Implement support for the MIT SHM extension (turned off by default).

This should be significantly faster, since we are not sending the entire
backing store over the wire for every paint event. It is turned off by
default for now because we don't synchronize paint events.

4 files changed, 118 insertions, 12 deletions

diff --git a/src/plugins/graphicssystems/testlite/qwindowsurface_testlite.cpp b/src/plugins/graphicssystems/testlite/qwindowsurface_testlite.cpp
index fde54a1..c0a0cc9 100644
--- a/src/plugins/graphicssystems/testlite/qwindowsurface_testlite.cpp
+++ b/src/plugins/graphicssystems/testlite/qwindowsurface_testlite.cpp
@@ -75,7 +75,7 @@ QTestLiteWindowSurface::~QTestLiteWindowSurface()
 
 QPaintDevice *QTestLiteWindowSurface::paintDevice()
 {
-    return &xw->img;
+    return xw->image();
 }
 
 void QTestLiteWindowSurface::flush(QWidget *widget, const QRegion &region, const QPoint &offset)
@@ -92,13 +92,12 @@ void QTestLiteWindowSurface::flush(QWidget *widget, const QRegion &region, const
 
 void QTestLiteWindowSurface::geometryChanged(const QRect &rect)
 {
+    bool resize = rect.size() != geometry().size();
     QWindowSurface::setGeometry(rect);
 
-    if (xw->img.size() != rect.size()) {
-        xw->img = QImage(rect.size(), mScreen->format());
+    if (resize) {
         window()->update(); //### this is the wrong place for this...
     }
-
 }
 
 
diff --git a/src/plugins/graphicssystems/testlite/testlite.pro b/src/plugins/graphicssystems/testlite/testlite.pro
index af8a437..d483f45 100644
--- a/src/plugins/graphicssystems/testlite/testlite.pro
+++ b/src/plugins/graphicssystems/testlite/testlite.pro
@@ -10,7 +10,7 @@ HEADERS = qgraphicssystem_testlite.h qwindowsurface_testlite.h
 HEADERS += x11util.h
 SOURCES += x11util.cpp
 
-LIBS += -lX11
+LIBS += -lX11 -lXext
 
 
 target.path += $$[QT_INSTALL_PLUGINS]/graphicssystems
diff --git a/src/plugins/graphicssystems/testlite/x11util.cpp b/src/plugins/graphicssystems/testlite/x11util.cpp
index cb08230..f3b6dc2 100644
--- a/src/plugins/graphicssystems/testlite/x11util.cpp
+++ b/src/plugins/graphicssystems/testlite/x11util.cpp
@@ -57,6 +57,11 @@
 
 #include <X11/cursorfont.h>
 
+# include <sys/ipc.h>
+# include <sys/shm.h>
+# include <X11/extensions/XShm.h>
+
+
 #include <QBitmap>
 #include <QCursor>
 #include <QDateTime>
@@ -68,6 +73,10 @@
 
 //#define MYX11_DEBUG
 
+//MIT SHM disabled by default, since we haven't implemented ShmCompletion synchronization yet
+
+#define DONT_USE_MIT_SHM
+
 static int (*original_x_errhandler)(Display *dpy, XErrorEvent *);
 static bool seen_badwindow;
 
@@ -307,12 +316,15 @@ MyDisplay::MyDisplay()
         exit(1);
     }
 
+#ifndef DONT_USE_MIT_SHM
+    Status MIT_SHM_extension_supported = XShmQueryExtension (display);
+    Q_ASSERT(MIT_SHM_extension_supported == True);
+#endif
     original_x_errhandler = XSetErrorHandler(qt_x_errhandler);
 
     if (qgetenv("DO_X_SYNCHRONIZE").toInt())
         XSynchronize(display, true);
 
-
     screen = DefaultScreen(display);
     width = DisplayWidth(display, screen);
     height = DisplayHeight(display, screen);
@@ -367,6 +379,16 @@ void MyDisplay::eventDispatcher()
     }
 }
 
+struct MyShmImageInfo {
+    MyShmImageInfo(Display *xdisplay) :  image(0), display(xdisplay) {}
+    ~MyShmImageInfo() { destroy(); }
+
+    void destroy();
+
+    XShmSegmentInfo shminfo;
+    XImage *image;
+    Display *display;
+};
 
 MyWindow::MyWindow(MyDisplay *display, int x, int y, int w, int h)
 {
@@ -407,6 +429,9 @@ MyWindow::MyWindow(MyDisplay *display, int x, int y, int w, int h)
     setWindowTitle(QLatin1String("Qt Lighthouse"));
 
     currentCursor = -1;
+
+    image_info = 0;
+
 }
 
 
@@ -432,6 +457,8 @@ MyWindow::~MyWindow()
     XDestroyWindow(xd->display, window);
 
     xd->windowList.removeAll(this);
+
+    delete image_info;
 }
 
 GC MyWindow::createGC()
@@ -453,9 +480,14 @@ void MyWindow::closeEvent()
 void MyWindow::paintEvent()
 {
     Visual *visual = DefaultVisual(xd->display, xd->screen);
-
-    if (!img.isNull()) {
-        QImage image = img.convertToFormat(QImage::Format_RGB32);
+#ifdef MYX11_DEBUG
+    qDebug() << "MyWindow::paintEvent" << shm_img.size();
+#endif
+#ifdef DONT_USE_MIT_SHM
+    // just convert the image every time...
+    if (!shm_img.isNull()) {
+        QImage image = shm_img;
+        //img.convertToFormat(
         XImage *xi = XCreateImage(xd->display, visual, 24, ZPixmap,
                                   0, (char *) image.scanLine(0), image.width(), image.height(),
                                   32, image.bytesPerLine());
@@ -468,6 +500,65 @@ void MyWindow::paintEvent()
         xi->data = 0; // QImage owns these bits
         XDestroyImage(xi);
     }
+#else
+    // Use MIT_SHM
+    if (image_info->image) {
+        //qDebug() << "Here we go" << image_info->image->width << image_info->image->height;
+        int x = 0;
+        int y = 0;
+        // We should really set send_event to true, and then use the XShmCompletionEvent
+        // to synchronize painting
+        XShmPutImage (xd->display, window, gc, image_info->image, 0, 0,
+                      x, y, image_info->image->width, image_info->image->height,
+                      /*send_event*/ false);
+
+        //### This makes output visible, probably not ideal from a performance point of view...
+        XFlush(xd->display);
+    }
+#endif
+}
+
+#ifndef DONT_USE_MIT_SHM
+void MyShmImageInfo::destroy()
+{
+    XShmDetach (display, &shminfo);
+    XDestroyImage (image);
+    shmdt (shminfo.shmaddr);
+    shmctl (shminfo.shmid, IPC_RMID, 0);
+}
+#endif
+
+void MyWindow::resizeShmImage(int width, int height)
+{
+#ifdef DONT_USE_MIT_SHM
+    shm_img = QImage(width, height, QImage::Format_RGB32);
+#else
+    if (image_info)
+        image_info->destroy();
+    else
+        image_info = new MyShmImageInfo(xd->display);
+
+    Visual *visual = DefaultVisual(xd->display, xd->screen);
+
+
+    XImage *image = XShmCreateImage (xd->display, visual, 24, ZPixmap, 0,
+                                     &image_info->shminfo, width, height);
+
+
+    image_info->shminfo.shmid = shmget (IPC_PRIVATE,
+          image->bytes_per_line * image->height, IPC_CREAT|0777);
+
+    image_info->shminfo.shmaddr = image->data = (char*)shmat (image_info->shminfo.shmid, 0, 0);
+    image_info->shminfo.readOnly = False;
+
+    image_info->image = image;
+
+    Status shm_attach_status = XShmAttach(xd->display, &image_info->shminfo);
+
+    Q_ASSERT(shm_attach_status == True);
+
+    shm_img = QImage( (uchar*) image->data, image->width, image->height, image->bytes_per_line, QImage::Format_RGB32 );
+#endif
 }
 
 void MyWindow::resizeEvent(XConfigureEvent *e)
@@ -484,8 +575,11 @@ void MyWindow::resizeEvent(XConfigureEvent *e)
     height = e->height;
 
 #ifdef MYX11_DEBUG
-    qDebug() << hex << window << dec << "ConfigureNotify" << e->x << e->y << e->width << e->height << "geometry" << xpos << ypos << width << height;
+    qDebug() << hex << window << dec << "ConfigureNotify" << e->x << e->y << e->width << e->height << "geometry" << xpos << ypos << width << height << "img:" << shm_img.size();
 #endif
+    if (shm_img.size() != QSize(width, height))
+        resizeShmImage(width, height);
+
     windowSurface->handleGeometryChange(xpos, ypos, width, height);
 }
 
@@ -499,9 +593,13 @@ void MyWindow::setSize(int w, int h)
 void MyWindow::setGeometry(int x, int y, int w, int h)
 {
 #ifdef MYX11_DEBUG
-    qDebug() << "MyWindow::setGeometry" << hex << window << dec << x << y << w << h;
+    qDebug() << "MyWindow::setGeometry" << hex << window << dec << x << y << w << h << "img:" << shm_img.size();
 #endif
     XMoveResizeWindow(xd->display, window, x, y, w, h);
+
+    if (shm_img.size() != QSize(w, h)) {
+        resizeShmImage(w, h);
+    }
 }
 
 
diff --git a/src/plugins/graphicssystems/testlite/x11util.h b/src/plugins/graphicssystems/testlite/x11util.h
index 2a73f3e..08fd0ce 100644
--- a/src/plugins/graphicssystems/testlite/x11util.h
+++ b/src/plugins/graphicssystems/testlite/x11util.h
@@ -86,6 +86,8 @@ public: //###
 
 class QTestLiteWindowSurface; //### abstract callback interface, anyone?
 
+struct MyShmImageInfo;
+
 class MyWindow : public QObject
 {
     Q_OBJECT;
@@ -120,11 +122,12 @@ public:
 
     void setWindowTitle(const QString &title);
 
+    QImage *image() { return &shm_img; }
+
 public: //###
 
     int xpos, ypos;
     int width, height;
-    QImage img;
     Window window;
     MyDisplay *xd;
     GC gc;
@@ -132,6 +135,12 @@ public: //###
     QTestLiteWindowSurface *windowSurface;
 
     int currentCursor;
+
+private:
+    void resizeShmImage(int width, int height);
+
+    QImage shm_img;
+    MyShmImageInfo *image_info;
 };
 
 class MyX11CursorNode