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Navigation: Code Documentation > RSVclSVG > RSSVG > Classes > TSVGDocument > Methods

TSVGDocument.DrawElement(TSVGGraphicElement,TSVGMatrix,TSVGCanvas,TSVGRect) Method

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Draw the svg element and its children to the specified canvas inside the specified rectangle.

No ancestors or siblings are drawn. The svg element is drawn where it would be if the entire SVG was drawn.

Namespace: RSSVG

Parameters

Element

Type: TSVGGraphicElement

Element to draw

aMatrix

Type: System.Void

cumulative transformations from the Parent element (and its Parents) to apply when drawing the element.

Canvas

Type: System.Void

Canvas to draw on

aRect

Type: System.Void

Rectangle to draw within

The following example uses the DrawBeforeElement, DrawElement, and DrawAfterElement methods to optimize the drawing of an svg where one element may be changed often (such as in an editor):

Delphi

procedure TfrmSVGEditor.PaintBox1Paint(Sender: TObject; Canvas: TCanvas);
var
   aRect: TSVGRect;
begin
   // do we need to update the background (elements before) and foreground (elements
   // after) the current Element.  By creating a bitmap of the background and
   // foreground, we can optimize the drawing of the SVG as the current Element
   // changes
   if UpdateBackground then
   begin
     // draw background and foreground
     Background.Canvas.BeginScene;
     try
       Background.Clear(TAlphaColorRec.Null);
       if Element is TSVGGraphicElement then
         SVG.DrawBeforeElement(TSVGGraphicElement(Element), Background.Canvas, RectF(0,0,Background.Width, Background.Height));
     finally
       Background.Canvas.EndScene;
     end;
     Foreground.Canvas.BeginScene;
     try
       Foreground.Clear(TAlphaColorRec.Null);
       if Element is TSVGGraphicElement then
         SVG.DrawAfterElement(TSVGGraphicElement(Element), Foreground.Canvas, RectF(0,0,Foreground.Width, Foreground.Height));
     finally
       Foreground.Canvas.EndScene;
     end;
     FUpdateBackground := False;
   end;
   if Element is TSVGGraphicElement then
   begin
     // if current Element is a graphical element, draw the background
     aRect := RectF(0, 0, Background.Width, Background.Height);
     Canvas.DrawBitmap(Background, aRect, aRect, 1);
     // draw the element
     SVG.DrawElement(TSVGGraphicElement(Element), Canvas, PaintBox1.ClipRect);
     // draw the foreground
     Canvas.DrawBitmap(Foreground, aRect, aRect, 1);
   end
   else
     // just draw the entire SVG without any background/foreground caching
     SVG.Draw(Canvas, PaintBox1.ClipRect);
   // draw the focus rectangle
   Canvas.DrawFocusRect(SelectRect);
end;

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