Added keyword documentation for BASE64 option for screenshots

Author: emanlove

src/SeleniumLibrary/keywords/screenshot.py

@@ -83,7 +83,14 @@ def capture_page_screenshot(self, filename: str = DEFAULT_FILENAME_PAGE) -> str:
 
         If ``filename`` equals to EMBED (case insensitive), then screenshot
         is embedded as Base64 image to the log.html. In this case file is not
-        created in the filesystem.
+        created in the filesystem. If ``filename`` equals to BASE64 (case
+        insensitive), then the base64 string is returned and the screenshot
+        is embedded to the log. This allows one to reuse the image elsewhere
+        in the report.
+
+        Example:
+        | ${ss}=            | `Capture Page Screenshot`  | BASE64                                          |
+        | Set Test Message  |   *HTML*Test Success<p><img src="data:image/png;base64,${ss}" width="256px"> |
 
         Starting from SeleniumLibrary 1.8, if ``filename`` contains marker
         ``{index}``, it will be automatically replaced with an unique running
@@ -93,9 +100,10 @@ def capture_page_screenshot(self, filename: str = DEFAULT_FILENAME_PAGE) -> str:
         format string syntax].
 
         An absolute path to the created screenshot file is returned or if
-        ``filename``  equals to EMBED, word `EMBED` is returned.
+        ``filename``  equals to EMBED, word `EMBED` is returned. If ``filename``
+        equals to BASE64, the base64 string containing the screenshot is returned.
 
-        Support for EMBED is new in SeleniumLibrary 4.2
+        Support for BASE64 is new in SeleniumLibrary 6.8
 
         Examples:
         | `Capture Page Screenshot` |                                        |
@@ -147,18 +155,24 @@ def capture_element_screenshot(
         See the `Locating elements` section for details about the locator
         syntax.
 
-        An absolute path to the created element screenshot is returned.
+        An absolute path to the created element screenshot is returned. If the ``filename``
+        equals to BASE64 (case insensitive), then the base64 string is returned in addition
+        to the screenshot embedded to the log. See ``Capture Page Screenshot`` for more
+        information.
 
         Support for capturing the screenshot from an element has limited support
         among browser vendors. Please check the browser vendor driver documentation
         does the browser support capturing a screenshot from an element.
 
         New in SeleniumLibrary 3.3. Support for EMBED is new in SeleniumLibrary 4.2.
+        Support for BASE64 is new in SeleniumLibrary 6.8.
 
         Examples:
         | `Capture Element Screenshot` | id:image_id |                                |
         | `Capture Element Screenshot` | id:image_id | ${OUTPUTDIR}/id_image_id-1.png |
         | `Capture Element Screenshot` | id:image_id | EMBED                          |
+        | ${ess}= | `Capture Element Screenshot` | id:image_id | BASE64               |
+
         """
         if not self.drivers.current:
             self.info(