Manage Ink

PowerPoint provides the ink function to allow you to draw non-standard figures, which can be used to highlight other objects, show connections and processes, and draw attention to specific items on a slide.

Aspose.Slides provides the Aspose.Slides.Ink interface, which contains the types you need to create and manage ink objects.

Differences between Regular Object and Ink Objects

Objects on a PowerPoint slide are typically represented by shape objects. A shape object, in its simplest form, is a container that defines the area of the object itself (its frame) alongside its properties. The latter includes the container area size, the shape of the container, the container’s background, etc. For information, see Shape Layout Format.

However, when PowerPoint is dealing with an ink object, it ignores all properties of the object frame (container) except its size. The size of the container area is determined by the standard width and height values:

ink_powerpoint1

Inkshape Traces

Trace is a basic element or standard used to record the trajectory of a pen as a user writes digital ink. Traces are recordings that describe sequences of connected points.

The simplest form of encoding specifies the X and Y coordinates of each sample point. When all the connected points are rendered, they produce an image like this:

ink_powerpoint2

Brush Properties For Drawing

You can use a brush to draw lines connecting trace elements' points. The brush has its own color and size, corresponding to the Brush.Color and Brush.Size properties.

Set Ink Brush Color

This C# code shows you how to set the color for a brush:

using (Presentation pres = new Presentation("pres.pptx"))
{
    IInk ink = (IInk)pres.Slides[0].Shapes[0];
    IInkTrace[] traces = ink.Traces;
    IInkBrush brush = traces[0].Brush;
    Color brushColor = brush.Color;
    brush.Color = Color.Red;
}

Set Ink Brush Size

This C# code shows you how to set the size for a brush:

using (Presentation pres = new Presentation("pres.pptx"))
{
    IInk ink = (IInk)pres.Slides[0].Shapes[0];
    IInkTrace[] traces = ink.Traces;
    IInkBrush brush = traces[0].Brush;
    SizeF brushSize = brush.Size;
    brush.Size = new SizeF(5f, 10f);
}

Generally, a brush’s width and height don’t match, so PowerPoint does not display the brush size (the data section is grayed out). But when the brush width and height match, PowerPoint displays its size this way:

ink_powerpoint3

For clarity, let’s increase the height of the ink object and review the important dimensions:

ink_powerpoint4

The container (frame) does not consider the size of the brushes–it always assumes that the thickness of the line is zero (see the last image).

Therefore, to determine the visible area of the entire ink object, we must consider the trace objects' brush size. Here, the target object (the handwritten text trace object) has been scaled to the container (frame) size. When the size of the container (frame) changes, the brush size remains constant and vice versa.

ink_powerpoint5

PowerPoint exhibits the same behavior when dealing with texts:

ink_powerpoint6

Further reading

PowerPoint Shapes PowerPoint SmartArt