Trait rat_widget::scrolled::ScrollingState

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pub trait ScrollingState {

Show 14 methods    // Required methods
    fn vertical_max_offset(&self) -> usize;
    fn vertical_offset(&self) -> usize;
    fn vertical_page(&self) -> usize;
    fn horizontal_max_offset(&self) -> usize;
    fn horizontal_offset(&self) -> usize;
    fn horizontal_page(&self) -> usize;
    fn set_vertical_offset(&mut self, offset: usize) -> bool;
    fn set_horizontal_offset(&mut self, offset: usize) -> bool;

    // Provided methods
    fn vertical_scroll(&self) -> usize { ... }
    fn horizontal_scroll(&self) -> usize { ... }
    fn scroll_up(&mut self, n: usize) -> bool { ... }
    fn scroll_down(&mut self, n: usize) -> bool { ... }
    fn scroll_left(&mut self, n: usize) -> bool { ... }
    fn scroll_right(&mut self, n: usize) -> bool { ... }

}
Expand description

Trait for the widget-state of a scrollable widget.

This trait works purely in item-space, none of the values correspond to screen coordinates.

The current visible page is represented as the pair (offset, page_len). The limit for scrolling is given as max_offset, which is the maximum offset where a full page can still be displayed. Note that the total length of the widgets data is NOT max_offset + page_len. The page_len can be different for every offset selected. Only if the offset is set to max_offset and after the next round of rendering len == max_offset + page_len will hold true.

The offset can be set to any value possible for usize. It’s the widgets job to limit the value if necessary. Of course, it’s possible for a user of this trait to set their own limits.

Required Methods§

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fn vertical_max_offset(&self) -> usize

Maximum offset that is accessible with scrolling.

This is shorter than the length of the content by whatever fills the last page. This is the base for the scrollbar content_length.

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fn vertical_offset(&self) -> usize

Current vertical offset.

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fn vertical_page(&self) -> usize

Vertical page-size at the current offset.

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fn horizontal_max_offset(&self) -> usize

Maximum offset that is accessible with scrolling.

This is shorter than the length of the content by whatever fills the last page. This is the base for the scrollbar content_length.

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fn horizontal_offset(&self) -> usize

Current horizontal offset.

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fn horizontal_page(&self) -> usize

Horizontal page-size at the current offset.

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fn set_vertical_offset(&mut self, offset: usize) -> bool

Change the vertical offset.

Due to overscroll it’s possible that this is an invalid offset for the widget. The widget must deal with this situation.

The widget returns true if the offset changed at all.

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fn set_horizontal_offset(&mut self, offset: usize) -> bool

Change the horizontal offset.

Due to overscroll it’s possible that this is an invalid offset for the widget. The widget must deal with this situation.

The widget returns true if the offset changed at all.

Provided Methods§

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fn vertical_scroll(&self) -> usize

Suggested scroll per scroll-event.

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fn horizontal_scroll(&self) -> usize

Suggested scroll per scroll-event.

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fn scroll_up(&mut self, n: usize) -> bool

Scroll up by n items. The widget returns true if the offset changed at all.

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fn scroll_down(&mut self, n: usize) -> bool

Scroll down by n items. The widget returns true if the offset changed at all.

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fn scroll_left(&mut self, n: usize) -> bool

Scroll up by n items. The widget returns true if the offset changed at all.

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fn scroll_right(&mut self, n: usize) -> bool

Scroll down by n items. The widget returns true if the offset changed at all.

Implementors§