Basic Drawing Primitives

The following example introduces how an image can be created in OEDepict TK to generate a single black line across an image:

1. Create an OEImage object with a specific width and height.

2. Specify the two end points of the line with OE2DPoint objects.

3. Draw the line with the OEImage::DrawLine method using the OEDepict::OEBlackPen to specify the graphical properties of the line.

4. Write the image into a file by calling the OEWriteImage function.

   The OEImage class is implemented as a container of drawing commands. When a method such as OEImage::DrawLine is called, rather than immediately drawing the line specified by the parameters, a line drawing operation is created in the OEImage class for later execution.

Listing 1: Example of line drawing

int main()
{
  const auto width  = 100u;
  const auto height = 100u;
  // Create image
  OEImage image(width, height);

  // Draw line with default pen
  image.DrawLine(OE2DPoint(10.0, 10.0), OE2DPoint(90.0, 90.0), OEBlackPen);

  // Write image to SVG file
  OEWriteImage("DrawLine.svg", image);
  return 0;
}

The image created by Listing 1 is shown in Figure: Example of line drawing.

Example of line drawing

See also

• OEPen class

• OEImage class

• OEWriteImage function

Coordinate System

The coordinate system used in OEDepict TK has the origin (x=0.0, y=0.0) at the top left with the x-axis pointing to the right and the y-axis pointing down.

2D coordinate system (X = horizontal, Y = vertical)

See also

• OE2DPoint class

Basic Shapes

OEDepict TK supports drawing the following basic shapes:

OEImageBase::DrawArc	OEImageBase::DrawCircle	OEImageBase::DrawCubicBezier
OEImageBase::DrawLine	OEImageBase::DrawPath	OEImageBase::DrawPie
OEImageBase::DrawPoint	OEImageBase::DrawPolygon	OEImageBase::DrawQuadraticBezier
OEImageBase::DrawRectangle	OEImageBase::DrawText	OEImageBase::DrawTriangle

Image File Formats

OEDepict TK natively supports a variety of graphical file formats. OEWriteImage automatically detects the desired file format from the file name passed to the function. The following table lists the file formats natively supported in OEDepict TK and their associated file extensions:

Graphics File Format	Format Type	File Extension
PNG (Portable Network Graphics)	raster image	.png
SVG (Scalable Vector Graphics)	vector image	.svg
bare SVG (with no header)	vector image	.bsvg
Postscript	vector image	.ps
Encapsulated PostScript	vector image	.eps
PDF (Portable Document Format)	vector image	.pdf

The OEIsRegisteredImageFile function can be used to query whether a given file extension is supported by OEDepict TK. All the supported file formats can be queried using the OEGetSupportedImageFileExtensions function.