PHP Imagick setResolution()用法及代碼示例

Imagick::setResolution()函數是PHP中的內置函數，用於設置圖像的分辨率。此函數不會更改圖像的實際分辨率，而隻是在讀取或創建圖像之前將其設置在Imagick對象中，要更改圖像分辨率，請使用setImageResolution()函數。在讀取圖像或創建圖像之前，需要先調用此函數。

用法:

bool Imagick::setResolution( float $x_resolution, float $y_resolution )

參數：該函數接受上述和以下描述的兩個參數：

• $x_resolution:它指定水平分辨率。
• $y_resolution:它指定垂直分辨率。

返回值：成功時此函數返回TRUE。

異常：該函數在錯誤時引發ImagickException。

以下示例程序旨在說明PHP中的Imagick::setResolution()函數：

程序1:

<?php 
  
// Create a new imagick object 
$imagick = new Imagick(); 
  
// Set the resolution 
$imagick->setResolution(18, 13); 
  
// Create new image 
$imagick->newimage(100, 100, 'none');    
  
// Read the properties of image 
print("<pre>".print_r($imagick->identifyImage(), true)."</pre>"); 
?>

輸出：

Array
(
[imageName] =>
[mimetype] => image/x-
[units] => Undefined
[type] => Bilevel
[colorSpace] => sRGB
[compression] => Undefined
[fileSize] => 0B
[geometry] => Array
(
[width] => 100
[height] => 100
)
// you can see the temporary resolution here
[resolution] => Array
(
[x] => 18
[y] => 13
)

[signature] => e7e2dcff542de95352682dc186432e98f0188084896773f1973276b0577d5305
)

程序2:

<?php 
  
// Create a new imagick object 
$imagick = new Imagick(); 
  
// Set the resolution 
$imagick->setResolution(10, 10); 
  
// Read the image 
$imagick->readimage( 
'https://media.geeksforgeeks.org/wp-content/uploads/geeksforgeeks-13.png'); 
  
// Read the properties of image 
print("<pre>".print_r($imagick->identifyImage(), true)."</pre>"); 
?>

Output:
Array
(
[imageName] =>
[mimetype] => image/png
[format] => PNG (Portable Network Graphics)
[units] => PixelsPerCentimeter
[type] => TrueColorAlpha
[colorSpace] => sRGB
[compression] => Zip
[fileSize] => 45.4KB
[geometry] => Array
(
[width] => 667
[height] => 184
)
// Here resolution is changed because new image is read
[resolution] => Array
(
[x] => 37.8
[y] => 37.8
)

[signature] => f64054f5bcb4cfb82c6126eff6d3d4e6be7d0e72d5620033442cecb4b9feabbd
)

參考： https://www.php.net/manual/en/imagick.setresolution.php