Scale an image using the given new width and height

# imagescale

(PHP 5 >= 5.5.0, PHP 7, PHP 8)

imagescale — Scale an image using the given new width and height

### 说明

function imagescale(
GdImage `$image`,
int `$width`,
int `$height` = -1,
int `$mode` = `IMG_BILINEAR_FIXED`
): GdImage|false

imagescale() 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.

### 参数

`image`
  由图象创建函数(例如imagecreatetruecolor())返回的 GdImage 对象。
`width`

  The width to scale the image to.

`height`

  The 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_WEIGHTED4` is not yet supported.

### 返回值

Return the scaled image object on success 或者在失败时返回 `false`.

### 错误／异常

Throws a ValueError if `width` or `height` would cause over-/underflow.

Throws a ValueError if `mode` is invalid.

### 更新日志

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。

### 参见

- imagecopyresized() - 拷贝部分图像并调整大小
- imagecopyresampled() - 重采样拷贝部分图像并调整大小

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