WindowServer+LibGUI: Allow specifying a "launch origin" for new windows

The launch_origin_rect parameter to create_window() specifies where on
screen the window was launched from. It's optional, but if you provide
it, the new window will have a short wireframe animation from the origin
to the initial window frame rect.

GUI::Window looks for the "__libgui_launch_origin_rect" environment
variable. Put your launch origin rect in there with the format
"<x>,<y>,<width>,<height>" and the first GUI::Window shown by the app
will use that as the launch origin rect.

Also it looks pretty neat, although I'm sure we can improve it. :^)

1 files changed, 20 insertions, 0 deletions

diff --git a/Userland/Services/WindowServer/Window.cpp b/Userland/Services/WindowServer/Window.cpp
index 98a33c34e9..3253f0dba8 100644
--- a/Userland/Services/WindowServer/Window.cpp
+++ b/Userland/Services/WindowServer/Window.cpp
@@ -365,6 +365,26 @@ void Window::start_minimize_animation()
     m_animation->start();
 }
 
+void Window::start_launch_animation(Gfx::IntRect const& launch_origin_rect)
+{
+    m_animation = Animation::create();
+    m_animation->set_length(150);
+    m_animation->on_update = [this, launch_origin_rect](float progress, Gfx::Painter& painter, Screen& screen, Gfx::DisjointRectSet& flush_rects) {
+        Gfx::PainterStateSaver saver(painter);
+        painter.set_draw_op(Gfx::Painter::DrawOp::Invert);
+
+        auto rect = interpolate_rect(launch_origin_rect, frame().rect(), progress);
+
+        painter.draw_rect(rect, Color::Transparent); // Color doesn't matter, we draw inverted
+        flush_rects.add(rect.intersected(screen.rect()));
+        Compositor::the().invalidate_screen(rect);
+    };
+    m_animation->on_stop = [this] {
+        m_animation = nullptr;
+    };
+    m_animation->start();
+}
+
 void Window::set_opacity(float opacity)
 {
     if (m_opacity == opacity)