From dc7562af529647404f6a1ee1ee12b54b4771a087 Mon Sep 17 00:00:00 2001
From: Rekketstone <rekketstone@proton.me>
Date: Thu, 16 Jan 2025 14:35:29 -0700
Subject: [PATCH] Another poor attempt to fix vim

At least I think I'm geting closer?
---
 cowterm.c | 46 ++++++++++++++++++++--------------------------
 1 file changed, 20 insertions(+), 26 deletions(-)

diff --git a/cowterm.c b/cowterm.c
index 2fdd3ab..4ff4b52 100644
--- a/cowterm.c
+++ b/cowterm.c
@@ -308,6 +308,9 @@ static void draw_char(Display *display, Drawable d, int x, int y) {
   unsigned long fg_color = color_buffer[y][x];
   unsigned long bg_color = bg_color_buffer[y][x];
   int attrs = attr_buffer[y][x];
+  static unsigned long last_bg_color = 0;
+  static int last_x = -1;
+  static int last_y = -1;
 
   if (attrs & ATTR_REVERSE) {
     unsigned long temp = fg_color;
@@ -315,19 +318,24 @@ static void draw_char(Display *display, Drawable d, int x, int y) {
     bg_color = temp;
   }
 
-  // Clear the character position first
-  XSetForeground(display, gc, bg_color);
-  XFillRectangle(display, d, gc, x * CHAR_WIDTH, y * CHAR_HEIGHT, CHAR_WIDTH,
-                 CHAR_HEIGHT);
+  if (last_x != x || last_y != y || last_bg_color != bg_color) {
+    XSetForeground(display, gc, bg_color);
+    XFillRectangle(display, d, gc, x * CHAR_WIDTH, y * CHAR_HEIGHT, CHAR_WIDTH,
+                   CHAR_HEIGHT);
+    last_x = x;
+    last_y = y;
+    last_bg_color = bg_color;
+  }
+
   XSetForeground(display, gc, fg_color);
 
   char str[2] = {terminal_buffer[y][x], '\0'};
 
   // Select appropriate font based on attributes
   XFontStruct *font = regular_font;
-  if (attr_buffer[y][x] & ATTR_BOLD) {
+  if (attrs & ATTR_BOLD) {
     font = bold_font;
-  } else if (attr_buffer[y][x] & ATTR_ITALIC) {
+  } else if (attrs & ATTR_ITALIC) {
     font = italic_font;
   }
   XSetFont(display, gc, font->fid);
@@ -368,10 +376,12 @@ static void draw_terminal(Display *display, Window window) {
         term_rows * CHAR_HEIGHT, DefaultDepth(display, DefaultScreen(display)));
   }
 
-  // Draw to buffer first
-  for (int y = 0; y < term_rows; y++) {
-    for (int x = 0; x < term_cols; x++) {
-      draw_char(display, buffer_pixmap, x, y);
+  // Only draw the changed parts of the terminal to the buffer
+  if (needs_refresh) {
+    for (int y = 0; y < term_rows; y++) {
+      for (int x = 0; x < term_cols; x++) {
+        draw_char(display, buffer_pixmap, x, y);
+      }
     }
   }
 
@@ -400,22 +410,6 @@ static void check_refresh(Display *display, Window window) {
   }
 }
 
-static void clear_terminal(Display *display, Window window) {
-  if (!terminal_buffer || !color_buffer || !attr_buffer || !bg_color_buffer)
-    return;
-  for (int y = 0; y < term_rows; y++) {
-    memset(terminal_buffer[y], ' ', term_cols);
-    for (int x = 0; x < term_cols; x++) {
-      color_buffer[y][x] = current_color;
-      attr_buffer[y][x] = current_attr;
-      bg_color_buffer[y][x] = current_bg_color;
-    }
-  }
-  cursor_x = 0;
-  cursor_y = 0;
-  needs_refresh = 1;
-}
-
 // Scroll the terminal up one line
 static void scroll_up(void) {
   // Move all lines up one position