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drawpicture.go
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drawpicture.go
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package main
import (
"fmt"
"image"
"os"
"time"
"unsafe"
"launchpad.net/gommap"
_ "image/jpeg"
"github.com/JesterSks/drm"
"github.com/JesterSks/drm/mode"
)
type (
framebuffer struct {
id uint32
handle uint32
data []byte
fb *mode.FB
size uint64
stride uint32
}
// msetData just store the pair (mode, fb) and the saved CRTC of the mode.
msetData struct {
mode *mode.Modeset
fb framebuffer
savedCrtc *mode.Crtc
}
)
func createFramebuffer(file *os.File, dev *mode.Modeset) (framebuffer, error) {
fb, err := mode.CreateFB(file, dev.Width, dev.Height, 32)
if err != nil {
return framebuffer{}, fmt.Errorf("Failed to create framebuffer: %s", err.Error())
}
stride := fb.Pitch
size := fb.Size
handle := fb.Handle
fbID, err := mode.AddFB(file, dev.Width, dev.Height, 24, 32, stride, handle)
if err != nil {
return framebuffer{}, fmt.Errorf("Cannot create dumb buffer: %s", err.Error())
}
offset, err := mode.MapDumb(file, handle)
if err != nil {
return framebuffer{}, err
}
mmap, err := gommap.MapAt(0, uintptr(file.Fd()), int64(offset), int64(size), gommap.PROT_READ|gommap.PROT_WRITE, gommap.MAP_SHARED)
if err != nil {
return framebuffer{}, fmt.Errorf("Failed to mmap framebuffer: %s", err.Error())
}
for i := uint64(0); i < size; i++ {
mmap[i] = 0
}
framebuf := framebuffer{
id: fbID,
handle: handle,
data: mmap,
fb: fb,
size: size,
stride: stride,
}
return framebuf, nil
}
func draw(msets []msetData) {
var off uint32
reader, err := os.Open("glenda.jpg")
if err != nil {
fmt.Fprintf(os.Stderr, "error: %s\n", err.Error())
return
}
defer reader.Close()
m, _, err := image.Decode(reader)
if err != nil {
fmt.Fprintf(os.Stderr, "error: %s\n", err.Error())
return
}
bounds := m.Bounds()
for j := 0; j < len(msets); j++ {
mset := msets[j]
for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
for x := bounds.Min.X; x < bounds.Max.X; x++ {
r, g, b, _ := m.At(x, y).RGBA()
off = (mset.fb.stride * uint32(y)) + (uint32(x) * 4)
val := uint32((uint32(r) << 16) | (uint32(g) << 8) | uint32(b))
*(*uint32)(unsafe.Pointer(&mset.fb.data[off])) = val
}
}
}
time.Sleep(10 * time.Second)
}
func destroyFramebuffer(modeset *mode.SimpleModeset, mset msetData, file *os.File) error {
handle := mset.fb.handle
data := mset.fb.data
fb := mset.fb
err := gommap.MMap(data).UnsafeUnmap()
if err != nil {
return fmt.Errorf("Failed to munmap memory: %s\n", err.Error())
}
err = mode.RmFB(file, fb.id)
if err != nil {
return fmt.Errorf("Failed to remove frame buffer: %s\n", err.Error())
}
err = mode.DestroyDumb(file, handle)
if err != nil {
return fmt.Errorf("Failed to destroy dumb buffer: %s\n", err.Error())
}
return modeset.SetCrtc(mset.mode, mset.savedCrtc)
}
func cleanup(modeset *mode.SimpleModeset, msets []msetData, file *os.File) {
for _, mset := range msets {
destroyFramebuffer(modeset, mset, file)
}
}
func main() {
file, err := drm.OpenCard(0)
if err != nil {
fmt.Printf("error: %s", err.Error())
return
}
defer file.Close()
if !drm.HasDumbBuffer(file) {
fmt.Printf("drm device does not support dumb buffers")
return
}
modeset, err := mode.NewSimpleModeset(file)
if err != nil {
fmt.Fprintf(os.Stderr, "error: %s\n", err.Error())
os.Exit(1)
}
var msets []msetData
for _, mod := range modeset.Modesets {
framebuf, err := createFramebuffer(file, &mod)
if err != nil {
fmt.Fprintf(os.Stderr, "error: %s\n", err.Error())
cleanup(modeset, msets, file)
return
}
// save current CRTC of this mode to restore at exit
savedCrtc, err := mode.GetCrtc(file, mod.Crtc)
if err != nil {
fmt.Fprintf(os.Stderr, "error: Cannot get CRTC for connector %d: %s", mod.Conn, err.Error())
cleanup(modeset, msets, file)
return
}
// change the mode
err = mode.SetCrtc(file, mod.Crtc, framebuf.id, 0, 0, &mod.Conn, 1, &mod.Mode)
if err != nil {
fmt.Fprintf(os.Stderr, "Cannot set CRTC for connector %d: %s", mod.Conn, err.Error())
cleanup(modeset, msets, file)
return
}
msets = append(msets, msetData{
mode: &mod,
fb: framebuf,
savedCrtc: savedCrtc,
})
}
draw(msets)
cleanup(modeset, msets, file)
}