The following attributes affect drawing operations and are used in the IlvPalette class: Line Width, Fill Style, Fill Rule, Arc Mode, Draw Mode, Alpha Value, and Anti-Aliasing Mode.

These attributes are represented by C++ type definitions. Although they cannot be called “resources,” as they are not represented by subclasses of IlvResource, they operate in conjunction with the graphic resources to define the drawing attributes of Views drawings.

The line width is an unsigned short integer. Zero (0) is a valid value, producing a line whose width is such that it can be drawn as thin and rapidly as possible.

IlvBorderPosition indicates where the border is drawn when creating a rectangle or a rounded rectangle. The IlvRect drawing methods determine the position of the border relative to the bounds of the rectangle. The possible values are:

The border position is a property in IlvPalette. The value is specified either when getting the palette from IlvDisplay::getPalette or with IlvPalette::setBorderPosition(). The parameter affects drawings made with:

The other drawing methods are not affected by the border position: drawArc, drawPolyline, drawReliefRectangle, drawReliefDiamond, drawClosedBezier, drawOutlineRectangle, fillRectangle, and so forth.

The most complex of the graphic resources is that of patterns, where there are the simple masking patterns of the monochrome (two-color) domain, the rich pixel patterns of color and the gradient patterns. This aspect is referred to as the fill style.

The fill style indicates the way in which patterns are used to fill shapes. There are four possible cases represented in the IlvFillStyle enumeration type. A monochrome pattern is used when the fill mode is IlvFillPattern or IlvFillMaskPattern. Its value is an instance of IlvPattern, whether created by the user or returned by specific member functions of the IlvDisplay class. Color pattern refers to what is used to fill shapes when the fill mode is IlvFillColorPattern. Gradient pattern refers to what is used to fill shapes when the fill mode is IlvFillGradientPattern.

With IlvFillPattern a shape is filled by being copied with the chosen pattern. In a Views object, there is a pattern property, which refers to an object of the IlvPattern class. To fill a shape with a given pattern:

This is the default value of the fill-style property of an IlvPalette object.

IlvFillMaskPattern is similar to the IlvFillPattern style, except that “0” pixels in the relevant IlvPattern object have no effect upon the corresponding pixels in the destination port. That is, the drawing masks its destination.

In the case of IlvFillColorPattern, the pattern used to fill a shape is indicated, not by the pattern property of the IlvPalette object, but rather by its colored  pattern property. It is used when you wish to fill a region with a full-color pattern; that is, an actual object of the IlvGradientPattern class. The pattern property plays no role in the case of this filling mode.

In the case of IlvFillGradientPattern, the pattern used to fill a shape is indicated by its gradient  pattern property. It is used when you wish to fill a region with a gradient pattern; that is, an actual object of the IlvGradientPattern class. The pattern and color pattern properties play no role in the case of this filling mode.

This attribute indicates how self-intersecting polygons are filled, since there is an ambiguity concerning what is meant by “fill” in the case of such surfaces.

The fill rule indicates which points are to be considered as inside a filled polygon, depending on the count of crossing segments that define the shape of the area to be filled. The IlvFillRule provides two possibilities:

The arc mode indicates the way to close arcs in order to fill them, that is, the way in which filled arcs are to be drawn: either by radii that form a wedge-shaped “pie” or by a simple “chord” line segment. There are two possible cases that are handled by the IlvArcMode enumeration type.

The draw mode specifies the operation to be performed on pixels when they are sent to the destination port. The operation is the one that affects the destination pixel value when the source pixel value is to be drawn at that place. The draw mode has several possible values, which are handled by the IlvDrawMode enumeration type. Except for the IlvModeXor value, used in temporary drawings, these types produce no significant graphic result when drawing in color.

The alpha value indicates the amount of transparency the drawing will be given. A value of 0 means that the drawing will be completely transparent, that is, nothing will be drawn. A value of IlvFullIntensity means that the drawing will be opaque.

Drawing involves the use of two objects:

It is possible to control transparency at both levels: For example, you can set an alpha value on the port (using IlvPort::setAlpha) and also on the palette you are going to draw with (IlvPalette::setAlpha). In this case, the resulting drawing will use the composition of the two alpha values.

The anti-aliasing mode indicates whether smooth lines are drawn using anti-aliasing. The possible values for this mode are:

The anti-aliasing mode can be specified at different levels:

The following rules are applied to determine if the final drawing will use anti-aliasing or not: