use IMV to preview images, it works on DWL wayland

ranger/ext/img_display.py

@@ -22,7 +22,8 @@
 import warnings
 import json
 import threading
-from subprocess import Popen, PIPE
+from subprocess import Popen, PIPE, run
+import time
 from collections import defaultdict
 
 import termios
@@ -779,3 +780,39 @@ def quit(self):
                 self.process.communicate()
             finally:
                 timer_kill.cancel()
+
+
+@register_image_displayer("imv")
+class IMVImageDisplayer(ImageDisplayer):
+    """Implementation of ImageDisplayer using imv
+       add following line into rc.conf to make it work
+       set preview_images_method imv
+    """
+    is_initialized = False
+
+    def __init__(self):
+        self.process = None
+
+    def initialize(self):
+        """ start imv """
+        if (self.is_initialized and self.process.poll() is None
+                and not self.process.stdin.closed):
+            return
+
+        self.process = Popen(['imv'], cwd=self.working_dir, stdin=PIPE, universal_newlines=True)
+        self.is_initialized = True
+        sleep(5)
+
+    def draw(self, path, start_x, start_y, width, height):
+        self.initialize()
+        run(['imv-msg',str(self.process.pid),'close'])
+        run(['imv-msg',str(self.process.pid),'open',path])
+
+
+    def clear(self, start_x, start_y, width, height):
+        self.initialize()
+        run(['imv-msg',str(self.process.pid),'close'])
+
+    def quit(self):
+        if self.is_initialized and self.process.poll() is None:
+            self.process.terminate()