refactor(redraw): various simplifications

5 files changed, 79 insertions, 106 deletions

diff --git a/src/nvim/drawscreen.c b/src/nvim/drawscreen.c
index d2c2d7238b..7ad4193058 100644
--- a/src/nvim/drawscreen.c
+++ b/src/nvim/drawscreen.c
@@ -97,7 +97,7 @@ typedef enum {
 
 static bool redraw_popupmenu = false;
 static bool msg_grid_invalid = false;
-static bool resizing = false;
+static bool resizing_autocmd = false;
 
 static char *provider_err = NULL;
 
@@ -115,7 +115,7 @@ void conceal_check_cursor_line(void)
   }
 }
 
-/// Resize the screen to Rows and Columns.
+/// Resize default_grid to Rows and Columns.
 ///
 /// Allocate default_grid.chars[] and other grid arrays.
 ///
@@ -125,19 +125,18 @@ void conceal_check_cursor_line(void)
 /// default_grid.Columns to access items in default_grid.chars[].  Use Rows
 /// and Columns for positioning text etc. where the final size of the screen is
 /// needed.
-void screenalloc(void)
+bool default_grid_alloc(void)
 {
+  static bool resizing = false;
+
   // It's possible that we produce an out-of-memory message below, which
   // will cause this function to be called again.  To break the loop, just
   // return here.
   if (resizing) {
-    return;
+    return false;
   }
   resizing = true;
 
-  int retry_count = 0;
-
-retry:
   // Allocation of the screen buffers is done only when the size changes and
   // when Rows and Columns have been set and we have started doing full
   // screen stuff.
@@ -148,24 +147,9 @@ retry:
       || Columns == 0
       || (!full_screen && default_grid.chars == NULL)) {
     resizing = false;
-    return;
-  }
-
-  // Note that the window sizes are updated before reallocating the arrays,
-  // thus we must not redraw here!
-  RedrawingDisabled++;
-
-  // win_new_screensize will recompute floats position, but tell the
-  // compositor to not redraw them yet
-  ui_comp_set_screen_valid(false);
-  if (msg_grid.chars) {
-    msg_grid_invalid = true;
+    return false;
   }
 
-  win_new_screensize();      // fit the windows in the new sized screen
-
-  comp_col();           // recompute columns for shown command and ruler
-
   // We're changing the size of the screen.
   // - Allocate new arrays for default_grid
   // - Move lines from the old arrays into the new arrays, clear extra
@@ -193,26 +177,13 @@ retry:
   default_grid.col_offset = 0;
   default_grid.handle = DEFAULT_GRID_HANDLE;
 
-  must_redraw = UPD_CLEAR;  // need to clear the screen later
-
-  RedrawingDisabled--;
-
-  // Do not apply autocommands more than 3 times to avoid an endless loop
-  // in case applying autocommands always changes Rows or Columns.
-  if (starting == 0 && ++retry_count <= 3) {
-    apply_autocmds(EVENT_VIMRESIZED, NULL, NULL, false, curbuf);
-    // In rare cases, autocommands may have altered Rows or Columns,
-    // jump back to check if we need to allocate the screen again.
-    goto retry;
-  }
-
   resizing = false;
+  return true;
 }
 
 void screenclear(void)
 {
   check_for_delay(false);
-  screenalloc();  // allocate screen buffers if size changed
 
   int i;
 
@@ -281,13 +252,6 @@ void screen_resize(int width, int height)
     return;
   }
 
-  // curwin->w_buffer can be NULL when we are closing a window and the
-  // buffer has already been closed and removing a scrollbar causes a resize
-  // event. Don't resize then, it will happen after entering another buffer.
-  if (curwin->w_buffer == NULL) {
-    return;
-  }
-
   resizing_screen = true;
 
   Rows = height;
@@ -301,16 +265,54 @@ void screen_resize(int width, int height)
   width = Columns;
   p_lines = Rows;
   p_columns = Columns;
-  ui_call_grid_resize(1, width, height);
 
-  /// The window layout used to be adjusted here, but it now happens in
-  /// screenalloc() (also invoked from screenclear()).  That is because the
-  /// recursize "resizing_screen" check above may skip this, but not screenalloc().
+  // was invoked recursively from a VimResized autocmd, handled as a loop below
+  if (resizing_autocmd) {
+    return;
+  }
+
+  int retry_count = 0;
+  resizing_autocmd = true;
+
+  bool retry_resize = true;
+  while (retry_resize) {
+    retry_resize = default_grid_alloc();
 
-  if (State != MODE_ASKMORE && State != MODE_EXTERNCMD && State != MODE_CONFIRM) {
-    screenclear();
+    // Do not apply autocommands more than 3 times to avoid an endless loop
+    // in case applying autocommands always changes Rows or Columns.
+    if (++retry_count > 3) {
+      break;
+    }
+
+    if (retry_resize) {
+      // In rare cases, autocommands may have altered Rows or Columns,
+      // retry to check if we need to allocate the screen again.
+      apply_autocmds(EVENT_VIMRESIZED, NULL, NULL, false, curbuf);
+    }
+  }
+
+  resizing_autocmd = false;
+
+  ui_call_grid_resize(1, width, height);
+
+  // win_new_screensize will recompute floats position, but tell the
+  // compositor to not redraw them yet
+  ui_comp_set_screen_valid(false);
+  if (msg_grid.chars) {
+    msg_grid_invalid = true;
   }
 
+  // Note that the window sizes are updated before reallocating the arrays,
+  // thus we must not redraw here!
+  RedrawingDisabled++;
+
+  win_new_screensize();      // fit the windows in the new sized screen
+
+  comp_col();           // recompute columns for shown command and ruler
+
+  RedrawingDisabled--;
+  redraw_all_later(UPD_CLEAR);
+
   if (starting != NO_SCREEN) {
     maketitle();
 
@@ -320,14 +322,11 @@ void screen_resize(int width, int height)
     // We only redraw when it's needed:
     // - While at the more prompt or executing an external command, don't
     //   redraw, but position the cursor.
-    // - While editing the command line, only redraw that.
+    // - While editing the command line, only redraw that. TODO: lies
     // - in Ex mode, don't redraw anything.
     // - Otherwise, redraw right now, and position the cursor.
-    // Always need to call update_screen() or screenalloc(), to make
-    // sure Rows/Columns and the size of the screen is correct!
     if (State == MODE_ASKMORE || State == MODE_EXTERNCMD || State == MODE_CONFIRM
         || exmode_active) {
-      screenalloc();
       if (msg_grid.chars) {
         msg_grid_validate();
       }
@@ -378,7 +377,7 @@ int update_screen(void)
   // Don't do anything if the screen structures are (not yet) valid.
   // A VimResized autocmd can invoke redrawing in the middle of a resize,
   // which would bypass the checks in screen_resize for popupmenu etc.
-  if (!default_grid.chars || resizing) {
+  if (resizing_autocmd || !default_grid.chars) {
     return FAIL;
   }
 
@@ -387,34 +386,25 @@ int update_screen(void)
     diff_redraw(true);
   }
 
-  int type = 0;
-
-  if (must_redraw) {
-    if (type < must_redraw) {       // use maximal type
-      type = must_redraw;
-    }
-
-    // must_redraw is reset here, so that when we run into some weird
-    // reason to redraw while busy redrawing (e.g., asynchronous
-    // scrolling), or update_topline() in win_update() will cause a
-    // scroll, or a decoration provider requires a redraw, the screen
-    // will be redrawn later or in win_update().
-    must_redraw = 0;
-  }
-
   // Postpone the redrawing when it's not needed and when being called
   // recursively.
   if (!redrawing() || updating_screen) {
-    must_redraw = type;
-    if (type > UPD_INVERTED_ALL) {
-      curwin->w_lines_valid = 0;  // don't use w_lines[].wl_size now
-    }
     return FAIL;
   }
+
+  int type = must_redraw;
+
+  // must_redraw is reset here, so that when we run into some weird
+  // reason to redraw while busy redrawing (e.g., asynchronous
+  // scrolling), or update_topline() in win_update() will cause a
+  // scroll, or a decoration provider requires a redraw, the screen
+  // will be redrawn later or in win_update().
+  must_redraw = 0;
+
   updating_screen = 1;
 
-  display_tick++;           // let syntax code know we're in a next round of
-                            // display updating
+  display_tick++;  // let syntax code know we're in a next round of
+                   // display updating
 
   // Tricky: vim code can reset msg_scrolled behind our back, so need
   // separate bookkeeping for now.
@@ -525,7 +515,8 @@ int update_screen(void)
   }
 
   if (type == UPD_CLEAR) {          // first clear screen
-    screenclear();              // will reset clear_cmdline
+    screenclear();  // will reset clear_cmdline
+                    // and set UPD_NOT_VALID for each window
     cmdline_screen_cleared();   // clear external cmdline state
     type = UPD_NOT_VALID;
     // must_redraw may be set indirectly, avoid another redraw later
diff --git a/src/nvim/fileio.c b/src/nvim/fileio.c
index 76317298dc..b31b8336aa 100644
--- a/src/nvim/fileio.c
+++ b/src/nvim/fileio.c
@@ -1721,13 +1721,6 @@ failed:
       appended_lines_mark(from, linecnt);
     }
 
-    // If we were reading from the same terminal as where messages go,
-    // the screen will have been messed up.
-    // Switch on raw mode now and clear the screen.
-    if (read_stdin) {
-      screenclear();
-    }
-
     if (got_int) {
       if (!(flags & READ_DUMMY)) {
         filemess(curbuf, sfname, _(e_interr), 0);
diff --git a/src/nvim/main.c b/src/nvim/main.c
index 1119cee6ad..ddb3fbdd65 100644
--- a/src/nvim/main.c
+++ b/src/nvim/main.c
@@ -314,7 +314,7 @@ int main(int argc, char **argv)
   assert(p_ch >= 0 && Rows >= p_ch && Rows - p_ch <= INT_MAX);
   cmdline_row = (int)(Rows - p_ch);
   msg_row = cmdline_row;
-  screenalloc();  // allocate screen buffers
+  default_grid_alloc();  // allocate screen buffers
   set_init_2(headless_mode);
   TIME_MSG("inits 2");
 
@@ -346,13 +346,14 @@ int main(int argc, char **argv)
       ui_builtin_start();
     }
     TIME_MSG("done waiting for UI");
-
-    // prepare screen now, so external UIs can display messages
-    starting = NO_BUFFERS;
-    screenclear();
-    TIME_MSG("init screen for UI");
   }
 
+  // prepare screen now
+  starting = NO_BUFFERS;
+  screenclear();
+  win_new_screensize();
+  TIME_MSG("clear screen");
+
   if (ui_client_channel_id) {
     ui_client_init(ui_client_channel_id);
     ui_client_execute(ui_client_channel_id);
@@ -361,8 +362,8 @@ int main(int argc, char **argv)
 
   // Default mappings (incl. menus)
   Error err = ERROR_INIT;
-  Object o = nlua_exec(STATIC_CSTR_AS_STRING("return vim._init_default_mappings()"),
-                       (Array)ARRAY_DICT_INIT, &err);
+  Object o = NLUA_EXEC_STATIC("return vim._init_default_mappings()",
+                              (Array)ARRAY_DICT_INIT, &err);
   assert(!ERROR_SET(&err));
   api_clear_error(&err);
   assert(o.type == kObjectTypeNil);
@@ -432,10 +433,8 @@ int main(int argc, char **argv)
     p_ut = 1;
   }
 
-  //
   // Read in registers, history etc, from the ShaDa file.
   // This is where v:oldfiles gets filled.
-  //
   if (*p_shada != NUL) {
     shada_read_everything(NULL, false, true);
     TIME_MSG("reading ShaDa");
@@ -474,14 +473,7 @@ int main(int argc, char **argv)
 
   setmouse();  // may start using the mouse
 
-  if (exmode_active || use_remote_ui || use_builtin_ui) {
-    // Don't clear the screen when starting in Ex mode, or when a UI might have
-    // displayed messages.
-    redraw_later(curwin, UPD_VALID);
-  } else {
-    screenclear();  // clear screen
-    TIME_MSG("clearing screen");
-  }
+  redraw_later(curwin, UPD_VALID);
 
   no_wait_return = true;
 
diff --git a/src/nvim/message.c b/src/nvim/message.c
index 060d969f4b..d6835e04eb 100644
--- a/src/nvim/message.c
+++ b/src/nvim/message.c
@@ -1159,10 +1159,6 @@ void wait_return(int redraw)
     c = CAR;                    // no need for a return in ex mode
     got_int = false;
   } else {
-    // Make sure the hit-return prompt is on screen when 'guioptions' was
-    // just changed.
-    screenalloc();
-
     State = MODE_HITRETURN;
     setmouse();
     cmdline_row = msg_row;
diff --git a/src/nvim/version.c b/src/nvim/version.c
index 5888d4614e..d4d406482d 100644
--- a/src/nvim/version.c
+++ b/src/nvim/version.c
@@ -2324,6 +2324,7 @@ static void do_intro_line(long row, char *mesg, int attr)
 /// @param eap
 void ex_intro(exarg_T *eap)
 {
+  // TODO(bfredl): use msg_grid instead!
   screenclear();
   intro_message(true);
   wait_return(true);