NG HTMLPack

NG Controls - HTMLPack
(© by LMD Innovative, (http://www.lmd.de or http://www.lmdtools.com)

Contents
Introduction
Documentation
    Mini-HTML Reference
    Properties
    Events
    Methods
Demos

Introduction
NG MiniHTML engine is an enhanced version of the MiniHTML engine included in the LMD VCL series.
Included controls in the first release of HTMLPack are:

TNGHTMLLabel
TNGHTMLHeaderControl
TNGHTMLListBox
TNGHTMLPanel
TNGHTMLView
TNGHTMLDBLabel
TNGHTMLDBView
TNGHTMLStorage

Other controls will follow in future releases.

By focusing on features of recent Delphi/C++Builder several notable additions were integrated. Among others those are:

Enhanced support for embedded controls (<CONTROL> tag): three events OnControlCreated, OnAdjustControlPosition, OnSetControlVisibility have been added.
<HR> tag received three new parameters height, lightcolor, shadowcolor.
<IMG> tag's src param received two possible specifiers: "file:" and "res:"
<~~varName> can be used to form templates for db-aware version of TNGHTMLLabel. For example, if label has html code

Textfield1: <~~textfield1> Textfield2:<~~textfield2>

and IsTemplate property is set to true, then html engine will try to retrieve corresponding values from connected datasource using var names as field names. If no such fields are found, then OnVariableNeeded event is triggered (see demo for db-aware controls).
Components supporting html string storage received new property StorageItemNotFoundIndex and new event OnStorageItemChanged.
HTML color names support added.
<BODY> tag added. This tag has params bgcolor, bgcolorto, dir, bordercolor.

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Documentation

The following section provides overview about common NG HTMLPack properties, events and methods.

Properties

Property	Type	Description
Options	TNGHTMLOptions
Options.LineGap	integer	Height of the interval between two lines of text
Options.LinkColor	TColor	color of the text in <a></a> tag
Options.LinkStyle	TFontStyles	font style of the text in <a></a> tag
LinkPopupMenu	TPopupMenu	Menu that is invoked by right clicking the link
Storage	TNGHTMLStorage	A storage of HTML snippets with support of automatic jumps from one to another by link clicking. Each snippet has Name property that can be used as href in <a> tag. For example, clicking on a link <a href=”News”>News</a> will cause html control to display snippet with name = ‘News’.
StorageItemIndex	integer	An index of the Storage’s snippet to be shown.
StorageItemNotFoundIndex	integer	An index of the snippet to be shown when referred snippet is not found.
CheckStorageLinks	boolean	This flag allows to turn off automatic jumps between storage’s items.
IsHTML	boolean	Setting this property to true makes control to display html code instead of rendered html.
Offset	TPoint	Specifies left-top corner of the rectangle area being rendered. (0,0) by default.
PlainText	string	Use this property to get text without html tags.
Render	TNGHTMLRender	Allows to get direct access to render engine instance.

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Events

Event	Event type name	Description
OnGetImage	TNGHTMLImageNeededEvent	This event is used to retrieve image, when img tag has no source specifier (file:, res: or imagelist:).
OnGetVariable	TNGHTMLVariableNeededEvent	This event is triggered when html engine renders <~~varname> tag. Used for providing variable value.
OnLinkClick	TNGHTMLLinkClickEvent	Triggered when user click a link.
OnControlCreated	TNGHTMLControlCreatedEvent	Triggered right after an embedded control is created. Use this event to initialize control, e.g. name it, populate with data etc.
OnAdjustControlPosition	TNGHTMLControlPositionNeededEvent	This event is triggered before embedded control is displayed. You can adjust control position at this moment.
OnControlVisibilityNeeded	TNGHTMLControlVisibilityNeededEvent	Triggered before embedded control’s Visible property is set. You can add custom filters here to suppress showing of the embedded control.
OnStorageItemChanged	TNGHTMLStorageItemChangedEvent	This event is triggered when html control’s StorageItemIndex property is changed. In Features demo, this event is used to implement traverse through history.
OnTagFound	TNGHTMLTagFoundEvent	This event gives you total control on html engine. You can implement new tags, handle unknown tags (see Controls demo for example where unsupported <x> tag is substituted by <b> tag).

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Methods

INGHTMLControl interface

Most of INGHTMLControl’s methods are for internal use. However, you can use two of them to unify work with NG HTML controls. These are SetHTML and GetHTML.

function GetDefaultFont: TFont;
function GetHTMLOptions: TNGHTMLOptions;
function GetHTML: string;
procedure SetHTML(const Value: string);
function GetPadding: TPadding;
procedure SetRenderParameter(const aName: string; const aValue: string); (for internal use only)

Direct access to an engine singleton

function HTMLRender:TNGHTMLRender;

Direct access to a global rendering engine instance.

Direct rendering of HTML to a canvas

You can use following methods to draw HTML text to a canvas:

function NGHTMLDrawText(Canvas: TCanvas; szStr: string; ARect: TRect; LineGap: integer; LinkColor: TColor; WordWrap: boolean; bCalcOnly: Boolean = False):Integer; overload;

function NGHTMLDrawText(Canvas: TCanvas; szStr: string; ARect: TRect; bCalcOnly: Boolean = False): Integer; overload;

Both methods return height of rendered HTML texts. If bCalcOnly property is set ti true, then no final rendering is made.
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NG HTMLPack demos

To get a quick start we suggest that you check the demo projects which are shipped with any version of NG HTMLPack :

Folder	Description
\features	This project demonstrates all supported tags of MiniHTML engine.
\controls	This demo presents all controls included in NG HTMLPack.

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Properties

Events

Methods

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Documentation