Application of PHP functions in image processing

PHP provides a wealth of image processing functions, which are widely used to manipulate, edit and enhance images. These functions include: Change image size: imagecopyresized Crop image: imagecrop Rotate image: imagerotate Add watermark: imagecopymerge

Application of PHP functions in image processing

The PHP language provides a series of practical functions that can be used to perform various image processing tasks. These functions can be used extensively in the manipulation, editing and enhancement of images.

Change image size

imagecopyresized($dst_image, $src_image, 0, 0, 0, 0, 200, 100, 500, 250);

Crop image

imagecrop($image, ['x' => 100, 'y' => 100, 'width' => 200, 'height' => 200]);

Rotate image

imagerotate($image, 45, 0);

Add watermark

imagecopymerge($dst_image, $watermark, 10, 10, 0, 0, 50, 50, 50);

Practical case: thumbnail generation

To demonstrate the use of PHP image processing functions, let us create a function to Generate thumbnail:

function createThumbnail($filename, $width, $height)
{
    // 获取原始图像的信息
    list($originalWidth, $originalHeight) = getimagesize($filename);

    // 计算缩放比例
    $scaleX = $width / $originalWidth;
    $scaleY = $height / $originalHeight;

    // 创建一个新图像（透明的）
    $thumb = imagecreatetruecolor($width, $height);
    imagealphablending($thumb, false);
    imagesavealpha($thumb, true);

    // 保存缩略图
    switch (pathinfo($filename, PATHINFO_EXTENSION)) {
        case 'png':
            imagepng($thumb, $filename);
            break;
        case 'jpeg':
        case 'jpg':
            imagejpeg($thumb, $filename, 90);
            break;
    }
}

You can easily generate a thumbnail of any image using this function, which automatically scales and maintains the original aspect ratio of the image.

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