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English
In PHP, you first need to ensure that the GD library is enabled. If you're not sure whether it is enabled, you can check it by running the following code:
<?php
if (function_exists('gd_info')) {
echo "GD library is enabled!";
} else {
echo "GD library is not enabled.";
}
?>
If you see the message "GD library is enabled!", it means the GD library is active. If it is not enabled, you will need to install it based on your environment.
We will start by using imagefilledarc to draw an arc. imagefilledarc allows us to draw a filled arc on an image.
<?php
// Create a 400x400 image canvas
$image = imagecreatetruecolor(400, 400);
<p>// Set the background color (white)<br>
$background_color = imagecolorallocate($image, 255, 255, 255);<br>
imagefill($image, 0, 0, $background_color);</p>
<p>// Set the arc color (red)<br>
$arc_color = imagecolorallocate($image, 255, 0, 0);</p>
<p>// Draw a red arc<br>
imagefilledarc($image, 200, 200, 300, 300, 0, 180, $arc_color, IMG_ARC_PIE);</p>
<p>// Output the image<br>
header("Content-Type: image/png");<br>
imagepng($image);<br>
imagedestroy($image);<br>
?><br>
In this code, we created a 400x400 canvas and drew a red arc on it. The arc starts at an angle of 0 degrees and ends at 180 degrees, forming a semicircle.
Next, we will use imageconvolution to apply a blur effect to the arc image. The imageconvolution function is a powerful image processing tool that applies a convolution matrix to the image.
First, let's define a simple blur convolution matrix:
<?php
// Create the image canvas
$image = imagecreatetruecolor(400, 400);
<p>// Set the background color<br>
$background_color = imagecolorallocate($image, 255, 255, 255);<br>
imagefill($image, 0, 0, $background_color);</p>
<p>// Set the arc color<br>
$arc_color = imagecolorallocate($image, 255, 0, 0);</p>
<p>// Draw the arc<br>
imagefilledarc($image, 200, 200, 300, 300, 0, 180, $arc_color, IMG_ARC_PIE);</p>
<p>// Define the blur convolution matrix<br>
$matrix = [<br>
[1 / 9, 1 / 9, 1 / 9],<br>
[1 / 9, 1 / 9, 1 / 9],<br>
[1 / 9, 1 / 9, 1 / 9]<br>
];</p>
<p>// Apply the convolution matrix for blur effect<br>
imageconvolution($image, $matrix, 9, 0);</p>
<p>// Output the image<br>
header("Content-Type: image/png");<br>
imagepng($image);<br>
imagedestroy($image);<br>
?><br>
In this code, we defined a 3x3 blur convolution matrix, which averages the color values of each pixel with its surrounding pixels to create the blur effect.
By combining the arc drawn with imagefilledarc and the blur effect from imageconvolution, we can create a blurred arc image. This type of effect is commonly used in UI design and special effects processing, giving the image a softer and more layered appearance.
Through this tutorial, we learned how to use PHP's imagefilledarc and imageconvolution functions to create a blurred arc image. These functions help developers add rich image effects to web applications, enhancing the user experience.
If you wish to explore more image effects, refer to the official PHP documentation or other image processing tutorials. These tools and techniques extend beyond arcs and blur, allowing for more complex convolution matrices and color processing to create even richer visual effects.
