More work on dnd kitten

kittens/dnd/drag.go

@@ -2,10 +2,57 @@ package dnd
 
 import (
 	"fmt"
+	"maps"
+	"slices"
+	"strings"
+
+	"github.com/kovidgoyal/kitty/tools/utils"
 )
 
 var _ = fmt.Print
 
 type drag_status struct {
-	active bool
+	active                 bool
+	terminal_accepted_drag bool
+}
+
+func (dnd *dnd) on_potential_drag_start(cell_x, cell_y int) (err error) {
+	if !dnd.allow_drags || dnd.drag_status.active {
+		return
+	}
+	mimes := slices.Collect(maps.Keys(dnd.drag_sources))
+	actions := 3
+	if dnd.copy_button_region.has(cell_x, cell_y) {
+		actions = 1
+	} else if dnd.move_button_region.has(cell_x, cell_y) {
+		actions = 2
+	}
+	dnd.lp.QueueDnDData(DC{Type: 'o', Operation: actions, Payload: utils.UnsafeStringToBytes(strings.Join(mimes, " "))})
+	total_preloaded_data_sz := 0
+	for i, mt := range mimes {
+		s := dnd.drag_sources[mt]
+		if len(s.data) > 0 && len(s.data)+total_preloaded_data_sz < 64*1024*1024 {
+			total_preloaded_data_sz += len(s.data)
+			dnd.lp.QueueDnDData(DC{Type: 'p', X: i, Operation: actions, Payload: utils.UnsafeStringToBytes(strings.Join(mimes, " "))})
+		}
+	}
+	// TODO: set the drag image
+	dnd.lp.QueueDnDData(DC{Type: 'P', X: -1}) // start drag
+	dnd.drag_status.active = true
+
+	return dnd.render_screen()
+}
+
+func (dnd *dnd) on_drag_error(cmd DC) (err error) {
+	payload := string(cmd.Payload)
+	switch payload {
+	case "OK":
+		if dnd.drag_status.active && !dnd.drag_status.terminal_accepted_drag {
+			dnd.drag_status.terminal_accepted_drag = true
+			err = dnd.render_screen()
+		}
+	default:
+		err = fmt.Errorf("terminal responded with drag source error: %s", payload)
+	}
+	return
 }