<?xml version="1.0" encoding="UTF-8"?>
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Documentation for LCL (Lazarus Component Library) and LazUtils (Lazarus 
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Copyright (c) 1997-2023, by the Lazarus Development Team.

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<fpdoc-descriptions>
<package name="lazutils">
<!--
====================================================================
html2textrender
====================================================================
-->
<module name="html2textrender">
<short>
Contains an HTML-to-Text renderer.
</short>
<descr>
<p>
<file>html2textrender.pas</file> contains an HTML-to-Text renderer. It 
converts HTML into plain text by converting tags and their attributes to a 
representation as plain text.
</p>
<p>
<file>html2textrender.pas</file> is part of the <file>lazutils</file> package.
</p>
</descr>

<!-- unresolved externals -->
<element name="Classes"/>
<element name="SysUtils"/>
<element name="LConvEncoding"/>

<element name="THTML2TextRenderer">
<short>Implements an HTML-to-Text renderer.</short>
<descr>
<p>
<var>THTML2TextRenderer</var> is an HTML-to-Text renderer. It converts HTML 
into plain text by stripping tags and their attributes. Converted text 
includes configurable indentation for HTML tags that affect the indentation 
level. The following HTML tags include special processing in the renderer:
</p>
<ul>
<li>HTML</li>
<li>BODY</li>
<li>P</li>
<li>BR</li>
<li>HR</li>
<li>OL</li>
<li>UL</li>
<li>LI</li>
<li>DIV CLASS="TITLE" (forces title mark output)</li>
</ul>
<p>
The following Named character entities are converted to their plain text 
equivalent:
</p>
<dl>
<dt>&amp;nbsp;</dt>
<dd>' '</dd>
<dt>&amp;lt;</dt>
<dd>'&lt;'</dd>
<dt>&amp;gt;</dt>
<dd>'&gt;;'</dd>
<dt>&amp;amp;</dt>
<dd>'&amp;'</dd>
</dl>
<p>
Other named character entities or numeric character entities are included 
verbatim in the plain text output.
</p>
<p>
A UTF-8 Byte Order Mark in the HTML is ignored.
</p>
<p>
Set property values in the class instance to customize the content and 
formatting produced in the output. Use the Render method to parse and process 
the HTML content passed to the constructor, and generate the output for the 
class instance.
</p>
</descr>
<seealso>
<link id="THTML2TextRenderer.Create"/>
<link id="THTML2TextRenderer.Render"/>
</seealso>
</element>

<element name="THTML2TextRenderer.fHTML">
<short>HTML content examined in the class.</short>
</element>
<element name="THTML2TextRenderer.fOutput">
<short>Output value without HTML tags and attributes.</short>
</element>
<element name="THTML2TextRenderer.fMaxLines">
<short>Maximum number of lines allowed in the output from the class.</short>
</element>
<element name="THTML2TextRenderer.fLineEndMark">
<short>End of line marker, by default standard LineEnding.</short>
</element>
<element name="THTML2TextRenderer.fTitleMark">
<short>Markup used at the start/end of title text.</short>
</element>
<element name="THTML2TextRenderer.fHorzLine">
<short>Markup used for an HR Tag.</short>
</element>
<element name="THTML2TextRenderer.fLinkBegin">
<short>Markup used at the start of an Anchor Tag.</short>
</element>
<element name="THTML2TextRenderer.fLineEnd`">
<short>Markup used at the end of an Anchor Tag.</short>
</element>
<element name="THTML2TextRenderer.fListItemMark">
<short>Markup used for a list item tag.</short>
</element>
<element name="THTML2TextRenderer.fMoreMark">
<short>Text added when there are too many lines.</short>
</element>
<element name="THTML2TextRenderer.fInHeader">
<short>Flag used to suppress output of line breaks in the output.</short>
</element>
<element name="THTML2TextRenderer.fInDivTitle">
<short>
Flag used to indicate that a DIV tag with a TITLE attribute is being 
processed.
</short>
</element>
<element name="THTML2TextRenderer.fPendingSpace">
<short>
Flag used to indicate that a space character needs to be added the end of a 
wrapped line.
</short>
</element>
<element name="THTML2TextRenderer.fPendingNewLineCnt">
<short>Indicates a line break needs to be appended in the output.</short>
</element>
<element name="THTML2TextRenderer.fIndentStep">
<short>Increment (in spaces) for each nested HTML level.</short>
</element>
<element name="THTML2TextRenderer.fIndent">
<short>
The current indentation level for the renderer.
</short>
</element>
<element name="THTML2TextRenderer.fLineCnt">
<short>Number of lines added to the output for the class.</short>
</element>
<element name="THTML2TextRenderer.fHtmlLen">
<short>Length of the HTML examined in the class.</short>
</element>
<element name="THTML2TextRenderer.p">
<short>Current character position in the HTML.</short>
</element>

<element name="THTML2TextRenderer.AddNewLine">
<short>Sets a pending line break to be added later.</short>
</element>

<element name="THTML2TextRenderer.AddOneNewLine">
<short>Sets a maximum of one pending line break to be added later.</short>
</element>

<element name="THTML2TextRenderer.AddOutput">
<short>Appends text to the plaint-text output for the renderer.</short>
<descr>
<p>
<var>AddOutput</var> is a <var>Boolean</var> function used to append the 
value specified in <var>aText</var> to the output for the renderer.
</p>
<p>
AddOutput ensures that a space character is included for wrapped lines in the 
HTML when there are no pending new lines. Otherwise, the required number of 
line ending sequences are appended to the output for the render and the line 
count is increased accordingly. If the line count exceeds the maximum number 
allowed in <var>Render</var>, the value in <var>MoreMark</var> is appended to 
the output.
</p>
<p>
Pending new line(s) also cause indentation spaces to be appended to the 
output.
</p>
<p>
The value in aText is appended to the output for the renderer prior to 
exiting from the method.
</p>
<p>
AddOutput is used in the implementation of the <var>Render</var>, 
<var>HtmlTag</var>, and <var>HtmlEntity</var> methods.
</p>
</descr>
<seealso>
<link id="THTML2TextRenderer.Render"/>
<link id="THTML2TextRenderer.LineEndMark"/>
<link id="THTML2TextRenderer.MoreMark"/>
</seealso>
</element>
<element name="THTML2TextRenderer.AddOutput.aText">
<short>Text value appended to the output for the renderer.</short>
</element>
<element name="THTML2TextRenderer.AddOutput.Result">
<short>
<b>True</b> when the value was added to the output; <b>False</b> when the 
maximum number of lines is exceeded.
</short>
</element>

<element name="THTML2TextRenderer.HtmlTag">
<short>Handles an HTML tag and its attributes values.</short>
<descr>
<p>
<var>HtmlTag</var> is a <var>Boolean</var> function used to locate and 
process an HTML start or end tag, and any attribute name/value pairs present 
in the tag. HtmlTag handles the following HTML tag and attribute/value names:
</p>
<dl>
<dt>HTML</dt>
<dd>Sets the FInHeader flag to indicate that the content is for a whole 
page.</dd>
<dt>BODY</dt>
<dd>Call Reset to initialize the renderer.</dd>
<dt>P, /P, BR, /UL</dt>
<dd>Adds a new line sequence to the output.</dd>
<dt>DIV CLASS="Title"</dt>
<dd>
Sets the fInDivTitle flag, and adds a NewLine and a TitleMark to the output. 
When the CLASS attribute is omitted or has a different value, only a NewLine 
sequence is appended.
</dd>
<dt>/DIV</dt>
<dd>
Appends a trailing TitleMark, resets the FInDivTitle flag, and appends a 
NewLine sequence and decrements the indentation level.
</dd>
<dt>LI</dt>
<dd>
Increments the indentation level and adds a single NewLine prior to adding 
the content in the list.
</dd>
<dt>/LI</dt>
<dd>Decrements the indentation level.</dd>
<dt>A</dt>
<dd>Appends a Space character and the LinkBegin sequence to the output.</dd>
<dt>/A</dt>
<dd>Appends a LinkEnd sequence and a Space character to the output.</dd>
<dt>HR</dt>
<dd>Adds a single NewLine and the content in HorzLine to the output.</dd>
</dl>
<p>
All other tag names are ignored in the method.
</p>
<p>
The return value is <b>True</b> when the HTML content is successfully added 
by calling <var>AddOutput</var>. The return value is <b>False</b> when the 
maximum number of lines specified in the <var>Render</var> method is exceeded.
</p>
</descr>
</element>
<element name="THTML2TextRenderer.HtmlTag.Result">
<short>
<b>True</b> when output is successfully added; <b>False</b> when the maximum 
number of lines is exceeded.
</short>
</element>

<element name="THTML2TextRenderer.HtmlEntity">
<short>Handles an HTML character entity.</short>
<descr>
<p>
<var>HtmlEntity</var> is a <var>Boolean</var> function used to convert common 
character entities in HTML to their plain text equivalent. The following 
Named character entities are converted to their plain text equivalent:
</p>
<dl>
<dt>&amp;nbsp;</dt>
<dd>' '</dd>
<dt>&amp;lt;</dt>
<dd>'&lt;'</dd>
<dt>&amp;gt;</dt>
<dd>'&gt;;'</dd>
<dt>&amp;amp;</dt>
<dd>'&amp;'</dd>
</dl>
<p>
Other named character entities or numeric character entities are included 
verbatim in the plain text output.
</p>
<p>
The return value is the result from the <var>AddOutput</var> method, and 
contains <b>False</b> when the maximum number of lines has been exceeded in 
the renderer.
</p>
</descr>
<seealso/>
</element>
<element name="THTML2TextRenderer.HtmlEntity.Result">
<short>
<b>True</b> on success, <b>False</b> when the maximum number of lines is 
exceeded.
</short>
</element>

<element name="THTML2TextRenderer.Reset">
<short>Resets the state and output for the renderer.</short>
<descr>
<p>
<var>Reset</var> is a procedure used to reset the state and output for the 
renderer. Reset sets values for internal flags used in the class, and clears 
any content stored in the render output.
</p>
</descr>
</element>

<element name="THTML2TextRenderer.Create">
<short>Constructor for the class instance.</short>
<descr>
<p>
<var>Create</var> is the overloaded constructor for the class instance. HTML 
content is passed as an argument to the method using either a 
<var>String</var> value or a <var>TStream</var> instance. The Stream-based 
variant reads the content in Stream into a String variable for processing. 
The position in the stream is not changed prior to or after reading its 
content.
</p>
<p>
Create stores the HTML content in <var>aHTML</var> to an internal member used 
when parsing and processing using methods in the class. A UTF-8 Byte Order 
Mark (BOM) at the start of the HTML content is removed prior to processing.
</p>
<p>
Create sets the default values for the following properties:
</p>
<dl>
<dt>LineEndMark</dt>
<dd>Set to the value in the LineEnding constant for the platform or OS.</dd>
<dt>TitleMark</dt>
<dd>Set to the UTF-8 character '◈' (#9672 or #x25C8)</dd>
<dt>HorzLineMark</dt>
<dd>Set to the UTF-8 characters 
'——————————————————'.</dd>
<dt>LinkBeginMark</dt>
<dd>Set to the character '_'. </dd>
<dt>LinkEndMark</dt>
<dd>Set to the character '_'. </dd>
<dt>ListItemMark</dt>
<dd>Set to the UTF-8 characters '✶ ' (Hex  #$2736).</dd>
<dt>MoreMark</dt>
<dd>
Set to the characters '...' (Three Period characters - not an Ellipsis 
character).
</dd>
<dt>IndentStep</dt>
<dd>Set to 2.</dd>
</dl>
</descr>
<seealso/>
</element>
<element name="THTML2TextRenderer.Create.aHTML">
<short>String with the HTML content examined in the class.</short>
</element>
<element name="THTML2TextRenderer.Create.Stream">
<short>TStream instance with the HTML content examined in the class.</short>
</element>

<element name="THTML2TextRenderer.Destroy">
<short>Frees the class instance.</short>
<descr>
<p>
<var>Destroy</var> is the overridden destructor for the class instance. 
Destroy calls the inherited destructor.
</p>
</descr>
<seealso/>
</element>

<element name="THTML2TextRenderer.Render">
<short>
Parses the HTML and renders the plain text output.
</short>
<descr>
<p>
<var>Render</var> is a <var>String</var> function used to parse the HTML 
passed as an argument to the constructor, and to render the plain text output 
in the return value. The output is limited to the number of lines specified 
in the <var>aMaxLines</var> argument. The default value for the argument is 
the <var>MaxInt</var> constant.
</p>
<remark>
<var>AddOutput</var>, <var>HtmlTag</var>, and <var>HtmlEntity</var> return 
<b>False</b> if <var>aMaxLines</var> was exceeded.
</remark>
<p>
Renders calls the <var>Reset</var> method to set the initial values for 
members and flags used in the class instance. The parsing mechanism looks for 
HTML tags and character entities/references, processes their content, and 
calls the <var>AddOutput</var> method. Whitespace (characters #32, #9, #10, 
and #13) between tags and entities is always normalized into a single space 
character.
</p>
<p>
Render calls the HtmlTag, HtmlEntity, and AddOutput methods to process the 
HTML content passed to the method.
</p>
</descr>
<seealso/>
</element>
<element name="THTML2TextRenderer.Render.aMaxLines">
<short>Maximum number of lines to process in the method.</short>
</element>
<element name="THTML2TextRenderer.Render.Result">
<short>String with the plain text content extracted from the HTML.</short>
</element>

<element name="THTML2TextRenderer.LineEndMark">
<short>Defines the end-of-line character sequence.</short>
<descr>
<p>
<var>LineEndMark</var> is a <var>String</var> property which contains the 
end-of-line character sequence inserted in the plain text output for the 
renderer. By convention, the default value for the property is the value from 
the <var>LineEnding</var> constant defined for the platform or OS. The value 
is inserted in the renderer output in the <var>AddOutput</var> method.
</p>
</descr>
<seealso>
<link id="#rtl.system.LineEnding">LineEnding</link>
</seealso>
</element>

<element name="THTML2TextRenderer.TitleMark">
<short>Defines the character used to delimit a title or header.</short>
<descr>
<p>
<var>TitleMark</var> is inserted both prior to and following a title/header 
found in the HTML content in the <var>HtmlTag</var> method. The default value 
is the UTF-8 character '◈' (Decimal #9672 or Hex #x25C8).
</p>
</descr>
</element>

<element name="THTML2TextRenderer.HorzLineMark">
<short>Represents a HR tag in the plaint text output.</short>
<descr>
<p>
<var>HorzLineMark</var> is used in the implementation of the 
<var>HtmlTag</var> method when a <b>HR</b> tag is encountered in the HTML 
content. The default value for the property is the UTF-8  characters 
'——————————————————' (Eighteen Hex #$2013 
characters).
</p>
</descr>
<seealso/>
</element>

<element name="THTML2TextRenderer.LinkBeginMark">
<short>Represents an A start tag in the plain text output.</short>
<descr>
<p>
<var>LinkBeginMark</var> is a <var>String</var> property used to represent 
the start of the plain text output for an HTML A tag. <var>LinkEndMark</var> 
is used to represent the end of the anchor. The value is added to the plain 
text output for the renderer in the <var>HtmlTag</var> method.
</p>
</descr>
<seealso>
<link id="THTML2TextRenderer.LinkEndMark"/>
</seealso>
</element>

<element name="THTML2TextRenderer.LinkEndMark">
<short>Represents an A end tag in the plain text output.</short>
<descr>
<p>
<var>LinkEndMark</var> is a <var>String</var> property used to represent the 
end of the plain text output for an HTML A tag. <var>LinkBeginMark</var> is 
used to represent the start of the anchor. The value is added to the plain 
text output for the renderer in the <var>HtmlTag</var> method.
</p>
</descr>
<seealso>
<link id="THTML2TextRenderer.LinkBeginMark"/>
</seealso>
</element>

<element name="THTML2TextRenderer.ListItemMark">
<short>Represents a list item in the plain text output.</short>
<descr>
<p>
<var>ListItemMark</var> is a <var>String</var> property which contains the 
character(s) inserted before a HTML LI tag. The value is added to the plain 
text output for the renderer in the <var>HtmlTag</var> method.
</p>
</descr>
<seealso/>
</element>

<element name="THTML2TextRenderer.MoreMark">
<short>
Indicates that the plain text output is truncated due to a line limit 
restriction.
</short>
<descr>
<p>
The default value for the property is three (3) Period ('.') characters - 
<b>NOT</b> an Ellipsis character. The value is added to the plain text output 
for the renderer when the maximum number of lines has been exceeded in the 
<var>AddOutput</var> method.
</p>
</descr>
<seealso/>
</element>

<element name="THTML2TextRenderer.IndentStep">
<short>
Number of space characters used for each indentation level in the plain text 
output.
</short>
<descr>
<p>
<var>IndentStep</var> is an <var>Integer</var> property used to indicate the 
number of space characters generated for each indentation level in the plain 
text output for the renderer. The default value for the property is <b>2</b>, 
and is used in the implementation of the <var>AddOutput</var> method.
</p>
</descr>
<seealso/>
</element>

<element name="RenderHTML2Text">
<short>Converts the specified HTML content to a plain text value.</short>
<descr>
<p>
<var>RenderHTML2Text</var> is a <var>String</var> function used to convert 
the HTML content specified in <var>AHTML</var> to a string with the plain 
text for the content. RenderHTML2Text creates a temporary 
<var>THTML2TextRenderer</var> instance (using its default configuration 
values) to remove any HTML mark-up found in the AHTML argument by calling its 
<var>Render</var> method.
</p>
<p>
RenderHTML2Text is a convenience routine; use a THTML2TextRenderer instance 
when the HTML content is stored in a TStream instance, or to override the 
default configuration settings for the class instance.
</p>
</descr>
<seealso>
<link id="THTML2TextRenderer.Render"/>
</seealso>
</element>
<element name="RenderHTML2Text.Result">
<short>
String with the plain text value for the specified HTML content.
</short>
</element>
<element name="RenderHTML2Text.AHTML">
<short>String with the HTML content converted in the routine.</short>
</element>

</module>
<!-- html2textrender -->
</package>
</fpdoc-descriptions>
