- Step 1: Fetch the Online Image
- Step 2: Create an Image Resource
- Step 3: Load the Watermark Image
- Step 4: Get the Dimensions
- Step 5: Position the Watermark
- Step 6: Merge the Watermark with the Source Image
- Step 7: Output the Watermarked Image
- Step 8: Cleanup
Step 1: Fetch the Online Image
The first step is to fetch the image from the online URL. We use the
file_get_contents() function in PHP to read the online file into a string.
In this example we're going to use our default OpenGraph image as the image we're going to watermark, which looks like this:
$imageUrl = 'https://accreditly.io/img/og.png'; $imageContent = file_get_contents($imageUrl);
Step 2: Create an Image Resource
We use the
imagecreatefromstring() function to create an image resource from the string obtained from the previous step.
$sourceImage = imagecreatefromstring($imageContent);
Step 3: Load the Watermark Image
Next, we load the watermark image from a local file. For simplicity, let's assume that we have a PNG watermark image named 'watermark.png' in the same directory.
The image we're going to use as a watermark is the winking tongue emoji below:
$watermarkImage = imagecreatefrompng('watermark.png');
You'll need to adjust the function used here if you're using a jpg or other file type.
Step 4: Get the Dimensions
We need to get the width and height of both the source image and the watermark image.
$sourceWidth = imagesx($sourceImage); $sourceHeight = imagesy($sourceImage); $watermarkWidth = imagesx($watermarkImage); $watermarkHeight = imagesy($watermarkImage);
Step 5: Position the Watermark
We need to decide where to place the watermark on the source image. In this example, we will place it at the bottom right corner.
$destX = $sourceWidth - $watermarkWidth - 10; // 10px padding from right $destY = $sourceHeight - $watermarkHeight - 10; // 10px padding from bottom
Step 6: Merge the Watermark with the Source Image
We use the
imagecopy() function to merge the watermark image with the source image.
imagecopy($sourceImage, $watermarkImage, $destX, $destY, 0, 0, $watermarkWidth, $watermarkHeight);
Step 7: Output the Watermarked Image
Now, we can output the resulting watermarked image to the browser. Before we do this, we need to set the correct content type header.
header('Content-type: image/png'); imagepng($sourceImage);
Step 8: Cleanup
Finally, we should clean up the image resources that we have created.
That's it! Now you can dynamically add a watermark to any image on your PHP website.
You should be left with an image that looks like the following:
Please note, fetching images with
file_get_contents() might not work if 'allow_url_fopen' is disabled in your PHP configuration, and not all images on the internet can be accessed due to CORS policies.
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