The first plot

To create a plot in VectSharp, the first step is to create a Page object, providing the width and height of image. These are expressed in arbitrary units, and serve as a reference for the coordinates of objects that are drawn on the page.

using VectSharp;
using VectSharp.SVG;

// Width of the page.
double width = 100;

// Height of the page.
double height = 100;

// Create the page.
Page page = new Page(width, height);

Afterwards, you can access the Graphics property of the Page, and use methods on this object to draw elements on the plot.

// Get the Graphics object.
Graphics graphics = page.Graphics;

One of the simplest things that can be plotted is a rectangle, which can be achieved by using the FillRectangle method. This method has multiple overloads; one of these has five mandatory arguments:

• The X coordinate of the rectangle (i.e. the coordinate of the left side of the rectangle).
• The Y coordinate of the rectangle (i.e. the coordinate of the top side of the rectangle).
• The width of the rectangle.
• The height of the rectangle.
• The colour with which the rectangle will be filled.

// Position and size of the rectangle.
double rectangleX = 10;
double rectangleY = 10;
double rectangleWidth = 80;
double rectangleHeight = 80;

// Colour of the rectangle.
Colour fillColour = Colours.Green;

// Draw the rectangle.
graphics.FillRectangle(rectangleX, rectangleY, rectangleWidth, rectangleHeight, fillColour);

The colour of the rectangle can be chosen in two main ways: first, as we have done here, you can use one of the static members of the Colours class, which contains a list of “known” web colours. If you wish to specify the RGB values of the colour, instead, you can use the Colour.FromRgb and Colour.FromRgba methods.

Colour.FromRgb takes three arguments, corresponding to the red, green and blue components of the colour; Colour.FromRgba also takes a fourth argument corresponding to the alpha (opacity) component. These can be specified as ints from 0 to 255, or as doubles between 0 and 1.

For example:

// A known colour.
Colour cornflowerBlue = Colours.CornflowerBlue.

// An opaque red colour.
Colour red = Colour.FromRgb(255, 0, 0);

// A semi-transparent blue colour.
Colour blue = Colour.FromRgb(0, 0, 1.0, 0.5);

The rectangle could also be filled using a more complex “brush”, e.g. a gradient. This will be the topic of a different tutorial.

By default, the image will have a transparent background. You can change the background colour through the Background property of the Page object:

// Set the page background to a light grey.
page.Background = Colour.FromRgb(200, 200, 200);

Finally, now that you have drawn the rectangle on the page and changed its background, you can export the page as an SVG file:

// Output file name.
string outputFile = "Rectangle.svg";

// Save the page as an SVG document.
page.SaveAsSVG(outputFile);

This will create a file called Rectangle.svg in the same path as the executable. The resulting SVG image should look like this:

using VectSharp;
using VectSharp.SVG;

// Width of the page.
double width = 100;

// Height of the page.
double height = 100;

// Create the page.
Page page = new Page(width, height);

// Get the Graphics object.
Graphics graphics = page.Graphics;

// Position and size of the rectangle.
double rectangleX = 10;
double rectangleY = 10;
double rectangleWidth = 80;
double rectangleHeight = 80;

// Colour of the rectangle.
Colour fillColour = Colours.Green;

// Draw the rectangle.
graphics.FillRectangle(rectangleX, rectangleY, rectangleWidth, rectangleHeight, fillColour);

// Set the page background to a light grey.
page.Background = Colour.FromRgb(200, 200, 200);

// Output file name.
string outputFile = "Rectangle.svg";

// Save the page as an SVG document.
page.SaveAsSVG(outputFile);