crop an image after resizing in GD library

问题

I need to first resize an image proportionally (the width is the important dimension) and then crop afterwards to chop of any excess height and then store the new version in a directory.

I've managed to do the resizing fine and I end up with images that are the correct width in my directory. Somehwere in here I need to crop the excess height off. But I can't work out where I need to do it. Do I need to use copyimageresampled somehow. I want to crop all images so they're 50px in height.

Here's what I have so far fo the resizing:

$src = ImageCreateFromJpeg($upfile);
$dst = ImageCreateTrueColor($tn_width, $tn_height);
ImageCopyResized($dst, $src, 0, 0, 0, 0, $tn_width, $tn_height, $width, $height);
ImageJpeg($dst, 'images/' . $_FILES['image']['name']);

回答1:

This is what I was after. A 2 stage process. The trick is to resize the image in to a temporary image and then crop it:

http://salman-w.blogspot.com/2009/04/crop-to-fit-image-using-aspphp.html

回答2:

This might help you to crop after resize: 911-need-code-help

<?php
  //----------------------------------------------------------------
  // Crop-to-fit PHP-GD
  // Revision 2 [2009-06-01]
  // Corrected aspect ratio of the output image
  //----------------------------------------------------------------

  define( 'DESIRED_IMAGE_WIDTH', 150 );
  define( 'DESIRED_IMAGE_HEIGHT', 150 );

  $source_path = $_FILES[ 'Image1' ][ 'tmp_name' ];

  //
  // Add file validation code here
  //

  list( $source_width, $source_height, $source_type ) = getimagesize( $source_path );

  switch ( $source_type )
  {
    case IMAGETYPE_GIF:
      $source_gdim = imagecreatefromgif( $source_path );
      break;

    case IMAGETYPE_JPEG:
      $source_gdim = imagecreatefromjpeg( $source_path );
      break;

    case IMAGETYPE_PNG:
      $source_gdim = imagecreatefrompng( $source_path );
      break;
  }

  $source_aspect_ratio = $source_width / $source_height;
  $desired_aspect_ratio = DESIRED_IMAGE_WIDTH / DESIRED_IMAGE_HEIGHT;

  if ( $source_aspect_ratio > $desired_aspect_ratio )
  {
    //
    // Triggered when source image is wider
    //
    $temp_height = DESIRED_IMAGE_HEIGHT;
    $temp_width = ( int ) ( DESIRED_IMAGE_HEIGHT * $source_aspect_ratio );
  }
  else
  {
    //
    // Triggered otherwise (i.e. source image is similar or taller)
    //
    $temp_width = DESIRED_IMAGE_WIDTH;
    $temp_height = ( int ) ( DESIRED_IMAGE_WIDTH / $source_aspect_ratio );
  }

  //
  // Resize the image into a temporary GD image
  //

  $temp_gdim = imagecreatetruecolor( $temp_width, $temp_height );
  imagecopyresampled(
    $temp_gdim,
    $source_gdim,
    0, 0,
    0, 0,
    $temp_width, $temp_height,
    $source_width, $source_height
  );

  //
  // Copy cropped region from temporary image into the desired GD image
  //

  $x0 = ( $temp_width - DESIRED_IMAGE_WIDTH ) / 2;
  $y0 = ( $temp_height - DESIRED_IMAGE_HEIGHT ) / 2;

  $desired_gdim = imagecreatetruecolor( DESIRED_IMAGE_WIDTH, DESIRED_IMAGE_HEIGHT );
  imagecopy(
    $desired_gdim,
    $temp_gdim,
    0, 0,
    $x0, $y0,
    DESIRED_IMAGE_WIDTH, DESIRED_IMAGE_HEIGHT
  );

  //
  // Render the image
  // Alternatively, you can save the image in file-system or database
  //

  header( 'Content-type: image/jpeg' );
  imagejpeg( $desired_gdim );

  //
  // Add clean-up code here
  //
?>

回答3:

Croping is just like resizing with GD

Some sample code:

// Original image
$filename = 'someimage.jpg';

// Get dimensions of the original image
list($current_width, $current_height) = getimagesize($filename);

// The x and y coordinates on the original image where we
// will begin cropping the image
$left = 50;
$top = 50;

// This will be the final size of the image (e.g. how many pixels
// left and down we will be going)
$crop_width = 200;
$crop_height = 200;

// Resample the image
$canvas = imagecreatetruecolor($crop_width, $crop_height);
$current_image = imagecreatefromjpeg($filename);
imagecopy($canvas, $current_image, 0, 0, $left, $top, $current_width, $current_height);
imagejpeg($canvas, $filename, 100);

You define your crop width & height, and should be all set. Its not much more than a resize as you can see.

Reference: http://www.johnconde.net/blog/cropping-an-image-with-php-and-the-gd-library/

来源：https://stackoverflow.com/questions/8929759/crop-an-image-after-resizing-in-gd-library

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