jumpscroll.h File Reference

Jump scrolling. More...

#include <stdint.h>

Go to the source code of this file.

Data Structures
struct	jump_scroller
	A jump scroller. More...

Macros
#define	SCROLL(delta)   ( ( unsigned int ) ( uint16_t ) ( int16_t ) (delta) )
	Construct scroll movement. More...
#define	SCROLL_DELTA(scroll)   ( ( int16_t ) ( (scroll) & 0x0000ffffUL ) )
	Extract change in scroller position. More...
#define	SCROLL_FLAGS   0xffff0000UL
	Scroll movement flags. More...
#define	SCROLL_WRAP   0x80000000UL
	Wrap around scrolling. More...
#define	SCROLL_NONE   SCROLL ( 0 )
	Do not scroll. More...
#define	SCROLL_UP   SCROLL ( -1 )
	Scroll up by one line. More...
#define	SCROLL_DOWN   SCROLL ( +1 )
	Scroll down by one line. More...

Functions
	FILE_LICENCE (GPL2_OR_LATER_OR_UBDL)
static int	jump_scroll_is_first (struct jump_scroller *scroll)
	Check if jump scroller is currently on first page. More...
static int	jump_scroll_is_last (struct jump_scroller *scroll)
	Check if jump scroller is currently on last page. More...
unsigned int	jump_scroll_key (struct jump_scroller *scroll, int key)
	Jump scrolling. More...
unsigned int	jump_scroll_move (struct jump_scroller *scroll, unsigned int move)
	Move scroller. More...
int	jump_scroll (struct jump_scroller *scroll)
	Jump scroll to new page (if applicable) More...

Detailed Description

Jump scrolling.

Definition in file jumpscroll.h.

Macro Definition Documentation

SCROLL

#define SCROLL

(

delta

)

( ( unsigned int ) ( uint16_t ) ( int16_t ) (delta) )

Construct scroll movement.

Parameters

delta

Change in scroller position

Return values

move	Scroll movement

Definition at line 32 of file jumpscroll.h.

SCROLL_DELTA

#define SCROLL_DELTA

(

scroll

)

( ( int16_t ) ( (scroll) & 0x0000ffffUL ) )

Extract change in scroller position.

Parameters

move	Scroll movement

Return values

delta

Change in scroller position

Definition at line 40 of file jumpscroll.h.

SCROLL_FLAGS

#define SCROLL_FLAGS   0xffff0000UL

Scroll movement flags.

Definition at line 43 of file jumpscroll.h.

SCROLL_WRAP

#define SCROLL_WRAP   0x80000000UL

Wrap around scrolling.

Definition at line 44 of file jumpscroll.h.

SCROLL_NONE

#define SCROLL_NONE   SCROLL ( 0 )

Do not scroll.

Definition at line 47 of file jumpscroll.h.

SCROLL_UP

#define SCROLL_UP   SCROLL ( -1 )

Scroll up by one line.

Definition at line 50 of file jumpscroll.h.

SCROLL_DOWN

#define SCROLL_DOWN   SCROLL ( +1 )

Scroll down by one line.

Definition at line 53 of file jumpscroll.h.

Function Documentation

FILE_LICENCE()

FILE_LICENCE

(

GPL2_OR_LATER_OR_UBDL

)

jump_scroll_is_first()

static int jump_scroll_is_first ( struct jump_scroller *  scroll )

inlinestatic

Check if jump scroller is currently on first page.

Parameters

scroll

Jump scroller

Return values

is_first

Scroller is currently on first page

Definition at line 61 of file jumpscroll.h.

                                                                        {

        return ( scroll->first == 0 );
}

References jump_scroller::first.

Referenced by draw_menu_items(), and draw_setting_rows().

jump_scroll_is_last()

static int jump_scroll_is_last ( struct jump_scroller *  scroll )

inlinestatic

Check if jump scroller is currently on last page.

Parameters

scroll

Jump scroller

Return values

is_last

Scroller is currently on last page

Definition at line 72 of file jumpscroll.h.

                                                                       {

        return ( ( scroll->first + scroll->rows ) >= scroll->count );
}

References jump_scroller::count, jump_scroller::first, and jump_scroller::rows.

Referenced by draw_menu_items(), and draw_setting_rows().

jump_scroll_key()

unsigned int jump_scroll_key	(	struct jump_scroller *	scroll,
		int	key
	)

Jump scrolling.

Handle keypress

Parameters

scroll	Jump scroller
key	Key pressed by user

Return values

move	Scroller movement, or zero

Definition at line 42 of file jumpscroll.c.

                                                                       {
        unsigned int flags = 0;
        int16_t delta;

        /* Sanity checks */
        assert ( scroll->rows != 0 );
        assert ( scroll->count != 0 );
        assert ( scroll->current < scroll->count );
        assert ( scroll->first < scroll->count );
        assert ( scroll->first <= scroll->current );
        assert ( scroll->current < ( scroll->first + scroll->rows ) );

        /* Handle key, if applicable */
        switch ( key ) {
        case KEY_UP:
                delta = -1;
                break;
        case TAB:
                flags = SCROLL_WRAP;
                /* fall through */
        case KEY_DOWN:
                delta = +1;
                break;
        case KEY_PPAGE:
                delta = ( scroll->first - scroll->current - 1 );
                break;
        case KEY_NPAGE:
                delta = ( scroll->first - scroll->current + scroll->rows );
                break;
        case KEY_HOME:
                delta = -( scroll->count );
                break;
        case KEY_END:
                delta = +( scroll->count );
                break;
        default:
                delta = 0;
                break;
        }

        return ( SCROLL ( delta ) | flags );
}

References assert(), jump_scroller::count, jump_scroller::current, jump_scroller::first, flags, key, KEY_DOWN, KEY_END, KEY_HOME, KEY_NPAGE, KEY_PPAGE, KEY_UP, jump_scroller::rows, SCROLL, SCROLL_WRAP, and TAB.

Referenced by form_loop(), main_loop(), and menu_loop().

jump_scroll_move()

unsigned int jump_scroll_move	(	struct jump_scroller *	scroll,
		unsigned int	move
	)

Move scroller.

Parameters

scroll	Jump scroller
move	Scroller movement

Return values

move	Continuing scroller movement (if applicable)

Definition at line 92 of file jumpscroll.c.

                                                    {
        int16_t delta = SCROLL_DELTA ( move );
        int current = scroll->current;
        int last = ( scroll->count - 1 );

        /* Sanity checks */
        assert ( move != 0 );
        assert ( scroll->count != 0 );

        /* Move to the new current item */
        current += delta;

        /* Default to continuing movement in the same direction */
        delta = ( ( delta >= 0 ) ? +1 : -1 );

        /* Check for start/end of list */
        if ( ( current >= 0 ) && ( current <= last ) ) {
                /* We are still within the list.  Update the current
                 * item and continue moving in the same direction (if
                 * applicable).
                 */
                scroll->current = current;
        } else {
                /* We have attempted to move outside the list.  If we
                 * are wrapping around, then continue in the same
                 * direction (if applicable), otherwise reverse.
                 */
                if ( ! ( move & SCROLL_WRAP ) )
                        delta = -delta;

                /* Move to start or end of list as appropriate */
                if ( delta >= 0 ) {
                        scroll->current = 0;
                } else {
                        scroll->current = last;
                }
        }

        return ( SCROLL ( delta ) | ( move & SCROLL_FLAGS ) );
}

References assert(), jump_scroller::count, jump_scroller::current, last, move(), SCROLL, SCROLL_DELTA, SCROLL_FLAGS, and SCROLL_WRAP.

Referenced by form_loop(), main_loop(), and menu_loop().

jump_scroll()

int jump_scroll

(

struct jump_scroller *

scroll

)

Jump scroll to new page (if applicable)

Parameters

scroll

Jump scroller

Return values

jumped

Jumped to a new page

Definition at line 140 of file jumpscroll.c.

                                                 {
        unsigned int index;

        /* Sanity checks */
        assert ( scroll->rows != 0 );
        assert ( scroll->count != 0 );
        assert ( scroll->current < scroll->count );
        assert ( scroll->first < scroll->count );

        /* Do nothing if we are already on the correct page */
        index = ( scroll->current - scroll->first );
        if ( index < scroll->rows )
                return 0;

        /* Move to required page */
        while ( scroll->first < scroll->current )
                scroll->first += scroll->rows;
        while ( scroll->first > scroll->current )
                scroll->first -= scroll->rows;

        return 1;
}

References assert(), jump_scroller::count, jump_scroller::current, jump_scroller::first, index, and jump_scroller::rows.

Referenced by main_loop(), menu_loop(), and show_menu().