4 files changed, 40 insertions, 27 deletions

diff --git a/src/drivers/Cairo/Fl_Cairo_Graphics_Driver.H b/src/drivers/Cairo/Fl_Cairo_Graphics_Driver.H
index c2a7d4c54..6a782c3c5 100644
--- a/src/drivers/Cairo/Fl_Cairo_Graphics_Driver.H
+++ b/src/drivers/Cairo/Fl_Cairo_Graphics_Driver.H
@@ -28,12 +28,10 @@ typedef struct _PangoLayout  PangoLayout;
 typedef struct _PangoContext PangoContext;
 typedef struct _PangoFontDescription PangoFontDescription;
 
-#if USE_PANGO
-  struct flCairoRegion {
-    int count;
-    struct _cairo_rectangle *rects;
-  }; // a region is the union of a series of rectangles
-#endif
+struct flCairoRegion {
+  int count;
+  struct _cairo_rectangle *rects;
+}; // a region is the union of a series of rectangles
 
 class Fl_Cairo_Font_Descriptor : public Fl_Font_Descriptor {
 public:
diff --git a/src/drivers/Wayland/Fl_Wayland_Graphics_Driver.H b/src/drivers/Wayland/Fl_Wayland_Graphics_Driver.H
index d736df9de..5e3b13f8b 100644
--- a/src/drivers/Wayland/Fl_Wayland_Graphics_Driver.H
+++ b/src/drivers/Wayland/Fl_Wayland_Graphics_Driver.H
@@ -78,7 +78,7 @@ public:
   void copy_offscreen(int x, int y, int w, int h, Fl_Offscreen osrc, int srcx, int srcy) FL_OVERRIDE;
   static struct fl_wld_buffer *create_shm_buffer(int width, int height);
   static void buffer_release(struct wld_window *window);
-  static void buffer_commit(struct wld_window *window, bool need_damage = true);
+  static void buffer_commit(struct wld_window *window, struct flCairoRegion *r = NULL);
   static void cairo_init(struct fl_wld_buffer *buffer, int width, int height, int stride, cairo_format_t format);
   void *gc() FL_OVERRIDE;
   void gc(void *gc) FL_OVERRIDE;
diff --git a/src/drivers/Wayland/Fl_Wayland_Graphics_Driver.cxx b/src/drivers/Wayland/Fl_Wayland_Graphics_Driver.cxx
index 608a8c004..a7b3610d8 100644
--- a/src/drivers/Wayland/Fl_Wayland_Graphics_Driver.cxx
+++ b/src/drivers/Wayland/Fl_Wayland_Graphics_Driver.cxx
@@ -92,15 +92,44 @@ static void surface_frame_done(void *data, struct wl_callback *cb, uint32_t time
 }
 
 
-void Fl_Wayland_Graphics_Driver::buffer_commit(struct wld_window *window, bool need_damage) {
+// copy pixels in region r from the Cairo surface to the Wayland buffer
+static void copy_region(struct wld_window *window, struct flCairoRegion *r) {
+  struct fl_wld_buffer *buffer = window->buffer;
+  float f = Fl::screen_scale(window->fl_win->screen_num()) *
+    Fl_Wayland_Window_Driver::driver(window->fl_win)->wld_scale();
+  for (int i = 0; i < r->count; i++) {
+    int left = r->rects[i].x * f;
+    int top = r->rects[i].y * f;
+    int width = r->rects[i].width * f;
+    int height = r->rects[i].height * f;
+    int offset = top * buffer->stride + 4 * left;
+    int W4 = 4 * width;
+    for (int l = 0; l < height; l++) {
+      if (offset + W4 >= buffer->data_size) {
+        W4 = buffer->data_size - offset;
+        if (W4 <= 0) break;
+      }
+      memcpy((uchar*)buffer->data + offset, buffer->draw_buffer + offset, W4);
+      offset += buffer->stride;
+    }
+    wl_surface_damage_buffer(window->wl_surface, left, top, width, height);
+  }
+}
+
+
+void Fl_Wayland_Graphics_Driver::buffer_commit(struct wld_window *window,
+                                struct flCairoRegion *r) {
   cairo_surface_t *surf = cairo_get_target(window->buffer->cairo_);
   cairo_surface_flush(surf);
-  memcpy(window->buffer->data, window->buffer->draw_buffer, window->buffer->data_size);
+  if (r) copy_region(window, r);
+  else {
+    memcpy(window->buffer->data, window->buffer->draw_buffer, window->buffer->data_size);
+    wl_surface_damage_buffer(window->wl_surface, 0, 0, 1000000, 1000000);
+  }
   wl_surface_attach(window->wl_surface, window->buffer->wl_buffer, 0, 0);
   wl_surface_set_buffer_scale(window->wl_surface,
                               Fl_Wayland_Window_Driver::driver(window->fl_win)->wld_scale());
   window->buffer->cb = wl_surface_frame(window->wl_surface);
-  if (need_damage) wl_surface_damage_buffer(window->wl_surface, 0, 0, 1000000, 1000000);
   wl_callback_add_listener(window->buffer->cb, &surface_frame_listener, window);
   wl_surface_commit(window->wl_surface);
   window->buffer->draw_buffer_needs_commit = false;
diff --git a/src/drivers/Wayland/Fl_Wayland_Window_Driver.cxx b/src/drivers/Wayland/Fl_Wayland_Window_Driver.cxx
index d7031ace0..eee7892bf 100644
--- a/src/drivers/Wayland/Fl_Wayland_Window_Driver.cxx
+++ b/src/drivers/Wayland/Fl_Wayland_Window_Driver.cxx
@@ -395,27 +395,13 @@ void Fl_Wayland_Window_Driver::flush() {
 
   Fl_X *ip = Fl_X::flx(pWindow);
   struct flCairoRegion* r = (struct flCairoRegion*)ip->region;
-  float f = Fl::screen_scale(pWindow->screen_num()) * wld_scale();
-  if (r && window->buffer) {
-    for (int i = 0; i < r->count; i++) {
-      int left = r->rects[i].x * f;
-      int top = r->rects[i].y * f;
-      int width = r->rects[i].width * f;
-      int height = r->rects[i].height * f;
-      wl_surface_damage_buffer(window->wl_surface, left, top, width, height);
-//fprintf(stderr, "damage %dx%d %dx%d\n", left, top, width, height);
-    }
-  } else {
-    wl_surface_damage_buffer(window->wl_surface, 0, 0,
-    pWindow->w() * f, pWindow->h() * f);
-//fprintf(stderr, "damage 0x0 %dx%d\n", pWindow->w() * f, pWindow->h() * f);
-  }
+  if (!window->buffer) r = NULL;
 
   Fl_Wayland_Window_Driver::in_flush = true;
   Fl_Window_Driver::flush();
   Fl_Wayland_Window_Driver::in_flush = false;
   if (window->buffer->cb) wl_callback_destroy(window->buffer->cb);
-  Fl_Wayland_Graphics_Driver::buffer_commit(window, false);
+  Fl_Wayland_Graphics_Driver::buffer_commit(window, r);
 }
 
 
@@ -667,7 +653,7 @@ static void surface_enter(void *data, struct wl_surface *wl_surface, struct wl_o
       window->fl_win->size(window->fl_win->w(), window->fl_win->h());
       win_driver->is_a_rescale(false);
     } else if (window->buffer) {
-      Fl_Wayland_Graphics_Driver::buffer_commit(window, true);
+      Fl_Wayland_Graphics_Driver::buffer_commit(window);
     }
     if (window->fl_win->as_gl_window())
       wl_surface_set_buffer_scale(window->wl_surface, output->wld_scale);