Seemingly, you can't omit the width the same way you do with the height. If you write -1 for the width and specify a number for the height it will return false
(PHP 5 >= 5.5.0, PHP 7, PHP 8)
imagescale — Scale an image using the given new width and height
$image,$width,$height = -1,$mode = IMG_BILINEAR_FIXEDimagescale() scales an image using the given interpolation algorithm.
注意:
Unlike many of other image functions, imagescale() does not modify the passed
image; instead, a new image is returned.
image由图象创建函数(例如imagecreatetruecolor())返回的 GdImage 对象。
widthThe width to scale the image to.
heightThe height to scale the image to. If omitted or negative, the aspect ratio will be preserved.
mode
One of IMG_NEAREST_NEIGHBOUR,
IMG_BILINEAR_FIXED,
IMG_BICUBIC,
IMG_BICUBIC_FIXED or anything else (will use two
pass).
注意:
IMG_WEIGHTED4is not yet supported.
Return the scaled image object on success 或者在失败时返回 false.
Throws a ValueError if width
or height would cause over-/underflow.
Throws a ValueError if mode is invalid.
| 版本 | 说明 |
|---|---|
| 8.4.0 |
Now throws a ValueError if width
or height would cause over-/underflow.
|
| 8.4.0 |
Now throws a ValueError if mode is invalid.
|
| 8.0.0 | On success, this function returns a GDImage instance now; previously, a resource was returned. |
| 8.0.0 |
image 现在需要 GdImage 实例；之前需要有效的 gd resource。
|