轻松掌握：PHP图片载入与展示全攻略

简介

图片载入

1. 获取图片文件

// 从用户上传的文件中获取图片
if ($_FILES['image']['error'] == 0) {
    $imagePath = $_FILES['image']['tmp_name'];
} else {
    $imagePath = 'default.jpg'; // 如果上传失败，则显示默认图片
}

2. 验证图片类型

function isImage($path) {
    $imageTypes = ['image/jpeg', 'image/png', 'image/gif'];
    $fileInfo = getimagesize($path);
    return in_array($fileInfo['mime_type'], $imageTypes);
}

if (!isImage($imagePath)) {
    echo "上传的文件不是有效的图片格式。";
    exit;
}

图片处理

1. 改变图片大小

function resizeImage($path, $width, $height) {
    $imageInfo = getimagesize($path);
    $newWidth = $width;
    $newHeight = ($height / $imageInfo[1]) * $imageInfo[0];

    switch ($imageInfo[2]) {
        case IMAGETYPE_JPEG:
            $image = imagecreatefromjpeg($path);
            $newImage = imagecreatetruecolor($newWidth, $newHeight);
            imagecopyresampled($newImage, $image, 0, 0, 0, 0, $newWidth, $newHeight, $imageInfo[0], $imageInfo[1]);
            imagejpeg($newImage, $path);
            break;
        case IMAGETYPE_PNG:
            $image = imagecreatefrompng($path);
            $newImage = imagecreatetruecolor($newWidth, $newHeight);
            imagealphablending($newImage, false);
            imagesavealpha($newImage, true);
            imagecopyresampled($newImage, $image, 0, 0, 0, 0, $newWidth, $newHeight, $imageInfo[0], $imageInfo[1]);
            imagepng($newImage, $path);
            break;
        case IMAGETYPE_GIF:
            // GIF图片处理逻辑
            break;
    }
}

resizeImage($imagePath, 800, 600);

2. 添加水印

”`php function addWatermark(\(path, \)watermarkPath) {

$imageInfo = getimagesize($path);
$watermarkImage = imagecreatefrompng($watermarkPath);
$watermarkWidth = imagesx($watermarkImage);
$watermarkHeight = imagesy($watermarkImage);

switch ($imageInfo[2]) {
    case IMAGETYPE_JPEG:
        $image = imagecreatefromjpeg($path);
        $newImage = imagecreatetruecolor($imageInfo[0], $imageInfo[1]);
        imagealphablending($newImage, false);
        imagesavealpha($newImage, true);
        imagecopyresampled($newImage, $image, 0, 0, 0, 0, $imageInfo[0], $imageInfo[1], $imageInfo[0], $imageInfo[1]);
        imagecopy($newImage, $watermarkImage, $imageInfo[0] - $watermarkWidth - 10, $imageInfo[1] - $watermarkHeight - 10, 0, 0, $watermarkWidth, $watermarkHeight);
        imagejpeg($newImage, $path);
        break;
    case IMAGETYPE_PNG:
        $image = imagecreatefrompng($path);
        $newImage = imagecreatetruecolor($imageInfo[0], $imageInfo[1]);
        imagealphablending($newImage, false);
        imagesavealpha($newImage, true);
        imagecopyresampled($newImage, $image, 0, 0, 0, 0, $imageInfo[0], $imageInfo[1], $imageInfo[0], $imageInfo[