all: remove exported Decode methods on operations

Add decode functions to the packages that need them instead. For
TransformOp that is used in multiple packages, add the decode
function to the internal ops package.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

ui/internal/ops/ops.go

@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+package ops
+
+import (
+	"encoding/binary"
+	"math"
+
+	"gioui.org/ui"
+	"gioui.org/ui/f32"
+	"gioui.org/ui/internal/opconst"
+)
+
+func DecodeTransformOp(d []byte) ui.TransformOp {
+	bo := binary.LittleEndian
+	if opconst.OpType(d[0]) != opconst.TypeTransform {
+		panic("invalid op")
+	}
+	return ui.TransformOp{}.Offset(f32.Point{
+		X: math.Float32frombits(bo.Uint32(d[1:])),
+		Y: math.Float32frombits(bo.Uint32(d[5:])),
+	})
+}