如何在php中使用imagick？ （调整大小和裁剪）

Question

I use imagick for thumbnail crop, but sometimes cropped thumbnails are missing top part of the images (hair, eyes).

I was thinking to resize the image then crop it. Also, I need to keep the image size ratio.

Below is the php script I use for crop:

$im = new imagick( "img/20130815233205-8.jpg" );
$im->cropThumbnailImage( 80, 80 );
$im->writeImage( "thumb/th_80x80_test.jpg" );
echo '<img src="thumb/th_80x80_test.jpg">';

Thanks..

Answer 1

This task is not easy as the "important" part may not always be at the same place. Still, using something like this

$im = new imagick("c:\\temp\\523764_169105429888246_1540489537_n.jpg");
$imageprops = $im->getImageGeometry();
$width = $imageprops['width'];
$height = $imageprops['height'];
if($width > $height){
    $newHeight = 80;
    $newWidth = (80 / $height) * $width;
}else{
    $newWidth = 80;
    $newHeight = (80 / $width) * $height;
}
$im->resizeImage($newWidth,$newHeight, imagick::FILTER_LANCZOS, 0.9, true);
$im->cropImage (80,80,0,0);
$im->writeImage( "D:\\xampp\\htdocs\\th_80x80_test.jpg" );
echo '<img src="th_80x80_test.jpg">';

(tested)

should work. The cropImage parameters (0 and 0) determine the upper left corner of the cropping area. So playing with these gives you differnt results of what stays in the image.

Answer 2

Based on Martin's answer I made a more general function that resizes and crops Imagick image to fit given width and height (ie behaves exactly as CSS background-size: cover declaration):

/**
 * Resizes and crops $image to fit provided $width and $height.
 *
 * @param \Imagick $image
 *   Image to change.
 * @param int $width
 *   New desired width.
 * @param int $height
 *   New desired height.
 */
function image_cover(Imagick $image, $width, $height) {
  $ratio = $width / $height;

  // Original image dimensions.
  $old_width = $image->getImageWidth();
  $old_height = $image->getImageHeight();
  $old_ratio = $old_width / $old_height;

  // Determine new image dimensions to scale to.
  // Also determine cropping coordinates.
  if ($ratio > $old_ratio) {
    $new_width = $width;
    $new_height = $width / $old_width * $old_height;
    $crop_x = 0;
    $crop_y = intval(($new_height - $height) / 2);
  }
  else {
    $new_width = $height / $old_height * $old_width;
    $new_height = $height;
    $crop_x = intval(($new_width - $width) / 2);
    $crop_y = 0;
  }

  // Scale image to fit minimal of provided dimensions.
  $image->resizeImage($new_width, $new_height, imagick::FILTER_LANCZOS, 0.9, true);

  // Now crop image to exactly fit provided dimensions.
  $image->cropImage($new_width, $new_height, $crop_x, $crop_y);
}

Hope this may help somebody.