Product Home • Class Index • Download

CK_ScrollHandle

CK_Object
   |
   +----CK_Component
           |
           +----CK_Primitive
                   |
                   +----CK_ScrollHandle

The CK_ScrollHandle class represents a scroll bar. It is the scroll handle, as well as the channel along which the handle can move. The CK_ScrollHandle automatically responds to left mouse button clicks & drags. The mouse events are still sent to the CK_Screen's componentCB() method, allowing the application to respond to movement of the scroll bar.

The CP_Bitmap property specifies the bitmap that will represent the scroll handle. The scroll channel is transparent, but the CK_ScrollHandle can be the child of a manager component such as a CK_Frame, allowing the frame to provide the bitmap for the channel.

The scroll bar can be vertical or horizontal, and this is determined by the CP_LayoutDirection property. If the scroll bar is horizontal, the height of the channel is automatically set to the height of the handle bitmap. In this case, the CP_Width should be explicitly set, and it represents the width of the channel. If the scroll bar is vertical, the width of the channel is automatically set to the width of the handle bitmap. In this case, the CP_Height should be explicitly set, and it represents the height of the channel.

For horizontal scroll bars, the CP_Width represents the physical length, in pixels, of the channel. The channel can be given a logical length by setting the CP_ChannelLength property. The current position of the handle can be retrieved in logical units. The CP_HandlePosition property holds the current handle position. The handle position can range from 0 to (CP_ChannelLength - 1). If the scroll handle is at the top (or left) end of the channel, the CP_HandlePosition property will have the value 0. If the scroll handle is at the bottom (or right) end of the channel, the logical handle position is (CP_ChannelLength - 1).

Setting the CP_HandlePosition property will cause the scroll handle to move to that position.

See Example 34 and 35.

Properties

• CP_Bitmap - The bitmap representing the handle that moves within the channel.
• CP_BitmapRect - Specifies a rectangular portion (CK_Rect) of the CP_Bitmap to be used.  Otherwise the entire bitmap is used. (v1.02)
• CP_CallbackArg1 - An integer value to be passed to the screen's componentCB method when an event occurs in this component.
• CP_CallbackArg2 - Same as CP_CallbackArg1.
• CP_Cursor - The cursor to be displayed when the mouse pointer is over the component. (v1.02)
• CP_ChannelLength - The logical length of the channel. Can be any positive number greater than 0. If the channel length is 100, then the handle position be 0 when the handle is at the top (or left) of the channel, and 99 when the handle is at the bottom (or right) of the channel.
• CP_HandlePosition - Represents the current logical position of the scroll handle. Setting this property will cause the scroll handle to move to that location.
• CP_Height - The height of the scroll channel. If the layout direction is horizontal, then the height is determined by the height of the handle bitmap.
• CP_LayoutDirection - Can be either CV_LayoutVertical or CV_LayoutHorizontal.
• CP_PaletteIndex - If a bitmap is present, and it is 8-bit color, then this property will determine which palette in the bitmap's palette set is to be used.
• CP_RelativeX - Only used when this component is a child of a CK_BBoard or CK_ClipWindow. It is the X position of the component relative to the parent's left edge.
• CP_RelativeY - Only used when this component is a child of a CK_BBoard or CK_ClipWindow. It is the Y position of the component relative to the parent's top edge.
• CP_Width - The width of the scroll channel. If the layout direction is vertical, then the width is determined by the width of the handle bitmap.
• CP_X - The absolute X-position, in screen coordinates, of the component. This can only be set for the top-level component of a screen or a dialog.
• CP_Y - The absolute Y-position, in screen coordinates, of the component. This can only be set for the top-level component of a screen or a dialog.
• CP_ZOrder - Used when this component is a child of a CK_BBoard. The CK_BBoard uses this value to determine the order in which children are drawn. Smaller Z-order values are drawn before larger Z-order values.

Examples of creating a scroll handle:

extern CK_Bitmap *handle;
extern CK_Frame *frame;

CK_ScrollHandle *sHandle1 = (CK_ScrollHandle *) CreateComponent(CT_ScrollHandle, frame,
    CP_Bitmap, handle,
    CP_LayoutDirection, CV_LayoutVertical,
    CP_Height, 200,
    CP_ChannelLength, 1000,
    0);

CK_ScrollHandle *sHandle2 = (CK_ScrollHandle *) CreateComponent(CT_ScrollHandle, frame,
    CP_Bitmap, handle,
    CP_LayoutDirection, CV_LayoutHorizontal,
    CP_Width, 200,
    CP_ChannelLength, 1000,
    0);