Atomized the functionality of the base tomo package

elements/element.go

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+package elements
+
+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 {
+	// Element must implement the Canvas interface. Elements should start
+	// out with a completely blank buffer, and only allocate memory and draw
+	// on it for the first time when sent an EventResize event.
+	canvas.Canvas
+
+	// MinimumSize specifies the minimum amount of pixels this element's
+	// width and height may be set to. If the element is given a resize
+	// event with dimensions smaller than this, it will use its minimum
+	// instead of the offending dimension(s).
+	MinimumSize () (width, height int)
+
+	// DrawTo sets this element's canvas. This should only be called by the
+	// parent element. This is typically a region of the parent element's
+	// canvas.
+	DrawTo (canvas canvas.Canvas)
+
+	// OnDamage sets a function to be called when an area of the element is
+	// drawn on and should be pushed to the screen.
+	OnDamage (callback func (region canvas.Canvas))
+
+	// OnMinimumSizeChange sets a function to be called when the element's
+	// minimum size is changed.
+	OnMinimumSizeChange (callback func ())
+}
+
+// Focusable represents an element that has keyboard navigation support. This
+// includes inputs, buttons, sliders, etc. as well as any elements that have
+// children (so keyboard navigation events can be propagated downward).
+type Focusable interface {
+	Element
+
+	// Focused returns whether or not this element is currently focused.
+	Focused () (selected bool)
+
+	// Focus focuses this element, if its parent element grants the
+	// request.
+	Focus ()
+
+	// HandleFocus causes this element to mark itself as focused. If the
+	// element does not have children, it is disabled, or there are no more
+	// selectable children in the given direction, it should return false
+	// and do nothing. Otherwise, it should select itself and any children
+	// (if applicable) and return true.
+	HandleFocus (direction input.KeynavDirection) (accepted bool)
+
+	// HandleDeselection causes this element to mark itself and all of its
+	// children as unfocused.
+	HandleUnfocus ()
+
+	// OnFocusRequest sets a function to be called when this element wants
+	// its parent element to focus it. Parent elements should return true if
+	// the request was granted, and false if it was not.
+	OnFocusRequest (func () (granted bool))
+
+	// OnFocusMotionRequest sets a function to be called when this
+	// element wants its parent element to focus the element behind or in
+	// front of it, depending on the specified direction. Parent elements
+	// should return true if the request was granted, and false if it was
+	// not.
+	OnFocusMotionRequest (func (direction input.KeynavDirection) (granted bool))
+}
+
+// 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
+
+	// Each of these handler methods is passed the position of the mouse
+	// cursor at the time of the event as x, y.
+
+	// 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)
+
+	// HandleMouseMove 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.
+	HandleMouseMove (x, y int)
+
+	// HandleScroll is called when the mouse is scrolled. The X and Y
+	// direction of the scroll event are passed as deltaX and deltaY.
+	HandleMouseScroll (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) (height int)
+
+	// OnFlexibleHeightChange sets a function to be called when the
+	// parameters affecting this element's flexible height are changed.
+	OnFlexibleHeightChange (callback func ())
+}
+
+// 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 () (bounds image.Rectangle)
+
+	// ScrollViewportBounds returns the size and position of the element's
+	// viewport relative to ScrollBounds.
+	ScrollViewportBounds () (bounds 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)
+
+	// OnScrollBoundsChange sets a function to be called when the element's
+	// ScrollContentBounds, ScrollViewportBounds, or ScrollAxes are changed.
+	OnScrollBoundsChange (callback func ())
+}

elements/window.go

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+package elements
+
+import "image"
+
+// Window represents a top-level container generated by the currently running
+// backend. It can contain a single element. It is hidden by default, and must
+// be explicitly shown with the Show() method. If it contains no element, it
+// displays a black (or transprent) background.
+type Window interface {
+	// Adopt sets the root element of the window. There can only be one of
+	// these at one time.
+	Adopt (child Element)
+
+	// Child returns the root element of the window.
+	Child () (child Element)
+
+	// SetTitle sets the title that appears on the window's title bar. This
+	// method might have no effect with some backends.
+	SetTitle (title string)
+
+	// SetIcon taks in a list different sizes of the same icon and selects
+	// the best one to display on the window title bar, dock, or whatever is
+	// applicable for the given backend. This method might have no effect
+	// for some backends.
+	SetIcon (sizes []image.Image)
+
+	// Show shows the window. The window starts off hidden, so this must be
+	// called after initial setup to make sure it is visible.
+	Show ()
+
+	// Hide hides the window.
+	Hide ()
+
+	// Close closes the window.
+	Close ()
+
+	// OnClose specifies a function to be called when the window is closed.
+	OnClose (func ())
+}