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tomo-old/elements/core/core.go
2023-02-08 00:22:40 -05:00

157 lines
4.4 KiB
Go

package core
import "image"
import "image/color"
import "git.tebibyte.media/sashakoshka/tomo/canvas"
// 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 canvas.Canvas
metrics struct {
minimumWidth int
minimumHeight int
}
drawSizeChange func ()
onMinimumSizeChange func ()
onDamage func (region canvas.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 canvas.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 canvas.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 canvas.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(canvas.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
}