Implemented QXcbIntegration::grabWindow().

1 files changed, 210 insertions, 6 deletions

diff --git a/src/plugins/platforms/xcb/qxcbintegration.cpp b/src/plugins/platforms/xcb/qxcbintegration.cpp
index 2c89bd6e80..81b6cda840 100644
--- a/src/plugins/platforms/xcb/qxcbintegration.cpp
+++ b/src/plugins/platforms/xcb/qxcbintegration.cpp
@@ -125,14 +125,218 @@ QPlatformFontDatabase *QXcbIntegration::fontDatabase() const
     return m_fontDatabase;
 }
 
+static QImage::Format imageFormatForVisual(QXcbConnection *connection, uint8_t depth, const xcb_visualtype_t *visual)
+{
+    const xcb_format_t *format = connection->formatForDepth(depth);
+
+    if (!visual || !format)
+        return QImage::Format_Invalid;
+
+    if (depth == 32 && format->bits_per_pixel == 32 && visual->red_mask == 0xff0000
+        && visual->green_mask == 0xff00 && visual->blue_mask == 0xff)
+        return QImage::Format_ARGB32_Premultiplied;
+
+    if (depth == 24 && format->bits_per_pixel == 32 && visual->red_mask == 0xff0000
+        && visual->green_mask == 0xff00 && visual->blue_mask == 0xff)
+        return QImage::Format_RGB32;
+
+    if (depth == 16 && format->bits_per_pixel == 16 && visual->red_mask == 0xf800
+        && visual->green_mask == 0x7e0 && visual->blue_mask == 0x1f)
+        return QImage::Format_RGB16;
+
+    return QImage::Format_Invalid;
+}
+
 QPixmap QXcbIntegration::grabWindow(WId window, int x, int y, int width, int height) const
 {
-    Q_UNUSED(window);
-    Q_UNUSED(x);
-    Q_UNUSED(y);
-    Q_UNUSED(width);
-    Q_UNUSED(height);
-    return QPixmap();
+    if (width == 0 || height == 0)
+        return QPixmap();
+
+    xcb_connection_t *connection = m_connection->xcb_connection();
+
+    xcb_get_geometry_cookie_t geometry_cookie = xcb_get_geometry(connection, window);
+
+    xcb_generic_error_t *error;
+    xcb_get_geometry_reply_t *reply =
+        xcb_get_geometry_reply(connection, geometry_cookie, &error);
+
+    if (!reply) {
+        if (error) {
+            m_connection->handleXcbError(error);
+            free(error);
+        }
+        return QPixmap();
+    }
+
+    if (width < 0)
+        width = reply->width - x;
+    if (height < 0)
+        height = reply->height - y;
+
+    // TODO: handle multiple screens
+    QXcbScreen *screen = m_connection->screens().at(0);
+    xcb_window_t root = screen->root();
+    geometry_cookie = xcb_get_geometry(connection, root);
+    xcb_get_geometry_reply_t *root_reply =
+        xcb_get_geometry_reply(connection, geometry_cookie, &error);
+
+    if (!root_reply) {
+        if (error) {
+            m_connection->handleXcbError(error);
+            free(error);
+        }
+        free(reply);
+        return QPixmap();
+    }
+
+    if (reply->depth == root_reply->depth) {
+        // if the depth of the specified window and the root window are the
+        // same, grab pixels from the root window (so that we get the any
+        // overlapping windows and window manager frames)
+
+        // map x and y to the root window
+        xcb_translate_coordinates_cookie_t translate_cookie =
+            xcb_translate_coordinates(connection, window, root, x, y);
+
+        xcb_translate_coordinates_reply_t *translate_reply =
+            xcb_translate_coordinates_reply(connection, translate_cookie, &error);
+
+        if (!translate_reply) {
+            if (error) {
+                m_connection->handleXcbError(error);
+                free(error);
+            }
+            free(reply);
+            free(root_reply);
+            return QPixmap();
+        }
+
+        x = translate_reply->dst_x;
+        y = translate_reply->dst_y;
+
+        window = root;
+        free(reply);
+        reply = root_reply;
+    } else {
+        free(root_reply);
+        root_reply = 0;
+    }
+
+    xcb_get_window_attributes_reply_t *attributes_reply =
+        xcb_get_window_attributes_reply(connection, xcb_get_window_attributes(connection, window), &error);
+
+    if (!attributes_reply) {
+        if (error) {
+            m_connection->handleXcbError(error);
+            free(error);
+        }
+        free(reply);
+        return QPixmap();
+    }
+
+    const xcb_visualtype_t *visual = screen->visualForId(attributes_reply->visual);
+    free(attributes_reply);
+
+    xcb_pixmap_t pixmap = xcb_generate_id(connection);
+    error = xcb_request_check(connection, xcb_create_pixmap_checked(connection, reply->depth, pixmap, window, width, height));
+    if (error) {
+        m_connection->handleXcbError(error);
+        free(error);
+    }
+
+    uint32_t gc_value_mask = XCB_GC_SUBWINDOW_MODE;
+    uint32_t gc_value_list[] = { XCB_SUBWINDOW_MODE_INCLUDE_INFERIORS };
+
+    xcb_gcontext_t gc = xcb_generate_id(connection);
+    xcb_create_gc(connection, gc, pixmap, gc_value_mask, gc_value_list);
+
+    error = xcb_request_check(connection, xcb_copy_area_checked(connection, window, pixmap, gc, x, y, 0, 0, width, height));
+    if (error) {
+        m_connection->handleXcbError(error);
+        free(error);
+    }
+
+    xcb_get_image_cookie_t get_image_cookie =
+        xcb_get_image(connection, XCB_IMAGE_FORMAT_Z_PIXMAP, pixmap, 0, 0, width, height, 0xffffffff);
+
+    xcb_get_image_reply_t *image_reply =
+    xcb_get_image_reply(connection, get_image_cookie, &error);
+
+    xcb_free_gc(connection, gc);
+    xcb_free_pixmap(connection, pixmap);
+
+    uint8_t depth = reply->depth;
+
+    free(reply);
+
+    if (!image_reply) {
+        if (error) {
+            m_connection->handleXcbError(error);
+            free(error);
+        }
+        return QPixmap();
+    }
+
+    uint8_t *data = xcb_get_image_data(image_reply);
+    uint32_t length = xcb_get_image_data_length(image_reply);
+
+    QPixmap result;
+
+    QImage::Format format = imageFormatForVisual(m_connection, depth, visual);
+    if (format != QImage::Format_Invalid) {
+        uint32_t bytes_per_line = length / height;
+        QImage image(const_cast<uint8_t *>(data), width, height, bytes_per_line, format);
+        uint8_t image_byte_order = m_connection->setup()->image_byte_order;
+
+        // we may have to swap the byte order
+        if ((QSysInfo::ByteOrder == QSysInfo::LittleEndian && image_byte_order == XCB_IMAGE_ORDER_MSB_FIRST)
+            || (QSysInfo::ByteOrder == QSysInfo::BigEndian && image_byte_order == XCB_IMAGE_ORDER_LSB_FIRST))
+        {
+            for (int i=0; i < image.height(); i++) {
+                switch (format) {
+                case QImage::Format_RGB16: {
+                    ushort *p = (ushort*)image.scanLine(i);
+                    ushort *end = p + image.width();
+                    while (p < end) {
+                        *p = ((*p << 8) & 0xff00) | ((*p >> 8) & 0x00ff);
+                        p++;
+                    }
+                    break;
+                }
+                case QImage::Format_RGB32: // fall-through
+                case QImage::Format_ARGB32_Premultiplied: {
+                    uint *p = (uint*)image.scanLine(i);
+                    uint *end = p + image.width();
+                    while (p < end) {
+                        *p = ((*p << 24) & 0xff000000) | ((*p << 8) & 0x00ff0000)
+                             | ((*p >> 8) & 0x0000ff00) | ((*p >> 24) & 0x000000ff);
+                        p++;
+                    }
+                    break;
+                }
+                default:
+                    Q_ASSERT(false);
+                }
+            }
+        }
+
+        // fix-up alpha channel
+        if (format == QImage::Format_RGB32) {
+            QRgb *p = (QRgb *)image.bits();
+            for (int y = 0; y < height; ++y) {
+                for (int x = 0; x < width; ++x)
+                    p[x] |= 0xff000000;
+                p += bytes_per_line / 4;
+            }
+        }
+
+        image.detach();
+        result = QPixmap::fromImage(image);
+    }
+
+    free(image_reply);
+
+    return result;
 }