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 } // Layoutable represents an element that needs to perform layout calculations // before it can draw itself. type Layoutable interface { Element // Layout causes this element to perform a layout operation. Layout () } // 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) // HandleChildMinimumSizeChange is called when a child's minimum size is // changed. HandleChildMinimumSizeChange (child Element) } // Enableable represents an element that can be enabled and disabled. Disabled // elements typically appear greyed out. type Enableable interface { Element // Enabled returns whether or not the element is enabled. Enabled () bool // 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 () } // 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) } // 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 } // 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) } // 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) } // 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) } // 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 { Element // SetTheme sets the element's theme to something fulfilling the // theme.Theme interface. SetTheme (Theme) } // Configurable represents an element that can modify its behavior to fit within // a set of configuration parameters. type Configurable interface { Element // SetConfig sets the element's configuration to something fulfilling // the config.Config interface. SetConfig (Config) }