Track window focus to prevent scrolling in inactive window

Author: bvschaik

src/input/mouse.c

@@ -77,6 +77,7 @@ void mouse_set_left_down(int down)
     data.left.system_change |= down ? SYSTEM_DOWN : SYSTEM_UP;
     data.is_touch = 0;
     data.is_inside_window = 1;
+    data.window_has_focus = 1;
     if (!down) {
         time_millis now = time_get_millis();
         int is_double_click = (last_click < now) && ((now - last_click) <= DOUBLE_CLICK_TIME);
@@ -90,6 +91,7 @@ void mouse_set_right_down(int down)
     data.right.system_change |= down ? SYSTEM_DOWN : SYSTEM_UP;
     data.is_touch = 0;
     data.is_inside_window = 1;
+    data.window_has_focus = 1;
     last_click = 0;
 }
 
@@ -99,6 +101,11 @@ void mouse_set_inside_window(int inside)
     data.is_touch = 0;
 }
 
+void mouse_set_window_focus(int focus)
+{
+    data.window_has_focus = focus;
+}
+
 static void update_button_state(mouse_button *button)
 {
     button->went_down = (button->system_change & SYSTEM_DOWN) == SYSTEM_DOWN;
@@ -145,6 +152,7 @@ const mouse *mouse_in_dialog(const mouse *m)
     dialog.right = m->right;
     dialog.scrolled = m->scrolled;
     dialog.is_inside_window = m->is_inside_window;
+    dialog.window_has_focus = m->window_has_focus;
     dialog.is_touch = m->is_touch;
 
     dialog.x = m->x - screen_dialog_offset_x();

src/input/mouse.h

@@ -35,6 +35,7 @@ typedef struct {
     mouse_button left; /**< Left mouse button */
     mouse_button right; /**< Right mouse button */
     int is_inside_window; /**< Whether the mouse is in the window */
+    int window_has_focus; /**< Whether the window has focus */
     int is_touch; /**< Whether the mouse is a translated touch event */
 } mouse;
 
@@ -59,6 +60,8 @@ void mouse_set_scroll(scroll_state state);
 
 void mouse_set_inside_window(int inside);
 
+void mouse_set_window_focus(int focus);
+
 /**
  * Changes the mouse information from touch information
  * @param first The first touch

src/input/scroll.c

@@ -332,15 +332,16 @@ static int set_arrow_input(key *arrow, const key *opposite_arrow, float *modifie
 
 static int get_direction(const mouse *m)
 {
-    int is_inside_window = m->is_inside_window;
+    int is_inside_active_window = m->is_inside_window && m->window_has_focus;
     int width = screen_width();
     int height = screen_height();
-    if (setting_fullscreen() && m->x < width && m->y < height) {
+    if (setting_fullscreen() && m->window_has_focus) {
         // For Windows 10, in fullscreen mode, on HiDPI screens, this is needed
-        // to get scrolling to work
-        is_inside_window = 1;
+        // to get scrolling to work, because the mouse leaves the window on the
+        // rightmost and bottommost pixel, even though we have grabbed the mouse.
+        is_inside_active_window = 1;
     }
-    if (!is_inside_window && !m->is_touch) {
+    if (!is_inside_active_window && !m->is_touch) {
         return DIR_8_NONE;
     }
     int top = 0;

src/platform/julius.c

@@ -238,6 +238,12 @@ static void handle_window_event(SDL_WindowEvent *event, int *window_active)
         case SDL_WINDOWEVENT_LEAVE:
             mouse_set_inside_window(0);
             break;
+        case SDL_WINDOWEVENT_FOCUS_LOST:
+            mouse_set_window_focus(0);
+            break;
+        case SDL_WINDOWEVENT_FOCUS_GAINED:
+            mouse_set_window_focus(1);
+            break;
         case SDL_WINDOWEVENT_SIZE_CHANGED:
             SDL_Log("Window resized to %d x %d", (int) event->data1, (int) event->data2);
             platform_screen_resize(event->data1, event->data2);
@@ -641,6 +647,7 @@ int main(int argc, char **argv)
     setup(&args);
 
     mouse_set_inside_window(1);
+    mouse_set_window_focus(1);
     run_and_draw();
 
 #ifdef __EMSCRIPTEN__