Supervisor, Frame Pack and Misc Fixes

* Button: do not call MoveTo inside of Compute().
* Label: do not call MoveTo inside of Compute().
* MainWindow: add OnLoop callback function support so you can run custom code
  each loop and react to the event.State before the UI updates.
* Supervisor: locate widgets using AbsolutePosition() instead of w.Point()
  to play nice with Frame and Window packed widgets.
* Widget interface: rename Adopt() to SetParent() which makes more sense for
  what the function actually does.
* Window: set itself as the parent of the body Frame so that the Supervisor
  can locate widgets anywhere inside a window's frames.

Frame packing fixes:

* Widgets with Expand:true grow their space with ResizeAuto to preserve the
  FixedSize() boolean, instead of being hard-resized to fill the Frame.
* Widgets that Fill their space are resized with ResizeAuto too.

Outstanding bugs:

* Labels don't expand (window title bars, etc.)

README.md

@@ -11,8 +11,8 @@ applications (SDL2, for Linux, MacOS and Windows) as well as web browsers
 > _(Screenshot is from Project: Doodle's GUITest debug screen showing a_
 > _Window, several Frames, Labels, Buttons and a Checkbox widget.)_
 
-It is very much a **work in progress** and it's a bit buggy. See the
-[Known Issues](#known-issues) at the bottom of this document.
+It is very much a **work in progress** and may contain bugs and its API may
+change as bugs are fixed or features added.
 
 This library is being developed in conjunction with my drawing-based maze
 game, [Project: Doodle](https://www.kirsle.net/doodle). The rendering engine
@@ -214,24 +214,6 @@ MainWindow includes its own Supervisor: just call the `.Add(Widget)`
 method to add interactive widgets to the supervisor. The MainLoop() of the
 window calls Supervisor.Loop() automatically.
 
-# Known Issues
-
-The frame packing algorithm (frame_pack.go) is currently very buggy and in
-need of a re-write. Some examples of issues with it:
-
-* Currently, when the Frame is iterating over packed widgets to decide their
-  location and size, it explicitly calls MoveTo() and Resize() giving them
-  their pixel-coordinates, relative to the Frame's own position.
-  * When Frames nest other Frames this becomes more of an issue.
-  * The Supervisor sometimes can't determine the correct position of a
-    button packed inside of nested frames. It currently checks the
-    Point() of the button (set by its parent Frame) and this doesn't
-    account for the grandparent frame's position. Using the
-    AbsolutePosition() helper function (which recursively crawls up a
-    widget tree) also yields incorrect results, as the position of each
-    Frame is _added_ to the position of the Button which throws it off even
-    further.
-
 # License
 
 MIT.

button.go

@@ -91,7 +91,6 @@ func (w *Button) Present(e render.Engine, P render.Point) {
 	}
 
 	w.Compute(e)
-	w.MoveTo(P)
 	var (
 		S         = w.Size()
 		ChildSize = w.child.Size()

debug.go

@@ -1,15 +1,28 @@
 package ui
 
-import "strings"
+import (
+	"fmt"
+	"strings"
+)
 
 // WidgetTree returns a string representing the tree of widgets starting
 // at a given widget.
 func WidgetTree(root Widget) []string {
 	var crawl func(int, Widget) []string
+
 	crawl = func(depth int, node Widget) []string {
 		var (
-			prefix = strings.Repeat("  ", depth)
-			lines  = []string{prefix + node.ID()}
+			prefix    = strings.Repeat("  ", depth)
+			size      = node.Size()
+			width     = size.W
+			height    = size.H
+			fixedSize = node.FixedSize()
+
+			lines = []string{
+				fmt.Sprintf("%s%s   P:%s   S:%dx%d (fixedSize: %+v)",
+					prefix, node.ID(), node.Point(), width, height, fixedSize,
+				),
+			}
 		)
 
 		for _, child := range node.Children() {

frame_pack.go

@@ -47,7 +47,7 @@ func (w *Frame) Pack(child Widget, config ...Pack) {
 	}
 
 	// Adopt the child widget so it can access the Frame.
-	child.Adopt(w)
+	child.SetParent(w)
 
 	w.packs[C.Side] = append(w.packs[C.Side], packedWidget{
 		widget: child,
@@ -65,7 +65,7 @@ func (w *Frame) computePacked(e render.Engine) {
 		// that the Frame must be to contain all of its children. If the Frame
 		// was configured with an explicit Size, the Frame will be that Size,
 		// but we still calculate how much space the widgets _actually_ take
-		// so we can expand them to fill remaining space in fixed size widgets.
+		// so we can expand them to fill remaining space in fixed size Frames.
 		maxWidth  int
 		maxHeight int
 		visited   = []packedWidget{}
@@ -82,8 +82,8 @@ func (w *Frame) computePacked(e render.Engine) {
 		var (
 			x          int
 			y          int
-			yDirection int = 1
-			xDirection int = 1
+			yDirection = 1
+			xDirection = 1
 		)
 
 		if side.IsSouth() {
@@ -128,12 +128,15 @@ func (w *Frame) computePacked(e render.Engine) {
 				x -= size.W - pack.PadX
 			}
 
+			// NOTE: we place the child's position relative to the Frame's
+			// position. So a child placed at the top/left of the Frame gets
+			// an x,y near zero regardless of the Frame's position.
 			child.MoveTo(render.NewPoint(x, y))
 
 			if side.IsNorth() {
 				y += size.H + pack.PadY
 			}
-			if side == W {
+			if side.IsWest() {
 				x += size.W + pack.PadX
 			}
 
@@ -147,14 +150,20 @@ func (w *Frame) computePacked(e render.Engine) {
 	// If we have extra space in the Frame and any expanding widgets, let the
 	// expanding widgets grow and share the remaining space.
 	computedSize := render.NewRect(maxWidth, maxHeight)
-	if len(expanded) > 0 && !frameSize.IsZero() && frameSize.Bigger(computedSize) {
+	if len(expanded) > 0 && !frameSize.IsZero() { // && frameSize.Bigger(computedSize) {
 		// Divy up the size available.
 		growBy := render.Rect{
 			W: ((frameSize.W - computedSize.W) / len(expanded)) - w.BoxThickness(4),
 			H: ((frameSize.H - computedSize.H) / len(expanded)) - w.BoxThickness(4),
 		}
 		for _, pw := range expanded {
-			pw.widget.ResizeBy(growBy)
+			// Grow the widget but maintain its auto-size flag, in case the widget
+			// was not given an explicit size before.
+			size := pw.widget.Size()
+			pw.widget.ResizeAuto(render.Rect{
+				W: size.W + growBy.W,
+				H: size.H + growBy.H,
+			})
 			pw.widget.Compute(e)
 		}
 	}
@@ -190,10 +199,16 @@ func (w *Frame) computePacked(e render.Engine) {
 		)
 
 		if pack.Side.IsNorth() || pack.Side.IsSouth() {
+			// Aligned to the top or bottom. If the widget Fills horizontally,
+			// resize it so its Width matches the frame's Width.
 			if pack.FillX && resize.W < innerFrameSize.W {
-				resize.W = innerFrameSize.W - w.BoxThickness(2)
+				resize.W = innerFrameSize.W - w.BoxThickness(2) // TODO: child.BoxThickness instead??
 				resized = true
 			}
+
+			// If it does not Fill horizontally and there is extra horizontal
+			// space, center the widget inside the space. TODO: Anchor option
+			// could align the widget to the left or right instead of center.
 			if resize.W < innerFrameSize.W-w.BoxThickness(4) {
 				if pack.Side.IsCenter() {
 					point.X = (innerFrameSize.W / 2) - (resize.W / 2)
@@ -206,19 +221,19 @@ func (w *Frame) computePacked(e render.Engine) {
 				moved = true
 			}
 		} else if pack.Side.IsWest() || pack.Side.IsEast() {
+			// Similar logic to the above, but widget is packed against the
+			// left or right edge. Handle vertical Fill to grow the widget.
 			if pack.FillY && resize.H < innerFrameSize.H {
-				resize.H = innerFrameSize.H - w.BoxThickness(2) // BoxThickness(2) for parent + child
-				// point.Y -= (w.BoxThickness(4) + child.BoxThickness(2))
-				moved = true
+				resize.H = innerFrameSize.H - w.BoxThickness(2) // TODO: child.BoxThickness instead??
 				resized = true
 			}
 
 			// Vertically align the widgets.
 			if resize.H < innerFrameSize.H {
 				if pack.Side.IsMiddle() {
-					point.Y = (innerFrameSize.H / 2) - (resize.H / 2) - w.BoxThickness(1)
+					point.Y = (innerFrameSize.H / 2) - (resize.H / 2) // - w.BoxThickness(1)
 				} else if pack.Side.IsNorth() {
-					point.Y = pack.PadY - w.BoxThickness(4)
+					point.Y = pack.PadY // - w.BoxThickness(4)
 				} else if pack.Side.IsSouth() {
 					point.Y = innerFrameSize.H - resize.H - pack.PadY
 				}
@@ -229,7 +244,7 @@ func (w *Frame) computePacked(e render.Engine) {
 		}
 
 		if resized && size != resize {
-			child.Resize(resize)
+			child.ResizeAuto(resize)
 			child.Compute(e)
 		}
 		if moved {
@@ -237,6 +252,9 @@ func (w *Frame) computePacked(e render.Engine) {
 		}
 	}
 
+	// TODO: the Frame should ResizeAuto so it doesn't mark fixedSize=true.
+	// Currently there's a bug where frames will grow when the window grows but
+	// never shrink again when the window shrinks.
 	// if !w.FixedSize() {
 	w.Resize(render.NewRect(
 		frameSize.W-w.BoxThickness(2),

functions.go

@@ -1,6 +1,8 @@
 package ui
 
-import "git.kirsle.net/go/render"
+import (
+	"git.kirsle.net/go/render"
+)
 
 // AbsolutePosition computes a widget's absolute X,Y position on the
 // window on screen by crawling its parent widget tree.

label.go

@@ -101,11 +101,6 @@ func (w *Label) Compute(e render.Engine) {
 			H: maxRect.H + (padY * 2),
 		})
 	}
-
-	w.MoveTo(render.Point{
-		X: maxRect.X + w.BoxThickness(1),
-		Y: maxRect.Y + w.BoxThickness(1),
-	})
 }
 
 // Present the label widget.

main_window.go

@@ -7,6 +7,7 @@ import (
 	"time"
 
 	"git.kirsle.net/go/render"
+	"git.kirsle.net/go/render/event"
 	"git.kirsle.net/go/render/sdl"
 )
 
@@ -17,20 +18,22 @@ var (
 
 // MainWindow is the parent window of a UI application.
 type MainWindow struct {
-	Engine     render.Engine
-	supervisor *Supervisor
-	frame      *Frame
-	w          int
-	h          int
+	Engine        render.Engine
+	supervisor    *Supervisor
+	frame         *Frame
+	loopCallbacks []func(*event.State)
+	w             int
+	h             int
 }
 
 // NewMainWindow initializes the MainWindow. You should probably only have one
 // of these per application.
 func NewMainWindow(title string) (*MainWindow, error) {
 	mw := &MainWindow{
-		w:          800,
-		h:          600,
-		supervisor: NewSupervisor(),
+		w:             800,
+		h:             600,
+		supervisor:    NewSupervisor(),
+		loopCallbacks: []func(*event.State){},
 	}
 
 	mw.Engine = sdl.New(
@@ -64,6 +67,11 @@ func (mw *MainWindow) Pack(w Widget, pack Pack) {
 	mw.frame.Pack(w, pack)
 }
 
+// Frame returns the window's main frame, if needed.
+func (mw *MainWindow) Frame() *Frame {
+	return mw.frame
+}
+
 // resized handles the window being resized.
 func (mw *MainWindow) resized() {
 	mw.frame.Resize(render.Rect{
@@ -82,6 +90,14 @@ func (mw *MainWindow) Present() {
 	mw.supervisor.Present(mw.Engine)
 }
 
+// OnLoop registers a function to be called on every loop of the main window.
+// This enables your application to register global event handlers or whatnot.
+// The function is called between the event polling and the updating of any UI
+// elements.
+func (mw *MainWindow) OnLoop(callback func(*event.State)) {
+	mw.loopCallbacks = append(mw.loopCallbacks, callback)
+}
+
 // MainLoop starts the main event loop and blocks until there's an error.
 func (mw *MainWindow) MainLoop() error {
 	for true {
@@ -114,11 +130,16 @@ func (mw *MainWindow) Loop() error {
 		}
 	}
 
+	// Ping any loop callbacks.
+	for _, cb := range mw.loopCallbacks {
+		cb(ev)
+	}
+
 	mw.frame.Compute(mw.Engine)
 
 	// Render the child widgets.
 	mw.supervisor.Loop(ev)
-	mw.supervisor.Present(mw.Engine)
+	mw.frame.Present(mw.Engine, mw.frame.Point())
 	mw.Engine.Present()
 
 	// Delay to maintain target frames per second.

supervisor.go

@@ -2,6 +2,7 @@ package ui
 
 import (
 	"errors"
+	"fmt"
 	"sync"
 
 	"git.kirsle.net/go/render"
@@ -165,7 +166,7 @@ func (s *Supervisor) Hovering(cursor render.Point) (hovering, outside []WidgetSl
 	for child := range s.Widgets() {
 		var (
 			w  = child.widget
-			P  = w.Point()
+			P  = AbsolutePosition(w)
 			S  = w.Size()
 			P2 = render.Point{
 				X: P.X + S.W,
@@ -204,10 +205,11 @@ func (s *Supervisor) Present(e render.Engine) {
 	s.lock.RLock()
 	defer s.lock.RUnlock()
 
-	for child := range s.Widgets() {
-		var w = child.widget
-		w.Present(e, w.Point())
-	}
+	fmt.Println("!!! ui.Supervisor.Present() is deprecated")
+	// for child := range s.Widgets() {
+	// 	var w = child.widget
+	// 	w.Present(e, w.Point())
+	// }
 }
 
 // Add a widget to be supervised.

widget.go

@@ -1,8 +1,6 @@
 package ui
 
 import (
-	"fmt"
-
 	"git.kirsle.net/go/render"
 	"git.kirsle.net/go/ui/theme"
 )
@@ -67,8 +65,8 @@ type Widget interface {
 	// Container widgets like Frames can wire up associations between the
 	// child widgets and the parent.
 	Parent() (parent Widget, ok bool)
-	Adopt(parent Widget) // for the container to assign itself the parent
-	Children() []Widget  // for containers to return their children
+	SetParent(parent Widget) // for the container to assign itself the parent
+	Children() []Widget      // for containers to return their children
 
 	// Run any render computations; by the end the widget must know its
 	// Width and Height. For example the Label widget will render itself onto
@@ -254,18 +252,13 @@ func (w *BaseWidget) ResizeBy(v render.Rect) {
 
 // ResizeAuto sets the size of the widget but doesn't set the fixedSize flag.
 func (w *BaseWidget) ResizeAuto(v render.Rect) {
-	if w.ID() == "Frame<Window Body>" {
-		fmt.Printf("%s: ResizeAuto Called: %+v\n",
-			w.ID(),
-			v,
-		)
-	}
 	w.width = v.W
 	w.height = v.H
 }
 
 // BoxThickness returns the full sum of the padding, border and outline.
-// m = multiplier, i.e., 1 or 2
+// m = multiplier, i.e., 1 or 2. If m=1 this returns the box thickness of one
+// edge of the widget, if m=2 it would account for both edges of the widget.
 func (w *BaseWidget) BoxThickness(m int) int {
 	if m == 0 {
 		m = 1
@@ -279,10 +272,10 @@ func (w *BaseWidget) Parent() (Widget, bool) {
 	return w.parent, w.hasParent
 }
 
-// Adopt sets the widget's parent. This function is called by container
+// SetParent sets the widget's parent. This function is called by container
 // widgets like Frame when they add a child widget to their care.
 // Pass a nil parent to unset the parent.
-func (w *BaseWidget) Adopt(parent Widget) {
+func (w *BaseWidget) SetParent(parent Widget) {
 	if parent == nil {
 		w.hasParent = false
 		w.parent = nil

window.go

@@ -66,6 +66,9 @@ func NewWindow(title string) *Window {
 	})
 	w.content = content
 
+	// Set up parent/child relationships
+	w.body.SetParent(w)
+
 	return w
 }