Add "LockAxis" key (Shift) to move the selection in X or Y axis only.

Now "Alt" modifier is the key used to snap to grid the selection.

data/gui.xml

@@ -196,7 +196,11 @@
 
       <!-- When you move the selection, pressing this
            keyboard shortcut you can snap to grid -->
-      <key action="SnapToGrid" shortcut="Shift" />
+      <key action="SnapToGrid" shortcut="Alt" />
+
+      <!-- When you move the selection, pressing this keyboard
+           shortcut so you lock the movement to one axis -->
+      <key action="LockAxis" shortcut="Shift" />
 
       <!-- When you rotate the selection, pressing this
            keyboard shortcut you activate angle snap -->

src/modules/editors.cpp

@@ -152,6 +152,14 @@ public:
       return false;
   }
 
+  bool isLockAxisKeyPressed() OVERRIDE {
+    JAccel accel = get_accel_to_lock_axis();
+    if (accel)
+      return jaccel_check_from_key(accel);
+    else
+      return false;
+  }
+
 };
 
 class MiniEditor : public Editor

src/modules/gui.cpp

@@ -65,6 +65,7 @@
 #define SPRITEDITOR_ACTION_SNAPTOGRID           "SnapToGrid"
 #define SPRITEDITOR_ACTION_ANGLESNAP            "AngleSnap"
 #define SPRITEDITOR_ACTION_MAINTAINASPECTRATIO  "MaintainAspectRatio"
+#define SPRITEDITOR_ACTION_LOCKAXIS             "LockAxis"
 
 //////////////////////////////////////////////////////////////////////
 
@@ -789,6 +790,15 @@ JAccel get_accel_to_maintain_aspect_ratio()
     return NULL;
 }
 
+JAccel get_accel_to_lock_axis()
+{
+  Shortcut* shortcut = get_keyboard_shortcut_for_spriteeditor(SPRITEDITOR_ACTION_LOCKAXIS);
+  if (shortcut)
+    return shortcut->accel;
+  else
+    return NULL;
+}
+
 tools::Tool* get_selected_quicktool(tools::Tool* currentTool)
 {
   if (currentTool && currentTool->getInk(0)->isSelection()) {

src/modules/gui.h

@@ -82,6 +82,7 @@ ui::JAccel get_accel_to_copy_selection();
 ui::JAccel get_accel_to_snap_to_grid();
 ui::JAccel get_accel_to_angle_snap();
 ui::JAccel get_accel_to_maintain_aspect_ratio();
+ui::JAccel get_accel_to_lock_axis();
 
 tools::Tool* get_selected_quicktool(tools::Tool* currentTool);
 

src/widgets/editor/editor_customization_delegate.h

@@ -51,6 +51,10 @@ public:
   // Returns true if the user wants to maintain the aspect ratio when
   // he is scaling the selection.
   virtual bool isMaintainAspectRatioKeyPressed() = 0;
+
+  // Returns true if the user wants to lock the X or Y axis when he is
+  // dragging the selection.
+  virtual bool isLockAxisKeyPressed() = 0;
 };
 
 #endif  // WIDGETS_EDITOR_CUSTOMIZATION_DELEGATE_H_INCLUDED

src/widgets/editor/moving_pixels_state.cpp

@@ -249,6 +249,9 @@ bool MovingPixelsState::onMouseMove(Editor* editor, Message* msg)
     if (editor->getCustomizationDelegate()->isMaintainAspectRatioKeyPressed())
       moveModifier |= PixelsMovement::MaintainAspectRatioMovement;
 
+    if (editor->getCustomizationDelegate()->isLockAxisKeyPressed())
+      moveModifier |= PixelsMovement::LockAxisMovement;
+
     // Invalidate handles area.
     Decorator* decorator = static_cast<Decorator*>(editor->getDecorator());
     TransformHandles* transfHandles = decorator->getTransformHandles(editor);

src/widgets/editor/pixels_movement.cpp

@@ -216,6 +216,16 @@ gfx::Rect PixelsMovement::moveImage(int x, int y, MoveModifier moveModifier)
         x2 += gridOffset.x;
         y2 += gridOffset.y;
       }
+      else if ((moveModifier & LockAxisMovement) == LockAxisMovement) {
+        if (ABS(dx) < ABS(dy)) {
+          x1 -= dx;
+          x2 -= dx;
+        }
+        else {
+          y1 -= dy;
+          y2 -= dy;
+        }
+      }
       break;
 
     case ScaleNWHandle:

src/widgets/editor/pixels_movement.h

@@ -41,7 +41,8 @@ public:
     NormalMovement = 1,
     SnapToGridMovement = 2,
     AngleSnapMovement = 4,
-    MaintainAspectRatioMovement = 8
+    MaintainAspectRatioMovement = 8,
+    LockAxisMovement = 16
   };
 
   // The "moveThis" image specifies the chunk of pixels to be moved.