crop: Refactor remove_crop() out of toggle_crop()

Another approach to occivink/mpv-scripts#77
The code for removing the last crop filter is already in toggle_crop(),
I just have to break it down into smaller functions.

Firstly, remove_delogo() is invoked to remove the last delogo filter.
If a delogo filter exists, the function will remove it and return true;
remove_hard() won't be called.
Conversely, if no delogo filter is found, remove_hard() is invoked to
determine the state of video-crop.
Finally, if no delogo filter is present or video-crop is disabled,
toggle_crop() will call start_crop().

The order of crop removal will be made configurable in the next few
commits.

scripts/crop.lua

@@ -357,6 +357,41 @@ function cancel_crop()
  active = false
 end
 
+function remove_crop()
+ local remove_delogo = function()
+ local vf_table = mp.get_property_native("vf")
+ if #vf_table > 0 then
+ for i = #vf_table, 1, -1 do
+ if vf_table[i].name == "delogo" then
+ for j = i, #vf_table-1 do
+ vf_table[j] = vf_table[j+1]
+ end
+ vf_table[#vf_table] = nil
+ mp.set_property_native("vf", vf_table)
+ mp.osd_message("Removed delogo filter.")
+ local subdata = mp.get_property_native("sub-ass-extradata")
+ if subdata ~= nil and opts.fix_borders then
+ local playresx = subdata:match("PlayResX:%s*(%d+)")
+ mp.set_property_native("sub-ass-force-style", "PlayResX=" .. playresx)
+ end
+ return true
+ end
+ end
+ end
+ return false
+ end
+ local remove_hard = function()
+ video_crop = mp.get_property_native("video-crop")
+ if video_crop == "" then
+ return false
+ end
+ mp.set_property_native("video-crop", "")
+ mp.osd_message("Reset video-crop to empty.")
+ return true
+ end
+ return remove_delogo() or remove_hard()
+end
+
 function start_crop(mode)
  if active then return end
  if not mp.get_property_native("osd-dimensions") then return end
@@ -395,40 +430,7 @@ function toggle_crop(mode)
  end
  local toggle_mode = mode or opts.mode
  if toggle_mode == "soft" then return end -- can't toggle soft mode
-
- local remove_delogo = function()
- local vf_table = mp.get_property_native("vf")
- if #vf_table > 0 then
- for i = #vf_table, 1, -1 do
- if vf_table[i].name == "delogo" then
- for j = i, #vf_table-1 do
- vf_table[j] = vf_table[j+1]
- end
- vf_table[#vf_table] = nil
- mp.set_property_native("vf", vf_table)
- local subdata = mp.get_property_native("sub-ass-extradata")
- if subdata ~= nil and opts.fix_borders then
- local playresx = subdata:match("PlayResX:%s*(%d+)")
- mp.set_property_native("sub-ass-force-style", "PlayResX=" .. playresx)
- end
- return true
- end
- end
- end
- return false
- end
- if toggle_mode == "delogo" and not remove_delogo() then
- start_crop(mode)
- end
- local remove_hard = function()
- video_crop = mp.get_property_native("video-crop")
- if video_crop == "" then
- return false
- end
- mp.set_property_native("video-crop", "")
- return true
- end
- if toggle_mode == "hard" and not remove_hard() then
+ if not remove_crop() then -- only start_crop if no crops are removed
  start_crop(mode)
  end
 end
@@ -459,6 +461,6 @@ bindings_repeat[opts.right_fine] = movement_func(opts.fine_movement, 0)
 bindings_repeat[opts.up_fine] = movement_func(0, -opts.fine_movement)
 bindings_repeat[opts.down_fine] = movement_func(0, opts.fine_movement)
 
-
+mp.add_key_binding(nil, "remove-crop", remove_crop)
 mp.add_key_binding(nil, "start-crop", start_crop)
 mp.add_key_binding(nil, "toggle-crop", toggle_crop)