From f4e02a5c1bdd3e9fe212df31470f2a672af8bcda Mon Sep 17 00:00:00 2001
From: Manuel Alfayate Corchete <redwindwanderer@gmail.com>
Date: Mon, 31 Aug 2020 19:17:17 +0200
Subject: [PATCH] kmsdrm: Do NOT modify window size manually from the backend:
 doing so caused renderer scaling params miscalculation.

---
 src/video/kmsdrm/SDL_kmsdrmopengles.c |  8 +++---
 src/video/kmsdrm/SDL_kmsdrmvideo.c    | 38 ++++++++++++++++++---------
 src/video/kmsdrm/SDL_kmsdrmvideo.h    |  2 ++
 3 files changed, 32 insertions(+), 16 deletions(-)

diff --git a/src/video/kmsdrm/SDL_kmsdrmopengles.c b/src/video/kmsdrm/SDL_kmsdrmopengles.c
index 01d5a8b6c..59dadab94 100644
--- a/src/video/kmsdrm/SDL_kmsdrmopengles.c
+++ b/src/video/kmsdrm/SDL_kmsdrmopengles.c
@@ -143,8 +143,8 @@ KMSDRM_GLES_SwapWindow(_THIS, SDL_Window * window)
     info.crtc_id = dispdata->crtc->crtc->crtc_id;
     info.fb_id = fb->fb_id;
 
-    info.src_w = window->w;
-    info.src_h = window->h;
+    info.src_w = windata->src_w;
+    info.src_h = windata->src_h;
     info.crtc_w = windata->output_w;
     info.crtc_h = windata->output_h;
     info.crtc_x = windata->output_x;
@@ -240,8 +240,8 @@ KMSDRM_GLES_SwapWindowDB(_THIS, SDL_Window * window)
     info.crtc_id = dispdata->crtc->crtc->crtc_id;
     info.fb_id = fb->fb_id;
 
-    info.src_w = window->w;
-    info.src_h = window->h;
+    info.src_w = windata->src_w;
+    info.src_h = windata->src_h;
     info.crtc_w = windata->output_w;
     info.crtc_h = windata->output_h;
     info.crtc_x = windata->output_x;
diff --git a/src/video/kmsdrm/SDL_kmsdrmvideo.c b/src/video/kmsdrm/SDL_kmsdrmvideo.c
index db2808051..e933095d4 100644
--- a/src/video/kmsdrm/SDL_kmsdrmvideo.c
+++ b/src/video/kmsdrm/SDL_kmsdrmvideo.c
@@ -652,7 +652,7 @@ KMSDRM_CreateDevice(int devindex)
         device->GL_SwapWindow = KMSDRM_GLES_SwapWindowDB;
     else
         device->GL_SwapWindow = KMSDRM_GLES_SwapWindow;
-
+    
     device->GL_DeleteContext = KMSDRM_GLES_DeleteContext;
 #endif
     device->PumpEvents = KMSDRM_PumpEvents;
@@ -815,15 +815,26 @@ KMSDRM_CreateSurfaces(_THIS, SDL_Window * window)
 {
     SDL_VideoData *viddata = ((SDL_VideoData *)_this->driverdata);
     SDL_WindowData *windata = (SDL_WindowData *)window->driverdata;
-    Uint32 width = window->w;
-    Uint32 height = window->h;
-    Uint32 surface_fmt = GBM_FORMAT_ARGB8888;
-    Uint32 surface_flags = GBM_BO_USE_SCANOUT | GBM_BO_USE_RENDERING;
+    SDL_DisplayData *dispdata = (SDL_DisplayData *) SDL_GetDisplayForWindow(window)->driverdata;
+    uint32_t surface_fmt = GBM_FORMAT_ARGB8888;
+    uint32_t surface_flags = GBM_BO_USE_SCANOUT | GBM_BO_USE_RENDERING;
+    uint32_t width, height;
+
 #if SDL_VIDEO_OPENGL_EGL
     EGLContext egl_context;
     SDL_EGL_SetRequiredVisualId(_this, surface_fmt);
     egl_context = (EGLContext)SDL_GL_GetCurrentContext();
 #endif
+
+    if (window->flags & SDL_WINDOW_FULLSCREEN) {
+        width = dispdata->mode.hdisplay;
+        height = dispdata->mode.vdisplay;
+    }
+    else {
+        width = window->w;
+        height = window->h;
+    }
+
     if (!KMSDRM_gbm_device_is_format_supported(viddata->gbm_dev, surface_fmt, surface_flags)) {
         SDL_LogWarn(SDL_LOG_CATEGORY_VIDEO, "GBM surface format not supported. Trying anyway.");
     }
@@ -861,16 +872,17 @@ KMSDRM_ReconfigureWindow( _THIS, SDL_Window * window) {
 
     KMSDRM_SetPendingSurfacesDestruction(_this, window);
 
-    if (window->flags & SDL_WINDOW_FULLSCREEN ) {
-        /* Windows only have one possible size in fullscreen mode. */
-        window->w = dispdata->mode.hdisplay;
-        window->h = dispdata->mode.vdisplay;
+    if (window->flags & SDL_WINDOW_FULLSCREEN) {
+        windata->src_w = dispdata->mode.hdisplay;
+        windata->src_h = dispdata->mode.vdisplay;
         windata->output_w = dispdata->mode.hdisplay;
         windata->output_h = dispdata->mode.vdisplay;
         windata->output_x = 0;
     } else {
         /* Get output (CRTC) size and position, for AR correction. */
         ratio = (float)window->w / (float)window->h;
+        windata->src_w = window->w;
+        windata->src_h = window->h;
         windata->output_w = dispdata->mode.vdisplay * ratio;
         windata->output_h = dispdata->mode.vdisplay;
         windata->output_x = (dispdata->mode.hdisplay - windata->output_w) / 2;
@@ -1339,15 +1351,16 @@ KMSDRM_CreateWindow(_THIS, SDL_Window * window)
     dispdata = display->driverdata;
 
     if (window->flags & SDL_WINDOW_FULLSCREEN) {
-        /* Windows only have one possible size in fullscreen mode. */
-        window->w = dispdata->mode.hdisplay;
-        window->h = dispdata->mode.vdisplay;
+        windata->src_w = dispdata->mode.hdisplay;
+        windata->src_h = dispdata->mode.vdisplay;
         windata->output_w = dispdata->mode.hdisplay;
         windata->output_h = dispdata->mode.vdisplay;
         windata->output_x = 0;
     } else {
         /* Get output (CRTC) size and position, for AR correction. */
         ratio = (float)window->w / (float)window->h;
+        windata->src_w = window->w;
+        windata->src_h = window->h;
         windata->output_w = dispdata->mode.vdisplay * ratio;
         windata->output_h = dispdata->mode.vdisplay;
         windata->output_x = (dispdata->mode.hdisplay - windata->output_w) / 2;
@@ -1455,6 +1468,7 @@ KMSDRM_SetWindowFullscreen(_THIS, SDL_Window * window, SDL_VideoDisplay * displa
 {
     KMSDRM_ReconfigureWindow(_this, window);  
 }
+
 void
 KMSDRM_ShowWindow(_THIS, SDL_Window * window)
 {
diff --git a/src/video/kmsdrm/SDL_kmsdrmvideo.h b/src/video/kmsdrm/SDL_kmsdrmvideo.h
index 72acb1099..fb707f2b3 100644
--- a/src/video/kmsdrm/SDL_kmsdrmvideo.h
+++ b/src/video/kmsdrm/SDL_kmsdrmvideo.h
@@ -127,6 +127,8 @@ typedef struct SDL_WindowData
 #endif
 
     /* For scaling and AR correction. */
+    int32_t src_w;
+    int32_t src_h;
     int32_t output_w;
     int32_t output_h;
     int32_t output_x;