imageflip

(PHP 5 >= 5.5.0, PHP 7)

imageflip — Flips an image using a given mode

说明

imageflip ( resource $image , int $mode ) : bool

Flips the image image using the given mode.

参数

image

由图象创建函数(例如imagecreatetruecolor())返回的图象资源。

mode

Flip mode, this can be one of the IMG_FLIP_* constants:

Constant Meaning
IMG_FLIP_HORIZONTAL Flips the image horizontally.
IMG_FLIP_VERTICAL Flips the image vertically.
IMG_FLIP_BOTH Flips the image both horizontally and vertically.

返回值

成功时返回 TRUE， 或者在失败时返回 FALSE。

范例

Example #1 Flips an image vertically

This example uses the IMG_FLIP_VERTICAL constant.

<?php
// File
$filename = 'phplogo.png';

// Content type
header('Content-type: image/png');

// Load
$im = imagecreatefrompng($filename);

// Flip it vertically
imageflip($im, IMG_FLIP_VERTICAL);

// Output
imagejpeg($im);
imagedestroy($im);
?>

以上例程的输出类似于：

Output of example: Vertically flipped image

Example #2 Flips the image horizontally

This example uses the IMG_FLIP_HORIZONTAL constant.

<?php
// File
$filename = 'phplogo.png';

// Content type
header('Content-type: image/png');

// Load
$im = imagecreatefrompng($filename);

// Flip it horizontally
imageflip($im, IMG_FLIP_HORIZONTAL);

// Output
imagejpeg($im);
imagedestroy($im);
?>

以上例程的输出类似于：

Output of example: Horizontally flipped image

User Contributed Notes

Daniel Klein 04-Feb-2016 01:26
If you're using PHP < 5.5 you can use this code to add the same functionality. If you pass the wrong $mode in it will silently fail. You might want to add your own error handling for this case.

<?php
if (!function_exists('imageflip')) {
  define('IMG_FLIP_HORIZONTAL', 0);
  define('IMG_FLIP_VERTICAL', 1);
  define('IMG_FLIP_BOTH', 2);

  function imageflip($image, $mode) {
    switch ($mode) {
      case IMG_FLIP_HORIZONTAL: {
        $max_x = imagesx($image) - 1;
        $half_x = $max_x / 2;
        $sy = imagesy($image);
        $temp_image = imageistruecolor($image)? imagecreatetruecolor(1, $sy): imagecreate(1, $sy);
        for ($x = 0; $x < $half_x; ++$x) {
          imagecopy($temp_image, $image, 0, 0, $x, 0, 1, $sy);
          imagecopy($image, $image, $x, 0, $max_x - $x, 0, 1, $sy);
          imagecopy($image, $temp_image, $max_x - $x, 0, 0, 0, 1, $sy);
        }
        break;
      }
      case IMG_FLIP_VERTICAL: {
        $sx = imagesx($image);
        $max_y = imagesy($image) - 1;
        $half_y = $max_y / 2;
        $temp_image = imageistruecolor($image)? imagecreatetruecolor($sx, 1): imagecreate($sx, 1);
        for ($y = 0; $y < $half_y; ++$y) {
          imagecopy($temp_image, $image, 0, 0, 0, $y, $sx, 1);
          imagecopy($image, $image, 0, $y, 0, $max_y - $y, $sx, 1);
          imagecopy($image, $temp_image, 0, $max_y - $y, 0, 0, $sx, 1);
        }
        break;
      }
      case IMG_FLIP_BOTH: {
        $sx = imagesx($image);
        $sy = imagesy($image);
        $temp_image = imagerotate($image, 180, 0);
        imagecopy($image, $temp_image, 0, 0, 0, 0, $sx, $sy);
        break;
      }
      default: {
        return;
      }
    }
    imagedestroy($temp_image);
  }
}
?>