jcs.org
Serenity Operating System
1/*
2 * Copyright (c) 2022, Tim Flynn <trflynn89@serenityos.org>
3 *
4 * SPDX-License-Identifier: BSD-2-Clause
5 */
6
7#include <AK/Optional.h>
8#include <LibGfx/Bitmap.h>
9#include <LibGfx/Rect.h>
10#include <LibWeb/DOM/Document.h>
11#include <LibWeb/DOM/ElementFactory.h>
12#include <LibWeb/HTML/AnimationFrameCallbackDriver.h>
13#include <LibWeb/HTML/BrowsingContext.h>
14#include <LibWeb/HTML/HTMLCanvasElement.h>
15#include <LibWeb/HTML/TagNames.h>
16#include <LibWeb/HTML/Window.h>
17#include <LibWeb/Namespace.h>
18#include <LibWeb/Page/Page.h>
19#include <LibWeb/Platform/EventLoopPlugin.h>
20#include <LibWeb/WebDriver/Error.h>
21#include <LibWeb/WebDriver/Screenshot.h>
22
23namespace Web::WebDriver {
24
25// https://w3c.github.io/webdriver/#dfn-encoding-a-canvas-as-base64
26static Response encode_canvas_element(HTML::HTMLCanvasElement const& canvas)
27{
28 // FIXME: 1. If the canvas element’s bitmap’s origin-clean flag is set to false, return error with error code unable to capture screen.
29
30 // 2. If the canvas element’s bitmap has no pixels (i.e. either its horizontal dimension or vertical dimension is zero) then return error with error code unable to capture screen.
31 if (canvas.bitmap()->width() == 0 || canvas.bitmap()->height() == 0)
32 return Error::from_code(ErrorCode::UnableToCaptureScreen, "Captured screenshot is empty"sv);
33
34 // 3. Let file be a serialization of the canvas element’s bitmap as a file, using "image/png" as an argument.
35 // 4. Let data url be a data: URL representing file. [RFC2397]
36 auto data_url = canvas.to_data_url("image/png"sv, {});
37
38 // 5. Let index be the index of "," in data url.
39 auto index = data_url.find(',');
40 VERIFY(index.has_value());
41
42 // 6. Let encoded string be a substring of data url using (index + 1) as the start argument.
43 auto encoded_string = data_url.substring(*index + 1);
44
45 // 7. Return success with data encoded string.
46 return JsonValue { move(encoded_string) };
47}
48
49// Common animation callback steps between:
50// https://w3c.github.io/webdriver/#take-screenshot
51// https://w3c.github.io/webdriver/#take-element-screenshot
52Response capture_element_screenshot(Painter const& painter, Page& page, DOM::Element& element, Gfx::IntRect& rect)
53{
54 Optional<Response> encoded_string_or_error;
55
56 element.document().window().animation_frame_callback_driver().add([&](auto) {
57 auto viewport_rect = page.top_level_browsing_context().viewport_rect();
58 rect.intersect(page.enclosing_device_rect(viewport_rect).to_type<int>());
59
60 auto canvas_element = DOM::create_element(element.document(), HTML::TagNames::canvas, Namespace::HTML).release_value_but_fixme_should_propagate_errors();
61 auto& canvas = verify_cast<HTML::HTMLCanvasElement>(*canvas_element);
62
63 if (!canvas.create_bitmap(rect.width(), rect.height())) {
64 encoded_string_or_error = Error::from_code(ErrorCode::UnableToCaptureScreen, "Unable to create a screenshot bitmap"sv);
65 return;
66 }
67
68 painter(rect, *canvas.bitmap());
69 encoded_string_or_error = encode_canvas_element(canvas);
70 });
71
72 Platform::EventLoopPlugin::the().spin_until([&]() { return encoded_string_or_error.has_value(); });
73 return encoded_string_or_error.release_value();
74}
75
76}