Sets the image opacity level

# Imagick::setImageOpacity

(PECL imagick 2, PECL imagick 3)

Imagick::setImageOpacity — Sets the image opacity level

警告

此函数在 Imagick 3.4.4 中被 废弃，强烈建议不要应用此函数。

### 说明

public function Imagick::setImageOpacity(float `$opacity`): bool

Sets the image to the specified opacity level. 此方法在Imagick基于ImageMagick 6.3.1以上版本编译时可用。 This method operates on all channels, which means that for example opacity value of 0.5 will set all transparent areas to partially opaque. To add transparency to areas that are not already transparent use Imagick::evaluateImage()

### 参数

`opacity`

  The level of transparency: 1.0 is fully opaque and 0.0 is fully transparent.

### 返回值

成功时返回 `true`。

### 示例

示例 #1 A Imagick::setImageOpacity() example

An example of using Imagick::setImageOpacity()

    <?php
    /* Create the object */
    $image = new Imagick('source.png');

    /* Set the opacity */
    $image->setImageOpacity(0.7);

    /* output the image */
    header('Content-type: image/png');
    echo $image;

    ?>

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