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package draw
import (
"fmt"
"os"
"strconv"
"strings"
)
// NamedImage looks up an image the window system published by name and
// installs it under a fresh id of ours. The 'n' message also sets the
// client's infoid, so the image's geometry comes back from a plain read of
// the ctl file -- the same 12-field block that draw/new returns.
func (d *Display) NamedImage(name string) (*Image, error) {
if name == "" || len(name) >= 256 {
return nil, fmt.Errorf("namedimage: bad name %q", name)
}
d.mu.Lock()
d.nextid++
id := d.nextid
d.mu.Unlock()
b := make([]byte, 6+len(name))
b[0] = 'n'
put32(b, 1, id)
b[5] = byte(len(name))
copy(b[6:], name)
if err := d.write(b); err != nil {
return nil, fmt.Errorf("namedimage %q: %w", name, err)
}
var info [12 * 12]byte
n, err := d.ctl.ReadAt(info[:], 0)
if err != nil && n < len(info) {
return nil, fmt.Errorf("namedimage %q: ctl read: %w", name, err)
}
fld := func(i int) int32 {
v, _ := strconv.Atoi(trim(string(info[i*12 : i*12+12])))
return int32(v)
}
return &Image{
d: d,
id: id,
chn: strToChan(trim(string(info[2*12 : 3*12]))),
repl: fld(3) != 0,
R: Rect(fld(4), fld(5), fld(6), fld(7)),
Clipr: Rect(fld(8), fld(9), fld(10), fld(11)),
}, nil
}
// Window returns the image to draw into: the rio window named by
// <dev>/winname if there is one, otherwise the raw screen.
//
// Without this a program draws to image 0 -- the screen itself -- straight
// over the window system. Nothing stops it: /dev/draw is the kernel's
// device, not rio's, and rio publishes the window by name rather than
// proxying the device. Being a good citizen is opt-in, and this is the
// opt-in.
func (d *Display) Window(dev string) (*Image, error) {
if dev == "" {
dev = "/dev"
}
buf, err := os.ReadFile(dev + "/winname")
if err != nil {
return d.Screen, nil // not under a window system
}
name := strings.TrimRight(string(buf), "\x00\n ")
if name == "" {
return d.Screen, nil
}
win, err := d.NamedImage(name)
if err != nil {
return nil, err
}
return win, nil
}
// Reattach re-reads winname and looks the window up again. rio replaces the
// window's image on resize rather than resizing it in place, so a resize
// event means "throw the old one away and ask again".
func (d *Display) Reattach(dev string, old *Image) (*Image, error) {
if old != nil && old.id != 0 {
old.Free() // ignore errors: the old image may already be gone
}
return d.Window(dev)
}
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