<h1>Web View API</h1>

<h3 id="m:webview"><tt><nowiki>
  (import webview)
</nowiki></tt></h3>

This multi-platform library for [https://www.call-cc.org/|CHICKEN]
allows you to show HTML user interfaces in a window, inject JavaScript
code and HTML content into the page and receive messages from JavaScript
on the page.

<h2>Web View</h2>

<h3 id="p:webview"><tt><nowiki>
  (webview? VALUE) ⇒ BOOLEAN
</nowiki></tt></h3>

Predicate for the tagged pointer type representing a web view window.

<h3 id="c:webview"><tt><nowiki>
  (webview TITLE PROC [#:url URL] [#:width WIDTH] [#:height HEIGHT] [#:resizable? RESIZABLE] [#:debug? DEBUG] [#:yield! YIELD]) ⇒ VOID
</nowiki></tt></h3>

Creates a web view window with the given <tt>TITLE</tt> and runs an
event loop until the user closes the window or termination is requested
using [#p:webview-terminate!|<tt>webview-terminate!</tt>].

The message callback is invoked as <tt>(PROC WEBVIEW STRING)</tt>
whenever a script on the web page calls <tt>window.external.invoke(STRING)</tt>.

If you specify a <tt>URL</tt> that is not <tt>#f</tt>, the page at that
location is loaded into the web view. Otherwise, a blank page is loaded
which sends a <tt>"load"</tt> message when ready and contains a
<tt>&lt;div id="app"&gt;</tt> element that you can fill with custom
content, for example using [#p:webview-html-set!|<tt>webview-html-set!</tt>].

Window properties may be specified using the <tt>WIDTH</tt>,
<tt>HEIGHT</tt> and <tt>RESIZABLE</tt> keyword arguments. If the
<tt>DEBUG</tt> keyword argument is not <tt>#f</tt> and the platform
supports it, the web view will allow access to debugging tools.

If <tt>YIELD</tt> is not given or <tt>#f</tt>, the event loop will block
the operating system thread when no events are pending. You can set
<tt>YIELD</tt> to a number of seconds sleep period between iterations of
the web view event loop; this reduces responsiveness of the user
interface but allows other CHICKEN threads to run and does not hog the
CPU. You can also set <tt>YIELD</tt> to <tt>#t</tt> to call
<tt>thread-yield!</tt> between iterations of the event loop; this allows
other CHICKEN threads to run without delaying user interface event
processing but will use a lot of CPU cycles.

<h3 id="p:webview-terminate!"><tt><nowiki>
  (webview-terminate! WEBVIEW) ⇒ VOID
</nowiki></tt></h3>

Requests termination of the event loop for the given <tt>WEBVIEW</tt>.

<h3 id="p:webview-title-set!"><tt><nowiki>
  (webview-title-set! WEBVIEW TITLE) ⇒ VOID
</nowiki></tt></h3>

Sets the <tt>TITLE</tt> of the given <tt>WEBVIEW</tt> window.

<h3 id="p:webview-fullscreen-set!"><tt><nowiki>
  (webview-fullscreen-set! WEBVIEW FULLSCREEN) ⇒ VOID
</nowiki></tt></h3>

Changes the <tt>FULLSCREEN</tt> state of the given <tt>WEBVIEW</tt>
window.

<h3 id="p:webview-eval"><tt><nowiki>
  (webview-eval WEBVIEW SCRIPT) ⇒ VOID
</nowiki></tt></h3>

Asynchronously triggers evaluation of the given <tt>SCRIPT</tt> code in
the context of the page displayed by the given <tt>WEBVIEW</tt>.

<h3 id="p:webview-style-set!"><tt><nowiki>
  (webview-style-set! WEBVIEW SELECTOR PROPERTY VALUE [PRIORITY]) ⇒ VOID
</nowiki></tt></h3>

Asynchronously triggers a style modification of all DOM elements matching the
given <tt>SELECTOR</tt> on the page displayed by the given <tt>WEBVIEW</tt>.
The given style <tt>PROPERTY</tt> is set to the given <tt>VALUE</tt> for the
selected elements, optionally specifying a <tt>PRIORITY</tt> other than the
default.

<tt>SELECTOR</tt> is specified as for [https://developer.mozilla.org/en-US/docs/Learn/CSS/Introduction_to_CSS/Selectors|CSS].

<h3 id="p:webview-style-set!"><tt><nowiki>
  (webview-style-set! WEBVIEW SELECTOR PROPERTY VALUE [PRIORITY]) ⇒ VOID
</nowiki></tt></h3>

Asynchronously triggers a style modification of all DOM elements matching the given
<tt>SELECTOR</tt> on the page displayed by the given <tt>WEBVIEW</tt>. The
given style <tt>PROPERTY</tt> is removed from the selected elements.

<tt>SELECTOR</tt> is specified as for [https://developer.mozilla.org/en-US/docs/Learn/CSS/Introduction_to_CSS/Selectors|CSS].

<h3 id="p:webview-html-set!"><tt><nowiki>
  (webview-html-set! WEBVIEW SELECTOR HTML [OUTER?]) ⇒ VOID
</nowiki></tt></h3>

Asynchronously triggers replacement of the first DOM element matching the given
<tt>SELECTOR</tt> on the page displayed by the given <tt>WEBVIEW</tt> with the
given <tt>HTML</tt> content.

<tt>SELECTOR</tt> is specified as for [https://developer.mozilla.org/en-US/docs/Learn/CSS/Introduction_to_CSS/Selectors|CSS].

<tt>HTML</tt> content is specified in the form accepted by
[#p:write-html|<tt>write-html</tt>].

If <tt>OUTER?</tt> is <tt>#f</tt> or not given, only the <em>contents</em> of
the specified element are replaced, otherwise the entire element is replaced.

<h3 id="p:webview-html-delete!"><tt><nowiki>
  (webview-html-delete! WEBVIEW SELECTOR [OUTER?]) ⇒ VOID
</nowiki></tt></h3>

Asynchronously triggers removal of the first DOM element matching the given
<tt>SELECTOR</tt> from the page displayed by the given <tt>WEBVIEW</tt>.

<tt>SELECTOR</tt> is specified as for [https://developer.mozilla.org/en-US/docs/Learn/CSS/Introduction_to_CSS/Selectors|CSS].

If <tt>OUTER?</tt> is <tt>#f</tt> or not given, only the <em>contents</em> of
the specified element are removed, otherwise the entire element is deleted.

<h2>Dialogs</h2>

<h3 id="p:webview-dialog"><tt><nowiki>
  (webview-dialog WEBVIEW TITLE TYPE [VALUE]) ⇒ VALUE
</nowiki></tt></h3>

Shows a modal dialog with the given <tt>TITLE</tt> in the context of the
given <tt>WEBVIEW</tt>.

If <tt>TYPE</tt> is <tt>#:open</tt> or <tt>#:save</tt>, a file selection

meaningful result in this case.

The running operating system thread will be blocked until the dialog is
dismissed.

<h2>Logging</h2>

<h3 id="p:webview-log"><tt><nowiki>
  (webview-log MESSAGE) ⇒ VOID
</nowiki></tt></h3>

Outputs a message using a platform-specific logging mechanism.

<h2>Content Generation</h2>

<h3 id="m:webview-content"><tt><nowiki>
  (import webview-content)
</nowiki></tt></h3>

This support module contains procedures that write
[https://developer.mozilla.org/en-US/docs/Web/JavaScript|JavaScript] strings
and [https://developer.mozilla.org/en-US/docs/Web/HTML|HTML] document trees
with proper escaping.

<h3 id="char-set:no-js-escape"><tt><nowiki>
  char-set:no-js-escape
</nowiki></tt></h3>

A [https://srfi.schemers.org/srfi-14/srfi-14.html|SRFI-14] set of characters
that do not need to be escaped inside a JavaScript string.


<h3 id="p:write-js"><tt><nowiki>
  (write-js STRING [PORT] [QUOTES]) ⇒ VOID
</nowiki></tt></h3>

Writes a <tt>STRING</tt> to the given <tt>PORT</tt> or the current output port
using JavaScript escaping rules. If <tt>QUOTES</tt> is given and not
<tt>#f</tt>, its content is printed before and after the <tt>STRING</tt>
contents. If <tt>QUOTES</tt> is not given, double quotes are put around the
string.

<h3 id="p:html-tag-rule"><tt><nowiki>
  (html-tag-rule TAG) ⇒ RULE
</nowiki></tt></h3>
<h3><tt><nowiki>
  (html-tag-rule TAG RULE) ⇒ VOID
</nowiki></tt></h3>

Retrieves or sets the content rule for HTML elements named <tt>TAG</tt>.
The <tt>RULE</tt> can be one of the symbols <tt>normal</tt>,
<tt>raw</tt> or <tt>void</tt>.

<h3 id="p:write-html"><tt><nowiki>
  (write-html ELEMENT [PORT]) ⇒ VOID
</nowiki></tt></h3>

Writes an HTML5 rendering of the X-expression <tt>ELEMENT</tt> to the given
<tt>PORT</tt> or the current output port.

<tt>ELEMENT</tt> must conform to the following grammar:
<verbatim>
  X-EXPR  = ELEMENT
          | CONTENT
  ELEMENT = (SYMBOL ((SYMBOL CONTENT ...) ...) X-EXPR ...) ;; element with optional attributes
          | (SYMBOL X-EXPR ...)                            ;; element without attributes