xcb: Add experimental legacy support for native X11 painting

This commit revives the old native QPixmap and QPaintEngine
implementations that were present in Qt4. The backing store supports
regular raster windows in this commit. Support for render-to-texture
widgets and OpenGL compositing will be added in a follow-up commit.

Change-Id: I80a9c4f0c42a6f68f571dfee930d95000d5dd950
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

1 files changed, 315 insertions, 0 deletions

diff --git a/src/plugins/platforms/xcb/nativepainting/qxcbnativepainting.cpp b/src/plugins/platforms/xcb/nativepainting/qxcbnativepainting.cpp
new file mode 100644
index 0000000000..23500eb4ab
--- /dev/null
+++ b/src/plugins/platforms/xcb/nativepainting/qxcbnativepainting.cpp
@@ -0,0 +1,315 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the plugins of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL21$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see http://www.qt.io/terms-conditions. For further
+** information use the contact form at http://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 or version 3 as published by the Free
+** Software Foundation and appearing in the file LICENSE.LGPLv21 and
+** LICENSE.LGPLv3 included in the packaging of this file. Please review the
+** following information to ensure the GNU Lesser General Public License
+** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** As a special exception, The Qt Company gives you certain additional
+** rights. These rights are described in The Qt Company LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qxcbconnection.h"
+#include "qcolormap_x11_p.h"
+#include "qxcbnativepainting.h"
+#include "qt_x11_p.h"
+
+QT_BEGIN_NAMESPACE
+
+QXcbX11Data *qt_x11Data = Q_NULLPTR;
+
+void qt_xcb_native_x11_info_init(QXcbConnection *conn)
+{
+    qt_x11Data = new QXcbX11Data;
+    X11->display = (Display *) conn->xlib_display();
+    X11->defaultScreen = DefaultScreen(X11->display);
+    X11->screenCount = ScreenCount(X11->display);
+
+    X11->screens = new QX11InfoData[X11->screenCount];
+    X11->argbVisuals = new Visual *[X11->screenCount];
+    X11->argbColormaps = new Colormap[X11->screenCount];
+
+    for (int s = 0; s < X11->screenCount; s++) {
+        QX11InfoData *screen = X11->screens + s;
+        //screen->ref = 1; // ensures it doesn't get deleted
+        screen->screen = s;
+
+        int widthMM = DisplayWidthMM(X11->display, s);
+        if (widthMM != 0) {
+            screen->dpiX = (DisplayWidth(X11->display, s) * 254 + widthMM * 5) / (widthMM * 10);
+        } else {
+            screen->dpiX = 72;
+        }
+
+        int heightMM = DisplayHeightMM(X11->display, s);
+        if (heightMM != 0) {
+            screen->dpiY = (DisplayHeight(X11->display, s) * 254 + heightMM * 5) / (heightMM * 10);
+        } else {
+            screen->dpiY = 72;
+        }
+
+        X11->argbVisuals[s] = 0;
+        X11->argbColormaps[s] = 0;
+    }
+
+    X11->use_xrender = conn->hasXRender() && !qEnvironmentVariableIsSet("QT_XCB_NATIVE_PAINTING_NO_XRENDER");
+
+#if QT_CONFIG(xrender)
+    memset(X11->solid_fills, 0, sizeof(X11->solid_fills));
+    for (int i = 0; i < X11->solid_fill_count; ++i)
+        X11->solid_fills[i].screen = -1;
+    memset(X11->pattern_fills, 0, sizeof(X11->pattern_fills));
+    for (int i = 0; i < X11->pattern_fill_count; ++i)
+        X11->pattern_fills[i].screen = -1;
+#endif
+
+    QXcbColormap::initialize();
+
+#if QT_CONFIG(xrender)
+    if (X11->use_xrender) {
+        // XRender is supported, let's see if we have a PictFormat for the
+        // default visual
+        XRenderPictFormat *format =
+            XRenderFindVisualFormat(X11->display,
+                                    (Visual *) QXcbX11Info::appVisual(X11->defaultScreen));
+
+        if (!format) {
+            X11->use_xrender = false;
+        }
+    }
+#endif // QT_CONFIG(xrender)
+}
+
+QVector<XRectangle> qt_region_to_xrectangles(const QRegion &r)
+{
+    const int numRects = r.rectCount();
+    const QVector<QRect> input = r.rects();
+    QVector<XRectangle> output(numRects);
+    for (int i = 0; i < numRects; ++i) {
+        const QRect &in = input[i];
+        XRectangle &out = output[i];
+        out.x = qMax(SHRT_MIN, in.x());
+        out.y = qMax(SHRT_MIN, in.y());
+        out.width = qMin((int)USHRT_MAX, in.width());
+        out.height = qMin((int)USHRT_MAX, in.height());
+    }
+    return output;
+}
+
+class QXcbX11InfoData : public QSharedData, public QX11InfoData
+{};
+
+QXcbX11Info::QXcbX11Info()
+    : d(Q_NULLPTR)
+{}
+
+QXcbX11Info::~QXcbX11Info()
+{}
+
+QXcbX11Info::QXcbX11Info(const QXcbX11Info &other)
+    : d(other.d)
+{}
+
+QXcbX11Info &QXcbX11Info::operator=(const QXcbX11Info &other)
+{
+    d = other.d;
+    return *this;
+}
+
+QXcbX11Info QXcbX11Info::fromScreen(int screen)
+{
+    QXcbX11InfoData *xd = new QXcbX11InfoData;
+    xd->screen = screen;
+    xd->depth = QXcbX11Info::appDepth(screen);
+    xd->cells = QXcbX11Info::appCells(screen);
+    xd->colormap = QXcbX11Info::appColormap(screen);
+    xd->defaultColormap = QXcbX11Info::appDefaultColormap(screen);
+    xd->visual = (Visual *)QXcbX11Info::appVisual(screen);
+    xd->defaultVisual = QXcbX11Info::appDefaultVisual(screen);
+
+    QXcbX11Info info;
+    info.d = xd;
+    return info;
+}
+
+void QXcbX11Info::setDepth(int depth)
+{
+    if (!d)
+        *this = fromScreen(appScreen());
+
+    d->depth = depth;
+}
+
+Display *QXcbX11Info::display()
+{
+    return X11 ? X11->display : 0;
+}
+
+int QXcbX11Info::screen() const
+{
+    return d ? d->screen : QXcbX11Info::appScreen();
+}
+
+int QXcbX11Info::depth() const
+{
+    return d ? d->depth : QXcbX11Info::appDepth();
+}
+
+Colormap QXcbX11Info::colormap() const
+{
+    return d ? d->colormap : QXcbX11Info::appColormap();
+}
+
+void *QXcbX11Info::visual() const
+{
+    return d ? d->visual : QXcbX11Info::appVisual();
+}
+
+void QXcbX11Info::setVisual(void *visual)
+{
+    if (!d)
+        *this = fromScreen(appScreen());
+
+    d->visual = (Visual *) visual;
+}
+
+int QXcbX11Info::appScreen()
+{
+    return X11 ? X11->defaultScreen : 0;
+}
+
+int QXcbX11Info::appDepth(int screen)
+{
+    return X11 ? X11->screens[screen == -1 ? X11->defaultScreen : screen].depth : 32;
+}
+
+int QXcbX11Info::appCells(int screen)
+{
+    return X11 ? X11->screens[screen == -1 ? X11->defaultScreen : screen].cells : 0;
+}
+
+Colormap QXcbX11Info::appColormap(int screen)
+{
+    return X11 ? X11->screens[screen == -1 ? X11->defaultScreen : screen].colormap : 0;
+}
+
+void *QXcbX11Info::appVisual(int screen)
+{
+    return X11 ? X11->screens[screen == -1 ? X11->defaultScreen : screen].visual : 0;
+}
+
+Window QXcbX11Info::appRootWindow(int screen)
+{
+    return X11 ? RootWindow(X11->display, screen == -1 ? X11->defaultScreen : screen) : 0;
+}
+
+bool QXcbX11Info::appDefaultColormap(int screen)
+{
+    return X11 ? X11->screens[screen == -1 ? X11->defaultScreen : screen].defaultColormap : true;
+}
+
+bool QXcbX11Info::appDefaultVisual(int screen)
+{
+    return X11 ? X11->screens[screen == -1 ? X11->defaultScreen : screen].defaultVisual : true;
+}
+
+int QXcbX11Info::appDpiX(int screen)
+{
+    if (!X11)
+        return 75;
+    if (screen < 0)
+        screen = X11->defaultScreen;
+    if (screen > X11->screenCount)
+        return 0;
+    return X11->screens[screen].dpiX;
+}
+
+int QXcbX11Info::appDpiY(int screen)
+{
+    if (!X11)
+        return 75;
+    if (screen < 0)
+        screen = X11->defaultScreen;
+    if (screen > X11->screenCount)
+        return 0;
+    return X11->screens[screen].dpiY;
+}
+
+#if QT_CONFIG(xrender)
+Picture QXcbX11Data::getSolidFill(int screen, const QColor &c)
+{
+    if (!X11->use_xrender)
+        return XNone;
+
+    XRenderColor color = preMultiply(c);
+    for (int i = 0; i < X11->solid_fill_count; ++i) {
+        if (X11->solid_fills[i].screen == screen
+            && X11->solid_fills[i].color.alpha == color.alpha
+            && X11->solid_fills[i].color.red == color.red
+            && X11->solid_fills[i].color.green == color.green
+            && X11->solid_fills[i].color.blue == color.blue)
+            return X11->solid_fills[i].picture;
+    }
+    // none found, replace one
+    int i = qrand() % 16;
+
+    if (X11->solid_fills[i].screen != screen && X11->solid_fills[i].picture) {
+        XRenderFreePicture (X11->display, X11->solid_fills[i].picture);
+        X11->solid_fills[i].picture = 0;
+    }
+
+    if (!X11->solid_fills[i].picture) {
+        Pixmap pixmap = XCreatePixmap (X11->display, RootWindow (X11->display, screen), 1, 1, 32);
+        XRenderPictureAttributes attrs;
+        attrs.repeat = True;
+        X11->solid_fills[i].picture = XRenderCreatePicture (X11->display, pixmap,
+                                                            XRenderFindStandardFormat(X11->display, PictStandardARGB32),
+                                                            CPRepeat, &attrs);
+        XFreePixmap (X11->display, pixmap);
+    }
+
+    X11->solid_fills[i].color = color;
+    X11->solid_fills[i].screen = screen;
+    XRenderFillRectangle (X11->display, PictOpSrc, X11->solid_fills[i].picture, &color, 0, 0, 1, 1);
+    return X11->solid_fills[i].picture;
+}
+
+XRenderColor QXcbX11Data::preMultiply(const QColor &c)
+{
+    XRenderColor color;
+    const uint A = c.alpha(),
+            R = c.red(),
+            G = c.green(),
+            B = c.blue();
+    color.alpha = (A | A << 8);
+    color.red   = (R | R << 8) * color.alpha / 0x10000;
+    color.green = (G | G << 8) * color.alpha / 0x10000;
+    color.blue  = (B | B << 8) * color.alpha / 0x10000;
+    return color;
+}
+#endif // QT_CONFIG(xrender)
+
+
+QT_END_NAMESPACE