const2bit is broken

[oxplot]

Due to the change from Glypher to Glyph.

Attempting to use a font created by tinyfontgen-ttf and using it, yields:

main.go:31:28: cannot use font (variable of type *Font) as tinyfont.Fonter value in argument to tinyfont.WriteLine: *Font does not implement tinyfont.Fonter (wrong type for method GetGlyph)
		have GetGlyph(rune) tinyfont.Glypher
		want GetGlyph(rune) tinyfont.Glyph

Relevant code:

tinyfont.WriteLine(&ssd, TinyFont, 0, 20, "Hi there", color.RGBA{1, 0, 0, 0})

[sago35]

const2bit is for representing 2-bit color fonts.
Glyph cannot handle 2-bit colors.
In addition, we would like to support colored emoji in the future, but tinyfont.Glyph cannot handle them either.

However, trying to return a Glypher results in heap allocs for each call to GetGlyph().

Any suggestions? @deadprogram @aykevl @conejoninja

[sago35]

const2bit works with the following versions of tinyfont.

$ go get tinygo.org/x/tinyfont@34f5899f6c1e34aa6daa4e12e2b96a2ea370dff9

[scraly]

I've tried to convert a TTF font to a tiny go format:

$ go run ./cmd/tinyfontgen-ttf --package fonts --size 32 --fontname Regular58pt ./CharacterCats.ttf --output cats
58.go

But I can`t use it

	tinyfont.DrawChar(&display, &fonts.Regular58pt, 5, 140, 'B', green)

# command-line-arguments
main.go:87:30: cannot use fonts.Regular58pt (variable of type const2bit.Font) as tinyfont.Fonter value in argument to tinyfont.DrawChar: const2bit.Font does not implement tinyfont.Fonter (method GetGlyph has pointer receiver)

[sago35]

This issue should be fixed in PR #46.

[sago35]

Since #46 has been merged, this issue should be resolved.

[deadprogram]

Added label to close on next release.

[scraly]

For the moment the issue is not resolved.

main.go:155:31: cannot use &tomthumb.TomThumb24pt (value of type *const2bit.Font) as tinyfont.Fonter value in argument to tinyfont.WriteLine: *const2bit.Font does not implement tinyfont.Fonter (wrong type for method GetGlyph)
                have GetGlyph(rune) tinyfont.Glypher
                want GetGlyph(rune) tinyfont.Glyph

[sago35]

@scraly
I believe the latest version of tinyfont does not include func GetGlyph(rune) Glyph. Could you share the entire source code or a minimal reproducible example?

[scraly]

My bad, I had a old version of TinyFont in my dependecy:

	tinygo.org/x/tinyfont v0.3.1-0.20230427174829-145dfcef90ab

Upgraded the tinyfont version fixed the bug.

tinygo.org/x/tinyfont v0.5.0 

So you can close this issue :)

I've just got a stange behavior but I need to analyze it deeper:

	tinyfont.WriteLine(&display, &tomthumb.TomThumb24pt, 85, 20, "Hello", white)

[sago35]

I'm glad the issue seems to be resolved.

For now, the background color is assumed to be white. If you apply a patch to the following section, it should work well with any background color of your choice. It might be a good idea to either specify the background color or implement proper alpha blending in the code.

tinyfont/const2bit/const2bit.go

Lines 35 to 52 in cba4856

	// TODO: allow the user to set the color
	func (glyph Glyph) Draw(display drivers.Displayer, x int16, y int16, c color.RGBA) {
	bitmapOffset := 0
	bitmap := byte(0)
	if len(glyph.Bitmaps) > 0 {
	bitmap = glyph.Bitmaps[bitmapOffset]
	}
	bit := uint8(0)
	for j := int16(0); j < int16(glyph.Height); j++ {
	for i := int16(0); i < int16(glyph.Width); i++ {
	switch bitmap & 0xC0 {
	case 0xC0:
	display.SetPixel(x+int16(glyph.XOffset)+i, y+int16(glyph.YOffset)+j, color.RGBA{0x00, 0x00, 0x00, 0xFF})
	case 0x80:
	display.SetPixel(x+int16(glyph.XOffset)+i, y+int16(glyph.YOffset)+j, color.RGBA{0x80, 0x80, 0x80, 0xFF})
	case 0x40:
	display.SetPixel(x+int16(glyph.XOffset)+i, y+int16(glyph.YOffset)+j, color.RGBA{0xD0, 0xD0, 0xD0, 0xFF})
	default:

[deadprogram]

It might be a good idea to either specify the background color or implement proper alpha blending in the code.

That seems like a very good idea for someone to add. 😸