ISVG Interface

Unit: SVGInterfaces

Description

ISVG is the core interface for SVG document manipulation and rendering. It is implemented by factory-specific classes (Image32, Skia4Delphi, Direct2D, SVGMagic) and provides a unified API regardless of the underlying rendering engine.

Properties

Size Properties (Read-Only)

property Width: Single;
property Height: Single;

Natural size of the SVG document.

Rendering Properties

property Opacity: Single;                      // 0.0 to 1.0
property GrayScale: Boolean;
property FixedColor: TColor;
property ApplyFixedColorToRootOnly: Boolean;

• Opacity is limited to the range 0..1 (a value outside it is clamped).
• FixedColor: SVG_INHERIT_COLOR (clDefault) and SVG_NONE_COLOR (clNone) both mean "no fixed color": the original colors of the SVG are used. fill="none" is always preserved, so outline icons stay outlines.
• ApplyFixedColorToRootOnly: the color is applied only to what the root element passes down (its fill, stroke and currentColor); elements with their own colors keep them.

Content

property Source: string;

SVG XML source code. It always returns the text as it was assigned or loaded (also with engines that rewrite it internally, like Skia4Delphi with <style> blocks). Assigning an invalid SVG raises ESVGException; assigning '' empties the document.

Methods

State

function IsEmpty: Boolean;
procedure Clear;

Clear empties the document: after it IsEmpty is True, Source is '', Width and Height are 0, and PaintTo paints nothing.

File/Stream Operations

procedure SaveToStream(Stream: TStream);
procedure SaveToFile(const FileName: string);
procedure LoadFromStream(Stream: TStream);
procedure LoadFromFile(const FileName: string);

LoadFromStream and LoadFromFile raise ESVGException if the content is not a valid SVG, with every engine.

Rendering

procedure PaintTo(DC: HDC; R: TRectF; KeepAspectRatio: Boolean = True);

Global Functions

Factory Management

function GlobalSVGFactory: ISVGFactory;
procedure SetGlobalSvgFactory(const AFactory: ISVGFactory);

Factory Getters

function GetImage32SVGFactory: ISVGFactory;
function GetD2DSVGFactory: ISVGFactory;
function GetSkiaSVGFactory: ISVGFactory;
function GetSVGMagicFactory: ISVGFactory;

Examples

Direct SVG Usage

var
  SVG: ISVG;
begin
  SVG := GlobalSVGFactory.NewSvg;
  SVG.LoadFromFile('icon.svg');
  SVG.FixedColor := clBlue;
  SVG.Opacity := 0.8;
  SVG.PaintTo(Canvas.Handle, TRectF.Create(0, 0, 100, 100));
end;

Change Rendering Engine

// Switch to Skia4Delphi
SetGlobalSvgFactory(GetSkiaSVGFactory);

// All new SVG objects will use Skia
var SVG := GlobalSVGFactory.NewSvg;

See Also

• Choice of Factories
• VCL Reference Overview