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在PHP中，可以使用GD库或Imagick扩展来实现图像的缩放。以下是两种方法的示例：
方法一：使用GD库
function resizeImage($sourceImage, $destinationWidth, $destinationHeight, $savePath) { // 获取原始图像尺寸 list($sourceWidth, $sourceHeight, $sourceType) = getimagesize($sourceImage); // 根据原始图像类型创建图像资源 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; } // 创建一个空白画布，用于保存缩放后的图像 $destinationResource = imagecreatetruecolor($destinationWidth, $destinationHeight); // 保持 PNG 和 GIF 图像的透明度 if ($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, $transparent); } // 将原始图像缩放到目标画布上 imagecopyresampled($destinationResource, $sourceResource, 0, 0, 0, 0, $destinationWidth, $destinationHeight, $sourceWidth, $sourceHeight); // 保存缩放后的图像 switch ($sourceType) { case IMAGETYPE_GIF: imagegif($destinationResource, $savePath); break; case IMAGETYPE_JPEG: imagejpeg($destinationResource, $savePath); break; case IMAGETYPE_PNG: imagepng($destinationResource, $savePath); break; } // 销毁图像资源 imagedestroy($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, $savePath); 方法二：使用Imagick扩展
function resizeImage($sourceImage, $destinationWidth, $destinationHeight, $savePath) { try { // 创建Imagick对象 $sourceResource = new Imagick($sourceImage); // 设置目标尺寸 $sourceResource->resizeImage($destinationWidth, $destinationHeight, Imagick::FILTER_LANCZOS, 1); // 保存缩放后的图像 $sourceResource->writeImage($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); 请注意，这两种方法都需要相应的图像处理库（GD库或Imagick扩展）已经安装并启用。同时，确保您的PHP环境已经配置了这些库。
