all: delete the ui.Op type

It's no longer used.

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

ui/draw/draw.go

@@ -69,8 +69,6 @@ func (i *OpImage) Decode(d []byte, refs []interface{}) {
 	}
 }
 
-func (OpImage) ImplementsOp() {}
-
 // RectPath constructs a path corresponding to
 // a pixel aligned rectangular area.
 func RectPath(r image.Rectangle) *Path {

ui/draw/path.go

@@ -280,5 +280,3 @@ func (p *PathBuilder) Path() *Path {
 	}
 	return data
 }
-
-func (p OpClip) ImplementsOp() {}

ui/key/key.go

@@ -99,9 +99,6 @@ func (h OpHideInput) Add(o *ui.Ops) {
 	o.Write(data)
 }
 
-func (OpHandler) ImplementsOp()   {}
-func (OpHideInput) ImplementsOp() {}
-
 func (Edit) ImplementsEvent()  {}
 func (Chord) ImplementsEvent() {}
 func (Focus) ImplementsEvent() {}

ui/ops.go

@@ -75,5 +75,3 @@ func (b OpBlock) Add(o *Ops) {
 	bo.PutUint32(data[1:], uint32(b.idx))
 	o.Write(data)
 }
-
-func (OpBlock) ImplementsOp() {}

ui/pointer/pointer.go

@@ -134,5 +134,4 @@ func (s Source) String() string {
 	}
 }
 
-func (OpHandler) ImplementsOp() {}
-func (Event) ImplementsEvent()  {}
+func (Event) ImplementsEvent() {}

ui/ui.go

@@ -36,12 +36,6 @@ func (c *Config) Pixels(v Value) float32 {
 	}
 }
 
-// Op is implemented by all drawing and control
-// operations.
-type Op interface {
-	ImplementsOp()
-}
-
 // OpLayer represents a semantic layer of UI.
 type OpLayer struct {
 }
@@ -141,7 +135,3 @@ func Offset(o f32.Point) Transform {
 
 // Inf is the int value that represents an unbounded maximum constraint.
 const Inf = int(^uint(0) >> 1)
-
-func (OpLayer) ImplementsOp()     {}
-func (OpTransform) ImplementsOp() {}
-func (OpRedraw) ImplementsOp()    {}