axeloz · September 17, 2024 12:52 · axeloz · Jan 17, 2024
diff --git a/function.php b/function.php
 <?php
 function generateImagePreview(String $file):String {
 	// Supported image formats
 	$mimetypes = [
 		'image/jpeg'		=> [
 			'mime'			=> 'image/jpeg',
 			'function' 		=> 'imagecreatefromjpeg',
 			'extensions'	=> ['jpeg', 'jpg']
 		],
 		'image/png'		=> [
 			'function' 		=> 'imagecreatefrompng',
 			'extensions'	=> ['png']
 		],
 		'image/webp'		=> [
 			'function' 		=> 'imagecreatefromwebp',
 			'extensions'	=> ['webp']
 		],
 		'image/gif'		=> [
 			'function' 		=> 'imagecreatefromgif',
 			'extensions'	=> ['gif']
 		]
 	];

 	// Checking that GD extension is enabled
 	if (! extension_loaded('gd')) {
 		throw new Exception('GD library is not installed on this instance');
 	}

 	// Reading EXIF data
 	if ($exif = exif_read_data($file)) {
 		$type = $exif['MimeType'] ?? null;
 	}

 	// Getting correct function to use
 	$function = $mimetypes[$type]['function'] ?? null;
 	if (empty($function) || ! is_callable($function) || ! function_exists($function)) {
 		throw new Exception('This image format is not supported');
 	}

 	// Calling the function
 	if (false === $gd = call_user_func($function, $file)) {
 		throw new Exception('Unable to generate a GD image from source');
 	}

 	// Does this image needs to be rotated or flipped?
 	if (! empty($exif['Orientation']) && $exif['Orientation'] !== 1) {
 		// It's a rotate
 		if (in_array($exif['Orientation'], [3, 6, 8])) {
 			switch ($exif['Orientation']) {
 				case 3:
 					$angle = 180;
 				break;
 				case 6:
 					$angle = 270;
 				break;
 				case 8:
 					$angle = 90;
 				break;
 			}

 			if (false === $gd = imagerotate($gd, $angle, 0)) {
 				// Should we block the preview generation because this image is not rotated?
 			}
 		}
 		// It's a flip
 		else {
 			switch ($exif['Orientation']) {
 				case 2:
 					$flip = IMG_FLIP_HORIZONTAL;
 				break;
 				case 4:
 					$flip = IMG_FLIP_VERTICAL;
 				break;
 				case 5:
 					$flip = IMG_FLIP_BOTH;
 				break;
 			}

 			if (false === $gd = imageflip($gd, $flip)) {
 				// Should we block the preview generation because this image is not rotated?
 			}
 		}
 	}

 	// First we generate the new image sizes
 	$max_width 	= 4;
 	$width		= imagesx($gd);
 	$height		= imagesy($gd);
 	$ratio		= $width / $height;
 	$max_height	= max(round($max_width, 1) / $ratio, 1);

 	// Then we create a new image with correct size and ratio
 	if (false === $temp = imagecreatetruecolor($max_width, $max_height)) {
 		throw new Exception('Cannot create a new image container');
 	}

 	// Finally we copy the original image to the new container image
 	if (false === imagecopyresampled($temp, $gd, 0, 0, 0, 0, $max_width, $max_height, $width, $height)) {
 		throw new Exception('Cannot resample image');
 	}

 	// Adding blur and smoothing
 	imagefilter($temp, IMG_FILTER_GAUSSIAN_BLUR);
 	imagefilter($temp, IMG_FILTER_SMOOTH, IMG_FILTER_SMOOTH);

 	// Outputting image to GIF format
 	ob_start();
 	imagegif($temp);
 	$image = ob_get_contents();
 	ob_end_clean();

 	return base64_encode($image);
 }
diff --git a/Generate Image Placeholder b/Generate Image Placeholder
 <html>
  
  <body>
    	<img 
           width="300" 
           src="data:image/gif;base64,<?php echo generateImagePreview('./image/myimage.png'); ?>" 
      />
    
      <!-- 
      THIS IS THE ACTUAL SIZE OF THE BASE64 USED TO DISPLAY THE IMAGE. SHORT ENOUGHT TO BE STORED INTO A DATABASE FIELD
      <img 
           width="300" 
           src="data:image/gif;base64,R0lGODdhBAACAKIAAJSanJyipKSenJSepJyWlKSipJSapKSmpCwAAAAABAACAAADBih1QTYgAQA7" 
      />
      -->
  </body>
  
 </html>
	<?php
	function generateImagePreview(String $file):String {
	// Supported image formats
	$mimetypes = [
	'image/jpeg' => [
	'mime' => 'image/jpeg',
	'function' => 'imagecreatefromjpeg',
	'extensions' => ['jpeg', 'jpg']
	],
	'image/png' => [
	'function' => 'imagecreatefrompng',
	'extensions' => ['png']
	],
	'image/webp' => [
	'function' => 'imagecreatefromwebp',
	'extensions' => ['webp']
	],
	'image/gif' => [
	'function' => 'imagecreatefromgif',
	'extensions' => ['gif']
	]
	];

	// Checking that GD extension is enabled
	if (! extension_loaded('gd')) {
	throw new Exception('GD library is not installed on this instance');
	}

	// Reading EXIF data
	if ($exif = exif_read_data($file)) {
	$type = $exif['MimeType'] ?? null;
	}

	// Getting correct function to use
	$function = $mimetypes[$type]['function'] ?? null;
	if (empty($function) \|\| ! is_callable($function) \|\| ! function_exists($function)) {
	throw new Exception('This image format is not supported');
	}

	// Calling the function
	if (false === $gd = call_user_func($function, $file)) {
	throw new Exception('Unable to generate a GD image from source');
	}

	// Does this image needs to be rotated or flipped?
	if (! empty($exif['Orientation']) && $exif['Orientation'] !== 1) {
	// It's a rotate
	if (in_array($exif['Orientation'], [3, 6, 8])) {
	switch ($exif['Orientation']) {
	case 3:
	$angle = 180;
	break;
	case 6:
	$angle = 270;
	break;
	case 8:
	$angle = 90;
	break;
	}

	if (false === $gd = imagerotate($gd, $angle, 0)) {
	// Should we block the preview generation because this image is not rotated?
	}
	}
	// It's a flip
	else {
	switch ($exif['Orientation']) {
	case 2:
	$flip = IMG_FLIP_HORIZONTAL;
	break;
	case 4:
	$flip = IMG_FLIP_VERTICAL;
	break;
	case 5:
	$flip = IMG_FLIP_BOTH;
	break;
	}

	if (false === $gd = imageflip($gd, $flip)) {
	// Should we block the preview generation because this image is not rotated?
	}
	}
	}

	// First we generate the new image sizes
	$max_width = 4;
	$width = imagesx($gd);
	$height = imagesy($gd);
	$ratio = $width / $height;
	$max_height = max(round($max_width, 1) / $ratio, 1);

	// Then we create a new image with correct size and ratio
	if (false === $temp = imagecreatetruecolor($max_width, $max_height)) {
	throw new Exception('Cannot create a new image container');
	}

	// Finally we copy the original image to the new container image
	if (false === imagecopyresampled($temp, $gd, 0, 0, 0, 0, $max_width, $max_height, $width, $height)) {
	throw new Exception('Cannot resample image');
	}

	// Adding blur and smoothing
	imagefilter($temp, IMG_FILTER_GAUSSIAN_BLUR);
	imagefilter($temp, IMG_FILTER_SMOOTH, IMG_FILTER_SMOOTH);

	// Outputting image to GIF format
	ob_start();
	imagegif($temp);
	$image = ob_get_contents();
	ob_end_clean();

	return base64_encode($image);
	}
	<html>

	<body>
	<img
	width="300"
	src="data:image/gif;base64,<?php echo generateImagePreview('./image/myimage.png'); ?>"
	/>

	<!--
	THIS IS THE ACTUAL SIZE OF THE BASE64 USED TO DISPLAY THE IMAGE. SHORT ENOUGHT TO BE STORED INTO A DATABASE FIELD
	<img
	width="300"
	src="data:image/gif;base64,R0lGODdhBAACAKIAAJSanJyipKSenJSepJyWlKSipJSapKSmpCwAAAAABAACAAADBih1QTYgAQA7"
	/>
	-->
	</body>

	</html>