feat(preview): add use_float option for preview mode, closes #134 (#502)

Author: cseickel

README.md

@@ -198,6 +198,8 @@ use {
             },
             ["<2-LeftMouse>"] = "open",
             ["<cr>"] = "open",
+            ["<esc>"] = "revert_preview",
+            ["P"] = { "toggle_preview", config = { use_float = true } },
             ["S"] = "open_split",
             ["s"] = "open_vsplit",
             -- ["S"] = "split_with_window_picker",

doc/neo-tree.txt

@@ -13,6 +13,7 @@ Configuration ............... |neo-tree-configuration|
   Setup ..................... |neo-tree-setup|
   Source Selector ........... |neo-tree-source-selector|
   Filtered Items ............ |neo-tree-filtered-items|
+  Preview Mode .............. |neo-tree-preview-mode|
   Hijack Netrw Behavior ..... |neo-tree-netrw-hijack|
   Component Configs ......... |neo-tree-component-configs|
   Git Status ................ |neo-tree-git-status|
@@ -169,9 +170,9 @@ in a custom mapping.
 
 Note: The "selected" item is the line the cursor is currently on.
 
-<             = prev_source  Switches to the previous source.
+<             = prev_source: Switches to the previous source.
 
->             = next_source  Switches to the next source.
+>             = next_source: Switches to the next source.
 
 <bs>          = navigate_up: Moves the root directory up one level.
 
@@ -192,6 +193,12 @@ z         = close_all_nodes: Close all nodes in the tree.
 
            expand_all_nodes: Expand all directory nodes in the tree recursively.
 
+P          = toggle_preview: Toggles "preview mode", see |neo-tree-preview-mode| 
+
+<esc>      = revert_preview: Ends "preview_mode" if it is enabled, and reverts
+                             any preview windows to what was being shown before
+                             preview mode began.
+
 S             = open_split:  Same as open, but opens in a new horizontal split.
 
 s             = open_vsplit: Same as open, but opens in a vertical split.
@@ -311,6 +318,34 @@ f = filter_on_submit:       Same as above, but does not search until you hit
 
 <C-x> = clear_filter:       Removes the filter.
 
+PREVIEW MODE                                             *neo-tree-preview-mode*
+
+Preview mode will temporarily show whatever file the cursor is on without 
+switching focus from the Neo-tree window. By default, files will be previewed 
+in a new floating window. This can also be configured to automatically choose 
+an existing split by configuring the command like this:
+
+>
+    require("neo-tree").setup({
+      window = {
+        mappings = {
+          ["P"] = { "toggle_preview", config = { use_float = false } },
+        }
+      }
+    })
+<
+Anything that causes Neo-tree to lose focus will end preview mode. When
+`use_float = false`, the window that was taken over by preview mode will revert
+back to whatever was shown in that window before preview mode began.
+
+If you want to work with the floating preview mode window in autocmds or other
+custom code, the window will have the `neo-tree-preview` filetype. 
+
+When preview mode is not using floats, the window will have the window local
+variable `neo_tree_preview` set to `1` to indicate that it is being used as a
+preview window. You can refer to this in statusline and winbar configs to mark a
+window as being used as a preview.
+
 
 CUSTOM MAPPINGS                                       *neo-tree-custom-mappings*
 

lua/neo-tree/defaults.lua

@@ -309,6 +309,8 @@ local config = {
       },
       ["<2-LeftMouse>"] = "open",
       ["<cr>"] = "open",
+      ["<esc>"] = "revert_preview",
+      ["P"] = { "toggle_preview", config = { use_float = true } },
       ["S"] = "open_split",
       -- ["S"] = "split_with_window_picker",
       ["s"] = "open_vsplit",
@@ -317,7 +319,6 @@ local config = {
       -- ["<cr>"] = "open_drop",
       -- ["t"] = "open_tab_drop",
       ["w"] = "open_with_window_picker",
-      --["P"] = "toggle_preview",
       ["C"] = "close_node",
       ["z"] = "close_all_nodes",
       --["Z"] = "expand_all_nodes",

lua/neo-tree/sources/common/commands.lua

@@ -347,13 +347,14 @@ end
 
 M.preview = function(state)
   local node = state.tree:get_node()
-  if state.current_position == "current" or node.type == "directory" then
+  if node.type == "directory" then
     return
   end
 
   if not state.preview then
     state.preview = Preview:new(state)
   else
+    state.preview.active = true
     state.preview:findWindow(state)
   end
 
@@ -363,20 +364,23 @@ M.preview = function(state)
   local path = node.path or node:get_id()
   local bufnr = extra.bufnr or vim.fn.bufadd(path)
 
-  if bufnr and bufnr > 0 then
-    state.preview:preview(bufnr, position, end_position)
+  if bufnr and bufnr > 0 and state.preview then
+    if renderer.is_window_valid(state.preview.winid) then
+      state.preview:preview(bufnr, position, end_position)
+    else
+      log.warn("Preview window is not valid")
+      Preview.dispose(state)
+    end
   end
 end
 
 M.revert_preview = function(state)
-  if state.preview and state.preview.active then
-    state.preview:revert()
-  end
+  Preview.dispose(state)
 end
 
 M.toggle_preview = function(state)
-  if state.preview and state.preview.active then
-    state.preview:revert()
+  if state.preview then
+    M.revert_preview(state)
   else
     state.commands.preview(state)
     if not state.preview then
@@ -385,25 +389,20 @@ M.toggle_preview = function(state)
     local preview_event = {
       event = events.VIM_CURSOR_MOVED,
       handler = function()
+        if not state.preview then
+          return
+        end
         if vim.api.nvim_get_current_win() == state.winid then
-          state.commands.preview(state)
+          if state.preview.active then
+            state.commands.preview(state)
+          end
+        else
+          Preview.dispose(state)
         end
       end,
       id = "preview-event",
     }
-    local preview_buf_leave_event = {
-      event = events.NEO_TREE_BUFFER_LEAVE,
-      handler = function()
-        local winid, bufnr = state.preview.winid, state.preview.bufnr
-        state.preview:revert()
-        if vim.api.nvim_get_current_win() == winid then
-          vim.api.nvim_set_current_buf(bufnr)
-        end
-      end,
-      id = "preview-buf-leave-event",
-    }
     state.preview:subscribe(state.name, preview_event)
-    state.preview:subscribe(state.name, preview_buf_leave_event)
   end
 end
 
@@ -424,6 +423,7 @@ local open_with_cmd = function(state, open_cmd, toggle_directory, open_file)
   end
 
   local function open()
+    M.revert_preview(state)
     local path = node.path or node:get_id()
     if type(open_file) == "function" then
       open_file(state, path, open_cmd)