Add angle snap with Shift key to rotation.

data/gui.xml

@@ -165,6 +165,14 @@
       <!-- When you drag-and-drop the selection, pressing this
            keyboard shortcut you can copy instead of move -->
       <key action="CopySelection" shortcut="Ctrl" />
+
+      <!-- When you move the selection, pressing this
+           keyboard shortcut you can snap to grid -->
+      <key action="SnapToGrid" shortcut="Shift" />
+
+      <!-- When you rotate the selection, pressing this
+           keyboard shortcut you activate angle snap -->
+      <key action="AngleSnap" shortcut="Shift" />
     </spriteeditor>
 
   </keyboard>

src/modules/editors.cpp

@@ -128,6 +128,22 @@ public:
       return false;
   }
 
+  bool isSnapToGridKeyPressed() OVERRIDE {
+    JAccel accel = get_accel_to_snap_to_grid();
+    if (accel)
+      return jaccel_check_from_key(accel);
+    else
+      return false;
+  }
+
+  bool isAngleSnapKeyPressed() OVERRIDE {
+    JAccel accel = get_accel_to_angle_snap();
+    if (accel)
+      return jaccel_check_from_key(accel);
+    else
+      return false;
+  }
+
 };
 
 class MiniEditor : public Editor

src/modules/gui.cpp

@@ -65,6 +65,8 @@
 #define MONITOR_TIMER_MSECS     100
 
 #define SPRITEDITOR_ACTION_COPYSELECTION "CopySelection"
+#define SPRITEDITOR_ACTION_SNAPTOGRID    "SnapToGrid"
+#define SPRITEDITOR_ACTION_ANGLESNAP     "AngleSnap"
 
 //////////////////////////////////////////////////////////////////////
 
@@ -939,6 +941,24 @@ JAccel get_accel_to_copy_selection()
     return NULL;
 }
 
+JAccel get_accel_to_snap_to_grid()
+{
+  Shortcut* shortcut = get_keyboard_shortcut_for_spriteeditor(SPRITEDITOR_ACTION_SNAPTOGRID);
+  if (shortcut)
+    return shortcut->accel;
+  else
+    return NULL;
+}
+
+JAccel get_accel_to_angle_snap()
+{
+  Shortcut* shortcut = get_keyboard_shortcut_for_spriteeditor(SPRITEDITOR_ACTION_ANGLESNAP);
+  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

@@ -116,6 +116,8 @@ Command* get_command_from_key_message(Message* msg);
 JAccel get_accel_to_execute_command(const char* command, Params* params = NULL);
 JAccel get_accel_to_change_tool(tools::Tool* tool);
 JAccel get_accel_to_copy_selection();
+JAccel get_accel_to_snap_to_grid();
+JAccel get_accel_to_angle_snap();
 
 tools::Tool* get_selected_quicktool(tools::Tool* currentTool);
 

src/widgets/editor/editor_customization_delegate.h

@@ -39,6 +39,14 @@ public:
   // Returns true if the user wants to copy the selection instead of
   // to move it.
   virtual bool isCopySelectionKeyPressed() = 0;
+
+  // Returns true if the user wants to snap to grid when he's moving
+  // the selection.
+  virtual bool isSnapToGridKeyPressed() = 0;
+
+  // Returns true if the user wants to activate angle snap, so he can
+  // easily specify common angles (45, 90, 135, 180, etc.).
+  virtual bool isAngleSnapKeyPressed() = 0;
 };
 
 #endif  // WIDGETS_EDITOR_CUSTOMIZATION_DELEGATE_H_INCLUDED

src/widgets/editor/moving_pixels_state.cpp

@@ -187,8 +187,13 @@ bool MovingPixelsState::onMouseMove(Editor* editor, Message* msg)
     int x, y;
     editor->screenToEditor(msg->mouse.x, msg->mouse.y, &x, &y);
 
+    PixelsMovement::MoveModifier moveModifier = PixelsMovement::NormalMovement;
+
+    if (editor->getCustomizationDelegate()->isAngleSnapKeyPressed())
+      moveModifier = PixelsMovement::AngleSnapMovement;
+
     // Drag the image to that position
-    gfx::Rect bounds = m_pixelsMovement->moveImage(x, y);
+    gfx::Rect bounds = m_pixelsMovement->moveImage(x, y, moveModifier);
 
     // If "bounds" is empty is because the cel was not moved
     if (!bounds.isEmpty()) {

src/widgets/editor/pixels_movement.cpp

@@ -148,7 +148,7 @@ void PixelsMovement::maskImage(const Image* image, int x, int y)
   update_screen_for_document(m_documentReader);
 }
 
-gfx::Rect PixelsMovement::moveImage(int x, int y)
+gfx::Rect PixelsMovement::moveImage(int x, int y, MoveModifier moveModifier)
 {
   DocumentWriter documentWriter(m_documentReader);
   Image* image = documentWriter->getExtraCelImage();
@@ -241,6 +241,32 @@ gfx::Rect PixelsMovement::moveImage(int x, int y)
           - atan2((double)(-m_catchY + abs_initial_pivot.y),
                   (double)(+m_catchX - abs_initial_pivot.x));
 
+        // Put the angle in -180 to 180 range.
+        while (newAngle < -PI) newAngle += 2*PI;
+        while (newAngle > PI) newAngle -= 2*PI;
+
+        // Is the "angle snap" is activated, we've to snap the angle
+        // to common (pixel art) angles.
+        if ((moveModifier & AngleSnapMovement) == AngleSnapMovement) {
+          // TODO make this configurable
+          static const double keyAngles[] = {
+            0.0, 26.565, 45.0, 63.435, 90.0, 116.565, 135.0, 153.435, -180.0,
+            180.0, -153.435, -135.0, -116, -90.0, -63.435, -45.0, -26.565
+          };
+
+          double newAngleDegrees = 180.0 * newAngle / PI;
+
+          int closest = 0;
+          int last = sizeof(keyAngles) / sizeof(keyAngles[0]) - 1;
+          for (int i=0; i<=last; ++i) {
+            if (std::fabs(newAngleDegrees-keyAngles[closest]) >
+                std::fabs(newAngleDegrees-keyAngles[i]))
+              closest = i;
+          }
+
+          newAngle = PI * keyAngles[closest] / 180.0;
+        }
+
         m_currentData.angle(newAngle);
       }
       break;

src/widgets/editor/pixels_movement.h

@@ -36,6 +36,12 @@ class Sprite;
 class PixelsMovement
 {
 public:
+  enum MoveModifier {
+    NormalMovement = 1,
+    SnapToGridMovement = 2,
+    AngleSnapMovement = 4
+  };
+
   // The "moveThis" image specifies the chunk of pixels to be moved.
   // The "x" and "y" parameters specify the initial position of the image.
   PixelsMovement(Document* document, Sprite* sprite, const Image* moveThis, int x, int y, int opacity,
@@ -54,7 +60,7 @@ public:
   // Moves the image to the new position (relative to the start
   // position given in the ctor). Returns the rectangle that should be
   // redrawn.
-  gfx::Rect moveImage(int x, int y);
+  gfx::Rect moveImage(int x, int y, MoveModifier moveModifier);
 
   void dropImageTemporarily();
   void dropImage();