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tomo-old/elements/core/core.go

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package core
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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.
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type Core struct {
canvas tomo.BasicCanvas
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parent tomo.Element
metrics struct {
minimumWidth int
minimumHeight int
}
onMinimumSizeChange func ()
onDamage func (region tomo.Canvas)
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}
// NewCore creates a new element core and its corresponding control.
func NewCore (parent tomo.Element) (core *Core, control CoreControl) {
core = &Core { parent: parent }
control = CoreControl { core: core }
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return
}
// ColorModel fulfills the draw.Image interface.
func (core *Core) ColorModel () (model color.Model) {
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return color.RGBAModel
}
// ColorModel fulfills the draw.Image interface.
func (core *Core) At (x, y int) (pixel color.Color) {
return core.canvas.At(x, y)
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}
// ColorModel fulfills the draw.Image interface.
func (core *Core) Bounds () (bounds image.Rectangle) {
return core.canvas.Bounds()
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}
// ColorModel fulfills the draw.Image interface.
func (core *Core) Set (x, y int, c color.Color) () {
core.canvas.Set(x, y, c)
}
// Buffer fulfills the tomo.Canvas interface.
func (core *Core) Buffer () (data []color.RGBA, stride int) {
return core.canvas.Buffer()
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}
// 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
}
// 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 {
tomo.BasicCanvas
core *Core
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}
// 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.Bounds().Empty()
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}
// 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, bounds))
}
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}
// DamageAll pushes all pixels to the parent element. This does not need to be
// called when responding to a resize event.
func (control CoreControl) DamageAll () {
control.DamageRegion(control.Bounds())
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}
// AllocateCanvas resizes the canvas, constraining the width and height so that
// they are not less than the specified minimum width and height.
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func (control *CoreControl) AllocateCanvas (width, height int) {
control.core.canvas = tomo.NewBasicCanvas(width, height)
control.BasicCanvas = control.core.canvas
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}
// 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()
}
// if there is an image buffer, and the current size is less
// than this new minimum size, send core.parent a resize event.
if control.HasImage() {
bounds := control.Bounds()
imageWidth,
imageHeight,
constrained := control.ConstrainSize(bounds.Dx(), bounds.Dy())
if constrained {
core.parent.Resize(imageWidth, imageHeight)
}
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}
}
// 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 (
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inWidth, inHeight int,
) (
outWidth, outHeight int,
constrained bool,
) {
core := control.core
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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
}