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PHP圖像處理怎樣實現縮放

PHP
小樊
81
2024-10-24 17:38:41
欄目: 編程語言

在PHP中，可以使用GD庫或Imagick擴展來實現圖像的縮放。以下是兩種方法的示例：

方法一：使用GD庫

function resizeImage($sourceImage, $destinationWidth, $destinationHeight, $savePath) {
    // 獲取原始圖像尺寸
    list($sourceWidth, $sourceHeight, $sourceType) = getimagesize($sourceImage);

    // 根據原始圖像類型創(chuàng)建圖像資源
    switch ($sourceType) {
        case IMAGETYPE_GIF:
            $sourceResource = imagecreatefromgif($sourceImage);
            break;
        case IMAGETYPE_JPEG:
            $sourceResource = imagecreatefromjpeg($sourceImage);
            break;
        case IMAGETYPE_PNG:
            $sourceResource = imagecreatefrompng($sourceImage);
            break;
        default:
            return false;
    }

    // 創(chuàng)建一個空白畫布，用于保存縮放后的圖像
    $destinationResource = imagecreatetruecolor($destinationWidth, $destinationHeight);

    // 保持 PNG 和 GIF 圖像的透明度
    if ($sourceType == IMAGETYPE_PNG || $sourceType == IMAGETYPE_GIF) {
        imagealphablending($destinationResource, false);
        imagesavealpha($destinationResource, true);
        $transparent = imagecolorallocatealpha($destinationResource, 255, 255, 255, 127);
        imagefilledrectangle($destinationResource, 0, 0, $destinationWidth, $destinationHeight, $transparent);
    }

    // 將原始圖像縮放到目標畫布上
    imagecopyresampled($destinationResource, $sourceResource, 0, 0, 0, 0, $destinationWidth, $destinationHeight, $sourceWidth, $sourceHeight);

    // 保存縮放后的圖像
    switch ($sourceType) {
        case IMAGETYPE_GIF:
            imagegif($destinationResource, $savePath);
            break;
        case IMAGETYPE_JPEG:
            imagejpeg($destinationResource, $savePath);
            break;
        case IMAGETYPE_PNG:
            imagepng($destinationResource, $savePath);
            break;
    }

    // 銷毀圖像資源
    imagedestroy($sourceResource);
    imagedestroy($destinationResource);

    return true;
}

// 使用示例
$sourceImage = 'path/to/your/image.jpg';
$destinationWidth = 300;
$destinationHeight = 200;
$savePath = 'path/to/your/resized_image.jpg';

resizeImage($sourceImage, $destinationWidth, $destinationHeight, $savePath);

方法二：使用Imagick擴展

function resizeImage($sourceImage, $destinationWidth, $destinationHeight, $savePath) {
    try {
        // 創(chuàng)建Imagick對象
        $sourceResource = new Imagick($sourceImage);

        // 設置目標尺寸
        $sourceResource->resizeImage($destinationWidth, $destinationHeight, Imagick::FILTER_LANCZOS, 1);

        // 保存縮放后的圖像
        $sourceResource->writeImage($savePath);
        $sourceResource->clear();
        $sourceResource->destroy();

        return true;
    } catch (Exception $e) {
        return false;
    }
}

// 使用示例
$sourceImage = 'path/to/your/image.jpg';
$destinationWidth = 300;
$destinationHeight = 200;
$savePath = 'path/to/your/resized_image.jpg';

resizeImage($sourceImage, $destinationWidth, $destinationHeight, $savePath);

請注意，這兩種方法都需要相應的圖像處理庫（GD庫或Imagick擴展）已經安裝并啟用。同時，確保您的PHP環(huán)境已經配置了這些庫。

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