optimise HUD widget erasing, avoid flicker when screen size is reduced (#1349)

src/d_main.c

@@ -317,6 +317,7 @@ void D_Display (void)
       if (borderdrawcount)
         {
           R_DrawViewBorder ();    // erase old menu stuff
+          HU_Drawer ();
           borderdrawcount--;
         }
     }

src/hu_lib.c

@@ -22,6 +22,8 @@
 #include "m_swap.h"
 #include "hu_lib.h"
 #include "hu_stuff.h"
+#include "r_draw.h"
+#include "v_video.h"
 
 // [FG] horizontal alignment
 
@@ -121,12 +123,11 @@ boolean HUlib_add_key_to_line(hu_line_t *const l, unsigned char ch)
 {
   if (ch >= ' ' && ch <= '_')
     add_char_to_line(l, (char) ch);
-  else
-    if (ch == KEY_BACKSPACE)                  // phares
+  else if (ch == KEY_BACKSPACE)                  // phares
     del_char_from_line(l);
-  else
-    if (ch != KEY_ENTER)                      // phares
+  else if (ch != KEY_ENTER)                      // phares
     return false;                                // did not eat key
+
   return true;                                   // ate the key
 }
 
@@ -503,6 +504,28 @@ void HUlib_init_multiline(hu_multiline_t *m,
   m->built = false;
 }
 
+void HUlib_erase_widget (const hu_widget_t *const w)
+{
+  const hu_multiline_t *const m = w->multiline;
+  const hu_font_t *const f = *m->font;
+
+  const int height = m->numlines * f->line_height;
+  const int y = vert_align_widget(w, m, f, w->h_align, w->v_align);
+
+  if (y < scaledviewy || y >= scaledviewy + scaledviewheight)
+  {
+    // erase entire line
+    R_VideoErase(0, y, video.unscaledw, height);
+  }
+  else
+  {
+    // erase left border
+    R_VideoErase(0, y, scaledviewx, height);
+    // erase right border
+    R_VideoErase(scaledviewx + scaledviewwidth, y, scaledviewx, height);
+  }
+}
+
 //----------------------------------------------------------------------------
 //
 // $Log: hu_lib.c,v $

src/hu_lib.h

@@ -137,6 +137,8 @@ void HUlib_init_multiline (hu_multiline_t *const m, int nl, hu_font_t **f, char
 boolean HUlib_add_key_to_line (hu_line_t *const l, unsigned char ch);
 boolean HUlib_add_key_to_cur_line (hu_multiline_t *const m, unsigned char ch);
 
+void HUlib_erase_widget (const hu_widget_t *const w);
+
 #endif
 
 //----------------------------------------------------------------------------

src/hu_stuff.c

@@ -24,6 +24,7 @@
 #include "hu_stuff.h"
 #include "hu_obituary.h"
 #include "hu_lib.h"
+#include "r_state.h"
 #include "st_stuff.h" /* jff 2/16/98 need loc of status bar */
 #include "w_wad.h"
 #include "s_sound.h"
@@ -1423,15 +1424,6 @@ void HU_Drawer(void)
 
   HUlib_reset_align_offsets();
 
-  // jff 4/24/98 Erase current lines before drawing current
-  // needed when screen not fullsize
-  // killough 11/98: only do it when not fullsize
-  // moved here to properly update the w_sttime and w_monsec widgets
-  if (scaledviewheight < 200)
-  {
-    HU_Erase();
-  }
-
   w = doom_widget;
   while (w->multiline)
   {
@@ -1482,9 +1474,32 @@ void WI_DrawTimeWidget(void)
 
 void HU_Erase(void)
 {
-  // [FG] TODO optimize!
-  if (!automapactive && viewwindowx)
-    R_DrawViewBorder();
+  hu_widget_t *w;
+
+  if (automapactive || !scaledviewx)
+    return;
+
+  HUlib_reset_align_offsets();
+
+  w = doom_widget;
+  while (w->multiline)
+  {
+    if (*w->multiline->on)
+    {
+      HUlib_erase_widget(w);
+    }
+    w++;
+  }
+
+  w = boom_widget;
+  while (w->multiline)
+  {
+    if (w->multiline->built)
+    {
+      HUlib_erase_widget(w);
+    }
+    w++;
+  }
 }
 
 //

src/r_draw.c

@@ -913,8 +913,11 @@ void R_FillBackScreen (void)
 // Copy a screen buffer.
 //
 
-static void R_VideoErase(int x, int y, int w, int h)
+void R_VideoErase(int x, int y, int w, int h)
 {
+  if (background_buffer == NULL)
+    return;
+
   V_CopyRect(x, y, background_buffer, w, h, x, y);
 }
 

src/r_draw.h

@@ -82,6 +82,7 @@ void R_InitBuffer(void);
 void R_InitTranslationTables(void);
 
 // Rendering function.
+void R_VideoErase(int x, int y, int w, int h);
 void R_FillBackScreen(void);
 void R_DrawBorder(int x, int y, int w, int h);
 

src/r_main.c

@@ -558,8 +558,6 @@ void R_ExecuteSetViewSize (void)
         }
     }
 
-    //HU_disable_all_widgets();
-
     // [crispy] forcefully initialize the status bar backing screen
     ST_refreshBackground(true);