imagecropauto

(PHP 5 >= 5.5.0, PHP 7)

imagecropauto — Crop an image automatically using one of the available modes

说明

imagecropauto ( resource $image [, int $mode = IMG_CROP_DEFAULT [, float $threshold = .5 [, int $color = -1 ]]] ) : resource

Automatically crops an image according to the given mode.

参数

image

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

mode

One of the following constants:

IMG_CROP_DEFAULT
Same as IMG_CROP_TRANSPARENT. Before PHP 7.4.0, the bundled libgd fell back to IMG_CROP_SIDES, if the image had no transparent color.
IMG_CROP_TRANSPARENT
Crops out a transparent background.
IMG_CROP_BLACK
Crops out a black background.
IMG_CROP_WHITE
Crops out a white background.
IMG_CROP_SIDES
Uses the 4 corners of the image to attempt to detect the background to crop.
IMG_CROP_THRESHOLD
Crops an image using the given threshold and color.
threshold

Specifies the tolerance in percent to be used while comparing the image color and the color to crop. The method used to calculate the color difference is based on the color distance in the RGB(a) cube.

Used only in IMG_CROP_THRESHOLD mode.

Note: Before PHP 7.4.0, the bundled libgd used a somewhat different algorithm, so the same threshold yielded different results for system and bundled libgd.

color

Either an RGB color value or a palette index.

Used only in IMG_CROP_THRESHOLD mode.

返回值

Returns a cropped image resource on success 或者在失败时返回 FALSE. If the complete image was cropped, imagecrop() returns FALSE.

更新日志

版本 说明
7.4.0 The behavior of imagecropauto() in the bundled libgd has been synced with that of system libgd: IMG_CROP_DEFAULT no longer falls back to IMG_CROP_SIDES and threshold-cropping now uses the same algorithm as system libgd.
7.4.0 The default value of mode has been changed to IMG_CROP_AUTO. Formerly, the default value has been -1 which corresponds to IMG_CROP_DEFAULT, but passing -1 is now deprecated.

范例

Example #1 Proper handling of auto-cropping

As noted in the return value section, imagecropauto() returns FALSE if the whole image was cropped. In this example we have an image resource $im which should be automatically cropped only if there is something to crop; otherwise we want to proceed with the original image.

<?php
$cropped = imagecropauto($im, IMG_CROP_DEFAULT);
if ($cropped !== false) { // in case a new image resource was returned
    imagedestroy($im);    // we destroy the original image
    $im = $cropped;       // and assign the cropped image to $im
}
?>

参见