gui, tracker/{aruco,pt}, api: detect whether widget is visible on screen

Sadly, it's only implemented right now on win32.

Remove "set enabled" code for the video widget since it only works for
explicit window minimization, not covering by other windows.

1 files changed, 26 insertions, 0 deletions

diff --git a/opentrack/is-window-visible.hpp b/opentrack/is-window-visible.hpp
new file mode 100644
index 00000000..300e541a
--- /dev/null
+++ b/opentrack/is-window-visible.hpp
@@ -0,0 +1,26 @@
+#ifdef _WIN32
+
+#include <windows.h>
+#include <QWidget>
+#include <QRect>
+#include <QDebug>
+
+template<typename=void>
+bool is_window_visible(const QWidget* widget)
+{
+    const QWidget* window = widget->window();
+
+    if (!window)
+        return true;
+
+    const QPoint p = widget->mapToGlobal(widget->pos());
+    const QSize s = widget->size();
+    POINT pt = { p.x() + s.width()/2, p.y() + s.height()/2 };
+
+    return WindowFromPoint(pt) == (HWND) widget->winId();
+}
+
+#else
+template<typename=void>
+bool is_window_visible(const QWidget* widget) { return true; }
+#endif