display: Create Interfaces for text displays (#42)

* Create Interfaces for text displays

* Print errors in interactive mode.

display/displaytest/text.go

@@ -0,0 +1,207 @@
+// Copyright 2024 The Periph Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
+
+package displaytest
+
+import (
+	"errors"
+	"fmt"
+	"time"
+
+	"periph.io/x/conn/v3/display"
+)
+
+// TestTextDisplay exercises the methods provided by the interface. It can be
+// used interactively as a quick smoke test of an implementation, and from test
+// routines. This doesn't test brightness or contrast to avoid EEPROM wear
+// issues.
+func TestTextDisplay(dev display.TextDisplay, interactive bool) []error {
+	var result []error
+	var err error
+
+	pauseTime := time.Duration(0)
+	if interactive {
+		pauseTime = 3 * time.Second
+	}
+	// Turn the dev on and write the String() value.
+	if err = dev.Display(true); err != nil {
+		result = append(result, err)
+	}
+
+	if err = dev.Clear(); err != nil {
+		result = append(result, err)
+	}
+
+	if _, err = dev.WriteString(dev.String()); err != nil {
+		result = append(result, err)
+	}
+	time.Sleep(pauseTime)
+
+	if err = dev.Clear(); err != nil {
+		result = append(result, err)
+	}
+	_, err = dev.WriteString("Auto Scroll Test")
+	if err != nil {
+		result = append(result, err)
+	}
+	time.Sleep(pauseTime)
+	err = dev.AutoScroll(true)
+	if err != nil {
+		result = append(result, err)
+	}
+	// Test Display fill
+	for line := range dev.Rows() {
+		c := rune('A')
+		if err = dev.MoveTo(dev.MinRow()+line, dev.MinCol()); err != nil {
+			result = append(result, err)
+		}
+		for col := range dev.Cols() {
+			if col%5 == 0 && col > 0 {
+				_, err = dev.Write([]byte{byte(' ')})
+			} else {
+				_, err = dev.Write([]byte{byte(c)})
+			}
+			if err != nil {
+				result = append(result, err)
+			}
+			c = c + 1
+		}
+	}
+	// Test AutoScroll working
+	time.Sleep(pauseTime)
+	nWritten, err := dev.WriteString("auto scroll happen")
+	if err != nil {
+		result = append(result, err)
+	}
+	if nWritten != 18 {
+		result = append(result, fmt.Errorf("dev.WriteString() expected %d chars written, received %d", 18, nWritten))
+	}
+	time.Sleep(pauseTime)
+	if err = dev.AutoScroll(false); err != nil {
+		result = append(result, err)
+	}
+	time.Sleep(pauseTime)
+
+	// Test Absolute Positioning
+	if err = dev.Clear(); err != nil {
+		result = append(result, err)
+	}
+	if _, err = dev.WriteString("Absolute Positioning"); err != nil {
+		result = append(result, err)
+	}
+	time.Sleep(pauseTime)
+	if err = dev.Clear(); err != nil {
+		result = append(result, err)
+	}
+	for ix := range dev.Rows() {
+		if err = dev.MoveTo(dev.MinRow()+ix, dev.MinCol()+ix); err != nil {
+			result = append(result, err)
+		}
+		if _, err = dev.WriteString(fmt.Sprintf("(%d,%d)", dev.MinRow()+ix, dev.MinCol()+ix)); err != nil {
+			result = append(result, err)
+		}
+	}
+	time.Sleep(pauseTime)
+
+	// Test that MoveTo returns error for invalid coordinates
+	moveCases := []struct {
+		row int
+		col int
+	}{
+		{row: dev.MinRow() - 1, col: dev.MinCol()},
+		{row: dev.MinRow(), col: dev.MinCol() - 1},
+		{row: dev.Rows() + 1, col: dev.Cols()},
+		{row: dev.Rows(), col: dev.Cols() + 1},
+	}
+	for _, tc := range moveCases {
+		if err = dev.MoveTo(tc.row, tc.col); err == nil {
+			result = append(result, fmt.Errorf("did not receive expected error on MoveTo(%d,%d)", tc.row, tc.col))
+		}
+	}
+
+	// Test Cursor Modes
+	if err = dev.Clear(); err != nil {
+		result = append(result, err)
+	}
+	modes := []string{"Off", "Underline", "Block", "Blink"}
+	for ix := display.CursorOff; ix <= display.CursorBlink; ix++ {
+		if err = dev.MoveTo(dev.MinRow()/2+1, dev.MinCol()); err != nil {
+			result = append(result, err)
+		}
+		if _, err = dev.WriteString("Cursor: " + modes[ix]); err != nil {
+			result = append(result, err)
+		}
+		if err = dev.Cursor(ix); err != nil {
+			result = append(result, err)
+		}
+		time.Sleep(pauseTime)
+		if err = dev.Cursor(display.CursorOff); err != nil {
+			result = append(result, err)
+		}
+		if err = dev.Clear(); err != nil {
+			result = append(result, err)
+		}
+	}
+	if err = dev.Cursor(display.CursorBlink + 1); err == nil {
+		result = append(result, errors.New("did not receive expected error on Cursor() with invalid value"))
+	}
+
+	// Test Move Forward and Backward. 2 Should overwrite the 1
+	if err = dev.Clear(); err != nil {
+		result = append(result, err)
+	}
+	if _, err = dev.WriteString("Testing >"); err != nil {
+		result = append(result, err)
+	}
+	if err = dev.Move(display.Forward); err != nil {
+		result = append(result, err)
+	}
+	if err = dev.Move(display.Forward); err != nil {
+		result = append(result, err)
+	}
+	for ix := range 10 {
+		if _, err = dev.WriteString(fmt.Sprintf("%d", ix)); err != nil {
+			result = append(result, err)
+		}
+		time.Sleep(pauseTime)
+		if err = dev.Move(display.Backward); err != nil {
+			result = append(result, err)
+		}
+	}
+	if err = dev.Move(display.Down + 1); err == nil {
+		result = append(result, errors.New("did not receive expected error on Move() with invalid value"))
+	}
+
+	// Test Display on/off
+	if err = dev.Clear(); err != nil {
+		result = append(result, err)
+	}
+	if _, err = dev.WriteString("Set dev off"); err != nil {
+		result = append(result, err)
+	}
+	time.Sleep(pauseTime)
+	if err = dev.Display(false); err != nil {
+		result = append(result, err)
+	}
+	time.Sleep(pauseTime)
+	if err = dev.Display(true); err != nil {
+		result = append(result, err)
+	}
+	if err = dev.Clear(); err != nil {
+		result = append(result, err)
+	}
+	if _, err = dev.WriteString("Set dev on"); err != nil {
+		result = append(result, err)
+	}
+	time.Sleep(pauseTime)
+
+	if interactive {
+		for _, e := range result {
+			if !errors.Is(err, display.ErrNotImplemented) {
+				fmt.Println(e)
+			}
+		}
+	}
+	return result
+}

display/text_display.go

@@ -0,0 +1,105 @@
+// Copyright 2024 The Periph Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
+
+package display
+
+import (
+	"errors"
+)
+
+type CursorDirection int
+
+const (
+	// Constants for moving the cursor relative to it's current position.
+	//
+	// Move the cursor one unit back.
+	Backward CursorDirection = iota
+	// Move the cursor one unit forward.
+	Forward
+	Up
+	Down
+)
+
+type CursorMode int
+
+const (
+	// Turn the cursor Off
+	CursorOff CursorMode = iota
+	// Enable Underline Cursor
+	CursorUnderline
+	// Enable Block Cursor
+	CursorBlock
+	// Blinking
+	CursorBlink
+)
+
+// TextDisplay represents an interface to a basic character device. It provides
+// standard methods implemented by a majority of character LCD devices. Pixel
+// type displays can implement this interface if desired.
+type TextDisplay interface {
+	// Enable/Disable auto scroll
+	AutoScroll(enabled bool) (err error)
+	// Return the number of columns the display supports
+	Cols() int
+	// Clear the display and move the cursor home.
+	Clear() (err error)
+	// Set the cursor mode. You can pass multiple arguments.
+	// Cursor(CursorOff, CursorUnderline)
+	//
+	// Implementations should return an error if the value of mode is not
+	// mode>= CursorOff && mode <= CursorBlink
+	Cursor(mode ...CursorMode) (err error)
+	// Move the cursor home (MinRow(),MinCol())
+	Home() (err error)
+	// Return the min column position.
+	MinCol() int
+	// Return the min row position.
+	MinRow() int
+	// Move the cursor forward or backward.
+	Move(dir CursorDirection) (err error)
+	// Move the cursor to arbitrary position. Implementations should return an
+	// error if row < MinRow() || row > (Rows()-MinRow()), or col < MinCol()
+	// || col > (Cols()-MinCol())
+	MoveTo(row, col int) (err error)
+	// Return the number of rows the display supports.
+	Rows() int
+	// Turn the display on / off
+	Display(on bool) (err error)
+	// return info about the display.
+	String() string
+	// Write a set of bytes to the display.
+	Write(p []byte) (n int, err error)
+	// Write a string output to the display.
+	WriteString(text string) (n int, err error)
+}
+
+type Intensity int
+
+// Interface for displays that support a monochrome backlight.  Displays that
+// support RGB Backlights should implement this as well for maximum
+// compatibility.
+//
+// Many units that support this command write the value to EEPROM, which has a
+// finite number of writes. To turn the unit on/off, use TextDisplay.Display()
+type DisplayBacklight interface {
+	Backlight(intensity Intensity) error
+}
+
+// Interface for displays that support a RGB Backlight. E.G. the Sparkfun SerLCD
+type DisplayRGBBacklight interface {
+	RGBBacklight(red, green, blue Intensity) error
+}
+
+type Contrast int
+
+// Interface for displays that support a programmable contrast adjustment.
+// As with SetBacklight(), many devices serialize the value to EEPROM,
+// which support only a finite number of writes, so this should be used
+// sparingly.
+type DisplayContrast interface {
+	Contrast(contrast Contrast) error
+}
+
+var ErrNotImplemented = errors.New("not implemented")
+var ErrInvalidCommand = errors.New("invalid command")