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tomo-old/element.go

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package tomo
import "image"
import "git.tebibyte.media/sashakoshka/tomo/input"
import "git.tebibyte.media/sashakoshka/tomo/canvas"
// Element represents a basic on-screen object.
type Element interface {
// Draw causes the element to draw to the specified canvas. The bounds
// of this canvas specify the area that is actually drawn to, while the
// Entity bounds specify the actual area of the element.
Draw (canvas.Canvas)
// Entity returns this element's entity.
Entity () Entity
}
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// Layoutable represents an element that needs to perform layout calculations
// before it can draw itself.
type Layoutable interface {
Element
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// Layout causes this element to perform a layout operation.
Layout ()
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}
// Container represents an element capable of containing child elements.
type Container interface {
Element
Layoutable
// DrawBackground causes the element to draw its background pattern to
// the specified canvas. The bounds of this canvas specify the area that
// is actually drawn to, while the Entity bounds specify the actual area
// of the element.
DrawBackground (canvas.Canvas)
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// HandleChildMinimumSizeChange is called when a child's minimum size is
// changed.
HandleChildMinimumSizeChange (child Element)
}
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// Enableable represents an element that can be enabled and disabled. Disabled
// elements typically appear greyed out.
type Enableable interface {
Element
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// Enabled returns whether or not the element is enabled.
Enabled () bool
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// SetEnabled sets whether or not the element is enabled.
SetEnabled (bool)
}
// Focusable represents an element that has keyboard navigation support.
type Focusable interface {
Element
Enableable
// HandleFocusChange is called when the element is focused or unfocused.
HandleFocusChange ()
}
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// Selectable represents an element that can be selected. This includes things
// like list items, files, etc. The difference between this and Focusable is
// that multiple Selectable elements may be selected at the same time, whereas
// only one Focusable element may be focused at the same time. Containers who's
// purpose is to contain selectable elements can determine when to select them
// by implementing MouseTargetContainer and listening for HandleChildMouseDown
// events.
type Selectable interface {
Element
Enableable
// HandleSelectionChange is called when the element is selected or
// deselected.
HandleSelectionChange ()
}
// KeyboardTarget represents an element that can receive keyboard input.
type KeyboardTarget interface {
Element
// HandleKeyDown is called when a key is pressed down or repeated while
// this element has keyboard focus. It is important to note that not
// every key down event is guaranteed to be paired with exactly one key
// up event. This is the reason a list of modifier keys held down at the
// time of the key press is given.
HandleKeyDown (key input.Key, modifiers input.Modifiers)
// HandleKeyUp is called when a key is released while this element has
// keyboard focus.
HandleKeyUp (key input.Key, modifiers input.Modifiers)
}
// MouseTarget represents an element that can receive mouse events.
type MouseTarget interface {
Element
// HandleMouseDown is called when a mouse button is pressed down on this
// element.
HandleMouseDown (x, y int, button input.Button)
// HandleMouseUp is called when a mouse button is released that was
// originally pressed down on this element.
HandleMouseUp (x, y int, button input.Button)
}
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// MouseTargetContainer represents an element that wants to know when one
// of its children is clicked. Children do not have to implement MouseTarget for
// a container satisfying MouseTargetContainer to be notified that they have
// been clicked.
type MouseTargetContainer interface {
Container
// HandleMouseDown is called when a mouse button is pressed down on a
// child element.
HandleChildMouseDown (x, y int, button input.Button, child Element)
// HandleMouseUp is called when a mouse button is released that was
// originally pressed down on a child element.
HandleChildMouseUp (x, y int, button input.Button, child Element)
}
// MotionTarget represents an element that can receive mouse motion events.
type MotionTarget interface {
Element
// HandleMotion is called when the mouse is moved over this element,
// or the mouse is moving while being held down and originally pressed
// down on this element.
HandleMotion (x, y int)
}
// ScrollTarget represents an element that can receive mouse scroll events.
type ScrollTarget interface {
Element
// HandleScroll is called when the mouse is scrolled. The X and Y
// direction of the scroll event are passed as deltaX and deltaY.
HandleScroll (x, y int, deltaX, deltaY float64)
}
// Flexible represents an element who's preferred minimum height can change in
// response to its width.
type Flexible interface {
Element
// FlexibleHeightFor returns what the element's minimum height would be
// if resized to a specified width. This does not actually alter the
// state of the element in any way, but it may perform significant work,
// so it should be called sparingly.
//
// It is reccomended that parent containers check for this interface and
// take this method's value into account in order to support things like
// flow layouts and text wrapping, but it is not absolutely necessary.
// The element's MinimumSize method will still return the absolute
// minimum size that the element may be resized to.
//
// It is important to note that if a parent container checks for
// flexible chilren, it itself will likely need to be flexible.
FlexibleHeightFor (width int) int
}
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// FlexibleContainer represents an element that is capable of containing
// flexible children.
type FlexibleContainer interface {
Container
// HandleChildFlexibleHeightChange is called when the parameters
// affecting a child's flexible height are changed.
HandleChildFlexibleHeightChange (child Flexible)
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}
// Scrollable represents an element that can be scrolled. It acts as a viewport
// through which its contents can be observed.
type Scrollable interface {
Element
// ScrollContentBounds returns the full content size of the element.
ScrollContentBounds () image.Rectangle
// ScrollViewportBounds returns the size and position of the element's
// viewport relative to ScrollBounds.
ScrollViewportBounds () image.Rectangle
// ScrollTo scrolls the viewport to the specified point relative to
// ScrollBounds.
ScrollTo (position image.Point)
// ScrollAxes returns the supported axes for scrolling.
ScrollAxes () (horizontal, vertical bool)
}
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// ScrollableContainer represents an element that is capable of containing
// scrollable children.
type ScrollableContainer interface {
Container
// HandleChildScrollBoundsChange is called when the content bounds,
// viewport bounds, or scroll axes of a child are changed.
HandleChildScrollBoundsChange (child Scrollable)
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}
// Collapsible represents an element who's minimum width and height can be
// manually resized. Scrollable elements should implement this if possible.
type Collapsible interface {
Element
// Collapse collapses the element's minimum width and height. A value of
// zero for either means that the element's normal value is used.
Collapse (width, height int)
}
// Themeable represents an element that can modify its appearance to fit within
// a theme.
type Themeable interface {
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Element
// SetTheme sets the element's theme to something fulfilling the
// theme.Theme interface.
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SetTheme (Theme)
}
// Configurable represents an element that can modify its behavior to fit within
// a set of configuration parameters.
type Configurable interface {
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Element
// SetConfig sets the element's configuration to something fulfilling
// the config.Config interface.
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SetConfig (Config)
}