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