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RSSVG.Text Namespace

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Defines SVG text elements (text, tspan, tref, etc)

Name

Description

Represents the common ancestor for all text elements (text, tref, tspan, text-path). Every svg text element potentially has multiple X, Y, DX, DY, and Rotate values to specify the location and orientation of each character in the text. If a text element does not specify its own X and Y values itself, it uses the RSSVG.Text.TSVGCustomText.CurrentTextPosition.

Notes to Implementers

Using default options on desktop platforms, all text elements in the RSCL work by converting the text into paths. First, the text of the parent and all of its text content children are divided into chunks. Each absolute position adjustment defines a new text chunk. A text chunk can span text child elements if they do not define a new absolute position. After the text is divided into chunks, the CreateTextShapes method (implemented in the TSVGText class) creates paths from all the text chunks.

Note that the TSVGTextPath class subverts this text chunking to provide an absolute position for every character so that the text aligns along its path.

When TSVGDocument.Options includes the soUseFillText option, text is not converted into paths but rendered directly to the canvas using FillText calls. On iOS and Android and when using the FMX GPU Canvas on desktop (FMX.Types.GlobalUseGPUCanvas), text is always filled.

The following differences exist between the two text rendering paths:

• Fill Text does not use the Pen and so cannot both fill and stroke text

• Fill Text cannot use gradients for filling (FMX)

• Fill Text uses less memory

• Fill Text generates better text at small sizes

• Fill Text does not do center and right alignment for complex text (i.e., text that has dx, dy, rotate, vertical writing mode, etc style properties defined)

• Fill Text has better compatibility with non-Western fonts

• Path-based text can both fill and stroke text (however, on non-Windows platforms gradients are not used in stroking text)

• Path-based text caches its shapes so subsequent draw calls are faster, even faster than fill text calls in many cases

• Path-based text allows pixel level selection of text; Fill Text can only be selected as a text bounding box

• Path-based text renders decorative fonts (underline, overline, and strike-out) using an extra path for the decoration (FMX will not generate paths with the decoration when converting text to paths). Surprisingly, this means that compatibility is higher with path-based text as the decoration gets its rendering configuration from the parent text element (e.g., strike-out text should use the parent text's font size and not vary as the size of child text span's font size changes).

•ShapeRendering affects the smoothness of text when filling path-based text (as text are shapes); TextRendering affects the smoothness of text when filling text

TSVGCustomTextContentChild

Base class for text content child elements: textPath, tref, and tspan

TSVGGraphicElementHack

Represents type TSVGGraphicElementHack.

TSVGText

Represents a SVG 'text' element. The ‘text’ element defines a graphics element consisting of text.

The attributes and properties on the ‘text’ element indicate such things as the writing direction, font specification and painting attributes which describe how exactly to render the characters.

Since ‘text’ elements are rendered using the same rendering methods as other graphics elements, all of the same coordinate system transformations, painting, clipping and masking features that apply to shapes such as paths and rectangles also apply to ‘text’ elements.

Note

The ‘text’ element renders its first glyph at the initial current text position, which is established by the ‘x’ and ‘y’ attributes on the ‘text’ element (with possible adjustments due to the value of the ‘text-anchor’ property, the presence of a ‘textPath’ element containing the first character, and/or an ‘x’, ‘y’, ‘dx’ or ‘dy’ attributes on a ‘tspan’, ‘tref’ or ‘altGlyph’ element which contains the first character). After the glyph(s) corresponding to the given character is(are) rendered, the current text position is updated for the next character. In the simplest case, the new current text position is the previous current text position plus the glyphs' advance value (horizontal or vertical).

TSVGTextPath

Represents a text-path svg element. The class displays a text string along a path. A path can be either an svg path element or a basic shape (rect, ellipse, etc).

Important Note
The parent RSSVG.Text.TSVGText class creates the actual path shape for the text in its ConvertToPath method (called indirectly at the end of the BeginDraw method). The class itself only transforms and draws the shape.

Notes to Implementers
TSVGTextPath works by manipulating the text chunks of itself and its children so that their X, Y, and Rotate values of the text chunks align along the path. The CalculateXYRotate(TSVGCanvas, TSVGMatrix) manipulates the text of the TSVGTextPath. The CalculateXYRotate(TSVGCanvas, TSVGMatrix, TSVGTextChunk, Integer, Single) aligns one character of a child text content element.

TSVGTextRef

Represents a SVG tref element. The textual content for a ‘text’ can be either character data directly embedded within the ‘text’ element or the character data content of a referenced element, where the referencing is specified with a ‘tref’ element.

TSVGTextSpan

Child element of a text element ( RSSVG.Text.TSVGText class). Within a ‘text’ element, text and font properties and the current text position can be adjusted with absolute or relative coordinate values by including a ‘tspan’ element.

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Name

Description

TSVGCharChunk

Defines a character chunk, which represents one character in a text chunk. It includes all information to position and format the character

TSVGTextChunk

Defines a text chunk, which is a segment of text. Each absolute position adjustment defines a new text chunk. A text chunk can span text child elements if they do not define a new absolute position.

The Text field holds the text. The Chars array holds the position and formatting information for each character in the text.

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	Name	Description
	TSVGCharChunks	Dynamic array of RSSVG.Text.TSVGCharChunk
	TSVGText.TLine	Represents an alias of the TObjectDictionary type.
	TSVGText.TLineSegment	Represents an alias of the TPair type.
	TSVGTextChunks	Dynamic array of RSSVG.Text.TSVGTextChunk

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RSSVG.Text Namespace

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