Create watermarks and background images using PHP and TCPDF

With the advent of the Internet and the digital age, the application of pictures is becoming more and more widespread. In particular, in some situations, watermarks or background images need to be added to pictures to ensure information security and copyright protection. At this time, we can use PHP language and TCPDF library to implement watermarking and background image processing of images. The following is the specific implementation method.

1. Install TCPDF library

TCPDF is an open source PHP library for creating PDF documents, but it also provides some tools to create images. The installation of the TCPDF class library is relatively simple. We only need to create the TCPDF directory in the project directory and extract the downloaded TCPDF class library file into the directory.

2. Create a watermark

Creating a watermark requires a watermark image. We can use the GD library to create it. The following is a piece of code to create a watermark image in PNG format.

$watermark = imagecreatefrompng('watermark.png');
$imgsizeX = imagesx($watermark);
$imgsizeY = imagesy($watermark);
$image = imagecreatetruecolor($imgsizeX, $imgsizeY);
$bg = imagecolorallocate($image, 255, 255, 255);
imagefill($image, 0, 0, $bg);
imagecolordeallocate($image, $bg);
imagecopy($image, $watermark, 0, 0, 0, 0, $imgsizeX, $imgsizeY);
imagepng($image, 'watermark_new.png');
imagedestroy($image);
imagedestroy($watermark);

In the above code, we first read the watermark image from the local watermark.png file, and then obtain the width and height of the image. Next, we create a blank image in true color and fill it with white. Then, we copy the watermark image to the newly created image, and finally save the newly created image into PNG format and release the resources.

Next, we can use the TCPDF library to add watermarks to images. The following is a piece of code for adding watermarks to images:

require_once('TCPDF/tcpdf.php');

$pdf = new TCPDF(PDF_PAGE_ORIENTATION, PDF_UNIT, PDF_PAGE_FORMAT, true, 'UTF-8', false);
$pdf->SetCreator(PDF_CREATOR);
$pdf->SetAuthor('author');
$pdf->SetTitle('title');
$pdf->setPrintHeader(false);
$pdf->setPrintFooter(false);

// 添加背景图
$pdf->setPageBackgroundImage('background.jpg', 0, 0, 595, 842, '', false, 50, array(0,0,0), array(255,255,255));

// 添加水印
$pdf->setImageScale(PDF_IMAGE_SCALE_RATIO);
$pdf->Image('dogs.jpg', 5, 5, 180, 0, 'JPG', '', '', false, 300, '', false, false, array(0,0,0,50));
$pdf->Image('watermark_new.png', 0, 0, 180, 0, 'PNG', '', '', false, 300, '', false, false, array(0,0,0,50));

$pdf->Output('output.pdf', 'I');

In the above code, we create a PDF document and set its properties, such as author, title, etc. Next, we add the background image to the document by calling the setPageBackgroundImage method. Among them, the first parameter is the path of the picture, and the next four parameters represent the width, height and position of the picture. In addition, we can also specify parameters such as whether the image is repeated, transparency, and background color.

Next, we added a dog.jpg picture by calling the Image method, and specified its position and size; then, we called the Image method to add the watermark to the picture, and we can also specify the image. Various attributes such as position, size, transparency, etc.

Finally, we can call the Output method to output the generated PDF document to the browser, so that users can view or download the document online.

3. Create a background image

Similar to creating a watermark, creating a background image also requires the use of the GD library. The following is a piece of code for creating a background image:

$width = 1000;
$height = 500;
$image = imagecreate($width, $height);
$bg = imagecolorallocate($image, 255, 255, 255);
imagefill($image, 0, 0, $bg);
imagedestroy($bg);
$line_color = imagecolorallocate($image, 0, 0, 0);

for($i = 0; $i < $width; $i += 50){
    imageline($image, $i, 0, $i, $height, $line_color);
}
for($i = 0; $i < $height; $i += 50){
    imageline($image, 0, $i, $width, $i, $line_color);
}

header('Content-Type:image/png');
imagepng($image);
imagedestroy($image);

In the above code, we create a 1000*500 blank image and fill it with white. We then drew a series of black horizontal and vertical lines spaced 50 pixels apart. Finally, we output the generated image to the browser in PNG format.

The above is how to create watermarks and background images using PHP and TCPDF. Whether it is making product promotional posters, protecting e-commerce website images, or other occasions, using this method can effectively improve the security of images and provide strong support for information protection and copyright protection.

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