d.mon: Delegate rendering to wx monitors

display/d.mon/render_cmd.py

@@ -1,12 +1,41 @@
 #!/usr/bin/env python3
 import os
 import sys
+import glob
 import tempfile
+from pathlib import Path
 
 from grass.script import core as grass
 from grass.script import task as gtask
 from grass.exceptions import CalledModuleError
 
+non_rendering_modules = (
+    "d.colorlist",
+    "d.font",
+    "d.fontlist",
+    "d.frame",
+    "d.info",
+    "d.mon",
+    "d.out.file",
+    "d.to.rast",
+    "d.what.rast",
+    "d.what.vect",
+    "d.where",
+)
+
+
+# remove empty mapfile from non-rendering modules
+def remove_mapfile(mapfile):
+    # adopted from Map.DeleteLayer() in gui/wxpython/core/render.py
+    base = os.path.split(mapfile)[0]
+    mapfile = os.path.split(mapfile)[1]
+    tempbase = mapfile.split(".")[0]
+    if base == "" or tempbase == "":
+        return
+    basefile = os.path.join(base, tempbase) + r".*"
+    for f in glob.glob(basefile):
+        os.remove(f)
+
 
 # read environment variables from file
 def read_env_file(env_file):
@@ -42,26 +71,18 @@ def render(cmd, mapfile):
         env["GRASS_RENDER_FILE"] = mapfile
     try:
         grass.run_command(cmd[0], env=env, **cmd[1])
+        # display driver can generate a blank map file unnecessarily for
+        # non-rendering modules; delete it
+        if cmd[0] in non_rendering_modules and os.path.exists(mapfile):
+            remove_mapfile(mapfile)
+
     except CalledModuleError as e:
         grass.debug("Unable to render: {0}".format(e), 1)
 
 
 # update cmd file
 def update_cmd_file(cmd_file, cmd, mapfile):
-    if cmd[0] in (
-        "d.colorlist",
-        "d.font",
-        "d.fontlist",
-        "d.frame",
-        "d.info",
-        "d.mon",
-        "d.out.file",
-        "d.redraw",
-        "d.to.rast",
-        "d.what.rast",
-        "d.what.vect",
-        "d.where",
-    ):
+    if cmd[0] in non_rendering_modules:
         return
 
     mode = "w" if cmd[0] == "d.erase" else "a"
@@ -157,13 +178,22 @@ def read_stdin(cmd):
             mapfile += ".png"
         else:
             mapfile += ".ppm"
+        # to force rendering by wx monitors, but don't create a map file for
+        # non-rendering modules
+        if cmd[0] not in non_rendering_modules:
+            Path(mapfile).touch()
     else:
         mapfile = None
         adjust_region(width, height)
 
     read_stdin(cmd)
 
-    render(cmd, mapfile)
+    # wx monitors will render new layers internally so don't render them here;
+    # also, some display modules print information to the terminal rather than
+    # rendering any contents on the monitor so allow them to run here
+    if not mon.startswith("wx") or cmd[0] in non_rendering_modules:
+        render(cmd, mapfile)
+
     update_cmd_file(os.path.join(path, "cmd"), cmd, mapfile)
     if cmd[0] == "d.erase" and os.path.exists(legfile):
         os.remove(legfile)