xcb: Reduce number of created colormaps

Create a colormap per visual, not per window.

Pick-to: 5.15
Change-Id: I97d94618f159b4beaffd4a1afe0611233ced6676
Reviewed-by: Liang Qi <liang.qi@qt.io>
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

1 files changed, 4 insertions, 11 deletions

diff --git a/src/plugins/platforms/xcb/qxcbwindow.cpp b/src/plugins/platforms/xcb/qxcbwindow.cpp
index 0dba120e30..147bac01dd 100644
--- a/src/plugins/platforms/xcb/qxcbwindow.cpp
+++ b/src/plugins/platforms/xcb/qxcbwindow.cpp
@@ -363,14 +363,9 @@ void QXcbWindow::create()
         return result;
     };
 
+    xcb_colormap_t cmap = XCB_COLORMAP_NONE;
     if ((window()->supportsOpenGL() && haveOpenGL()) || m_format.hasAlpha()) {
-        m_cmap = xcb_generate_id(xcb_connection());
-        xcb_create_colormap(xcb_connection(),
-                            XCB_COLORMAP_ALLOC_NONE,
-                            m_cmap,
-                            xcb_parent_id,
-                            m_visualId);
-
+        cmap = platformScreen->colormapForVisual(m_visualId);
         mask |= XCB_CW_COLORMAP;
     }
 
@@ -381,7 +376,7 @@ void QXcbWindow::create()
         type == Qt::Popup || type == Qt::ToolTip || (window()->flags() & Qt::BypassWindowManagerHint),
         type == Qt::Popup || type == Qt::Tool || type == Qt::SplashScreen || type == Qt::ToolTip || type == Qt::Drawer,
         defaultEventMask,
-        m_cmap
+        cmap
     };
 
     m_window = xcb_generate_id(xcb_connection());
@@ -552,9 +547,7 @@ void QXcbWindow::destroy()
         xcb_destroy_window(xcb_connection(), m_window);
         m_window = 0;
     }
-    if (m_cmap) {
-        xcb_free_colormap(xcb_connection(), m_cmap);
-    }
+
     m_mapped = false;
 
     if (m_pendingSyncRequest)