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tomo-old/elements/core/core.go
2023-03-14 18:30:32 -04:00

190 lines
5.4 KiB
Go

package core
import "image"
import "image/color"
import "git.tebibyte.media/sashakoshka/tomo/canvas"
import "git.tebibyte.media/sashakoshka/tomo/elements"
// 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
bounds image.Rectangle
parent elements.Parent
outer elements.Element
metrics struct {
minimumWidth int
minimumHeight int
}
drawSizeChange func ()
onDamage func (region image.Rectangle)
}
// NewCore creates a new element core and its corresponding control given the
// element that it will be a part of. If outer is nil, this function will return
// nil.
func NewCore (
outer elements.Element,
drawSizeChange func (),
) (
core *Core,
control CoreControl,
) {
if outer == nil { return }
core = &Core {
outer: outer,
drawSizeChange: drawSizeChange,
}
control = CoreControl { core: core }
return
}
// Bounds fulfills the tomo.Element interface. This should not need to be
// overridden.
func (core *Core) Bounds () (bounds image.Rectangle) {
if core.canvas == nil { return }
return core.bounds
}
// 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
}
// MinimumSize fulfils the tomo.Element interface. This should not need to be
// overridden, unless you want to detect when the element is parented or
// unparented.
func (core *Core) SetParent (parent elements.Parent) {
if core.parent != nil {
panic("core.SetParent: element already has a parent")
}
core.parent = parent
}
// DrawTo fulfills the tomo.Element interface. This should not need to be
// overridden.
func (core *Core) DrawTo (
canvas canvas.Canvas,
bounds image.Rectangle,
onDamage func (region image.Rectangle),
) {
core.canvas = canvas
core.bounds = bounds
core.onDamage = onDamage
if core.drawSizeChange != nil && core.canvas != nil {
core.drawSizeChange()
}
}
// 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
}
// ColorModel fulfills the draw.Image interface.
func (control CoreControl) ColorModel () (model color.Model) {
return color.RGBAModel
}
// At fulfills the draw.Image interface.
func (control CoreControl) At (x, y int) (pixel color.Color) {
if control.core.canvas == nil { return }
return control.core.canvas.At(x, y)
}
// Bounds fulfills the draw.Image interface.
func (control CoreControl) Bounds () (bounds image.Rectangle) {
if control.core.canvas == nil { return }
return control.core.canvas.Bounds()
}
// Set fulfills the draw.Image interface.
func (control CoreControl) Set (x, y int, c color.Color) () {
if control.core.canvas == nil { return }
control.core.canvas.Set(x, y, c)
}
// Buffer fulfills the canvas.Canvas interface.
func (control CoreControl) Buffer () (data []color.RGBA, stride int) {
if control.core.canvas == nil { return }
return control.core.canvas.Buffer()
}
// Parent returns the element's parent.
func (control CoreControl) Parent () elements.Parent {
return control.core.parent
}
// Outer returns the outer element given when the control was constructed.
func (control CoreControl) Outer () elements.Element {
return control.core.outer
}
// 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 (regions ...image.Rectangle) {
if control.core.canvas == nil { return }
if control.core.onDamage != nil {
for _, region := range regions {
control.core.onDamage(region)
}
}
}
// 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.parent != nil {
control.core.parent.NotifyMinimumSizeChange(control.core.outer)
}
}
// 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
}