Creates random art

placeholder-image-generator.php

<?php

/**
 * Copyright (c) 2025 Sybre Waaijer, CyberWire B.V.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

/**
 * Get placeholder image
 *
 * @since 0.0.1184
 *
 * @param $params array {
 *    Optional. Parameters for the image.
 *
 *    @type int $width  Width of the image in pixels. Default is 192.
 *    @type int $height Height of the image in pixels. Default is 192.
 * }
 * @return \WP_REST_Response
 */
function get_placeholder_image( $params ) {

	$width  = $params['width'] ?? 192;
	$height = $params['height'] ?? 192;

	if ( ! \extension_loaded( 'gd' ) )
		return new \WP_REST_Response(
			[ 'message' => 'GD extension is not enabled.' ],
			503,
		);

	// Create image
	$image = \imagecreatetruecolor( $width, $height );

	if ( ! $image )
		return new \WP_REST_Response(
			[ 'message' => 'Failed to create image resource.' ],
			500,
		);

	// Enable alpha blending
	\imagealphablending( $image, true );
	\imagesavealpha( $image, true );

	// Calculate scale factors from base SVG of 512x512
	$scale_x = $width / 512;
	$scale_y = $height / 512;

	// Helper function to scale point arrays
	$scale_points = fn( $points ) => \array_map(
		fn( $value, $index ) => (int) ( $index & 1
			? $value * $scale_y
			: $value * $scale_x ),
		$points,
		\array_keys( $points ),
	);

	// Helper function to add random variation to points
	$randomize_points = fn( $points, $variation = 5 ) => \array_map(
		fn( $value ) => $value + mt_rand( -$variation, $variation ),
		$points,
		\array_keys( $points ),
	);

	// Fill background
	\imagefill(
		$image,
		0,
		0,
		\imagecolorallocate(
			$image,
			mt_rand( 175, 225 ), // 255-80, 255-30
			mt_rand( 165, 215 ), // 255-90, 255-40
			mt_rand( 170, 220 ), // 255-85, 255-35
		),
	);

	$body_color   = \imagecolorallocatealpha(
		$image,
		mt_rand( 0, 75 ),    // 255-255, 255-180
		mt_rand( 75, 135 ),  // 255-180, 255-120
		mt_rand( 35, 105 ),  // 255-220, 255-150
		mt_rand( 20, 50 ),
	);
	$accent_color = \imagecolorallocatealpha(
		$image,
		mt_rand( 0, 55 ),    // 255-255, 255-200
		mt_rand( 105, 155 ), // 255-150, 255-100
		mt_rand( 25, 95 ),   // 255-230, 255-160
		mt_rand( 30, 70 ),
	);

	// phpcs:disable WordPress.Arrays.ArrayDeclarationSpacing.ArrayItemNoNewLine -- let's not.
	// Body and head
	\imagefilledpolygon(
		$image,
		$scale_points( $randomize_points(
			[
				471.82, 171.1, 459.8, 157.49, 443.37, 121.01, 441.78, 110.92,
				435.07, 106.86, 418.28, 89.36, 418.28, 89.36, 427.45, 81.78,
				424.82, 72.04, 424.82, 72.04, 423.72, 78.74, 406.44, 80.34,
				395.34, 81.37, 391.57, 85.11, 391.57, 85.11, 391.52, 85.15,
				391.47, 85.15, 387.03, 81.87, 376.94, 81.96, 365.95, 85.34,
				349.77, 88.08, 334.7, 95.77, 322.96, 107.54, 308.09, 122.42,
				299.72, 142.56, 299.67, 163.59, 299.62, 185.57, 281.87, 203.55,
				259.89, 203.55, 141.65, 203.55, 119.68, 203.55, 101.87, 221.36,
				101.87, 241.33, 101.87, 440.22, 141.65, 440.22, 141.65, 340.77, // left leg start
				// 152.2, 340.77, 162.32, 336.57, 169.77, 329.12, 177.23, 321.66, // hip start -- commented because it tends to create a penis
				181.42, 311.54, 181.42, 301.01, 181.42, 290.48, 203.29, 309.06, // belly start
				231.61, 320.9, 261.17, 320.9, 274.73, 320.82, 288.29, 318.41, // right leg start
				301.05, 313.81, 301.05, 440.24, 340.83, 440.24, 340.83, 291.11,
				366.06, 268.56, 380.51, 236.34, 380.61, 202.49, 380.61, 202.47,
				380.61, 162.71, 381.06, 162.71, 381.48, 162.67, 381.9, 162.61, // chin start
				383.93, 167.7, 390.23, 175.96, 409.74, 179.84, 439.07, 185.67,
				437.35, 194.39, 438.9, 200.51, 441.29, 209.96, 459.19, 209.66,
				// 463.02, 202.63, 464.61, 199.71, 470.71, 202.53, 473.19, 199.18, // mouth start
				// 474.41, 197.46, 473.8, 193.96, 476.37, 191.95, 483.46, 186.48, // -- commented for it creates too much noise
				481.28, 181.81, 471.82, 171.1,
			],
			mt_rand( 0, 15 ),
		) ),
		$body_color,
	);
	// Foot
	\imagefilledpolygon(
		$image,
		$scale_points( $randomize_points(
			[
				368.39, 313.98, 368.39, 313.98, 400.68, 313.98, 400.68, 322.44,
				397.31, 339.02, 391.32, 345.01, 385.33, 350.99, 377.21, 354.36,
				368.75, 354.36, 368.75, 386.28, 385.67, 386.28, 401.91, 380.04,
				413.88, 368.07, 425.85, 356.1, 432.59, 339.86, 432.59, 322.94,
				432.59, 291.02, 400.68, 291.02, 400.31, 291.02, 382.68, 282.06,
				368.39, 296.35, 368.39, 313.98,
			],
			mt_rand( 0, 5 ),
		) ),
		$accent_color,
	);
	// Tail
	\imagefilledpolygon(
		$image,
		$scale_points( $randomize_points(
			[
				33.93, 242.28, 33.93, 361.62, 73.71, 361.62, 73.71, 202.5,
				73.71, 202.5, 51.74, 202.5, 33.93, 220.31, 33.93, 242.28,
			],
			mt_rand( 0, 15 ),
		) ),
		$accent_color,
	);
	// phpcs:enable WordPress.Arrays.ArrayDeclarationSpacing.ArrayItemNoNewLine

	// Make random rectangle coordinates, opposing the sides
	$flip_rect_bias_x = mt_rand( 0, 1 );
	$flip_rect_bias_y = mt_rand( 0, 1 );
	for ( $i = mt_rand( 1, 2 ); $i--; ) {
		$biased_x = $flip_rect_bias_x
			? mt_rand( 275, 450 ) // bias right
			: mt_rand( 50, 175 ); // bias left

		$biased_y = $flip_rect_bias_y
			? mt_rand( 275, 450 ) // bias bottom
			: mt_rand( 50, 175 ); // bias top

		// Toggle bias for next rectangle
		$flip_rect_bias_x = ! $flip_rect_bias_x;
		$flip_rect_bias_y = ! $flip_rect_bias_y;

		// Generate dimensions with rectangular bias
		$_width  = mt_rand( 60, 180 );
		$_height = mt_rand( 20, 80 );

		// Randomly swap width/height to create both horizontal and vertical rectangles
		if ( mt_rand( 0, 1 ) ) {
			$__width = $_width; // Store original width
			$_width  = $_height;
			$_height = $__width;
		}

		$random_rect = [
			$biased_x,
			$biased_y,
			$_width,
			$_height,
		];

		$scaled_rect = \array_map(
			fn( $value, $index ) => (int) ( $value * (
				$index & 1 ? $scale_y : $scale_x
			) ),
			$random_rect,
			\array_keys( $random_rect )
		);

		$rect_color = \imagecolorallocatealpha(
			$image,
			mt_rand( 100, 255 ),
			mt_rand( 100, 255 ),
			mt_rand( 100, 255 ),
			mt_rand( 40, 80 ),
		);

		\imagefilledrectangle(
			$image,
			$scaled_rect[0],
			$scaled_rect[1],
			$scaled_rect[0] + $scaled_rect[2],
			$scaled_rect[1] + $scaled_rect[3],
			$rect_color,
		);
	}

	// Add random burning rectangle
	$burn_color = \imagecolorallocatealpha(
		$image,
		mt_rand( 0, 100 ),
		mt_rand( 0, 100 ),
		mt_rand( 0, 100 ),
		mt_rand( 70, 120 ),
	);

	$burn_rect = \array_map(
		fn( $val ) => (int) ( $val * ( $scale_x + $scale_y ) / 2 ),
		[
			mt_rand( 50, 300 ),
			mt_rand( 50, 300 ),
			mt_rand( 60, 120 ),
			mt_rand( 60, 120 ),
		]
	);

	\imagefilledrectangle(
		$image,
		$burn_rect[0],
		$burn_rect[1],
		$burn_rect[0] + $burn_rect[2],
		$burn_rect[1] + $burn_rect[3],
		$burn_color,
	);

	// Add 2-4 random color circles biased toward top half
	for ( $i = mt_rand( 2, 4 ); $i--; ) {
		$circle_color = \imagecolorallocatealpha(
			$image,
			mt_rand( 150, 255 ),
			mt_rand( 150, 255 ),
			mt_rand( 50, 150 ),
			mt_rand( 50, 90 ),
		);

		// Bias Y position toward top half with weighted random
		$y_bias = mt_rand( 1, 100 );
		$y_pos  = $y_bias <= 70
			? mt_rand( 50, 200 )   // 70% chance in upper area
			: mt_rand( 150, 300 ); // 30% chance in middle area

		$circle_data = \array_map(
			fn( $val ) => (int) ( $val * ( $scale_x + $scale_y ) / 2 ),
			[
				mt_rand( 80, 350 ), // x position
				$y_pos,             // biased y position
				mt_rand( 25, 60 ),  // radius
			]
		);

		\imagefilledellipse(
			$image,
			$circle_data[0],
			$circle_data[1],
			$circle_data[2] * 2,
			$circle_data[2] * 2,
			$circle_color,
		);
	}

	// Add texture effects
	\imagesetthickness(
		$image,
		(int) max( 1, 3 * ( $scale_x + $scale_y ) / 2 ),
	);

	// Add 2-4 random arcs
	for ( $i = mt_rand( 2, 4 ); $i--; ) {
		$start_angle = mt_rand( 0, 360 );
		$arc_length  = mt_rand( 30, 180 ); // Control arc length to avoid full circles
		$end_angle   = $start_angle + $arc_length;

		$curve = [
			mt_rand( 50, 450 ),  // x center
			mt_rand( 50, 450 ),  // y center
			mt_rand( 120, 300 ), // width (increased for more elliptical)
			mt_rand( 20, 60 ),   // height (decreased for more linear)
			$start_angle,        // start angle
			$end_angle,          // end angle
		];

		$randomized_curve = $randomize_points( $curve, 15 );
		$scaled_curve     = $scale_points( $randomized_curve );
		\imagearc(
			$image,
			$scaled_curve[0],
			$scaled_curve[1],
			$scaled_curve[2],
			$scaled_curve[3],
			$scaled_curve[4],
			$scaled_curve[5],
			\imagecolorallocatealpha(
				$image,
				mt_rand( 180, 255 ), // higher reds for gold
				mt_rand( 140, 200 ), // moderate greens for gold
				mt_rand( 50, 120 ),  // lower blues for gold
				mt_rand( 60, 100 ),
			),
		);
	}

	// Add random sun
	\imagefilledrectangle(
		$image,
		(int) ( $width * 0.85 ),
		0,
		$width - 1,
		(int) ( $height * 0.15 ),
		\imagecolorallocatealpha(
			$image,
			mt_rand( 200, 255 ), // bias toward yellows/oranges for sun
			mt_rand( 150, 220 ), // moderate yellows for sun warmth
			mt_rand( 50, 120 ),  // lower blues for sun colors
			mt_rand( 20, 60 ),
		),
	);

	// Add random noise
	for ( $i = 0; $i < 1000; $i++ )
		\imagesetpixel(
			$image,
			mt_rand( 0, $width - 1 ),
			mt_rand( 0, $height - 1 ),
			\imagecolorallocatealpha(
				$image,
				mt_rand( 0, 255 ),
				mt_rand( 0, 255 ),
				mt_rand( 0, 255 ),
				mt_rand( 50, 100 ),
			)
		);

	// Add 2-4 random boxed lines
	for ( $i = mt_rand( 2, 4 ); $i--; ) {
		// Randomly choose border width
		$border_width = mt_rand( 10, 25 );

		// Randomly choose border color
		$border_color = \imagecolorallocatealpha(
			$image,
			mt_rand( 0, 255 ),
			mt_rand( 0, 255 ),
			mt_rand( 0, 255 ),
			mt_rand( 50, 100 ),
		);

		// Draw rectangle with max 1/3rd of the image size
		$rect_width  = mt_rand( 10, $width / 3 );
		$rect_height = mt_rand( 10, $height / 3 );
		$rect_x      = mt_rand( 0, $width - $rect_width );
		$rect_y      = mt_rand( 0, $height - $rect_height );

		\imagerectangle(
			$image,
			$rect_x,
			$rect_y,
			$rect_x + $rect_width,
			$rect_y + $rect_height,
			$border_color,
		);
	}

	// Add 2 random canvas borders around the image, consider scaling
	for ( $i = mt_rand( 1, 4 ); $i--; ) {
		// Randomly choose border width (scaled)
		$border_width = mt_rand( 5, 15 ) * ( $scale_x + $scale_y ) / 2;

		// Randomly choose border color
		$border_color = \imagecolorallocatealpha(
			$image,
			...(
				60 >= mt_rand( 1, 100 )
					? [ // 60% bronze
						mt_rand( 139, 205 ),
						mt_rand( 69, 115 ),
						mt_rand( 19, 69 ),
					]
					: (
						70 >= mt_rand( 1, 100 )
							? [  // 28% wood
								mt_rand( 101, 160 ),
								mt_rand( 67, 101 ),
								mt_rand( 33, 67 ),
							]
							: [ // 12% white
								mt_rand( 220, 255 ),
								mt_rand( 220, 255 ),
								mt_rand( 220, 255 ),
							]
					)
			),
			// Workaround the positional argument unpacking issue
			...[ mt_rand( 50, 100 ) ],
		);

		// Draw border rectangle that touches image edges
		for ( $thickness = 0; $thickness < $border_width; $thickness++ ) {
			\imagerectangle(
				$image,
				$thickness,
				$thickness,
				$width - 1 - $thickness,
				$height - 1 - $thickness,
				$border_color,
			);
		}
	}

	// Start output buffering to capture the image data
	\ob_start();
	\imagepng( $image, null, 6 );
	$image_data = \ob_get_clean();

	// Destroy the image resource
	\imagedestroy( $image );

	return $image_data;
}

$px = 192;

header( 'Content-Type: text/html; charset=UTF-8' );

?>
<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<title>Placeholder Grid</title>
	<style>
		body {
			display: flex;
			flex-wrap: wrap;
			margin: 0;
			padding: 0;
			background: cadetblue;
		}
		image-grid {
			display: grid;
			grid-template-columns: repeat(auto-fill, minmax(<?= $px ?>px, 1fr));
			gap: <?= $px / 10 ?>px;
			width: 100%;
			padding: <?= $px / 10 ?>px;
		}
		img {
			width: <?= $px ?>px;
			height: <?= $px ?>px;
			object-fit: cover;
			margin: 0;
			padding: 0;
			display: block;
		}
	</style>
</head>
<body>
	<image-grid>
		<?php
		for ( $i = 100; $i--; ) {
			$png = get_placeholder_image( [
				'width'  => $px,
				'height' => $px,
			] );
			$b64 = base64_encode($png);
			echo "<img src=data:image/png;base64,$b64>";
		}
		?>
	</image-grid>
</body>
</html>