轻松掌握PHP：图片过滤与处理技巧解析

引言

图片上传

<?php
if ($_SERVER['REQUEST_METHOD'] == 'POST' && isset($_FILES['image'])) {
    $image = $_FILES['image'];
    $uploadPath = 'uploads/' . $image['name'];

    if (move_uploaded_file($image['tmp_name'], $uploadPath)) {
        echo "文件上传成功！";
    } else {
        echo "文件上传失败！";
    }
}
?>
<form action="" method="post" enctype="multipart/form-data">
    <input type="file" name="image" />
    <input type="submit" value="上传" />
</form>

在上面的代码中，我们首先检查是否有文件上传请求。如果有，我们获取上传的文件并尝试将其移动到服务器上的指定目录。

图片尺寸调整

<?php
$imagePath = 'uploads/image.jpg';
list($width, $height) = getimagesize($imagePath);
$desiredWidth = 100;
$desiredHeight = ($height * $desiredWidth) / $width;

$image = imagecreatetruecolor($desiredWidth, $desiredHeight);
$imageContent = imagecreatefromjpeg($imagePath);
imagecopyresampled($image, $imageContent, 0, 0, 0, 0, $desiredWidth, $desiredHeight, $width, $height);

imagejpeg($image, 'uploads/resized_image.jpg');

图片格式转换

<?php
$imagePath = 'uploads/image.jpg';
$imageContent = imagecreatefromjpeg($imagePath);
imagepng($imageContent, 'uploads/image.png');

图片裁剪

<?php
$imagePath = 'uploads/image.jpg';
$sourceImage = imagecreatefromjpeg($imagePath);
$desiredWidth = 100;
$desiredHeight = 100;
$sourceWidth = imagesx($sourceImage);
$sourceHeight = imagesy($sourceImage);

$sourceX = ($sourceWidth - $desiredWidth) / 2;
$sourceY = ($sourceHeight - $desiredHeight) / 2;

$destinationImage = imagecreatetruecolor($desiredWidth, $desiredHeight);
imagecopy($destinationImage, $sourceImage, 0, 0, $sourceX, $sourceY, $desiredWidth, $desiredHeight);

imagejpeg($destinationImage, 'uploads/cropped_image.jpg');

添加水印

<?php
$imagePath = 'uploads/image.jpg';
$watermarkText = 'Watermark';
$fontSize = 20;
$fontColor = imagecolorallocate($image, 255, 255, 255);
$fontFile = 'arial.ttf';

$sourceImage = imagecreatefromjpeg($imagePath);
$watermarkImage = imagettftext($sourceImage, $fontSize, 0, 10, 10, $fontColor, $fontFile, $watermarkText);

imagejpeg($sourceImage, 'uploads/watermarked_image.jpg');

总结