52 Chapter 3
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Ry - specifies (in pixels) the radius of the ellipse (from which the arc is derived) on the y
axis. This parameter is required and has no default value.
Startangle - indicates the point of the ellipse (from which the arc is derived) where the
arc begins. This parameter is required. There is no default value.
Endangle - indicates the point of the ellipse (from which the arc is derived) where the arc
ends. This parameter is required. There is no default value.
Opacity - specifies opacity of the drawn object. The default value is 255 (completely
solid).
Unlock - when set to true, causes the arc to display only where the specified color value
appears in the current (background) image. The default is false.
Color - sets the color of the ellipse.
Index - if a color palette exists for the source image, use this parameter to set the color of
the arc (as an alternative to the Color parameter).
NOTE: You cannot enter values in both the Color and Index fields.
Saturation - specifies a value for the weighting for the change in saturation for
destination pixels. A value of 255 changes the saturation of pixels to the specified color. A
value of 128 changes the saturation of a pixel to a mid-value between the pixel’s current
color and the specified color.
NOTE: The Saturation parameter only functions when the Blend parameter is set to
“colorize.”
PreserveAlpha - when set to true, preserves the alpha channel of the target image as the
alpha channel of the resulting image. The default value is false.
Blend - specifies the type of blending used to combine the drawn object with the images.
Blend options are: “Normal”, “Darken”, “Lighten”, “Hue”, “Saturation”, “Color”,
“Luminosity”, “Multiply”, “Screen”, “Dissolve”, “Overlay,” “HardLight”, “SoftLight”,
“Difference”, “Exclusion”, “Dodge”, “ColorBurn”, “Under”, “Colorize” (causes only the
hue component of the source to be stamped down on the image), and “Prenormal”.
NOTE: “Burn” has been deprecated. “ColorBurn” results in the same blend.
Width - specifies the thickness (in pixels) of the line that describes the arc. The default
value is 1. However, if the Fill parameter is set to true, the Width parameter is ignored.
Smooth - when set to true, makes the edges of the arc smooth, preventing a pixellated
effect. The default is false.
Fill - when set to true, fills in the arc with the color specified by the Color or Index
parameter. The default value is false.
Warpangles - when set to true, warps the angles to match the ellipse. The default value is
false.
