backend/internal/system/event.go

package system

import "image"
import "git.tebibyte.media/tomo/tomo/input"

// HandleFocusChange sets whether or not the window containing this Hierarchy
// has input focus.
func (this *Hierarchy) HandleFocusChange (focused bool) {
	if this.windowFocused == focused { return }
	this.windowFocused = focused
}

// HandleModifiers sets the modifier keys that are currently being pressed.
func (this *Hierarchy) HandleModifiers (modifiers input.Modifiers) {
	if this.modifiers == modifiers { return }
	this.modifiers = modifiers
}

// HandleKeyDown sends a key down event to the currently focused Box. If the
// event which triggers this comes with modifier key information,
// HandleModifiers must be called *before* HandleKeyDown.
func (this *Hierarchy) HandleKeyDown (key input.Key, numberPad bool) {
	if key == input.KeyTab && this.modifiers.Alt {
		if this.modifiers.Shift {
			this.focusPrevious()
		} else {
			this.focusNext()
		}
	} else if target := this.keyboardTarget(); target != nil {
		target.handleKeyDown(key, numberPad)
	}
}

// HandleKeyUp sends a key up event to the currently focused Box. If the event
// which triggers this comes with modifier key information, HandleModifiers must
// be called *before* HandleKeyUp.
func (this *Hierarchy) HandleKeyUp (key input.Key, numberPad bool) {
	if target := this.keyboardTarget(); target != nil {
		target.handleKeyUp(key, numberPad)
	}
}

// HandleMouseDown sends a mouse down event to the Box positioned underneath the
// mouse cursor and marks it as being "dragged" by that mouse button. If the
// event which triggers this comes with mouse position information,
// HandleMouseMove must be called *before* HandleMouseDown.
func (this *Hierarchy) HandleMouseDown (button input.Button) {
	underneath := this.boxUnder(this.mousePosition, eventCategoryMouse)
	this.drags[button] = underneath
	if underneath != nil {
		underneath.handleMouseDown(button)
	}
}

// HandleMouseUp sends a mouse up event to the Box currently being "dragged" by
// the specified mouse button, and marks it as being "not dragged" by that mouse
// button. If the event which triggers this comes with mouse position
// information, HandleMouseMove must be caleld *before* HandleMouseUp
func (this *Hierarchy) HandleMouseUp (button input.Button) {
	dragging := this.drags[button]
	this.drags[button] = nil
	if dragging != nil {
		dragging.handleMouseUp(button)
	}
}

// HandleMouseMove sends a mouse move event to any Boxes currently being
// "dragged" by a mouse button. If none are, it sends the event to the Box which
// is underneath the mouse pointer.
func (this *Hierarchy) HandleMouseMove (position image.Point) {
	if this.mousePosition == position { return }
	this.mousePosition = position

	handled := false
	for _, child := range this.drags {
		if child == nil { continue }
		child.handleMouseMove()
		handled = true
	}

	underneath := this.boxUnder(position, eventCategoryMouse)
	if underneath != nil {
		this.hover(underneath)
		if !handled {
			underneath.handleMouseMove()
		}
	}
}

// HandleScroll sends a scroll event to the Box currently underneath the mouse
// cursor. 
func (this *Hierarchy) HandleScroll (x, y float64) {
	underneath := this.boxUnder(this.mousePosition, eventCategoryScroll)
	if underneath != nil {
		underneath.handleScroll(x, y)
	}
}