imagefilledarc(): arc using PHP GD

<?Php
header ("Content-type: image/jpeg");
$width=300;$height=300;
$im = @ImageCreate ($width,$height) // added one pixel for border
or die ("Cannot Initialize new GD image stream");
$background_color = ImageColorAllocate ($im, 255, 255, 255);
$filled_color = ImageColorAllocate ($im, 255, 0,0);
imagefilledarc($im,150,150,290,290,0,160,$filled_color,IMG_ARC_PIE);
Imagejpeg($im);
imagedestroy($im); //memory cleared. 
?>

imagefilledarc($image,$center_x,$center_y,$width,$height,
	$start_angle,$end_angle,$color,$style)

Creating full circle using imagefilledarc()

Example

<?Php
header ("Content-type: image/jpeg");
$width=300;$height=300;
$im = @ImageCreate ($width,$height) // added one pixel for border
or die ("Cannot Initialize new GD image stream");

$background_color = ImageColorAllocate ($im, 255, 255, 255);
$text_color = ImageColorAllocate ($im, 255, 0,0);
imagearc($im,150,150,290,290,0,360,$text_color); // outer face
imagearc($im,80,100,50,50,0,360,$text_color); // left eye 
imagearc($im,220,100,50,50,0,360,$text_color); // right eye
imagearc($im,150,150,150,150,45,135,$text_color); // mouth

$text_color = ImageColorAllocate ($im, 128, 128,0);
imagefilledarc($im,80,100,20,20,0,360,$text_color,IMG_ARC_PIE); // left eye ball 
imagefilledarc($im,220,100,20,20,0,360,$text_color,IMG_ARC_PIE); // right eye ball 

Imagejpeg($im);
imagedestroy($im); //memory cleared. 
?>

$move_left=0; $move_top=15;

$move_left=15; $move_top=0;

$move_left=0; // x position is not changed 
$move_top=15; // Y position is moved up 
imagefilledarc($im,80-$move_left,100-$move_top,20,20,0,360,$text_color,IMG_ARC_PIE); // left eye ball 
imagefilledarc($im,220-$move_left,100-$move_top,20,20,0,360,$text_color,IMG_ARC_PIE); // right eye ball 

Concentric circle using imagefilledarc()

<?Php
header ("Content-type: image/jpeg");
$width=301;$height=301;
$im = @ImageCreate ($width,$height) // added one pixel for border
or die ("Cannot Initialize new GD image stream");
$gap=20; // change this value to increase the lines 
$background_color = ImageColorAllocate ($im, 255, 255, 255);
imagesetthickness($im,1);
$text_color = ImageColorAllocate ($im, 255, 0,0);
for($i=0;$i<=$width;$i +=$gap){
$r=rand(1,255); // random numbers 
$g=rand(1,255);  
$b=rand(1,255);	
$text_color = ImageColorAllocate ($im, $r, $g,$b);		
imagefilledarc($im,$width/2,$height/2,($width)-$i,($height)-$i,0,360,$text_color,IMG_ARC_PIE);
}

Imagejpeg ($im);
imagedestroy($im); //memory is removed. 
?>

imagefilledarc($im,$width/2,$height/2,$width,$height,$i,$i+$gap,$text_color,IMG_ARC_PIE);

How to create a Pie chart by using GD Library imagefilledarc()

Creating dynamic pie charts in PHP is possible using the GD library. By defining color-coded sections and calculating the proportional angles, we can generate a pie chart image. This example demonstrates how to use `imagefilledarc()` to create a simple pie chart with different colors for each segment.

<?php
header ("Content-type: image/jpeg"); // Set content type to display image

$width = 300;
$height = 300;
$image = imagecreate($width, $height);

// Define colors
$white = imagecolorallocate($image, 255, 255, 255);
$colors = [
    imagecolorallocate($image, 255, 0, 0),   // Red
    imagecolorallocate($image, 0, 255, 0),   // Green
    imagecolorallocate($image, 0, 0, 255),   // Blue
    imagecolorallocate($image, 255, 255, 0)    // Yellow
];

// Sample data for the pie chart
$data = [10, 10, 25, 25]; 

$my_sum = array_sum($data); // Calculate sum of data values

$start_angle = 0; // Start angle for first slice
$center_x = $width / 2;
$center_y = $height / 2;
$radius = 100; // Radius of pie chart

// Loop through data and draw pie chart slices
foreach ($data as $index => $value) {
    $end_angle = $start_angle + ($value * 360 / $my_sum);
    
    imagefilledarc($image, $center_x, $center_y, 
        $radius * 2, $radius * 2, 
        $start_angle, $end_angle, $colors[$index], IMG_ARC_PIE);
    
    $start_angle = $end_angle; // Update start angle for next slice
}

// Output the image as PNG format
imagepng($image);
imagedestroy($image); // Free up memory
?>

Code Explanation

• Initializing the Canvas: We create an image with a specified width and height using imagecreate().
• Defining Colors: Colors are assigned using imagecolorallocate(), with an array to store multiple segment colors.
• Data Handling: The script calculates the total sum of values and determines the proportion of each slice.
• Drawing the Pie Chart: Using a loop, each segment is drawn using imagefilledarc(), ensuring the correct start and end angles.
• Outputting the Image: The generated pie chart is displayed using imagepng(), and memory is freed with imagedestroy().

This method is lightweight and efficient, making it ideal for generating reports, statistics, and visual data representations in PHP applications.

Including this graph in a web page

<img src="test1.php?time=<?php echo time(); ?>" alt="Dynamic Image">