gesture,widget,f32: [API] use integer coordinates for gesture coordinates

Most widget code operate in integer coordinates. This change makes
gesture pointer coordinates integer, to lessen the number of float32
to int conversions.

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

f32/f32.go

@@ -81,6 +81,14 @@ func (p Point) In(r Rectangle) bool {
 		r.Min.Y <= p.Y && p.Y < r.Max.Y
 }
 
+// Round returns the integer point closest to p.
+func (p Point) Round() image.Point {
+	return image.Point{
+		X: int(math.Round(float64(p.X))),
+		Y: int(math.Round(float64(p.Y))),
+	}
+}
+
 // Size returns r's width and height.
 func (r Rectangle) Size() Point {
 	return Point{X: r.Dx(), Y: r.Dy()}

gesture/gesture.go

@@ -91,7 +91,7 @@ type Click struct {
 // TypeClick for a completed click.
 type ClickEvent struct {
 	Type      ClickType
-	Position  f32.Point
+	Position  image.Point
 	Source    pointer.Source
 	Modifiers key.Modifiers
 	// NumClicks records successive clicks occurring
@@ -198,7 +198,7 @@ func (c *Click) Events(q event.Queue) []ClickEvent {
 					c.clicks = 1
 				}
 				c.clickedAt = e.Time
-				events = append(events, ClickEvent{Type: TypeClick, Position: e.Position, Source: e.Source, Modifiers: e.Modifiers, NumClicks: c.clicks})
+				events = append(events, ClickEvent{Type: TypeClick, Position: e.Position.Round(), Source: e.Source, Modifiers: e.Modifiers, NumClicks: c.clicks})
 			} else {
 				events = append(events, ClickEvent{Type: TypeCancel})
 			}
@@ -224,7 +224,7 @@ func (c *Click) Events(q event.Queue) []ClickEvent {
 				break
 			}
 			c.pressed = true
-			events = append(events, ClickEvent{Type: TypePress, Position: e.Position, Source: e.Source, Modifiers: e.Modifiers})
+			events = append(events, ClickEvent{Type: TypePress, Position: e.Position.Round(), Source: e.Source, Modifiers: e.Modifiers})
 		case pointer.Leave:
 			if !c.pressed {
 				c.pid = e.PointerID

widget/button.go

@@ -6,7 +6,6 @@ import (
 	"image"
 	"time"
 
-	"gioui.org/f32"
 	"gioui.org/gesture"
 	"gioui.org/io/key"
 	"gioui.org/io/pointer"
@@ -39,7 +38,7 @@ type Click struct {
 // Press represents a past pointer press.
 type Press struct {
 	// Position of the press.
-	Position f32.Point
+	Position image.Point
 	// Start is when the press began.
 	Start time.Time
 	// End is when the press was ended by a release or cancel.

widget/material/button.go

@@ -297,7 +297,7 @@ func drawInk(gtx layout.Context, c widget.Press) {
 	ink := paint.ColorOp{Color: rgba}
 	ink.Add(gtx.Ops)
 	rr := size * .5
-	defer op.Offset(c.Position.Add(f32.Point{
+	defer op.Offset(layout.FPt(c.Position).Add(f32.Point{
 		X: -rr,
 		Y: -rr,
 	})).Push(gtx.Ops).Pop()