WindowServer: Support windows with alpha channels. And per-WSWindow opacity.

This patch also adds a Format concept to GraphicsBitmap. For now there are
only two formats: RGB32 and RGBA32. Windows with alpha channel have their
backing stores created in the RGBA32 format.

Use this to make Terminal windows semi-transparent for that comfy rice look.
There is one problem here, in that window compositing overdraw incurs
multiple passes of blending of the same pixels. This leads to a mismatch in
opacity which is obviously not good. I will work on this in a later patch.

The alpha blending is currently straight C++. It should be relatively easy
to optimize this using SSE instructions.

For now I'm just happy with the cute effect. :^)

1 files changed, 1 insertions, 1 deletions

diff --git a/LibGUI/GButton.cpp b/LibGUI/GButton.cpp
index 8d117ea178..9062baf181 100644
--- a/LibGUI/GButton.cpp
+++ b/LibGUI/GButton.cpp
@@ -36,7 +36,7 @@ void GButton::paint_event(GPaintEvent&)
             icon_location.move_by(1, 1);
         }
         if (m_icon) {
-            painter.blit_with_alpha(icon_location, *m_icon, m_icon->rect());
+            painter.blit(icon_location, *m_icon, m_icon->rect());
             painter.draw_text(content_rect, caption(), TextAlignment::Center, Color::Black);
         } else {
             painter.draw_text(content_rect, caption(), TextAlignment::Center, Color::Black);