dd basic drag thumbnail support to dnd kitten

kittens/dnd/drag.go

@@ -3,6 +3,7 @@ package dnd
 import (
 	"errors"
 	"fmt"
+	"image"
 	"io"
 	"maps"
 	"os"
@@ -11,6 +12,7 @@ import (
 	"strings"
 
 	"github.com/emmansun/base64"
+	"github.com/kovidgoyal/imaging"
 	"github.com/kovidgoyal/kitty/tools/tui/loop"
 	"github.com/kovidgoyal/kitty/tools/utils"
 	"github.com/kovidgoyal/kitty/tools/utils/streaming_base64"
@@ -50,6 +52,72 @@ type drag_status struct {
 	remote_item_write_id   loop.IdType
 }
 
+func find_drag_image(drag_sources map[string]*drag_source) image.Image {
+	for mime, ds := range drag_sources {
+		if strings.HasPrefix(mime, "image/") && ds.path != "" {
+			q, err := imaging.Open(ds.path)
+			if err == nil {
+				return q
+			}
+		}
+	}
+	var uri_list []string
+	if ds := drag_sources["text/uri-list"]; ds != nil && len(ds.data) > 0 {
+		if q, err := parse_uri_list(string(ds.data)); err == nil {
+			for _, path := range q {
+				if path != "" {
+					uri_list = append(uri_list, path)
+				}
+			}
+		}
+	}
+	for _, path := range uri_list {
+		q, err := imaging.Open(path)
+		if err == nil {
+			return q
+		}
+	}
+	// TODO: Try to generate an image based preview using the machinery from the choose-files kitten
+	return nil
+}
+
+func (dnd *dnd) set_drag_image() (err error) {
+	img := dnd.drag_thumbnail
+	if img == nil {
+		img = find_drag_image(dnd.drag_sources)
+	}
+	if img == nil {
+		return
+	}
+	num_channels := utils.IfElse(imaging.IsOpaque(img), 3, 4)
+	sz := dnd.opts.DragThumbnailSize
+	if max(img.Bounds().Dx(), img.Bounds().Dy()) > sz {
+		w, h := 0, 0
+		if img.Bounds().Dx() >= img.Bounds().Dy() {
+			w = sz
+		} else {
+			h = sz
+		}
+		img = imaging.ResizeWithOpacity(img, w, h, imaging.Lanczos, num_channels == 3)
+		if dnd.drag_thumbnail != nil {
+			dnd.drag_thumbnail = img
+		}
+	}
+	var pix []byte
+	if imaging.IsOpaque(img) {
+		_, pix = 3, imaging.AsRGBData8(img)
+	} else {
+		pix = imaging.AsRGBAData8(img)
+	}
+	cmd := DC{
+		Type: 'p', X: -1, Y: utils.IfElse(num_channels == 3, 24, 32), Xp: img.Bounds().Dx(), Yp: img.Bounds().Dy(),
+		Payload: pix}
+	dnd.lp.QueueDnDData(cmd)
+	cmd.Payload = nil
+	dnd.lp.QueueDnDData(cmd)
+	return nil
+}
+
 func (dnd *dnd) on_potential_drag_start(cell_x, cell_y int) (err error) {
 	if !dnd.allow_drags || dnd.drag_status.active {
 		return
@@ -72,7 +140,11 @@ func (dnd *dnd) on_potential_drag_start(cell_x, cell_y int) (err error) {
 		}
 	}
 	dnd.drag_status.offered_mimes = mimes
-	// TODO: set the drag image
+	err = dnd.set_drag_image()
+	if err != nil {
+		dnd.finish_drag("EIO")
+		return err
+	}
 	dnd.lp.QueueDnDData(DC{Type: 'P', X: -1}) // start drag
 	dnd.drag_status.active = true
 

kittens/dnd/main.go

@@ -5,6 +5,7 @@ package dnd
 import (
 	"bytes"
 	"fmt"
+	"image"
 	"io"
 	"maps"
 	"net/url"
@@ -15,6 +16,7 @@ import (
 	"strings"
 	"sync/atomic"
 
+	"github.com/kovidgoyal/imaging"
 	"github.com/kovidgoyal/kitty/tools/cli"
 	"github.com/kovidgoyal/kitty/tools/tty"
 	"github.com/kovidgoyal/kitty/tools/tui/loop"
@@ -78,6 +80,7 @@ type dnd struct {
 	opts                     *Options
 	drop_dests               map[string]*drop_dest
 	drag_sources             map[string]*drag_source
+	drag_thumbnail           image.Image
 	allow_drops, allow_drags bool
 
 	lp                                     *loop.Loop
@@ -382,6 +385,12 @@ func dnd_main(cmd *cli.Command, opts *Options, args []string) (rc int, err error
 		}
 	}
 	dnd := dnd{opts: opts, drop_dests: drop_dests, drag_sources: drag_sources}
+	if opts.DragThumbnail != "" {
+		if dnd.drag_thumbnail, err = imaging.Open(opts.DragThumbnail); err != nil {
+			return 1, err
+		}
+	}
+
 	defer func() {
 		dnd.end_drop(false)
 		if dnd.confirm_drop.staging_dir != nil {

kittens/dnd/main.py

@@ -33,6 +33,19 @@ default=disallowed
 type=choices
 Allow dropping anywhere, not just on the Copy or Move drop regions. Dropping anywhere will perform
 the specified action.
+
+
+--drag-thumbnail
+Path to an image to use as the drag icon when starting a drag. Must be in PNG/JPEG/GIF/WEBP formats.
+Other formats will require the presence of ImageMagick on the system to load the image.
+If not specified, an image is derived based on the data being dragged.
+
+
+--drag-thumbnail-size
+default=512
+type=int
+The thumbnail size for the image used as the drag icon. Images larger than this size are downscaled.
+Note that the terminal may reject the drag if the image is too large.
 '''.format
 
 

kitty/dnd.c

@@ -1405,6 +1405,8 @@ expand_png_data(Window *w, size_t idx) {
 }
 #undef fail
 
+static size_t last_total_image_size = 0;
+
 void
 drag_start(Window *w) {
     if (ds.state != DRAG_SOURCE_BEING_BUILT) abrt(EINVAL);
@@ -1424,6 +1426,7 @@ drag_start(Window *w) {
             if (img.sz != (size_t)img.width * (size_t)img.height * 4u) abrt(EINVAL);
         }
     }
+    last_total_image_size = total_size;
     int err = start_window_drag(w, dnd_is_test_mode());
     if (err != 0) {
         abrt(err);
@@ -2261,6 +2264,9 @@ dnd_test_probe_state(PyObject *self UNUSED, PyObject *args) {
             ans, i, PyUnicode_FromString(w->drag_source.items[i].mime_type));
         return ans;
     }
+    if (strcmp(q, "drag_thumbnail_size") == 0) {
+        return PyLong_FromSize_t(last_total_image_size);
+    }
     Py_RETURN_NONE;
 }
 

kitty_tests/dnd_kitten.py

@@ -328,6 +328,10 @@ class TestDnDKitten(BaseTest):
             self.assertEqual(fa.read(), fb.read(), f'{a} ({os.path.getsize(a)}) != {b} ({os.path.getsize(b)})')
 
     def test_dnd_kitten_drag(self):
+        from .graphics import png_data
+        drag_thumbnail = os.path.join(self.test_dir, 'drag.png')
+        with open(drag_thumbnail, 'wb') as f:
+            f.write(png_data)
         img_drag_path = 'image.png'
         def create_files():
             with open(os.path.join(self.kitten_wd, img_drag_path), 'wb') as f:
@@ -336,7 +340,7 @@ class TestDnDKitten(BaseTest):
             create_fs(self.src_data_dir)
         create_files()
         tl = tuple(os.path.join(self.src_data_dir, x) for x in os.listdir(self.src_data_dir))
-        self.finish_setup(cli_args=(f'--drag=image/png:{img_drag_path}', ) + tl) # )))
+        self.finish_setup(cli_args=(f'--drag-thumbnail={drag_thumbnail}', f'--drag=image/png:{img_drag_path}') + tl) # )))
         with self.subTest(remote_client=False):
             self.dnd_kitten_drag(False, img_drag_path)
         self.reset_kitten(True)
@@ -378,6 +382,7 @@ class TestDnDKitten(BaseTest):
             dnd_test_start_drag_offer(self.capture.window_id, x, y)
             wait_for_drag_active()
             self.wait_for_state('drag_operations', expected)
+            self.wait_for_state('drag_thumbnail_size', 4)
         def end_drag(canceled=True):
             dnd_test_drag_finish(self.capture.window_id, canceled)
             wait_for_drag_active(False)

kitty_tests/graphics.py

@@ -19,7 +19,7 @@ try:
     from PIL import Image
 except ImportError:
     Image = None
-
+png_data = base64_decode('iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mNk+P+/HgAFhAJ/wlseKgAAAABJRU5ErkJggg==')
 
 def send_command(screen, cmd, payload=b''):
     cmd = '\033_G' + cmd
@@ -505,7 +505,6 @@ class TestGraphics(BaseTest):
 
     def test_load_png_simple(self):
         # 1x1 transparent PNG
-        png_data = base64_decode('iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mNk+P+/HgAFhAJ/wlseKgAAAABJRU5ErkJggg==')
         expected = b'\x00\xff\xff\x7f'
         self.ae(load_png_data(png_data), (expected, 1, 1))
         s, g, pl, sl = load_helpers(self)