Fix palettes. Remove unnecessary memory alloc for pixels.

inky/impression.go

@@ -29,36 +29,36 @@ var _ draw.Image = &DevImpression{}
 var (
 	// For more: https://github.com/pimoroni/inky/issues/115#issuecomment-887453065
 	dsc = []color.NRGBA{
-		{0, 0, 0, 0},         // Black
+		{0, 0, 0, 255},       // Black
 		{255, 255, 255, 255}, // White
 		{0, 255, 0, 255},     // Green
 		{0, 0, 255, 255},     // Blue
 		{255, 0, 0, 255},     // Red
 		{255, 255, 0, 255},   // Yellow
 		{255, 140, 0, 255},   // Orange
-		{255, 255, 255, 255},
+		{255, 255, 255, 0},   // Clear
 	}
 
 	sc = []color.NRGBA{
-		{57, 48, 57, 0},      // Black
+		{57, 48, 57, 255},    // Black
 		{255, 255, 255, 255}, // White
 		{58, 91, 70, 255},    // Green
 		{61, 59, 94, 255},    // Blue
 		{156, 72, 75, 255},   // Red
 		{208, 190, 71, 255},  // Yellow
 		{177, 106, 73, 255},  // Orange
-		{255, 255, 255, 255},
+		{255, 255, 255, 0},   // Clear
 	}
 
 	sc7 = []color.NRGBA{
-		{0, 0, 0, 0},         // Black
+		{0, 0, 0, 255},       // Black
 		{217, 242, 255, 255}, // White
 		{3, 124, 76, 255},    // Green
 		{27, 46, 198, 255},   // Blue
 		{245, 80, 34, 255},   // Red
 		{255, 255, 68, 255},  // Yellow
 		{239, 121, 44, 255},  // Orange
-		{255, 255, 255, 255},
+		{255, 255, 255, 0},   // Clear
 	}
 )
 
@@ -224,10 +224,10 @@ func NewImpression(p spi.Port, dc gpio.PinOut, reset gpio.PinOut, busy gpio.PinI
 }
 
 // blend recalculates the palette based on the saturation level.
-func (d *DevImpression) blend() []color.Color {
-	sat := float64(d.saturation / 100)
+func (d *DevImpression) blend() color.Palette {
+	sat := float64(d.saturation) / 100.0
 
-	pr := []color.Color{}
+	pr := make([]color.Color, 0)
 	for i := 0; i < 7; i++ {
 		var rs, gs, bs uint8
 		if d.Dev.model == IMPRESSION73 {
@@ -295,7 +295,7 @@ func (d *DevImpression) Render() error {
 
 	merged := make([]uint8, len(d.Pix)/2)
 	for i, offset := 0, 0; i < len(d.Pix)-1; i, offset = i+2, offset+1 {
-		merged[offset] = (d.Pix[i]<<4)&0xF0 | d.Pix[i+1]&0x0F
+		merged[offset] = ((d.Pix[i] << 4) & 0xF0) | (d.Pix[i+1] & 0x0F)
 	}
 
 	return d.update(merged)
@@ -526,18 +526,16 @@ func (d *DevImpression) updateAC(pix []uint8) error {
 	}
 
 	// TODO there has to be a better way to force the white colour to be used instead of clear...
-	buf := make([]byte, len(pix))
 	for i := range pix {
-		buf[i] = pix[i]
-		if buf[i]&0xF == 7 {
-			buf[i] = (buf[i] & 0xF0) + 1
+		if pix[i]&0xF == 7 {
+			pix[i] = (pix[i] & 0xF0) + 1
 		}
-		if buf[i]&0xF0 == 0x70 {
-			buf[i] = (buf[i] & 0xF) + 0x10
+		if pix[i]&0xF0 == 0x70 {
+			pix[i] = (pix[i] & 0xF) + 0x10
 		}
 	}
 
-	if err := d.sendCommand(ac073TC1DTM, buf); err != nil {
+	if err := d.sendCommand(ac073TC1DTM, pix); err != nil {
 		return err
 	}
 
@@ -626,6 +624,7 @@ func (d *DevImpression) Draw(r image.Rectangle, src image.Image, sp image.Point)
 
 	// Dither the image using Floyd–Steinberg dithering algorithm otherwise it won't look as good on the screen.
 	draw.FloydSteinberg.Draw(d, r, src, image.Point{})
+
 	return d.Render()
 }