PHP draws elliptical arc

php editor Xigua introduces you how to draw elliptical arcs in PHP. An elliptical arc is a portion of an ellipse, often used to draw curves or shapes. In PHP, you can use the imagearc() function to draw an elliptical arc. By specifying parameters such as the starting angle, the ending angle, and the width and height of the ellipse, you can achieve elliptical arc effects of different shapes and sizes. Mastering the method of drawing elliptical arcs can add cooler visual effects to web pages and improve user experience.

PHP Draw elliptical arc

In php, you can use the imagearc() function to draw elliptical arcs. The parameters required by this function are as follows:

• image_resource: The image resource to draw the elliptical arc.
• cx: The x-coordinate of the center of the elliptical arc.
• cy: The y coordinate of the center of the elliptical arc.
• width: The width of the elliptical arc.
• height: The height of the elliptical arc.
• start: The starting angle of the elliptical arc (in degrees).
• end: The end angle of the elliptical arc (in degrees).
• color: The color of the elliptical arc.

The following is a sample code for drawing an elliptical arc using the imagearc() function:

<?php
header("Content-Type: image/png");

//Create a new image
$image = imagecreate(400, 400);

// assign color
$white = imagecolorallocate($image, 255, 255, 255);
$black = imagecolorallocate($image, 0, 0, 0);

//Draw elliptical arc
imagearc($image, 200, 200, 300, 200, 0, 360, $black);

//output image
imagepng($image);
imagedestroy($image);
?>

The above code will create a new image with a width of 400px and a height of 400px and draw a black elliptical arc in it from 0 degrees to 360 degrees.

Draw filled elliptical arc

To draw a filled elliptical arc, you can use the imagefilledarc() function. This function requires the same parameters as the imagearc() function, but adds an extra parameter:

• fill: The color used to fill the elliptical arc.

The following is a sample code for drawing a filled elliptical arc using the imagefilledarc() function:

<?php
header("Content-Type: image/png");

//Create a new image
$image = imagecreate(400, 400);

// assign color
$white = imagecolorallocate($image, 255, 255, 255);
$black = imagecolorallocate($image, 0, 0, 0);

//Draw filled elliptical arc
imagefilledarc($image, 200, 200, 300, 200, 0, 360, $black, IMG_ARC_PIE);

//output image
imagepng($image);
imagedestroy($image);
?>

The above code will create a new image with a width of 400px and a height of 400px and draw a black filled elliptical arc in it from 0 degrees to 360 degrees. The IMG_ARC_PIE constant in the imagefilledarc() function specifies that a sector be drawn.

Control the line width of the elliptical arc

To control the line width of the elliptical arc, you can use the imagesethickness() function. This function requires two parameters:

• image_resource: The image resource to set the line width.
• thickness: Line width in pixels.

The following is a sample code that uses the imagesethickness() function to set the line width of an elliptical arc:

<?php
header("Content-Type: image/png");

//Create a new image
$image = imagecreate(400, 400);

// assign color
$white = imagecolorallocate($image, 255, 255, 255);
$black = imagecolorallocate($image, 0, 0, 0);

//Set line width
imagesethickness($image, 5);

//Draw elliptical arc
imagearc($image, 200, 200, 300, 200, 0, 360, $black);

//output image
imagepng($image);
imagedestroy($image);
?>

The above code will create a new image with a width of 400px and a height of 400px, and draw a black elliptical arc with a line width of 5px in it.

Other tips

• You can use the imagecolortransparent() function to set the transparent color of the elliptical arc.
• You can use the imagecopymerge() function to merge elliptical arcs into an existing image.
• You can use the imagerotate() function to rotate the image before drawing the elliptical arc to obtain different effects.

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