Initial cut of eraser tool

[inkscape.git] / src / arc-context.cpp

diff --git a/src/arc-context.cpp b/src/arc-context.cpp
index d5a25b61bfc4e48a20b2944999eea89a8bc99f82..82c00fd05f05fe7ea2d028af895076ff6cefdfa0 100644 (file)
--- a/src/arc-context.cpp
+++ b/src/arc-context.cpp
@@ -291,7 +291,7 @@ static gint sp_arc_context_root_handler(SPEventContext *event_context, GdkEvent
                 
                 SnapManager const &m = desktop->namedview->snap_manager;            
                 motion_dt = m.freeSnap(Inkscape::Snapper::SNAPPOINT_NODE, motion_dt, ac->item).getPoint();
-                
+
                 sp_arc_drag(ac, motion_dt, event->motion.state);
 
                 gobble_motion_events(GDK_BUTTON1_MASK);
@@ -433,15 +433,60 @@ static void sp_arc_drag(SPArcContext *ac, NR::Point pt, guint state)
         sp_canvas_force_full_redraw_after_interruptions(desktop->canvas, 5);
     }
 
-    NR::Rect const r = Inkscape::snap_rectangular_box(desktop, ac->item, pt, ac->center, state);
+    bool ctrl_save = false;
+    if ((state & GDK_MOD1_MASK) && (state & GDK_CONTROL_MASK) && !(state & GDK_SHIFT_MASK)) {
+        // if Alt is pressed without Shift in addition to Control, temporarily drop the CONTROL mask
+        // so that the ellipse is not constrained to integer ratios
+        ctrl_save = true;
+        state = state ^ GDK_CONTROL_MASK;
+    }
+    NR::Rect r = Inkscape::snap_rectangular_box(desktop, ac->item, pt, ac->center, state);
+    if (ctrl_save) {
+        state = state ^ GDK_CONTROL_MASK;
+    }
+
+    NR::Point dir = r.dimensions() / 2;
+    if (state & GDK_MOD1_MASK) {
+        /* With Alt let the ellipse pass through the mouse pointer */
+        NR::Point c = r.midpoint();
+        if (!ctrl_save) {
+            if (fabs(dir[NR::X]) > 1E-6 && fabs(dir[NR::Y]) > 1E-6) {
+                NR::Matrix const i2d (sp_item_i2d_affine (ac->item));
+                NR::Point new_dir = pt * i2d - c;
+                new_dir[NR::X] *= dir[NR::Y] / dir[NR::X];
+                double lambda = NR::L2(new_dir) / dir[NR::Y];
+                r = NR::Rect (c - lambda*dir, c + lambda*dir);
+            }
+        } else {
+            /* with Alt+Ctrl (without Shift) we generate a perfect circle
+               with diameter click point <--> mouse pointer */
+                double l = NR::L2 (dir);
+                NR::Point d = NR::Point (l, l);
+                r = NR::Rect (c - d, c + d);
+        }
+    }
 
     sp_arc_position_set(SP_ARC(ac->item),
                         r.midpoint()[NR::X], r.midpoint()[NR::Y],
                         r.dimensions()[NR::X] / 2, r.dimensions()[NR::Y] / 2);
 
-    GString *xs = SP_PX_TO_METRIC_STRING(r.dimensions()[NR::X], desktop->namedview->getDefaultMetric());
-    GString *ys = SP_PX_TO_METRIC_STRING(r.dimensions()[NR::Y], desktop->namedview->getDefaultMetric());
-    ac->_message_context->setF(Inkscape::IMMEDIATE_MESSAGE, _("<b>Ellipse</b>: %s &#215; %s; with <b>Ctrl</b> to make circle or integer-ratio ellipse; with <b>Shift</b> to draw around the starting point"), xs->str, ys->str);
+    double rdimx = r.dimensions()[NR::X];
+    double rdimy = r.dimensions()[NR::Y];
+    GString *xs = SP_PX_TO_METRIC_STRING(rdimx, desktop->namedview->getDefaultMetric());
+    GString *ys = SP_PX_TO_METRIC_STRING(rdimy, desktop->namedview->getDefaultMetric());
+    if (state & GDK_CONTROL_MASK) {
+        int ratio_x, ratio_y;
+        if (fabs (rdimx) > fabs (rdimy)) {
+            ratio_x = (int) rint (rdimx / rdimy);
+            ratio_y = 1;
+        } else {
+            ratio_x = 1;
+            ratio_y = (int) rint (rdimy / rdimx);
+        }
+        ac->_message_context->setF(Inkscape::IMMEDIATE_MESSAGE, _("<b>Ellipse</b>: %s &#215; %s (constrained to ratio %d:%d); with <b>Shift</b> to draw around the starting point"), xs->str, ys->str, ratio_x, ratio_y);
+    } else {
+        ac->_message_context->setF(Inkscape::IMMEDIATE_MESSAGE, _("<b>Ellipse</b>: %s &#215; %s; with <b>Ctrl</b> to make square or integer-ratio ellipse; with <b>Shift</b> to draw around the starting point"), xs->str, ys->str);
+    }
     g_string_free(xs, FALSE);
     g_string_free(ys, FALSE);
 }