(PHP 5 >= 5.5.0, PHP 7)
imagecropauto — Crop an image automatically using one of the available modes
$image
[, int $mode = IMG_CROP_DEFAULT
[, float $threshold = .5
[, int $color = -1
]]] ) : resource
Automatically crops an image according to the given
mode.
image由图象创建函数(例如imagecreatetruecolor())返回的图象资源。
modeOne of the following constants:
IMG_CROP_DEFAULTIMG_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_TRANSPARENTIMG_CROP_BLACKIMG_CROP_WHITEIMG_CROP_SIDESIMG_CROP_THRESHOLDthreshold and
color.
thresholdSpecifies 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
thresholdyielded different results for system and bundled libgd.
colorEither an RGB color value or a palette index.
Used only in IMG_CROP_THRESHOLD mode.
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.
| 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.
|
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
}
?>
Please see the note on ImageCrop() that describes an extraneous black line at the bottom of the cropped image.
http://php.net/manual/en/function.imagecrop.php#119537
Bug 67447 applies to ImageCropAuto(), too.
https://bugs.php.net/bug.php?id=67447
In some cases the use of the IMG_CROP_WHITE or IMG_CROP_BLACK does not work. The function returns FALSE. It is best to use the IMG_CROP_THRESHOLD mode and specify the color in fourth argument as in the example below :
<?php
$original_img = imagecreatefromjpeg($image_path);
// Use this :
$cropped_img_white = imagecropauto($original_img , IMG_CROP_THRESHOLD, null, 16777215);
// Rather than :
$cropped_img_white = imagecropauto($original_img , IMG_CROP_WHITE);
// AND
// Use this :
$cropped_img_black = imagecropauto($original_img , IMG_CROP_THRESHOLD, null, 0);
// Rather than :
$cropped_img_black = imagecropauto($original_img , IMG_CROP_BLACK);
?>