go-tg-screenshot-bot

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//go:build !s390x && !ppc64le && !darwin && !windows && !freebsd && (linux || openbsd || netbsd)
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package screenshot
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import (
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	"fmt"
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	"github.com/godbus/dbus/v5"
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	"image"
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	"image/draw"
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	"image/png"
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	"net/url"
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	"os"
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	"sync/atomic"
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)
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var gTokenCounter uint64 = 0
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func captureDbus(x, y, width, height int) (img *image.RGBA, e error) {
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	c, err := dbus.ConnectSessionBus()
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	if err != nil {
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		return nil, fmt.Errorf("dbus.SessionBus() failed: %v", err)
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	}
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	defer func(c *dbus.Conn) {
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		err := c.Close()
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		if err != nil {
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			e = err
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		}
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	}(c)
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	token := atomic.AddUint64(&gTokenCounter, 1)
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	options := map[string]dbus.Variant{
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		"modal":        dbus.MakeVariant(false),
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		"interactive":  dbus.MakeVariant(false),
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		"handle_token": dbus.MakeVariant(token),
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	}
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	obj := c.Object("org.freedesktop.portal.Desktop", dbus.ObjectPath("/org/freedesktop/portal/desktop"))
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	call := obj.Call("org.freedesktop.portal.Screenshot.Screenshot", 0, "", options)
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	var path dbus.ObjectPath
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	err = call.Store(&path)
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	if err != nil {
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		return nil, fmt.Errorf("dbus.Store() failed: %v", err)
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	}
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	ch := make(chan *dbus.Message)
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	c.Eavesdrop(ch)
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	for msg := range ch {
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		o, ok := msg.Headers[dbus.FieldPath]
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		if !ok {
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			continue
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		}
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		s, ok := o.Value().(dbus.ObjectPath)
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		if !ok {
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			return nil, fmt.Errorf("dbus.FieldPath value does't have ObjectPath type")
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		}
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		if s != path {
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			continue
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		}
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		for _, body := range msg.Body {
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			v, ok := body.(map[string]dbus.Variant)
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			if !ok {
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				continue
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			}
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			uri, ok := v["uri"]
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			if !ok {
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				continue
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			}
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			path, ok := uri.Value().(string)
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			if !ok {
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				return nil, fmt.Errorf("uri is not a string")
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			}
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			fpath, err := url.Parse(path)
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			if err != nil {
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				return nil, fmt.Errorf("url.Parse(%v) failed: %v", path, err)
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			}
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			if fpath.Scheme != "file" {
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				return nil, fmt.Errorf("uri is not a file path")
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			}
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			file, err := os.Open(fpath.Path)
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			if err != nil {
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				return nil, fmt.Errorf("os.Open(%s) failed: %v", path, err)
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			}
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			defer func(file *os.File) {
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				_ = file.Close()
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				_ = os.Remove(fpath.Path)
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			}(file)
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			img, err := png.Decode(file)
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			if err != nil {
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				return nil, fmt.Errorf("png.Decode(%s) failed: %v", path, err)
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			}
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			canvas, err := createImage(image.Rect(0, 0, width, height))
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			if err != nil {
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				return nil, fmt.Errorf("createImage(%v) failed: %v", path, err)
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			}
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			draw.Draw(canvas, image.Rect(0, 0, width, height), img, image.Point{x, y}, draw.Src)
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			return canvas, e
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		}
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	}
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	return nil, fmt.Errorf("dbus.Message doesn't contain uri")
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}
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