gradientslider.gadget Reference¶

Comprehensive function reference for gradientslider.gadget, synthesised from the AmigaOS NDK 3.2 Release 4 (Autodocs/gradientslider).

This page documents 1 function of gradientslider.gadget. Each function entry follows the canonical autodoc format. struct Name, union Name, enum Name are clickable links to the type definition in the types reference.

Function index¶

• gradientslider.gadget()

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gradientslider.gadget()¶

gradientslider.gadget -- create a slider with a range of colors as its background.

Function

    The gradientslider gadget class is a type of non-proportional slider.
    The primary feature of the gradient slider is it's appearance. Unlike
    normal sliders, a gradient slider can display a "spread of colors" or
    "color gradient" in the slider container box. The "knob" or "thumb"
    of the slider appears to slide on top of this color gradient.

    The color gradient effect is built-up using a combination of multiple
    pens and half-tone dithering. The application must tell the slider
    exactly which pens to use in creating the gradient effect, and in
    what order to use them. Essentially, it does this by passing an
    array of pens (terminated by ~0, just like a PenSpec) to the slider.
    The first pen in the array is used as the color at the top of
    the slider (or left, if it is horizontal), and the last color in the
    array is used at the bottom (or right). The other pens will be
    used at evenly spaced intervals in between. Dithering is used to
    smoothly fade between the pens, allowing the illusion of a continuous
    change in color.

TAGS
    GRAD_MaxVal (ULONG) - Set the maximum value that the slider can
        represent, in the range 0..$FFFF. Default for this tag is
        $FFFF. Applicability is (ISGU). (V39)

    GRAD_CurVal (ULONG) - Set or get the current value of the slider, in
        the range 0..$FFFF. Default for this tag is 0. Applicability is
        (ISGNU). (V39)

    GRAD_SkipVal (ULONG) - Set the amount by which the slider should
        advance whenever the user clicks on either side of the knob.
        Default for this tag is $1111. Applicability is (ISGU). (V39)

    GRAD_KnobPixels (UWORD) - Set the size of the knob in pixels.
        Default for this tag is 5. Applicability is (I). (V39)

    GRAD_PenArray (UWORD *) - Specifies an array of pens that the slider
        should use to create its gradient background. The array can
        contain any number of pens, and is terminated with a pen
        value of ~0. These pens can be allocated as shared, since
        their RGB value is not altered by the slider. The first pen
        is used on the top or left of the slider, and the last pen is
        used on the bottom or right. All other pens are evenly spaced
        out and used in between. Dithering is used between the pens
        to enhance the smoothness of the gradient transition.

        A NULL pen array causes the background of the slider to be
        rendered in the screen's background color. A pen array
        containing only a single pen causes the background to be
        rendered using that pen.

        Default for this tag is NULL. Applicability is (ISU). (V39)

    PGA_FREEDOM (ULONG) - Determines the orientation of the slider. This
        can be LORIENT_HORIZ for a horizontal slider, or LORIENT_VERT
        for a vertical one. Default for this tag is LORIENT_HORIZ.
        Applicability is (I). (V39)

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