dst); break;
    case 'jpg': imagejpeg($new, $dst); break;
    case 'png': imagepng($new, $dst); break;
  }
  return true;
}       

该功能工作正常。但我还是有问题。例如：当我将（300 × 450）的肖像图像调整为（260 × 140）时，我得到一个我不想要的黑色侧边栏。

这是2张图片：

Answer 1

它对我有用。你可以试试：

$x=288; $y=202; // my final thumb
$ratio_thumb=$x/$y; // ratio thumb

list($xx, $yy) = getimagesize($image); // original size
$ratio_original=$xx/$yy; // ratio original

if ($ratio_original>=$ratio_thumb) {
    $yo=$yy; 
    $xo=ceil(($yo*$x)/$y);
    $xo_ini=ceil(($xx-$xo)/2);
    $xy_ini=0;
} else {
    $xo=$xx; 
    $yo=ceil(($xo*$y)/$x);
    $xy_ini=ceil(($yy-$yo)/2);
    $xo_ini=0;
}

imagecopyresampled($thumb, $source, 0, 0, $xo_ini, $xy_ini, $x, $y, $xo, $yo);

Answer 2

适用于：

imagecopyresampled($new, $img, 0, 0, 0, 0, $width, $height, $w, $h);