Code

Color Matrix Filter:
[inkscape.git] / src / object-edit.cpp
index 487caa09c503923bce9a949f5abdb701814e46cf..63ccf827e740cf4b55c1a632686031a9f104bdcc 100644 (file)
@@ -30,6 +30,7 @@
 #include "desktop-affine.h"
 #include <style.h>
 #include "desktop.h"
+#include "desktop-handles.h"
 #include "sp-namedview.h"
 
 #include "sp-pattern.h"
@@ -50,7 +51,7 @@
 
 static SPKnotHolder *sp_rect_knot_holder(SPItem *item, SPDesktop *desktop);
 //static 
-SPKnotHolder *sp_3dbox_knot_holder(SPItem *item, SPDesktop *desktop, guint number_of_handles);
+SPKnotHolder *sp_3dbox_knot_holder(SPItem *item, SPDesktop *desktop);
 static SPKnotHolder *sp_arc_knot_holder(SPItem *item, SPDesktop *desktop);
 static SPKnotHolder *sp_star_knot_holder(SPItem *item, SPDesktop *desktop);
 static SPKnotHolder *sp_spiral_knot_holder(SPItem *item, SPDesktop *desktop);
@@ -65,7 +66,7 @@ sp_item_knot_holder(SPItem *item, SPDesktop *desktop)
     if (SP_IS_RECT(item)) {
         return sp_rect_knot_holder(item, desktop);
     } else if (SP_IS_3DBOX(item)) {
-        return sp_3dbox_knot_holder(item, desktop, SP3DBoxContext::number_of_handles);
+        return sp_3dbox_knot_holder(item, desktop);
     } else if (SP_IS_ARC(item)) {
         return sp_arc_knot_holder(item, desktop);
     } else if (SP_IS_STAR(item)) {
@@ -224,7 +225,7 @@ static NR::Point snap_knot_position(SPItem *item, NR::Point const &p)
     NR::Matrix const i2d (sp_item_i2d_affine (item));
     NR::Point s = p * i2d;    
     SnapManager const &m = desktop->namedview->snap_manager;
-    s = m.freeSnap(Inkscape::Snapper::BBOX_POINT | Inkscape::Snapper::SNAP_POINT, s, item).getPoint();
+    s = m.freeSnap(Inkscape::Snapper::SNAPPOINT_NODE, s, item).getPoint();
     return s * i2d.inverse();
 }
 
@@ -529,132 +530,255 @@ static SPKnotHolder *sp_rect_knot_holder(SPItem *item, SPDesktop *desktop)
 
 /* 3D Box */
 
-static void sp_3dbox_knot_set(SPItem *item, guint knot_id, Box3D::Axis direction,
-                              NR::Point const &new_pos, NR::Point const &origin, guint state)
+static inline Box3D::Axis movement_axis_of_3dbox_corner (guint corner, guint state)
+{
+    // this function has the purpose to simplify a change in the resizing behaviour of boxes
+    switch (corner) {
+        case 0:
+        case 1:
+        case 2:
+        case 3:
+            return ((state & GDK_SHIFT_MASK) ? Box3D::Z : Box3D::XY);
+        case 4:
+        case 5:
+        case 6:
+        case 7:
+            return ((state & GDK_SHIFT_MASK) ? Box3D::XY : Box3D::Z);
+    }
+    return Box3D::NONE;
+}
+
+/* 
+ * To keep the snappoint from jumping randomly between the two lines when the mouse pointer is close to
+ * their intersection, we remember the last snapped line and keep snapping to this specific line as long
+ * as the distance from the intersection to the mouse pointer is less than remember_snap_threshold.
+ */
+
+// Should we make the threshold settable in the preferences?
+static double remember_snap_threshold = 30;
+static guint remember_snap_index = 0;
+static guint remember_snap_index_center = 0;
+
+static NR::Point snap_knot_position_3dbox (SP3DBox *box, guint corner, Box3D::Axis direction, NR::Point const &origin, NR::Point const &p, guint state)
 {
-    g_assert(item != NULL);
-    SP3DBox *box = SP_3DBOX(item);
+    SPDesktop * desktop = inkscape_active_desktop();
+    Box3D::Perspective3D *persp = sp_desktop_document (desktop)->get_persp_of_box (box);
 
-    // FIXME: Why must the coordinates be flipped vertically???
-    SPDocument *doc = SP_OBJECT_DOCUMENT(box);
-    gdouble height = sp_document_height(doc);
+    if (is_single_axis_direction (direction)) return p;
 
-    NR::Matrix const i2d (sp_item_i2d_affine (item));
-    if (direction == Box3D::Z) {
-         sp_3dbox_move_corner_in_Z_direction (box, knot_id, new_pos * i2d, !(state & GDK_SHIFT_MASK));
+    Box3D::Axis axis1 = Box3D::extract_first_axis_direction (direction);
+    Box3D::Axis axis2 = Box3D::extract_second_axis_direction (direction);
+
+    NR::Matrix const i2d (sp_item_i2d_affine (SP_ITEM (box)));
+    NR::Point origin_dt = origin * i2d;
+    NR::Point p_dt = p * i2d;
+
+    Box3D::PerspectiveLine pl1 (origin_dt, axis1, persp);
+    Box3D::PerspectiveLine pl2 (origin_dt, axis2, persp);
+    Box3D::Line diag1 (origin_dt, box->corners[corner ^ Box3D::XY]);
+
+    int num_snap_lines = 3;
+    NR::Point snap_pts[num_snap_lines];
+
+    snap_pts[0] = pl1.closest_to (p_dt);
+    snap_pts[1] = pl2.closest_to (p_dt);
+    snap_pts[2] = diag1.closest_to (p_dt);
+
+    gdouble const zoom = desktop->current_zoom();
+
+    double snap_dists[num_snap_lines];
+
+    for (int i = 0; i < num_snap_lines; ++i) {
+        snap_dists[i] = NR::L2 (snap_pts[i] - p_dt) * zoom;
+    }
+
+    bool within_tolerance = true;
+    for (int i = 0; i < num_snap_lines; ++i) {
+        if (snap_dists[i] > remember_snap_threshold) {
+            within_tolerance = false;
+            break;
+        }
+    }
+
+    int snap_index = -1;
+    double snap_dist = NR_HUGE;
+    for (int i = 0; i < num_snap_lines; ++i) {
+        if (snap_dists[i] < snap_dist) {
+            snap_index = i;
+            snap_dist = snap_dists[i];
+        }
+    }
+
+    if (within_tolerance) {
+        return snap_pts[remember_snap_index] * i2d.inverse();
     } else {
-        sp_3dbox_move_corner_in_XY_plane (box, knot_id, new_pos * i2d, (state & GDK_SHIFT_MASK) ? direction : Box3D::XY);
+        remember_snap_index = snap_index;
+        return snap_pts[snap_index] * i2d.inverse();
     }
-    sp_3dbox_update_curves (box);
 }
 
-static NR::Point sp_3dbox_knot_get(SPItem *item, guint knot_id)
+static NR::Point snap_center_position_3dbox (SP3DBox *box, NR::Point const &origin, NR::Point const &p)
 {
-    g_assert(item != NULL);
-    SP3DBox *box = SP_3DBOX(item);
+    SPDesktop * desktop = inkscape_active_desktop();
+    Box3D::Perspective3D *persp = sp_desktop_document (desktop)->get_persp_of_box (box);
 
-    NR::Matrix const i2d (sp_item_i2d_affine (item));
-    return sp_3dbox_get_corner(box, knot_id) * i2d;
-}
+    Box3D::Axis axis1 = Box3D::X;
+    Box3D::Axis axis2 = Box3D::Y;
 
-static void sp_3dbox_knot1_set(SPItem *item, NR::Point const &new_pos, NR::Point const &origin, guint state)
-{
-    sp_3dbox_knot_set (item, 1, Box3D::Y, new_pos, origin, state);
-}
+    NR::Matrix const i2d (sp_item_i2d_affine (SP_ITEM (box)));
+    NR::Point origin_dt = origin * i2d;
+    NR::Point p_dt = p * i2d;
 
-/*
-static void sp_3dbox_knot1_set_constrained(SPItem *item, NR::Point const &new_pos, NR::Point const &origin, guint state)
-{
-    sp_3dbox_knot_set (item, 1, Box3D::Y, new_pos, origin, state ^ GDK_SHIFT_MASK);
-}
-*/
+    Box3D::PerspectiveLine pl1 (origin_dt, axis1, persp);
+    Box3D::PerspectiveLine pl2 (origin_dt, axis2, persp);
+    NR::Point midpt1 = sp_3dbox_get_midpoint_in_axis_direction (box->old_corner1, box->old_corner5, Box3D::Z, persp);
+    NR::Point midpt2 = sp_3dbox_get_midpoint_in_axis_direction (box->old_corner3, box->old_corner7, Box3D::Z, persp);
+    Box3D::Line diag1 (origin_dt, midpt1);
+    Box3D::Line diag2 (origin_dt, midpt2);
 
-static void sp_3dbox_knot2_set(SPItem *item, NR::Point const &new_pos, NR::Point const &origin, guint state)
-{
-    sp_3dbox_knot_set (item, 2, Box3D::X, new_pos, origin, state);
-}
+    int num_snap_lines = 4;
+    NR::Point snap_pts[num_snap_lines];
 
-/*
-static void sp_3dbox_knot2_set_constrained(SPItem *item, NR::Point const &new_pos, NR::Point const &origin, guint state)
-{
-    sp_3dbox_knot_set (item, 2, Box3D::X, new_pos, origin, state ^ GDK_SHIFT_MASK);
-}
+    // should we snap to the closest point or to the projection along perspective lines?
+    snap_pts[0] = pl1.closest_to (p_dt);
+    snap_pts[1] = pl2.closest_to (p_dt);
+    snap_pts[2] = diag1.closest_to (p_dt);
+    snap_pts[3] = diag2.closest_to (p_dt);
 
-static void sp_3dbox_knot3_set(SPItem *item, NR::Point const &new_pos, NR::Point const &origin, guint state)
-{
-    if (!(state & GDK_SHIFT_MASK)) {
-        sp_3dbox_knot_set (item, 3, Box3D::Y, new_pos, origin, state);
+    gdouble const zoom = desktop->current_zoom();
+
+    double snap_dists[num_snap_lines];
+
+    for (int i = 0; i < num_snap_lines; ++i) {
+        snap_dists[i] = NR::L2 (snap_pts[i] - p_dt) * zoom;
+    }
+
+    bool within_tolerance = true;
+    for (int i = 0; i < num_snap_lines; ++i) {
+        if (snap_dists[i] > remember_snap_threshold) {
+            within_tolerance = false;
+            break;
+        }
+    }
+
+    int snap_index = -1;
+    double snap_dist = NR_HUGE;
+    for (int i = 0; i < num_snap_lines; ++i) {
+        if (snap_dists[i] < snap_dist) {
+            snap_index = i;
+            snap_dist = snap_dists[i];
+        }
+    }
+
+    if (within_tolerance) {
+        return snap_pts[remember_snap_index_center] * i2d.inverse();
     } else {
-        sp_3dbox_knot_set (item, 3, Box3D::Z, new_pos, origin, state ^ GDK_SHIFT_MASK);
+        remember_snap_index_center = snap_index;
+        return snap_pts[snap_index] * i2d.inverse();
     }
 }
-*/
 
-static void sp_3dbox_knot5_set(SPItem *item, NR::Point const &new_pos, NR::Point const &origin, guint state)
+static NR::Point sp_3dbox_knot_get(SPItem *item, guint knot_id)
 {
-    sp_3dbox_knot_set (item, 5, Box3D::Z, new_pos, origin, state);
+    g_assert(item != NULL);
+    SP3DBox *box = SP_3DBOX(item);
+
+    NR::Matrix const i2d (sp_item_i2d_affine (item));
+    return sp_3dbox_get_corner(box, knot_id) * i2d;
 }
 
-/*
-static void sp_3dbox_knot7_set(SPItem *item, NR::Point const &new_pos, NR::Point const &origin, guint state)
+static void sp_3dbox_knot_set(SPItem *item, guint knot_id, NR::Point const &new_pos, NR::Point const &origin, guint state)
 {
-    sp_3dbox_knot_set (item, 7, Box3D::Z, new_pos, origin, state);
+    g_assert(item != NULL);
+    SP3DBox *box = SP_3DBOX(item);
+
+    NR::Matrix const i2d (sp_item_i2d_affine (item));
+    Box3D::Axis direction = movement_axis_of_3dbox_corner (knot_id, state);
+    if ((state & GDK_CONTROL_MASK) && !is_single_axis_direction (direction)) {
+        // snap if Ctrl is pressed and movement isn't already constrained to a single axis
+        NR::Point const s = snap_knot_position_3dbox (box, knot_id, direction, origin, new_pos, state);
+        sp_3dbox_move_corner_in_Z_direction (box, knot_id, s * i2d, false);
+    } else {
+        if (direction == Box3D::Z) {
+            sp_3dbox_move_corner_in_Z_direction (box, knot_id, new_pos * i2d, true);
+        } else {
+            sp_3dbox_move_corner_in_Z_direction (box, knot_id, new_pos * i2d, false);
+        }
+    }
+    sp_3dbox_update_curves (box);
+    sp_3dbox_set_ratios (box);
+    sp_3dbox_update_perspective_lines ();
+    sp_3dbox_set_z_orders_later_on (box);
 }
-*/
 
-// defined a uniform behaviour for all knots
-static void sp_3dbox_knot_set_uniformly(SPItem *item, guint knot_id, Box3D::Axis direction, NR::Point const &new_pos, NR::Point const &origin, guint state)
+static void sp_3dbox_knot_center_set(SPItem *item, NR::Point const &new_pos, NR::Point const &origin, guint state)
 {
-    g_assert(item != NULL);
     SP3DBox *box = SP_3DBOX(item);
 
     NR::Matrix const i2d (sp_item_i2d_affine (item));
-    if (direction == Box3D::Z) {
-        sp_3dbox_move_corner_in_Z_direction (box, knot_id, new_pos * i2d, !(state & GDK_SHIFT_MASK));
+    NR::Point new_pt (new_pos);
+
+    if ((state & GDK_CONTROL_MASK) && !(state & GDK_SHIFT_MASK)) {
+        // snap if Ctrl is pressed and movement isn't already constrained to a single axis
+        new_pt = snap_center_position_3dbox (box, origin, new_pos);
+    }
+
+    if (state & GDK_SHIFT_MASK) {
+        sp_3dbox_recompute_Z_corners_from_new_center (box, new_pt * i2d);
     } else {
-        sp_3dbox_move_corner_in_Z_direction (box, knot_id, new_pos * i2d,  (state & GDK_SHIFT_MASK));
+        sp_3dbox_recompute_XY_corners_from_new_center (box, new_pt * i2d);
     }
+
     sp_3dbox_update_curves (box);
+    sp_3dbox_set_z_orders_later_on (box);
+}
+
+static NR::Point sp_3dbox_knot_center_get(SPItem *item)
+{
+    NR::Maybe<NR::Point> center = sp_3dbox_get_center(SP_3DBOX(item));
+    if (!center) return NR::Point (0, 0);
+    NR::Matrix const i2d (sp_item_i2d_affine (item));
+    return (*center) * i2d;
 }
 
-static void sp_3dbox_knot0_set_uniformly(SPItem *item, NR::Point const &new_pos, NR::Point const &origin, guint state)
+static void sp_3dbox_knot0_set(SPItem *item, NR::Point const &new_pos, NR::Point const &origin, guint state)
 {
-    sp_3dbox_knot_set_uniformly(item, 0, Box3D::XY, new_pos, origin, state);
+    sp_3dbox_knot_set(item, 0, new_pos, origin, state);
 }
 
-static void sp_3dbox_knot1_set_uniformly(SPItem *item, NR::Point const &new_pos, NR::Point const &origin, guint state)
+static void sp_3dbox_knot1_set(SPItem *item, NR::Point const &new_pos, NR::Point const &origin, guint state)
 {
-    sp_3dbox_knot_set_uniformly(item, 1, Box3D::XY, new_pos, origin, state);
+    sp_3dbox_knot_set(item, 1, new_pos, origin, state);
 }
 
-static void sp_3dbox_knot2_set_uniformly(SPItem *item, NR::Point const &new_pos, NR::Point const &origin, guint state)
+static void sp_3dbox_knot2_set(SPItem *item, NR::Point const &new_pos, NR::Point const &origin, guint state)
 {
-    sp_3dbox_knot_set_uniformly(item, 2, Box3D::XY, new_pos, origin, state);
+    sp_3dbox_knot_set(item, 2, new_pos, origin, state);
 }
 
-static void sp_3dbox_knot3_set_uniformly(SPItem *item, NR::Point const &new_pos, NR::Point const &origin, guint state)
+static void sp_3dbox_knot3_set(SPItem *item, NR::Point const &new_pos, NR::Point const &origin, guint state)
 {
-    sp_3dbox_knot_set_uniformly(item, 3, Box3D::XY, new_pos, origin, state);
+    sp_3dbox_knot_set(item, 3, new_pos, origin, state);
 }
 
-static void sp_3dbox_knot4_set_uniformly(SPItem *item, NR::Point const &new_pos, NR::Point const &origin, guint state)
+static void sp_3dbox_knot4_set(SPItem *item, NR::Point const &new_pos, NR::Point const &origin, guint state)
 {
-    sp_3dbox_knot_set_uniformly(item, 4, Box3D::Z, new_pos, origin, state);
+    sp_3dbox_knot_set(item, 4, new_pos, origin, state);
 }
 
-static void sp_3dbox_knot5_set_uniformly(SPItem *item, NR::Point const &new_pos, NR::Point const &origin, guint state)
+static void sp_3dbox_knot5_set(SPItem *item, NR::Point const &new_pos, NR::Point const &origin, guint state)
 {
-    sp_3dbox_knot_set_uniformly(item, 5, Box3D::Z, new_pos, origin, state);
+    sp_3dbox_knot_set(item, 5, new_pos, origin, state);
 }
 
-static void sp_3dbox_knot6_set_uniformly(SPItem *item, NR::Point const &new_pos, NR::Point const &origin, guint state)
+static void sp_3dbox_knot6_set(SPItem *item, NR::Point const &new_pos, NR::Point const &origin, guint state)
 {
-    sp_3dbox_knot_set_uniformly(item, 6, Box3D::Z, new_pos, origin, state);
+    sp_3dbox_knot_set(item, 6, new_pos, origin, state);
 }
 
-static void sp_3dbox_knot7_set_uniformly(SPItem *item, NR::Point const &new_pos, NR::Point const &origin, guint state)
+static void sp_3dbox_knot7_set(SPItem *item, NR::Point const &new_pos, NR::Point const &origin, guint state)
 {
-    sp_3dbox_knot_set_uniformly(item, 7, Box3D::Z, new_pos, origin, state);
+    sp_3dbox_knot_set(item, 7, new_pos, origin, state);
 }
 
 static NR::Point sp_3dbox_knot0_get(SPItem *item)
@@ -700,48 +824,33 @@ static NR::Point sp_3dbox_knot7_get(SPItem *item)
 
 //static
 SPKnotHolder *
-sp_3dbox_knot_holder(SPItem *item, SPDesktop *desktop, guint number_of_handles)
+sp_3dbox_knot_holder(SPItem *item, SPDesktop *desktop)
 {
     g_assert(item != NULL);
     SPKnotHolder *knot_holder = sp_knot_holder_new(desktop, item, NULL);
 
-    switch (number_of_handles) {
-    case 3:
-        sp_knot_holder_add(knot_holder, sp_3dbox_knot1_set, sp_3dbox_knot1_get, NULL,_("Resize box in X/Y direction"));
-        sp_knot_holder_add(knot_holder, sp_3dbox_knot2_set, sp_3dbox_knot2_get, NULL,_("Resize box in X/Y direction"));
-        sp_knot_holder_add(knot_holder, sp_3dbox_knot5_set, sp_3dbox_knot5_get, NULL,_("Resize box in Z direction"));
-        sp_pat_knot_holder(item, knot_holder);
-        break;
-    case 4:
-        /***
-        sp_knot_holder_add(knot_holder, sp_3dbox_knot1_set_constrained, sp_3dbox_knot1_get, NULL,_("Resize box in X/Y direction"));
-        sp_knot_holder_add(knot_holder, sp_3dbox_knot2_set_constrained, sp_3dbox_knot2_get, NULL,_("Resize box in X/Y direction"));
-        sp_knot_holder_add_full(knot_holder, sp_3dbox_knot3_set, sp_3dbox_knot3_get, NULL,
-                                SP_KNOT_SHAPE_CIRCLE,  SP_KNOT_MODE_XOR, _("Resize box in Y direction"));
-        sp_knot_holder_add(knot_holder, sp_3dbox_knot7_set, sp_3dbox_knot7_get, NULL,_("Resize box in Z direction"));
-        ***/
-        sp_knot_holder_add(knot_holder, sp_3dbox_knot0_set_uniformly, sp_3dbox_knot0_get, NULL,
-                           _("Resize box in X/Y direction; with <b>Shift</b> along the Z axis"));
-        sp_knot_holder_add(knot_holder, sp_3dbox_knot1_set_uniformly, sp_3dbox_knot1_get, NULL,
-                           _("Resize box in X/Y direction; with <b>Shift</b> along the Z axis"));
-        sp_knot_holder_add(knot_holder, sp_3dbox_knot2_set_uniformly, sp_3dbox_knot2_get, NULL,
-                           _("Resize box in X/Y direction; with <b>Shift</b> along the Z axis"));
-        sp_knot_holder_add(knot_holder, sp_3dbox_knot3_set_uniformly, sp_3dbox_knot3_get, NULL,
-                           _("Resize box in X/Y direction; with <b>Shift</b> along the Z axis"));
-        sp_knot_holder_add(knot_holder, sp_3dbox_knot4_set_uniformly, sp_3dbox_knot4_get, NULL,
-                           _("Resize box along the Z axis; with <b>Shift</b> in X/Y direction"));
-        sp_knot_holder_add(knot_holder, sp_3dbox_knot5_set_uniformly, sp_3dbox_knot5_get, NULL,
-                           _("Resize box along the Z axis; with <b>Shift</b> in X/Y direction"));
-        sp_knot_holder_add(knot_holder, sp_3dbox_knot6_set_uniformly, sp_3dbox_knot6_get, NULL,
-                           _("Resize box along the Z axis; with <b>Shift</b> in X/Y direction"));
-        sp_knot_holder_add(knot_holder, sp_3dbox_knot7_set_uniformly, sp_3dbox_knot7_get, NULL,
-                           _("Resize box along the Z axis; with <b>Shift</b> in X/Y direction"));
-        sp_pat_knot_holder(item, knot_holder);
-        break;
-    default:
-        g_print ("Wrong number of handles (%d): Not implemented yet.\n", number_of_handles);
-        break;
-    }
+    sp_knot_holder_add(knot_holder, sp_3dbox_knot0_set, sp_3dbox_knot0_get, NULL,
+                       _("Resize box in X/Y direction; with <b>Shift</b> along the Z axis; with <b>Ctrl</b> to constrain to the directions of edges or diagonals"));
+    sp_knot_holder_add(knot_holder, sp_3dbox_knot1_set, sp_3dbox_knot1_get, NULL,
+                       _("Resize box in X/Y direction; with <b>Shift</b> along the Z axis; with <b>Ctrl</b> to constrain to the directions of edges or diagonals"));
+    sp_knot_holder_add(knot_holder, sp_3dbox_knot2_set, sp_3dbox_knot2_get, NULL,
+                       _("Resize box in X/Y direction; with <b>Shift</b> along the Z axis; with <b>Ctrl</b> to constrain to the directions of edges or diagonals"));
+    sp_knot_holder_add(knot_holder, sp_3dbox_knot3_set, sp_3dbox_knot3_get, NULL,
+                       _("Resize box in X/Y direction; with <b>Shift</b> along the Z axis; with <b>Ctrl</b> to constrain to the directions of edges or diagonals"));
+    sp_knot_holder_add(knot_holder, sp_3dbox_knot4_set, sp_3dbox_knot4_get, NULL,
+                       _("Resize box along the Z axis; with <b>Shift</b> in X/Y direction; with <b>Ctrl</b> to constrain to the directions of edges or diagonals"));
+    sp_knot_holder_add(knot_holder, sp_3dbox_knot5_set, sp_3dbox_knot5_get, NULL,
+                       _("Resize box along the Z axis; with <b>Shift</b> in X/Y direction; with <b>Ctrl</b> to constrain to the directions of edges or diagonals"));
+    sp_knot_holder_add(knot_holder, sp_3dbox_knot6_set, sp_3dbox_knot6_get, NULL,
+                       _("Resize box along the Z axis; with <b>Shift</b> in X/Y direction; with <b>Ctrl</b> to constrain to the directions of edges or diagonals"));
+    sp_knot_holder_add(knot_holder, sp_3dbox_knot7_set, sp_3dbox_knot7_get, NULL,
+                       _("Resize box along the Z axis; with <b>Shift</b> in X/Y direction; with <b>Ctrl</b> to constrain to the directions of edges or diagonals"));
+
+    // center dragging
+    sp_knot_holder_add_full(knot_holder, sp_3dbox_knot_center_set, sp_3dbox_knot_center_get, NULL,
+                            SP_KNOT_SHAPE_CROSS, SP_KNOT_MODE_XOR,_("Move the box in perspective."));
+
+    sp_pat_knot_holder(item, knot_holder);
 
     return knot_holder;
 }
@@ -1250,7 +1359,7 @@ sp_offset_knot_holder(SPItem *item, SPDesktop *desktop)
 static SPKnotHolder *
 sp_misc_knot_holder(SPItem *item, SPDesktop *desktop) // FIXME: eliminate, instead make a pattern-drag similar to gradient-drag
 {
-    if ((SP_OBJECT(item)->style->fill.type == SP_PAINT_TYPE_PAINTSERVER)
+    if ((SP_OBJECT(item)->style->fill.isPaintserver())
         && SP_IS_PATTERN(SP_STYLE_FILL_SERVER(SP_OBJECT(item)->style)))
     {
         SPKnotHolder *knot_holder = sp_knot_holder_new(desktop, item, NULL);
@@ -1265,7 +1374,7 @@ sp_misc_knot_holder(SPItem *item, SPDesktop *desktop) // FIXME: eliminate, inste
 static void
 sp_pat_knot_holder(SPItem *item, SPKnotHolder *knot_holder)
 {
-    if ((SP_OBJECT(item)->style->fill.type == SP_PAINT_TYPE_PAINTSERVER)
+    if ((SP_OBJECT(item)->style->fill.isPaintserver())
         && SP_IS_PATTERN(SP_STYLE_FILL_SERVER(SP_OBJECT(item)->style)))
     {
         sp_knot_holder_add_full(knot_holder, sp_pattern_xy_set, sp_pattern_xy_get, NULL, SP_KNOT_SHAPE_CROSS, SP_KNOT_MODE_XOR,