waveshare213v2: Move display update to testable function

Signed-off-by: Michael Hanselmann <public@hansmi.ch>

waveshare2in13v2/controller.go

@@ -76,3 +76,14 @@ func configDisplayMode(ctrl controller, mode PartialUpdate, lut LUT) {
 
 	ctrl.waitUntilIdle()
 }
+
+func updateDisplay(ctrl controller, mode PartialUpdate) {
+	ctrl.sendCommand(displayUpdateControl1)
+	ctrl.sendData([]byte{0})
+
+	ctrl.sendCommand(displayUpdateControl2)
+	ctrl.sendData([]byte{0xC7})
+
+	ctrl.sendCommand(masterActivation)
+	ctrl.waitUntilIdle()
+}

waveshare2in13v2/controller_test.go

@@ -118,3 +118,40 @@ func TestConfigDisplayMode(t *testing.T) {
 		})
 	}
 }
+
+func TestUpdateDisplay(t *testing.T) {
+	for _, tc := range []struct {
+		name string
+		mode PartialUpdate
+		want []record
+	}{
+		{
+			name: "full",
+			mode: Full,
+			want: []record{
+				{cmd: displayUpdateControl1, data: []byte{0}},
+				{cmd: displayUpdateControl2, data: []byte{0xc7}},
+				{cmd: masterActivation},
+			},
+		},
+		{
+			name: "partial",
+			mode: Partial,
+			want: []record{
+				{cmd: displayUpdateControl1, data: []byte{0}},
+				{cmd: displayUpdateControl2, data: []byte{0xc7}},
+				{cmd: masterActivation},
+			},
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			var got fakeController
+
+			updateDisplay(&got, tc.mode)
+
+			if diff := cmp.Diff([]record(got), tc.want, cmpopts.EquateEmpty(), cmp.AllowUnexported(record{})); diff != "" {
+				t.Errorf("updateDisplay() difference (-got +want):\n%s", diff)
+			}
+		})
+	}
+}

waveshare2in13v2/waveshare213v2.go

@@ -223,7 +223,7 @@ func (d *Dev) Clear(color color.Color) error {
 	clearDisplay(&eh, image.Pt(d.opts.Width, d.opts.Height), c)
 
 	if eh.err == nil {
-		eh.err = d.turnOnDisplay()
+		updateDisplay(&eh, Full)
 	}
 
 	return eh.err
@@ -255,7 +255,7 @@ func (d *Dev) Draw(dstRect image.Rectangle, src image.Image, srcPts image.Point)
 	drawImage(&eh, &opts)
 
 	if eh.err == nil {
-		eh.err = d.turnOnDisplay()
+		updateDisplay(&eh, d.mode)
 	}
 
 	return eh.err
@@ -284,7 +284,7 @@ func (d *Dev) DrawPartial(dstRect image.Rectangle, src image.Image, srcPts image
 	}
 
 	if eh.err == nil {
-		eh.err = d.turnOnDisplay()
+		updateDisplay(&eh, d.mode)
 	}
 
 	return eh.err
@@ -300,18 +300,6 @@ func (d *Dev) String() string {
 	return fmt.Sprintf("epd.Dev{%s, %s, Height: %d, Width: %d}", d.c, d.dc, d.opts.Height, d.opts.Width)
 }
 
-func (d *Dev) turnOnDisplay() error {
-	eh := errorHandler{d: *d}
-
-	eh.sendCommand(displayUpdateControl2)
-	eh.sendData([]byte{0xC7})
-	eh.sendCommand(masterActivation)
-
-	eh.waitUntilIdle()
-
-	return eh.err
-}
-
 // Reset the hardware
 func (d *Dev) reset() error {
 	eh := errorHandler{d: *d}