From 35b642d43444c435094b9c7238c9c94b325d6ca0 Mon Sep 17 00:00:00 2001
From: rxi <rxi@users.noreply.github.com>
Date: Fri, 22 May 2020 09:00:48 +0100
Subject: [PATCH] Added rencache invalidation on window-exposed event

Fixes #63
---
 src/api/system.c | 5 ++++-
 src/rencache.c   | 7 ++++++-
 src/rencache.h   | 1 +
 3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/src/api/system.c b/src/api/system.c
index 0215a564..35843a00 100644
--- a/src/api/system.c
+++ b/src/api/system.c
@@ -6,6 +6,7 @@
 #include <errno.h>
 #include <sys/stat.h>
 #include "api.h"
+#include "rencache.h"
 #ifdef _WIN32
   #include <windows.h>
 #endif
@@ -56,7 +57,9 @@ top:
         lua_pushnumber(L, e.window.data2);
         return 3;
       } else if (e.window.event == SDL_WINDOWEVENT_EXPOSED) {
-        SDL_UpdateWindowSurface(window);
+        rencache_invalidate();
+        lua_pushstring(L, "exposed");
+        return 1;
       }
       /* on some systems, when alt-tabbing to the window SDL will queue up
       ** several KEYDOWN events for the `tab` key; we flush all keydown
diff --git a/src/rencache.c b/src/rencache.c
index 5ab1ff2d..b0b06cf9 100644
--- a/src/rencache.c
+++ b/src/rencache.c
@@ -150,6 +150,11 @@ int rencache_draw_text(RenFont *font, const char *text, int x, int y, RenColor c
 }
 
 
+void rencache_invalidate(void) {
+  memset(cells_prev, 0xff, sizeof(cells_buf1));
+}
+
+
 void rencache_begin_frame(void) {
   /* reset all cells if the screen width/height has changed */
   int w, h;
@@ -157,7 +162,7 @@ void rencache_begin_frame(void) {
   if (screen_rect.width != w || h != screen_rect.height) {
     screen_rect.width = w;
     screen_rect.height = h;
-    memset(cells_prev, 0xff, sizeof(cells_buf1));
+    rencache_invalidate();
   }
 }
 
diff --git a/src/rencache.h b/src/rencache.h
index 4407e8d5..c5fa80f4 100644
--- a/src/rencache.h
+++ b/src/rencache.h
@@ -9,6 +9,7 @@ void rencache_free_font(RenFont *font);
 void rencache_set_clip_rect(RenRect rect);
 void rencache_draw_rect(RenRect rect, RenColor color);
 int  rencache_draw_text(RenFont *font, const char *text, int x, int y, RenColor color);
+void rencache_invalidate(void);
 void rencache_begin_frame(void);
 void rencache_end_frame(void);