package core import "image" import "image/color" import "git.tebibyte.media/sashakoshka/tomo" // Core is a struct that implements some core functionality common to most // widgets. It is meant to be embedded directly into a struct. type Core struct { canvas tomo.Canvas metrics struct { minimumWidth int minimumHeight int } drawSizeChange func () onMinimumSizeChange func () onDamage func (region tomo.Canvas) } // NewCore creates a new element core and its corresponding control. func NewCore (drawSizeChange func ()) (core *Core, control CoreControl) { core = &Core { drawSizeChange: drawSizeChange } control = CoreControl { core: core } return } // ColorModel fulfills the draw.Image interface. func (core *Core) ColorModel () (model color.Model) { return color.RGBAModel } // ColorModel fulfills the draw.Image interface. func (core *Core) At (x, y int) (pixel color.Color) { if core.canvas == nil { return } return core.canvas.At(x, y) } // ColorModel fulfills the draw.Image interface. func (core *Core) Bounds () (bounds image.Rectangle) { if core.canvas == nil { return } return core.canvas.Bounds() } // ColorModel fulfills the draw.Image interface. func (core *Core) Set (x, y int, c color.Color) () { if core.canvas == nil { return } core.canvas.Set(x, y, c) } // Buffer fulfills the tomo.Canvas interface. func (core *Core) Buffer () (data []color.RGBA, stride int) { if core.canvas == nil { return } return core.canvas.Buffer() } // MinimumSize fulfils the tomo.Element interface. This should not need to be // overridden. func (core *Core) MinimumSize () (width, height int) { return core.metrics.minimumWidth, core.metrics.minimumHeight } // DrawTo fulfills the tomo.Element interface. This should not need to be // overridden. func (core *Core) DrawTo (canvas tomo.Canvas) { core.canvas = canvas if core.drawSizeChange != nil { core.drawSizeChange() } } // OnDamage fulfils the tomo.Element interface. This should not need to be // overridden. func (core *Core) OnDamage (callback func (region tomo.Canvas)) { core.onDamage = callback } // OnMinimumSizeChange fulfils the tomo.Element interface. This should not need // to be overridden. func (core *Core) OnMinimumSizeChange (callback func ()) { core.onMinimumSizeChange = callback } // CoreControl is a struct that can exert control over a Core struct. It can be // used as a canvas. It must not be directly embedded into an element, but // instead kept as a private member. When a Core struct is created, a // corresponding CoreControl struct is linked to it and returned alongside it. type CoreControl struct { core *Core } // HasImage returns true if the core has an allocated image buffer, and false if // it doesn't. func (control CoreControl) HasImage () (has bool) { return control.core.canvas != nil && !control.core.canvas.Bounds().Empty() } // DamageRegion pushes the selected region of pixels to the parent element. This // does not need to be called when responding to a resize event. func (control CoreControl) DamageRegion (bounds image.Rectangle) { if control.core.onDamage != nil { control.core.onDamage(tomo.Cut(control.core, bounds)) } } // DamageAll pushes all pixels to the parent element. This does not need to be // called when redrawing in response to a change in size. func (control CoreControl) DamageAll () { control.DamageRegion(control.core.Bounds()) } // SetMinimumSize sets the minimum size of this element, notifying the parent // element in the process. func (control CoreControl) SetMinimumSize (width, height int) { core := control.core if width == core.metrics.minimumWidth && height == core.metrics.minimumHeight { return } core.metrics.minimumWidth = width core.metrics.minimumHeight = height if control.core.onMinimumSizeChange != nil { control.core.onMinimumSizeChange() } } // ConstrainSize contstrains the specified width and height to the minimum width // and height, and returns wether or not anything ended up being constrained. func (control CoreControl) ConstrainSize ( inWidth, inHeight int, ) ( outWidth, outHeight int, constrained bool, ) { core := control.core outWidth = inWidth outHeight = inHeight if outWidth < core.metrics.minimumWidth { outWidth = core.metrics.minimumWidth constrained = true } if outHeight < core.metrics.minimumHeight { outHeight = core.metrics.minimumHeight constrained = true } return }