[QNX]Fix transparencies

It is not guaranteed that buffers are cleared when they
are allocated. So don't use a buffer for the root window,
and clear buffers for the actual content.

Change-Id: I42939baec03fa05968c83bbf2739ab8d1d70c8be
Reviewed-by: Matt Hoosier <matt.hoosier@garmin.com>
Reviewed-by: Rafael Roquetto <rafael.roquetto@kdab.com>

1 files changed, 14 insertions, 2 deletions

diff --git a/src/plugins/platforms/qnx/qqnxwindow.cpp b/src/plugins/platforms/qnx/qqnxwindow.cpp
index 5aa1c970fd..fb8e8075ad 100644
--- a/src/plugins/platforms/qnx/qqnxwindow.cpp
+++ b/src/plugins/platforms/qnx/qqnxwindow.cpp
@@ -418,15 +418,27 @@ QQnxBuffer &QQnxWindow::renderBuffer()
         // Get all buffers available for rendering
         errno = 0;
         screen_buffer_t buffers[MAX_BUFFER_COUNT];
-        const int result = screen_get_window_property_pv(m_window, SCREEN_PROPERTY_RENDER_BUFFERS, (void **)buffers);
+        int result = screen_get_window_property_pv(m_window, SCREEN_PROPERTY_RENDER_BUFFERS, (void **)buffers);
         if (result != 0)
             qFatal("QQnxWindow: failed to query window buffers, errno=%d", errno);
 
-        // Wrap each buffer
+        // Wrap each buffer and clear
         for (int i = 0; i < MAX_BUFFER_COUNT; ++i) {
             m_buffers[i] = QQnxBuffer(buffers[i]);
+
+            // Clear Buffer
+            errno = 0;
+            int bg[] = { SCREEN_BLIT_COLOR, 0x00000000, SCREEN_BLIT_END };
+            result = screen_fill(m_screen->nativeContext(), buffers[i], bg);
+            if (result != 0)
+                qFatal("QQnxWindow: failed to clear window buffer, errno=%d", errno);
         }
 
+        errno = 0;
+        result = screen_flush_blits(m_screen->nativeContext(), 0);
+        if (result != 0)
+            qFatal("QQnxWindow: failed to flush blits, errno=%d", errno);
+
         // Use the first available render buffer
         m_currentBufferIndex = 0;
         m_previousBufferIndex = -1;