feat: Initial commit

README.md

@@ -0,0 +1,5 @@
+# imagedrm
+
+A simple library that wraps [godrm](https://github.com/kytart/godrm) as [draw.Image](https://pkg.go.dev/image/draw#Image)
+
+See example usage in `examples/`.

drm.go

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+package imagedrm
+
+import (
+	"fmt"
+	"github.com/kytart/godrm/pkg/drm"
+	"github.com/kytart/godrm/pkg/mode"
+	"launchpad.net/gommap"
+	"os"
+)
+
+type Framebuffer struct {
+	*mode.FB
+	id   uint32
+	data []byte
+}
+
+type Image struct {
+	file     *os.File
+	modeset  *mode.SimpleModeset
+	displays []*Display
+}
+
+type Display struct {
+	mode      *mode.Modeset
+	fb        *Framebuffer
+	savedCrtc *mode.Crtc
+}
+
+func NewImage() (*Image, error) {
+	file, err := drm.OpenCard(0)
+	if err != nil {
+		return nil, fmt.Errorf("open drm card: %w", err)
+	}
+	defer file.Close()
+
+	if !drm.HasDumbBuffer(file) {
+		return nil, fmt.Errorf("drm device does not support dumb buffers")
+	}
+
+	modeset, err := mode.NewSimpleModeset(file)
+	if err != nil {
+		return nil, fmt.Errorf("create modeset: %w", err)
+	}
+
+	image := &Image{
+		file:    file,
+		modeset: modeset,
+	}
+
+	for _, mod := range modeset.Modesets {
+		display, err := image.setupDisplay(mod)
+		if err != nil {
+			image.Close()
+			return nil, fmt.Errorf("setup display: %w", err)
+		}
+
+		image.displays = append(image.displays, display)
+	}
+
+	return image, nil
+}
+
+func (i *Image) Close() error {
+	var err error
+	for _, display := range i.displays {
+		err = i.destroyFramebuffer(display)
+	}
+	return err
+}
+
+func (i *Image) createFramebuffer(dev *mode.Modeset) (*Framebuffer, error) {
+	fb, err := mode.CreateFB(i.file, dev.Width, dev.Height, 32)
+	if err != nil {
+		return nil, fmt.Errorf("create framebuffer: %w", err)
+	}
+
+	fbID, err := mode.AddFB(i.file, dev.Width, dev.Height, 24, 32, fb.Pitch, fb.Handle)
+	if err != nil {
+		return nil, fmt.Errorf("create dumb buffer: %w", err)
+	}
+
+	offset, err := mode.MapDumb(i.file, fb.Handle)
+	if err != nil {
+		return nil, fmt.Errorf("map dumb: %w", err)
+	}
+
+	mmap, err := gommap.MapAt(0, i.file.Fd(), int64(offset), int64(fb.Size), gommap.PROT_READ|gommap.PROT_WRITE, gommap.MAP_SHARED)
+	if err != nil {
+		return nil, fmt.Errorf("mmap framebuffer: %w", err)
+	}
+
+	for i := uint64(0); i < fb.Size; i++ {
+		mmap[i] = 0
+	}
+
+	return &Framebuffer{
+		FB:   fb,
+		id:   fbID,
+		data: mmap,
+	}, nil
+}
+
+func (i *Image) destroyFramebuffer(display *Display) error {
+	err := gommap.MMap(display.fb.data).UnsafeUnmap()
+	if err != nil {
+		return fmt.Errorf("munmap memory: %w", err)
+	}
+
+	err = mode.RmFB(i.file, display.fb.id)
+	if err != nil {
+		return fmt.Errorf("remove frame buffer: %w", err)
+	}
+
+	err = mode.DestroyDumb(i.file, display.fb.Handle)
+	if err != nil {
+		return fmt.Errorf("destroy dumb buffer: %w", err)
+	}
+
+	return i.modeset.SetCrtc(display.mode, display.savedCrtc)
+}
+
+func (i *Image) setupDisplay(mod mode.Modeset) (*Display, error) {
+	framebuf, err := i.createFramebuffer(&mod)
+	if err != nil {
+		return nil, fmt.Errorf("create framebuffer: %w", err)
+	}
+
+	// save current CRTC of this display to restore at exit
+	savedCrtc, err := mode.GetCrtc(i.file, mod.Crtc)
+	if err != nil {
+		return nil, fmt.Errorf("get CRTC for connector %d: %w", mod.Conn, err)
+	}
+
+	// change the display
+	err = mode.SetCrtc(i.file, mod.Crtc, framebuf.id, 0, 0, &mod.Conn, 1, &mod.Mode)
+	if err != nil {
+		return nil, fmt.Errorf("set CRTC for connector %d: %w", mod.Conn, err)
+	}
+
+	return &Display{
+		mode:      &mod,
+		fb:        framebuf,
+		savedCrtc: savedCrtc,
+	}, nil
+}

examples/jpeg/main.go

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+package main
+
+import (
+	"image"
+	"image/color"
+	"image/draw"
+	"os"
+	"time"
+
+	"github.com/ptrcnull/imagedrm"
+)
+
+func main() {
+	img, err := imagedrm.NewImage()
+	if err != nil {
+		panic(err)
+	}
+	defer img.Close()
+
+	sourceFile, err := os.Open("glenda.jpg")
+	if err != nil {
+		panic(err)
+	}
+	defer sourceFile.Close()
+
+	source, _, err := image.Decode(sourceFile)
+	if err != nil {
+		panic(err)
+	}
+
+	draw.Draw(img, source.Bounds(), source, image.Point{}, draw.Src)
+
+	for {
+		img.Set(100, 100, color.RGBA{R: 255, G: 255, B: 255})
+		time.Sleep(time.Second * 1)
+		img.Set(100, 100, color.RGBA{})
+		time.Sleep(time.Second * 1)
+	}
+}

go.mod

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+module github.com/ptrcnull/imagedrm
+
+go 1.17
+
+require (
+	github.com/kytart/godrm v0.0.0-20210309160922-6b139ef54591
+	launchpad.net/gommap v0.0.0-20121012075617-000000000015
+)

go.sum

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+github.com/kytart/godrm v0.0.0-20210309160922-6b139ef54591 h1:FeNG18vTIhxL15MKaAZytDbspAPlVteebfedo5gabT0=
+github.com/kytart/godrm v0.0.0-20210309160922-6b139ef54591/go.mod h1:Y+YdK8W4Pp8iogoLluZ0OenjBSNb9+8NqoNNEdYzxec=
+launchpad.net/gocheck v0.0.0-20140225173054-000000000087 h1:Izowp2XBH6Ya6rv+hqbceQyw/gSGoXfH/UPoTGduL54=
+launchpad.net/gocheck v0.0.0-20140225173054-000000000087/go.mod h1:hj7XX3B/0A+80Vse0e+BUHsHMTEhd0O4cpUHr/e/BUM=
+launchpad.net/gommap v0.0.0-20121012075617-000000000015 h1:ROjpWoAwfoub5UmgCuZwFvM/kWU+UFfuBXbJ6lz/awU=
+launchpad.net/gommap v0.0.0-20121012075617-000000000015/go.mod h1:+rB9VlRTGlxdpc/nkCoOe0Qxgn/pyVwo9lGtVndZbOo=

image.go

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+package imagedrm
+
+import (
+	"image"
+	"image/color"
+	"image/draw"
+	"unsafe"
+)
+
+func (i *Image) ColorModel() color.Model {
+	return &image.Uniform{}
+}
+
+func (i *Image) Bounds() image.Rectangle {
+	display := i.displays[0]
+
+	mode := display.mode
+	return image.Rectangle{
+		Min: image.Point{},
+		Max: image.Point{
+			X: int(mode.Width),
+			Y: int(mode.Height),
+		},
+	}
+}
+
+func (i *Image) At(x, y int) color.Color {
+	display := i.displays[0]
+
+	offset := (display.fb.Pitch * uint32(y)) + (uint32(x) * 4)
+	val := *(*uint32)(unsafe.Pointer(&display.fb.data[offset]))
+
+	return color.RGBA{
+		A: uint8((val & 0xff000000) >> 24),
+		R: uint8((val & 0x00ff0000) >> 16),
+		G: uint8((val & 0x0000ff00) >> 8),
+		B: uint8(val & 0x000000ff),
+	}
+}
+
+func (i *Image) Set(x, y int, c color.Color) {
+	display := i.displays[0]
+
+	r, g, b, a := c.RGBA()
+	val := (a << 24) | (r << 16) | (g << 8) | b
+
+	offset := (display.fb.Pitch * uint32(y)) + (uint32(x) * 4)
+	*(*uint32)(unsafe.Pointer(&display.fb.data[offset])) = val
+}
+
+var _ draw.Image = (*Image)(nil)