f32: replace Affine2D{} with AffineId() for identity transformations

References: https://todo.sr.ht/~eliasnaur/gio/655
Signed-off-by: Walter Werner SCHNEIDER <contact@schnwalter.eu>
Signed-off-by: Elias Naur <mail@eliasnaur.com>

gpu/gpu.go

@@ -957,7 +957,9 @@ func (d *drawOps) addClipPath(state *drawState, aux []byte, auxKey opKey, bounds
 
 func (d *drawOps) save(id int, state f32.Affine2D) {
 	if extra := id - len(d.states) + 1; extra > 0 {
-		d.states = append(d.states, make([]f32.Affine2D, extra)...)
+		for range extra {
+			d.states = append(d.states, f32.AffineId())
+		}
 	}
 	d.states[id] = state
 }
@@ -972,12 +974,13 @@ func (k opKey) SetTransform(t f32.Affine2D) opKey {
 }
 
 func (d *drawOps) collectOps(r *ops.Reader, viewport f32.Rectangle) {
-	var (
+	var quads quadsOp
-		quads quadsOp
+	state := drawState{
-		state drawState
+		t: f32.AffineId(),
-	)
+	}
 	reset := func() {
 		state = drawState{
+			t:     f32.AffineId(),
 			color: color.NRGBA{A: 0xff},
 		}
 	}
@@ -1163,6 +1166,7 @@ func expandPathOp(p *pathOp, clip image.Rectangle) {
 func (d *drawState) materialFor(rect f32.Rectangle, off f32.Point, partTrans f32.Affine2D, clip image.Rectangle) material {
 	m := material{
 		opacity: 1.,
+		uvTrans: f32.AffineId(),
 	}
 	switch d.matType {
 	case materialColor:
@@ -1521,6 +1525,7 @@ func decodeToOutlineQuads(qs *quadSplitter, tr f32.Affine2D, pathData []byte) {
 
 // create GPU vertices for transformed r, find the bounds and establish texture transform.
 func (d *drawOps) boundsForTransformedRect(r f32.Rectangle, tr f32.Affine2D) (aux []byte, bnd f32.Rectangle, ptr f32.Affine2D) {
+	ptr = f32.AffineId()
 	if isPureOffset(tr) {
 		// fast-path to allow blitting of pure rectangles
 		_, _, ox, _, _, oy := tr.Elems()
@@ -1573,7 +1578,7 @@ func (d *drawOps) boundsForTransformedRect(r f32.Rectangle, tr f32.Affine2D) (au
 	sx, sy := P2.X-P3.X, P2.Y-P3.Y
 	ptr = f32.NewAffine2D(sx, P2.X-P1.X, P1.X-sx, sy, P2.Y-P1.Y, P1.Y-sy).Invert()
 
-	return
+	return aux, bnd, ptr
 }
 
 func isPureOffset(t f32.Affine2D) bool {

internal/stroke/stroke.go

@@ -581,12 +581,10 @@ func ArcTransform(p, f1, f2 f32.Point, angle float32) (transform f32.Affine2D, s
 		}
 	}
 
-	var (
+	θ := angle / float32(segments)
-		θ   = angle / float32(segments)
+	ref := f32.AffineId() // transform from absolute frame to ellipse-based one
-		ref f32.Affine2D // transform from absolute frame to ellipse-based one
+	rot := f32.AffineId() // rotation matrix for each segment
-		rot f32.Affine2D // rotation matrix for each segment
+	inv := f32.AffineId() // transform from ellipse-based frame to absolute one
-		inv f32.Affine2D // transform from ellipse-based frame to absolute one
-	)
 	center := f32.Point{
 		X: 0.5 * (f1.X + f2.X),
 		Y: 0.5 * (f1.Y + f2.Y),

io/input/key.go

@@ -281,6 +281,7 @@ func (q *keyQueue) Focus(handlers map[event.Tag]*handler, state keyState, focus
 		return state, nil
 	}
 	state.content = EditorState{}
+	state.content.Selection.Transform = f32.AffineId()
 	var evts []taggedEvent
 	if state.focus != nil {
 		evts = append(evts, taggedEvent{tag: state.focus, event: key.FocusEvent{Focus: false}})

io/input/pointer.go

@@ -144,7 +144,9 @@ const (
 )
 
 func (c *pointerCollector) resetState() {
-	c.state = collectState{}
+	c.state = collectState{
+		t: f32.AffineId(),
+	}
 	c.nodeStack = c.nodeStack[:0]
 	// Pop every node except the root.
 	if len(c.q.hitTree) > 0 {

io/input/router.go

@@ -779,13 +779,15 @@ func (q *Router) collect() {
 	pc.Reset()
 	kq := &q.key.queue
 	q.key.queue.Reset()
-	var t f32.Affine2D
+	t := f32.AffineId()
 	for encOp, ok := q.reader.Decode(); ok; encOp, ok = q.reader.Decode() {
 		switch ops.OpType(encOp.Data[0]) {
 		case ops.TypeSave:
 			id := ops.DecodeSave(encOp.Data)
 			if extra := id - len(q.savedTrans) + 1; extra > 0 {
-				q.savedTrans = append(q.savedTrans, make([]f32.Affine2D, extra)...)
+				for range extra {
+					q.savedTrans = append(q.savedTrans, f32.AffineId())
+				}
 			}
 			q.savedTrans[id] = t
 		case ops.TypeLoad: