Mouse Panning

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Epsilon User's Manual and Reference

    Primitives and EEL Subroutines

       Input Primitives

          Keys

          The Mouse

             . . .

             Mouse Subroutines

             The Scroll Bar

             Mouse Panning

          Window Events

          . . .

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The Scroll Bar	Primitives and EEL Subroutines	Window Events

Epsilon User's Manual and Reference > Primitives and EEL Subroutines > Input Primitives > The Mouse >

Mouse Panning

int mouse_panning;

int mouse_panning_rate(int percent, int slow, int fast)

The mouse_panning variable and the mouse_panning_rate( ) primitive work together to support panning and auto-scroll with the Microsoft IntelliMouse (or any other three button mouse). The EEL subroutine that receives clicks of the third mouse button sets mouse_panning nonzero to tell Epsilon to begin panning and record the initial position of the mouse.

Then the subroutine can regularly call mouse_panning_rate( ) to determine how quickly, and in what direction, to scroll. The parameter percent specifies the percentage of the screen the mouse has to travel to reach maximum speed (usually 40%). The parameter slow specifies the minimum speed in milliseconds per screen line (usually 2000 ms/line). The parameter fast specifies the maximum speed in milliseconds per screen line (usually 1 ms/line).

The mouse_panning_rate( ) primitive uses these figures, plus the current position of the mouse, to return the scroll rate in milliseconds per screen line. It returns a positive number if Epsilon should scroll down, a negative number to scroll up, or zero if Epsilon should not scroll.

See the previous section for information on what happens when you roll the wheel on a wheeled mouse instead of clicking it.

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The Scroll Bar Primitives and EEL Subroutines Window Events