backend/internal/system/system.go

package system

import "io"
import "image"
import "git.tebibyte.media/tomo/tomo/canvas"
import "git.tebibyte.media/tomo/backend/style"
import "git.tebibyte.media/tomo/backend/internal/util"

// System is coupled to a tomo.Backend implementation, and manages Hierarchies
// and Boxes.
type System struct {
	link BackendLink

	style        *style.Style
	iconSet      style.IconSet
	faceSet      style.FaceSet
	styleNonce   int
	iconSetNonce int
	
	hierarchies util.Set[*Hierarchy]
}

// BackendLink allows the System to call up into the tomo.Backend implementation
// which contains it in order to do things such as create new textures.
type BackendLink interface {
	// NewTexture creates a new texture from an image.
	NewTexture (image.Image) canvas.TextureCloser
	// NewSurface creates a new surface with the specified bounds.
	NewSurface (image.Rectangle) (SurfaceLink, error)
}

// SurfaceLink wraps a Surface created by the backend implementation, allowing
// the System a higher level of control over it.
type SurfaceLink interface {
	io.Closer
	GetSurface () any
	SetSize    (image.Rectangle)
}

// New creates a new System.
func New (link BackendLink) *System {
	return &System {
		link:        link,
		hierarchies: make(util.Set[*Hierarchy]),
	}
}

// SetStyle sets the style that is applied to objects, and notifies them
// that the style has changed.
func (this *System) SetStyle (style *style.Style) {
	this.style = style
	this.styleNonce ++
	for hierarchy := range this.hierarchies {
		hierarchy.setStyle()
	}
}

// SetIconSet sets the icon set that provides icon textures, and notifies
// objects that the icons have changed.
func (this *System) SetIconSet (iconSet style.IconSet) {
	this.iconSet = iconSet
	this.iconSetNonce ++
	for hierarchy := range this.hierarchies {
		hierarchy.setIconSet()
	}
}

// SetFaceSet sets the face set that provides font faces.
func (this *System) SetFaceSet (faceSet style.FaceSet) {
	this.faceSet = faceSet
}

func (this *System) removeHierarchy (hierarchy *Hierarchy) {
	delete(this.hierarchies, hierarchy)
}