From d78aebf22474950e713a7770e6d509ed4b5dac9e Mon Sep 17 00:00:00 2001
From: Gabor Kiss-Vamosi <kisvegabor@gmail.com>
Date: Mon, 6 Mar 2023 11:51:32 +0100
Subject: [PATCH] feat(sdl): add PARTIAL_MODE to emulate setups with display
 controller

---
 lv_conf_template.h          |  1 +
 src/dev/sdl/lv_sdl_window.c | 29 ++++++++++++++++++++++++++++-
 src/lv_conf_internal.h      |  7 +++++++
 3 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/lv_conf_template.h b/lv_conf_template.h
index 8bb3c601f..f758e9fa2 100644
--- a/lv_conf_template.h
+++ b/lv_conf_template.h
@@ -752,6 +752,7 @@
 #define LV_USE_SDL              0
 #if LV_USE_SDL
     #define LV_SDL_INCLUDE_PATH    <SDL2/SDL.h>
+    #define LV_SDL_PARTIAL_MODE    0    /*Recommended only to emulate a setup with a display controller*/
 #endif
 
 /*Driver for /dev/fb*/
diff --git a/src/dev/sdl/lv_sdl_window.c b/src/dev/sdl/lv_sdl_window.c
index 6d5efba3e..0490d4eee 100644
--- a/src/dev/sdl/lv_sdl_window.c
+++ b/src/dev/sdl/lv_sdl_window.c
@@ -17,6 +17,9 @@
  *      DEFINES
  *********************/
 
+/*Recommended only to emulate a setup with a display controller*/
+#define LV_SDL_PARTIAL_MODE    0
+
 /**********************
  *      TYPEDEFS
  **********************/
@@ -85,8 +88,14 @@ lv_disp_t * lv_sdl_window_create(lv_coord_t hor_res, lv_coord_t ver_res)
     window_create(disp);
 
     lv_disp_set_flush_cb(disp, flush_cb);
+#if LV_SDL_PARTIAL_MODE
+    uint8_t * buf = malloc(32 * 1024);
+    lv_disp_set_draw_buffers(disp, buf, NULL,
+                             32 * 1024, LV_DISP_RENDER_MODE_PARTIAL);
+#else
     lv_disp_set_draw_buffers(disp, dsc->fb, NULL,
                              lv_disp_get_hor_res(disp) * lv_disp_get_hor_res(disp) * sizeof(lv_color_t), LV_DISP_RENDER_MODE_DIRECT);
+#endif
     lv_disp_add_event(disp, res_chg_event_cb, LV_EVENT_RESOLUTION_CHANGED, NULL);
 
     return disp;
@@ -131,6 +140,22 @@ static void flush_cb(lv_disp_t * disp, const lv_area_t * area, lv_color_t * colo
     LV_UNUSED(area);
     LV_UNUSED(color_p);
 
+#if LV_SDL_PARTIAL_MODE
+    int32_t y;
+    uint32_t w = lv_area_get_width(area);
+    lv_sdl_window_t * dsc = lv_disp_get_driver_data(disp);
+    lv_coord_t hor_res = lv_disp_get_hor_res(disp);
+    lv_color_t * fb_tmp = dsc->fb;
+    fb_tmp += area->y1 * hor_res;
+    fb_tmp += area->x1;
+    for(y = area->y1; y <= area->y2; y++) {
+        lv_memcpy(fb_tmp, color_p, w * sizeof(lv_color_t));
+        color_p += w;
+        fb_tmp += hor_res;
+    }
+#endif
+
+
     /* TYPICALLY YOU DO NOT NEED THIS
      * If it was the last part to refresh update the texture of the window.*/
     if(lv_disp_flush_is_last(disp)) {
@@ -238,8 +263,10 @@ static void texture_resize(lv_disp_t * disp)
     lv_sdl_window_t * dsc = lv_disp_get_driver_data(disp);
 
     dsc->fb = (lv_color_t *)realloc(dsc->fb, sizeof(lv_color_t) * hor_res * ver_res);
-    lv_disp_set_draw_buffers(disp, dsc->fb, NULL, hor_res * ver_res * sizeof(lv_color_t), LV_DISP_RENDER_MODE_DIRECT);
 
+#if LV_SDL_PARTIAL_MODE == 0
+    lv_disp_set_draw_buffers(disp, dsc->fb, NULL, hor_res * ver_res * sizeof(lv_color_t), LV_DISP_RENDER_MODE_DIRECT);
+#endif
     if(dsc->texture) SDL_DestroyTexture(dsc->texture);
 
 #if LV_COLOR_DEPTH == 32
diff --git a/src/lv_conf_internal.h b/src/lv_conf_internal.h
index dca302594..f1badf63a 100644
--- a/src/lv_conf_internal.h
+++ b/src/lv_conf_internal.h
@@ -2504,6 +2504,13 @@
             #define LV_SDL_INCLUDE_PATH    <SDL2/SDL.h>
         #endif
     #endif
+    #ifndef LV_SDL_PARTIAL_MODE
+        #ifdef CONFIG_LV_SDL_PARTIAL_MODE
+            #define LV_SDL_PARTIAL_MODE CONFIG_LV_SDL_PARTIAL_MODE
+        #else
+            #define LV_SDL_PARTIAL_MODE    0    /*Recommended only to emulate a setup with a display controller*/
+        #endif
+    #endif
 #endif
 
 /*Driver for /dev/fb*/