From 0557ba32746dfa5728ea9cde0a6481b1f7de3cea Mon Sep 17 00:00:00 2001
From: Dominic <dominic@domsplace.com>
Date: Mon, 16 Aug 2021 02:00:41 -0400
Subject: [PATCH] Cleaned some GBM code, looks great.

---
 platform/gbm/gbm.c | 112 +++++++++++++++++++++++++--------------------
 1 file changed, 62 insertions(+), 50 deletions(-)

diff --git a/platform/gbm/gbm.c b/platform/gbm/gbm.c
index 7e8d8702..c8f72abe 100644
--- a/platform/gbm/gbm.c
+++ b/platform/gbm/gbm.c
@@ -101,6 +101,49 @@ static uint32_t find_crtc_for_connector(
 }
 
 
+static void drm_fb_destroy_callback(struct gbm_bo *bo, void *data) {
+  struct drm_fb *fb = data;
+  struct gbm_device *gbm = gbm_bo_get_device(bo);
+
+  if(fb->fb_id) drmModeRmFB(drm.fd, fb->fb_id);
+  free(fb);
+}
+
+static struct drm_fb * drm_fb_get_from_bo(struct gbm_bo *bo) {
+  struct drm_fb *fb = gbm_bo_get_user_data(bo);
+  uint32_t width, height, stride, handle;
+  int ret;
+
+  if(fb)
+    return fb;
+
+  fb = calloc(1, sizeof *fb);
+  fb->bo = bo;
+
+  width = gbm_bo_get_width(bo);
+  height = gbm_bo_get_height(bo);
+  stride = gbm_bo_get_stride(bo);
+  handle = gbm_bo_get_handle(bo).u32;
+
+  ret = drmModeAddFB(drm.fd, width, height, 24, 32, stride, handle, &fb->fb_id);
+  if(ret) {
+    printf("failed to create fb: %s\n", strerror(errno));
+    free(fb);
+    return NULL;
+  }
+
+  gbm_bo_set_user_data(bo, fb, drm_fb_destroy_callback);
+  return fb;
+}
+
+static void page_flip_handler(
+  int fd, unsigned int frame, unsigned int sec, unsigned int usec, void *data
+) {
+  int *waiting_for_flip = data;
+  *waiting_for_flip = 0;
+}
+
+
 static int32_t drmInit(void) {
   drmModeRes *resources;
   drmModeConnector *connector = NULL;
@@ -123,9 +166,7 @@ static int32_t drmInit(void) {
   // Find an existing connected connector.
   for (i = 0; i < resources->count_connectors; i++) {
     connector = drmModeGetConnector(drm.fd, resources->connectors[i]);
-    if(connector->connection == DRM_MODE_CONNECTED) {
-      break;
-    }
+    if(connector->connection == DRM_MODE_CONNECTED) break;
     drmModeFreeConnector(connector);
     connector = NULL;
   }
@@ -143,7 +184,7 @@ static int32_t drmInit(void) {
     if(current_mode->type & DRM_MODE_TYPE_PREFERRED) drm.mode = current_mode;
 
     int current_area = current_mode->hdisplay * current_mode->vdisplay;
-    if(current_area >= area) {
+    if(current_area > area) {
       drm.mode = current_mode;
       area = current_area;
     }
@@ -187,7 +228,7 @@ static int32_t gbmInit(void) {
 
   gbm.surface = gbm_surface_create(
     gbm.dev,
-    drm.mode->vdisplay, drm.mode->vdisplay,
+    drm.mode->hdisplay, drm.mode->vdisplay,
     GBM_FORMAT_XRGB8888,
     GBM_BO_USE_SCANOUT | GBM_BO_USE_RENDERING
   );
@@ -270,47 +311,20 @@ static int32_t glInit(void) {
   return 0;
 }
 
+void gbmUpdateResolution(game_t *game) {
+  // Get the surface dimensions
+  EGLint width;
+  EGLint height;
+  eglQuerySurface(gl.display, gl.surface, EGL_WIDTH,&width);
+  eglQuerySurface(gl.display, gl.surface, EGL_HEIGHT,&height);
 
-static void drm_fb_destroy_callback(struct gbm_bo *bo, void *data) {
-  struct drm_fb *fb = data;
-  struct gbm_device *gbm = gbm_bo_get_device(bo);
+  bool needsUpdating = (
+    (width != game->engine.render.width) || 
+    (height != game->engine.render.height
+  );
 
-  if(fb->fb_id) drmModeRmFB(drm.fd, fb->fb_id);
-  free(fb);
-}
-
-static struct drm_fb * drm_fb_get_from_bo(struct gbm_bo *bo) {
-  struct drm_fb *fb = gbm_bo_get_user_data(bo);
-  uint32_t width, height, stride, handle;
-  int ret;
-
-  if(fb)
-    return fb;
-
-  fb = calloc(1, sizeof *fb);
-  fb->bo = bo;
-
-  width = gbm_bo_get_width(bo);
-  height = gbm_bo_get_height(bo);
-  stride = gbm_bo_get_stride(bo);
-  handle = gbm_bo_get_handle(bo).u32;
-
-  ret = drmModeAddFB(drm.fd, width, height, 24, 32, stride, handle, &fb->fb_id);
-  if(ret) {
-    printf("failed to create fb: %s\n", strerror(errno));
-    free(fb);
-    return NULL;
-  }
-
-  gbm_bo_set_user_data(bo, fb, drm_fb_destroy_callback);
-  return fb;
-}
-
-static void page_flip_handler(
-  int fd, unsigned int frame, unsigned int sec, unsigned int usec, void *data
-) {
-  int *waiting_for_flip = data;
-  *waiting_for_flip = 0;
+  if(!needsUpdating) return;
+  renderSetResolution(&game->engine.render, (int32_t)width, (int32_t)height);
 }
 
 int32_t main(int argc, char *argv[]) {
@@ -322,7 +336,6 @@ int32_t main(int argc, char *argv[]) {
   struct gbm_bo *bo;
   struct drm_fb *fb;
   int32_t ret;
-  int32_t width, height;
 
   // Init the DRM
   ret = drmInit();
@@ -356,9 +369,6 @@ int32_t main(int argc, char *argv[]) {
   // Now uh?
   bo = gbm_surface_lock_front_buffer(gbm.surface);
   fb = drm_fb_get_from_bo(bo);
-  width = gbm_bo_get_width(bo);
-  height = gbm_bo_get_height(bo);
-  stride = gbm_bo_get_stride(bo);
 
   // ?
   ret = drmModeSetCrtc(
@@ -372,8 +382,9 @@ int32_t main(int argc, char *argv[]) {
   // Init Game
   game_t *game = malloc(sizeof(game_t));
   printf("Game is %zu bytes.\n", sizeof(game_t));
-  printf("Resolution is %i x %i x %i\n", width, height, stride);
-  renderSetResolution(&game->engine.render, (int32_t)width, (int32_t)height);
+  gbmUpdateResolution(game);
+
+  // Get the surface dimensions
   if(!gameInit(game)) {
     printf("Game Init Error\n");
     return 1;
@@ -385,6 +396,7 @@ int32_t main(int argc, char *argv[]) {
 
     // Draw
     float fDelta = 0.016f;
+    gbmUpdateResolution(game);
     if(!gameUpdate(game, fDelta)) break;
     // Drawn