Fix: Wayland backend draws everything two or three times (#708)

1 files changed, 15 insertions, 6 deletions

diff --git a/src/drivers/Wayland/Fl_Wayland_Window_Driver.cxx b/src/drivers/Wayland/Fl_Wayland_Window_Driver.cxx
index a6c31ced2..9dad205cb 100644
--- a/src/drivers/Wayland/Fl_Wayland_Window_Driver.cxx
+++ b/src/drivers/Wayland/Fl_Wayland_Window_Driver.cxx
@@ -641,8 +641,9 @@ static void surface_enter(void *data, struct wl_surface *wl_surface, struct wl_o
     return;
 
 //printf("surface_enter win=%p wl_output=%p wld_scale=%d\n", window->fl_win, wl_output, output->wld_scale);
-  window->output = output;
   Fl_Wayland_Window_Driver *win_driver = Fl_Wayland_Window_Driver::driver(window->fl_win);
+  float pre_scale = Fl::screen_scale(win_driver->screen_num()) * win_driver->wld_scale();
+  window->output = output;
   if (!window->fl_win->parent()) { // for top-level, set its screen number
     Fl_Wayland_Screen_Driver::output *running_output;
     Fl_Wayland_Screen_Driver *scr_dr = (Fl_Wayland_Screen_Driver*)Fl::screen_driver();
@@ -660,9 +661,13 @@ static void surface_enter(void *data, struct wl_surface *wl_surface, struct wl_o
     Fl_Wayland_Graphics_Driver::buffer_release(window);
     window->fl_win->redraw();
   } else {
-    win_driver->is_a_rescale(true);
-    window->fl_win->size(window->fl_win->w(), window->fl_win->h());
-    win_driver->is_a_rescale(false);
+    float post_scale = Fl::screen_scale(win_driver->screen_num()) * output->wld_scale;
+    //printf("pre_scale=%.1f post_scale=%.1f\n", pre_scale, post_scale);
+    if (window->fl_win->as_gl_window() || post_scale != pre_scale) {
+      win_driver->is_a_rescale(true);
+      window->fl_win->size(window->fl_win->w(), window->fl_win->h());
+      win_driver->is_a_rescale(false);
+    }
     if (window->fl_win->as_gl_window())
       wl_surface_set_buffer_scale(window->wl_surface, output->wld_scale);
   }
@@ -690,6 +695,8 @@ static void handle_configure(struct libdecor_frame *frame,
   enum libdecor_window_state window_state;
   struct libdecor_state *state;
   Fl_Wayland_Window_Driver *driver = Fl_Wayland_Window_Driver::driver(window->fl_win);
+  // true exactly for the 1st run of handle_configure() for this window
+  bool is_1st_run = (window->xdg_surface == 0);
   // true exactly for the 2nd run of handle_configure() for this window
   bool is_2nd_run = (window->xdg_surface != 0 && driver->wait_for_expose_value);
   float f = Fl::screen_scale(window->fl_win->screen_num());
@@ -766,7 +773,6 @@ static void handle_configure(struct libdecor_frame *frame,
    }
   libdecor_state_free(state);
 
-  window->fl_win->redraw();
   // necessary with SSD
   driver->in_handle_configure = true;
   if (!window->fl_win->as_gl_window()) {
@@ -775,6 +781,9 @@ static void handle_configure(struct libdecor_frame *frame,
     driver->Fl_Window_Driver::flush(); // GL window
   }
   driver->in_handle_configure = false;
+  if (Fl_Wayland_Screen_Driver::compositor != Fl_Wayland_Screen_Driver::WESTON || !is_1st_run) {
+    window->fl_win->clear_damage();
+  }
 }
 
 
@@ -841,8 +850,8 @@ static void xdg_surface_configure(void *data, struct xdg_surface *xdg_surface, u
   }
   window->configured_width = window->fl_win->w();
   window->configured_height = window->fl_win->h();
-  window->fl_win->redraw();
   Fl_Window_Driver::driver(window->fl_win)->flush();
+  window->fl_win->clear_damage();
 }
 
 static const struct xdg_surface_listener xdg_surface_listener = {