# exif_thumbnail

(PHP 4 >= 4.2.0, PHP 5, PHP 7)

exif_thumbnail — 取得嵌入在 TIFF 或 JPEG 图像中的缩略图

### 说明

exif_thumbnail ( string `$filename` [, int `&$width` [, int `&$height` [, int `&$imagetype` ]]] ) : string

exif_thumbnail() 读取 TIFF 或 JPEG 图像中的嵌入缩略图。如果图像不包含缩略图则返回 `FALSE`。

If you want to deliver thumbnails through this function, you should send the mimetype information using the header() function.

It is possible that exif_thumbnail() cannot create an image but can determine its size. In this case, the return value is `FALSE` but `width` and `height` are set.

### 参数

`filename`

  The name of the image file being read. This image contains an embedded thumbnail.

`width`

  The return width of the returned thumbnail.

`height`

  The returned height of the returned thumbnail.

`imagetype`

  The returned image type of the returned thumbnail. This is either TIFF or JPEG.

### 返回值

Returns the embedded thumbnail, or `FALSE` if the image contains no thumbnail.

### 更新日志

版本 | 说明
--- | ---
4.3.0 | The optional parameters `width`, `height`, and `imagetype` all became available.
4.3.0 | May return thumbnails in the TIFF format.

### 范例

Example #1 exif_thumbnail() 例子

    <?php
    if (array_key_exists('file',$_REQUEST)) {
        $image = exif_thumbnail($_REQUEST['file'], $width, $height, $type);
    } else {
        $image = false;
    }
    if ($image!==false) {
        header("Content-type: ".image_type_to_mime_type($type));
        echo $image;
        exit;
    } else {
        // no thumbnail available, handle the error here
        echo "No thumbnail available";
    }
    ?>

### 参见

- exif_read_data() - 从 JPEG 或 TIFF 文件中读取 EXIF 头信息
- image_type_to_mime_type() - 取得 getimagesize，exif_read_data，exif_thumbnail，exif_imagetype 所返回的图像类型的 MIME 类型