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BeginAccess

Begin drawing access to the framebuffer to exclude the software cursor image

Declaration

void NAPI GA_cursorFuncs::BeginAccess(
N_int32 left,
N_int32 top,
N_int32 right,
N_int32 bottom)

Prototype In

snap/graphics.h

Parameters

left | Left coordinate of display affected
top | Top coordinate of display affected
right | Right coordinate of display affected (exclusive)
bottom | Bottom coordinate of display affected (exclusive)

Description

This function must be used by the application when the 2d reference rasteriser is using a software based cursor image. The cursor images are stored in either system memory of offscreen memory buffers, and either a software or hardware blitter is used to draw the cursor images on the screen. Since the cursor images are physically drawn on the display screen, this function must be used to inform the 2d reference rasteriser that the application is about to draw to a particular location on the screen. The 2d reference rasteriser will then remove the cursor image from the screen temporarily while the drawing is taking place if the region being drawn to and the cursor image overlap.

This function is not used when the cursor is implemented entirely in hardware on the display device. It will also not be provided by hardware drivers, just by the 2d reference rasteriser library. Optimised applications and shell drivers should disable calls to this function when a hardware cursor is in use (see the IsHardwareCursor function to determine this at runtime).

Note: This function must always be used for all drawing operations, regardless of whether the drawing is being done in software or hardware or directly by the application program writing to the framebuffer.

See Also

SetMonoCursor, SetMonoCursorColor, SetColorCursor, SetCursorPos, ShowCursor, BeginAccess, EndAccess, SetColorCursor256, SetColorCursorRGBA, IsHardwareCursor, SetColorCursorRGB

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