image: add support for image/jpeg and image/png (#303)

* Copy from go1.17 image package
* Remove unnecessary files
* Reduce memory usage
* Add examples/ili9341/slideshow
* image: add ./image/README.md
* image: change convert2bin to . /cmd
* Makefile: add ./cmd to NOTEST

Author: sago35

Makefile

@@ -75,6 +75,8 @@ smoke-test:
 	@md5sum ./build/test.hex
 	tinygo build -size short -o ./build/test.hex -target=xiao ./examples/ili9341/scroll
 	@md5sum ./build/test.hex
+	tinygo build -size short -o ./build/test.hex -target=pyportal ./examples/ili9341/slideshow
+	@md5sum ./build/test.hex
 	tinygo build -size short -o ./build/test.hex -target=circuitplay-express ./examples/lis3dh/main.go
 	@md5sum ./build/test.hex
 	tinygo build -size short -o ./build/test.hex -target=microbit ./examples/lsm303agr/main.go
@@ -208,7 +210,7 @@ DRIVERS = $(wildcard */)
 NOTESTS = build examples flash semihosting pcd8544 shiftregister st7789 microphone mcp3008 gps microbitmatrix \
 		hcsr04 ssd1331 ws2812 thermistor apa102 easystepper ssd1351 ili9341 wifinina shifter hub75 \
 		hd44780 buzzer ssd1306 espat l9110x st7735 bmi160 l293x dht keypad4x4 max72xx p1am tone tm1637 \
-		pcf8563 mcp2515 servo sdcard rtl8720dn
+		pcf8563 mcp2515 servo sdcard rtl8720dn image cmd
 TESTS = $(filter-out $(addsuffix /%,$(NOTESTS)),$(DRIVERS))
 
 unit-test:

cmd/convert2bin/convert2bin.go

@@ -0,0 +1,49 @@
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+	"strings"
+)
+
+// See ../../image/README.md for the usage.
+
+func main() {
+	err := run(os.Args)
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+
+func run(args []string) error {
+	if len(args) < 2 {
+		return fmt.Errorf("usage: %s FILE")
+	}
+
+	b, err := ioutil.ReadFile(args[1])
+	if err != nil {
+		return err
+	}
+
+	fmt.Printf("const %s = \"\" +\n", strings.Replace(args[1], ".", "_", -1))
+
+	i := 0
+	max := 32
+	for i = 0; i < len(b); i++ {
+		bb := b[i]
+		if (i % max) == 0 {
+			fmt.Printf("	\"")
+		}
+		fmt.Printf("\\x%02X", bb)
+		if (i%max) == max-1 && i != len(b)-1 {
+			fmt.Printf("\" + \n")
+		}
+	}
+	if (i % max) < max-1 {
+		fmt.Printf("\"\n")
+	}
+
+	return nil
+}

examples/ili9341/slideshow/README.md

@@ -0,0 +1,18 @@
+# examples/ili9341/slideshow
+
+![](./slideshow.jpg)
+
+This example uses the image package for TinyGo to display png and jpeg images.  
+
+## How to create an image
+
+The following program will output an image binary like the one in [images.go](./images.go).  
+
+```
+go run ./examples/ili9341/slideshow/convert2bin ./path/to/png_or_jpg.png
+```
+
+## Notes
+
+Displaying a 320x240 png or jpeg often requires more than 50KB of memory.  
+The examples include samd21 settings, but if you run them as is, you will get a memory size error.  

examples/ili9341/slideshow/atsamd21.go

@@ -0,0 +1,29 @@
+// +build atsamd21
+
+package main
+
+import (
+	"machine"
+
+	"tinygo.org/x/drivers/ili9341"
+)
+
+var (
+	display = ili9341.NewSPI(
+		machine.SPI0,
+		machine.D0,
+		machine.D1,
+		machine.D2,
+	)
+
+	backlight = machine.D3
+)
+
+func init() {
+	machine.SPI0.Configure(machine.SPIConfig{
+		SCK:       machine.SPI0_SCK_PIN,
+		SDO:       machine.SPI0_SDO_PIN,
+		SDI:       machine.SPI0_SDI_PIN,
+		Frequency: 24000000,
+	})
+}

examples/ili9341/slideshow/images.go

@@ -0,0 +1,94 @@
+package main
+
+import (
+	"fmt"
+	"image/color"
+	"machine"
+	"strings"
+	"time"
+
+	"tinygo.org/x/drivers/ili9341"
+	"tinygo.org/x/drivers/image/jpeg"
+	"tinygo.org/x/drivers/image/png"
+)
+
+var (
+	black = color.RGBA{0, 0, 0, 255}
+	white = color.RGBA{255, 255, 255, 255}
+	red   = color.RGBA{255, 0, 0, 255}
+	blue  = color.RGBA{0, 0, 255, 255}
+	green = color.RGBA{0, 255, 0, 255}
+)
+
+func main() {
+	err := run()
+	for err != nil {
+		errorMessage(err)
+	}
+}
+
+func run() error {
+	backlight.Configure(machine.PinConfig{machine.PinOutput})
+
+	display.Configure(ili9341.Config{})
+
+	width, height := display.Size()
+	if width < 320 || height < 240 {
+		display.SetRotation(ili9341.Rotation270)
+	}
+
+	display.FillScreen(black)
+	backlight.High()
+
+	for {
+		err := drawJpeg(display)
+		if err != nil {
+			return err
+		}
+		time.Sleep(time.Second)
+
+		err = drawPng(display)
+		if err != nil {
+			return err
+		}
+		time.Sleep(time.Second)
+	}
+
+	return nil
+}
+
+// Define the buffer required for the callback. In most cases, this setting
+// should be sufficient.  For jpeg, the callback will always be called every
+// 3*8*8*4 pix. png will be called every line, i.e. every width pix.
+var buffer [3 * 8 * 8 * 4]uint16
+
+func drawPng(display *ili9341.Device) error {
+	p := strings.NewReader(pngImage)
+	png.SetCallback(buffer[:], func(data []uint16, x, y, w, h, width, height int16) {
+		err := display.DrawRGBBitmap(x, y, data[:w*h], w, h)
+		if err != nil {
+			errorMessage(fmt.Errorf("error drawPng: %s", err))
+		}
+	})
+
+	return png.Decode(p)
+}
+
+func drawJpeg(display *ili9341.Device) error {
+	p := strings.NewReader(jpegImage)
+	jpeg.SetCallback(buffer[:], func(data []uint16, x, y, w, h, width, height int16) {
+		err := display.DrawRGBBitmap(x, y, data[:w*h], w, h)
+		if err != nil {
+			errorMessage(fmt.Errorf("error drawJpeg: %s", err))
+		}
+	})
+
+	return jpeg.Decode(p)
+}
+
+func errorMessage(err error) {
+	for {
+		fmt.Printf("%s\r\n", err.Error())
+		time.Sleep(5 * time.Second)
+	}
+}

examples/ili9341/slideshow/main.go

@@ -0,0 +1,22 @@
+// +build pyportal
+
+package main
+
+import (
+	"machine"
+
+	"tinygo.org/x/drivers/ili9341"
+)
+
+var (
+	display = ili9341.NewParallel(
+		machine.LCD_DATA0,
+		machine.TFT_WR,
+		machine.TFT_DC,
+		machine.TFT_CS,
+		machine.TFT_RESET,
+		machine.TFT_RD,
+	)
+
+	backlight = machine.TFT_BACKLIGHT
+)

examples/ili9341/slideshow/pyportal.go

@@ -0,0 +1,29 @@
+// +build wioterminal
+
+package main
+
+import (
+	"machine"
+
+	"tinygo.org/x/drivers/ili9341"
+)
+
+var (
+	display = ili9341.NewSPI(
+		machine.SPI3,
+		machine.LCD_DC,
+		machine.LCD_SS_PIN,
+		machine.LCD_RESET,
+	)
+
+	backlight = machine.LCD_BACKLIGHT
+)
+
+func init() {
+	machine.SPI3.Configure(machine.SPIConfig{
+		SCK:       machine.LCD_SCK_PIN,
+		SDO:       machine.LCD_SDO_PIN,
+		SDI:       machine.LCD_SDI_PIN,
+		Frequency: 40000000,
+	})
+}

examples/ili9341/slideshow/slideshow.jpg

@@ -0,0 +1,60 @@
+# tinygo.org/x/drivers/image
+
+This is an image package that uses less RAM to run on a microcontroller.
+Unlike Go's original image package, `image.Decode()` does not return `image.Image`.
+
+Instead, a callback can be set to process the data corresponding to the image.
+
+## How to use
+
+First, use `SetCallback()` to set the callback.
+Then call `png.Decode()` or `jpeg.Decode()`.
+The callback will be called as many times as necessary to load the image.
+
+`SetCallback()` needs to be given a Buffer to handle the callback and the actual function to be called.
+The `data []uint16` in the callback is in RGB565 format.
+
+The `io.Reader` to pass to `Decode()` specifies the binary data of the image.
+
+```go
+func drawPng(display *ili9341.Device) error {
+	p := strings.NewReader(pngImage)
+	png.SetCallback(buffer[:], func(data []uint16, x, y, w, h, width, height int16) {
+		err := display.DrawRGBBitmap(x, y, data[:w*h], w, h)
+		if err != nil {
+			errorMessage(fmt.Errorf("error drawPng: %s", err))
+		}
+	})
+
+	return png.Decode(p)
+}
+```
+
+```go
+func drawJpeg(display *ili9341.Device) error {
+	p := strings.NewReader(jpegImage)
+	jpeg.SetCallback(buffer[:], func(data []uint16, x, y, w, h, width, height int16) {
+		err := display.DrawRGBBitmap(x, y, data[:w*h], w, h)
+		if err != nil {
+			errorMessage(fmt.Errorf("error drawJpeg: %s", err))
+		}
+	})
+
+	return jpeg.Decode(p)
+}
+```
+
+## How to create an image
+
+The following program will output an image binary like the one in [images.go](./examples/ili9341/slideshow/images.go).  
+
+```
+go run ./cmd/convert2bin ./path/to/png_or_jpg.png
+```
+
+## Examples
+
+An example can be found below.
+Processing jpegs requires a minimum of 32KB of RAM.
+
+* [./examples/ili9341/slideshow](./examples/ili9341/slideshow)