サムネイル作成用のPHPクラス。GDベース。サムネイル画像をバイナリーデータとして返してくれる。

gistfile1.php

<?php

class ThumbnailUtility {
    
    const TYPE_KEEP_RATIO = 0;
    const TYPE_TRIM = 1;

    public static function Resize(
            $file_path_or_url, 
            $thumbnail_width = null, 
            $thumbnail_height = null,
            $type = ThumbnailUtility::TYPE_KEEP_RATIO) {
        if (($original_image_source = @imagecreatefromstring(file_get_contents($file_path_or_url))) === false) {
            throw new ThumbnailUtilityException('failed in load image data');
        }
        if (($original_image_size = @getimagesize($file_path_or_url)) === false) {
            throw new ThumbnailUtilityException('failed get image size');
        }
        $original_image_width = $original_image_size[0];
        $original_image_height = $original_image_size[1];
        switch ($type) {
            case ThumbnailUtility::TYPE_KEEP_RATIO:
                if ($thumbnail_width != null) {
                    $thumbnail_height = intval($original_image_height * $thumbnail_width / $original_image_width);
                }
                else if ($thumbnail_height != null) {
                    $thumbnail_width = intval($original_image_width * $thumbnail_height / $original_image_height);
                }
                else {
                    throw new ThumbnailUtilityException('need width or height for keep ratio resizing');
                }
                if (($thumbnail_source = @imagecreatetruecolor($thumbnail_width, $thumbnail_height)) === false) {
                    throw new ThumbnailUtilityException('failed to create new image');
                }
                if ($original_image_size[2] == IMAGETYPE_PNG) {
                    if (@imagecolortransparent($thumbnail_source) === false) {
                        throw new ThumbnailUtilityException();
                    }
                    if (@imagealphablending($thumbnail_source, false) === false) {
                        throw new ThumbnailUtilityException();
                    }
                    if (($color = @imagecolorallocatealpha($thumbnail_source, 0, 0, 0, 127)) === false ||
                            @imagefill($thumbnail_source, 0, 0, $color) === false) {
                        throw new ThumbnailUtilityException();
                    }
                    if (@imagesavealpha($thumbnail_source, true) === false) {
                        throw new ThumbnailUtilityException();
                    }
                }
                if (@imagecopyresampled($thumbnail_source, $original_image_source, 0, 0, 0, 0,
                        $thumbnail_width, $thumbnail_height, $original_image_width, 
                                $original_image_height) === false) {
                    throw new ThumbnailUtilityException('failed in imagecopyresized');
                }
                break;
            case ThumbnailUtility::TYPE_TRIM:
                if ($thumbnail_width == null || $thumbnail_height == null) {
                    throw new ThumbnailUtilityException('need width and height for trim resizing');
                }
                if (($thumbnail_source = @imagecreatetruecolor($thumbnail_width, $thumbnail_height)) === false) {
                    throw new ThumbnailUtilityException('failed to create new image');
                }
                $thumbnail_ratio = $thumbnail_width / $thumbnail_height;
                $desired_width = $original_image_height * $thumbnail_ratio;
                if ($desired_width < $original_image_width) {
                    $cut_width =  $original_image_width - $desired_width;
                    $cut_height = 0;
                }
                else if ($desired_width > $original_image_width) {
                    $cut_width = 0;
                    $cut_height = $original_image_height - $original_image_width / $thumbnail_ratio;
                }
                if (@imagecopyresampled($thumbnail_source, $original_image_source, 
                        0, 0, $cut_width * 0.5, $cut_height * 0.5,
                                $thumbnail_width, $thumbnail_height, $original_image_width - $cut_width, 
                                        $original_image_height - $cut_height) === false) {
                    throw new ThumbnailUtilityException('failed in imagecopyresized');
                }
                break;
            default:
                throw new ThumbnailUtilityException('invalid generating thumbnail type');
        }
        if (($thumbnail_information = @getimagesize($file_path_or_url)) === false) {
            throw new ThumbnailUtilityException('cannot get image type');
        }
        ob_start();
        switch ($thumbnail_information[2]) {
            case IMAGETYPE_JPEG:
            case IMAGETYPE_JPEG2000:
                if (@imagejpeg($thumbnail_source, null, 100) === false) {
                    throw new ThumbnailUtilityException('failed to get string of thumbnail');
                }
                break;
            case IMAGETYPE_GIF:
                if (@imagegif($thumbnail_source) === false) {
                    throw new ThumbnailUtilityException('failed to get string of thumbnail');
                }
                break;
            case IMAGETYPE_PNG:
                if (@imagepng($thumbnail_source, null, 0) === false) {
                    throw new ThumbnailUtilityException('failed to get string of thumbnail');
                }
                break;
            default:
                throw new ThumbnailUtilityException('unsupported image type');
        }
        imagedestroy($original_image_source);
        imagedestroy($thumbnail_source);
        return ob_get_clean();    
    }
}

class ThumbnailUtilityException extends Exception {
}

?>

S3にサムネイルをアップするときに、サーバー上に一時ファイルを作りたく無かったから作った。