Table of Contents

Class HtmlRender

Namespace
TheArtOfDev.HtmlRenderer.WPF
Assembly
StockSharp.Xaml.dll

Standalone static class for simple and direct HTML rendering.
For WPF UI prefer using HTML controls: HtmlPanel or HtmlLabel.
For low-level control and performance consider using HtmlContainer.

public static class HtmlRender
Inheritance
HtmlRender
Inherited Members

Examples

Simple rendering
HtmlRender.Render(g, "<div>Hello <b>World</b></div>");
HtmlRender.Render(g, "<div>Hello <b>World</b></div>", 10, 10, 500, CssData.Parse("body {font-size: 20px}")");

Image rendering
HtmlRender.RenderToImage("<div>Hello <b>World</b></div>", new Size(600,400));
HtmlRender.RenderToImage("<div>Hello <b>World</b></div>", 600);
HtmlRender.RenderToImage(existingImage, "<div>Hello <b>World</b></div>");

Remarks

Rendering to image
// TODO:a update! See https://htmlrenderer.codeplex.com/wikipage?title=Image%20generation
Because of GDI text rendering issue with alpha channel clear type text rendering rendering to image requires special handling.
Solid color background - generate an image where the background is filled with solid color and all the html is rendered on top of the background color, GDI text rendering will be used. (RenderToImage method where the first argument is html string)
Image background - render html on top of existing image with whatever currently exist but it cannot have transparent pixels, GDI text rendering will be used. (RenderToImage method where the first argument is Image object)
Transparent background - render html to empty image using GDI+ text rendering, the generated image can be transparent.

Overwrite stylesheet resolution
Exposed by optional "stylesheetLoad" delegate argument.
Invoked when a stylesheet is about to be loaded by file path or URL in 'link' element.
Allows to overwrite the loaded stylesheet by providing the stylesheet data manually, or different source (file or URL) to load from.
Example: The stylesheet 'href' can be non-valid URI string that is interpreted in the overwrite delegate by custom logic to pre-loaded stylesheet object
If no alternative data is provided the original source will be used.

Overwrite image resolution
Exposed by optional "imageLoad" delegate argument.
Invoked when an image is about to be loaded by file path, URL or inline data in 'img' element or background-image CSS style.
Allows to overwrite the loaded image by providing the image object manually, or different source (file or URL) to load from.
Example: image 'src' can be non-valid string that is interpreted in the overwrite delegate by custom logic to resource image object
Example: image 'src' in the html is relative - the overwrite intercepts the load and provide full source URL to load the image from
Example: image download requires authentication - the overwrite intercepts the load, downloads the image to disk using custom code and provide file path to load the image from.
If no alternative data is provided the original source will be used.
Note: Cannot use asynchronous scheme overwrite scheme.

Methods

AddFontFamily(FontFamily)

Adds a font family to be used in html rendering.
The added font will be used by all rendering function including HtmlContainer and all WPF controls.

public static void AddFontFamily(FontFamily fontFamily)

Parameters

fontFamily FontFamily

The font family to add.

Remarks

The given font family instance must be remain alive while the renderer is in use.
If loaded from file then the file must not be deleted.

AddFontFamilyMapping(string, string)

Adds a font mapping from fromFamily to toFamily iff the fromFamily is not found.
When the fromFamily font is used in rendered html and is not found in existing fonts (installed or added) it will be replaced by toFamily.

public static void AddFontFamilyMapping(string fromFamily, string toFamily)

Parameters

fromFamily string

the font family to replace

toFamily string

the font family to replace with

Remarks

This fonts mapping can be used as a fallback in case the requested font is not installed in the client system.

Measure(string, double, CssData, EventHandler<HtmlStylesheetLoadEventArgs>, EventHandler<HtmlImageLoadEventArgs>)

Measure the size (width and height) required to draw the given html under given max width restriction.
If no max width restriction is given the layout will use the maximum possible width required by the content, it can be the longest text line or full image width.

public static Size Measure(string html, double maxWidth = 0, CssData cssData = null, EventHandler<HtmlStylesheetLoadEventArgs> stylesheetLoad = null, EventHandler<HtmlImageLoadEventArgs> imageLoad = null)

Parameters

html string

HTML source to render

maxWidth double

optional: bound the width of the html to render in (default - 0, unlimited)

cssData CssData

optional: the style to use for html rendering (default - use W3 default style)

stylesheetLoad EventHandler<HtmlStylesheetLoadEventArgs>

optional: can be used to overwrite stylesheet resolution logic

imageLoad EventHandler<HtmlImageLoadEventArgs>

optional: can be used to overwrite image resolution logic

Returns

Size

the size required for the html

ParseStyleSheet(string, bool)

Parse the given stylesheet to CssData object.
If combineWithDefault is true the parsed css blocks are added to the default css data (as defined by W3), merged if class name already exists. If false only the data in the given stylesheet is returned.

public static CssData ParseStyleSheet(string stylesheet, bool combineWithDefault = true)

Parameters

stylesheet string

the stylesheet source to parse

combineWithDefault bool

true - combine the parsed css data with default css data, false - return only the parsed css data

Returns

CssData

the parsed css data

Render(DrawingContext, string, double, double, double, CssData, EventHandler<HtmlStylesheetLoadEventArgs>, EventHandler<HtmlImageLoadEventArgs>)

Renders the specified HTML source on the specified location and max width restriction.
If maxWidth is zero the html will use all the required width, otherwise it will perform line wrap as specified in the html
Returned is the actual width and height of the rendered html.

public static Size Render(DrawingContext g, string html, double left = 0, double top = 0, double maxWidth = 0, CssData cssData = null, EventHandler<HtmlStylesheetLoadEventArgs> stylesheetLoad = null, EventHandler<HtmlImageLoadEventArgs> imageLoad = null)

Parameters

g DrawingContext

Device to render with

html string

HTML source to render

left double

optional: the left most location to start render the html at (default - 0)

top double

optional: the top most location to start render the html at (default - 0)

maxWidth double

optional: bound the width of the html to render in (default - 0, unlimited)

cssData CssData

optional: the style to use for html rendering (default - use W3 default style)

stylesheetLoad EventHandler<HtmlStylesheetLoadEventArgs>

optional: can be used to overwrite stylesheet resolution logic

imageLoad EventHandler<HtmlImageLoadEventArgs>

optional: can be used to overwrite image resolution logic

Returns

Size

the actual size of the rendered html

Render(DrawingContext, string, Point, Size, CssData, EventHandler<HtmlStylesheetLoadEventArgs>, EventHandler<HtmlImageLoadEventArgs>)

Renders the specified HTML source on the specified location and max size restriction.
If maxSize.Width is zero the html will use all the required width, otherwise it will perform line wrap as specified in the html
If maxSize.Height is zero the html will use all the required height, otherwise it will clip at the given max height not rendering the html below it.
Returned is the actual width and height of the rendered html.

public static Size Render(DrawingContext g, string html, Point location, Size maxSize, CssData cssData = null, EventHandler<HtmlStylesheetLoadEventArgs> stylesheetLoad = null, EventHandler<HtmlImageLoadEventArgs> imageLoad = null)

Parameters

g DrawingContext

Device to render with

html string

HTML source to render

location Point

the top-left most location to start render the html at

maxSize Size

the max size of the rendered html (if height above zero it will be clipped)

cssData CssData

optional: the style to use for html rendering (default - use W3 default style)

stylesheetLoad EventHandler<HtmlStylesheetLoadEventArgs>

optional: can be used to overwrite stylesheet resolution logic

imageLoad EventHandler<HtmlImageLoadEventArgs>

optional: can be used to overwrite image resolution logic

Returns

Size

the actual size of the rendered html

RenderToImage(string, int, int, Color, CssData, EventHandler<HtmlStylesheetLoadEventArgs>, EventHandler<HtmlImageLoadEventArgs>)

Renders the specified HTML into a new image of unknown size that will be determined by max width/height and HTML layout.
If maxWidth is zero the html will use all the required width, otherwise it will perform line wrap as specified in the html
If maxHeight is zero the html will use all the required height, otherwise it will clip at the given max height not rendering the html below it.

Limitation: The image cannot have transparent background, by default it will be white.
See "Rendering to image" remarks section on HtmlRender.

public static BitmapFrame RenderToImage(string html, int maxWidth = 0, int maxHeight = 0, Color backgroundColor = default, CssData cssData = null, EventHandler<HtmlStylesheetLoadEventArgs> stylesheetLoad = null, EventHandler<HtmlImageLoadEventArgs> imageLoad = null)

Parameters

html string

HTML source to render

maxWidth int

optional: the max width of the rendered html, if not zero and html cannot be layout within the limit it will be clipped

maxHeight int

optional: the max height of the rendered html, if not zero and html cannot be layout within the limit it will be clipped

backgroundColor Color

optional: the color to fill the image with (default - white)

cssData CssData

optional: the style to use for html rendering (default - use W3 default style)

stylesheetLoad EventHandler<HtmlStylesheetLoadEventArgs>

optional: can be used to overwrite stylesheet resolution logic

imageLoad EventHandler<HtmlImageLoadEventArgs>

optional: can be used to overwrite image resolution logic

Returns

BitmapFrame

the generated image of the html

RenderToImage(string, Size, Size, Color, CssData, EventHandler<HtmlStylesheetLoadEventArgs>, EventHandler<HtmlImageLoadEventArgs>)

Renders the specified HTML into a new image of unknown size that will be determined by min/max width/height and HTML layout.
If maxSize.Width.Width is zero the html will use all the required width, otherwise it will perform line wrap as specified in the html
If maxSize.Height.Height is zero the html will use all the required height, otherwise it will clip at the given max height not rendering the html below it.
If minSize (Width/Height) is above zero the rendered image will not be smaller than the given min size.

Limitation: The image cannot have transparent background, by default it will be white.
See "Rendering to image" remarks section on HtmlRender.

public static BitmapFrame RenderToImage(string html, Size minSize, Size maxSize, Color backgroundColor = default, CssData cssData = null, EventHandler<HtmlStylesheetLoadEventArgs> stylesheetLoad = null, EventHandler<HtmlImageLoadEventArgs> imageLoad = null)

Parameters

html string

HTML source to render

minSize Size

optional: the min size of the rendered html (zero - not limit the width/height)

maxSize Size

optional: the max size of the rendered html, if not zero and html cannot be layout within the limit it will be clipped (zero - not limit the width/height)

backgroundColor Color

optional: the color to fill the image with (default - white)

cssData CssData

optional: the style to use for html rendering (default - use W3 default style)

stylesheetLoad EventHandler<HtmlStylesheetLoadEventArgs>

optional: can be used to overwrite stylesheet resolution logic

imageLoad EventHandler<HtmlImageLoadEventArgs>

optional: can be used to overwrite image resolution logic

Returns

BitmapFrame

the generated image of the html

RenderToImage(string, Size, CssData, EventHandler<HtmlStylesheetLoadEventArgs>, EventHandler<HtmlImageLoadEventArgs>)

Renders the specified HTML into a new image of the requested size.
The HTML will be layout by the given size but will be clipped if cannot fit.

public static BitmapFrame RenderToImage(string html, Size size, CssData cssData = null, EventHandler<HtmlStylesheetLoadEventArgs> stylesheetLoad = null, EventHandler<HtmlImageLoadEventArgs> imageLoad = null)

Parameters

html string

HTML source to render

size Size

The size of the image to render into, layout html by width and clipped by height

cssData CssData

optional: the style to use for html rendering (default - use W3 default style)

stylesheetLoad EventHandler<HtmlStylesheetLoadEventArgs>

optional: can be used to overwrite stylesheet resolution logic

imageLoad EventHandler<HtmlImageLoadEventArgs>

optional: can be used to overwrite image resolution logic

Returns

BitmapFrame

the generated image of the html