Debug and improve arrows drawing

src/game_tab/left_panel/board/BoardCanvas.cpp

@@ -3,8 +3,10 @@
 #define TRANS(PT) { \
 wxPoint2DDouble tmp((PT).x,(PT).y); \
 tmp=rot_m.TransformPoint(tmp); \
-tmp=trans_m.TransformPoint(tmp); \
+(PT).x=tmp.m_x+xsrc;(PT).y=tmp.m_y+ysrc;}
-(PT).x=tmp.m_x;(PT).y=tmp.m_y;}
+
+#define TRANS2(PT) { \
+(PT).x+=xsrc;(PT).y+=ysrc;}
 
 wxDEFINE_EVENT(PLAY_MOVE_EVENT, wxCommandEvent);
 
@@ -140,6 +142,7 @@ void BoardCanvas::SetupBoard(const GameState &new_gs) {
   gs.black_time=new_gs.black_time;
   gs.white_time=new_gs.white_time;
   gs.squares_hl=new_gs.squares_hl;
+  gs.arrows=new_gs.arrows;
   Refresh();
 }
 
@@ -155,7 +158,7 @@ void BoardCanvas::Animate(const GameState &new_gs, const std::string &src, const
 
   // Now compute piece start position and translation vector
   std::uint32_t centrer_offset = (square_width - piece_width) / 2;
-    if (!black_side) {
+  if (!black_side) {
         prank = 7 - prank;
         pfile = 7 - pfile;
   }
@@ -393,6 +396,35 @@ void BoardCanvas::DrawBoard(wxDC &dc) {
     dc.DrawText(time, wxPoint(boardX + square_width * 8 - width,
                               boardY + square_width * 8 + numbers_size.y*2));
   }
+  // Draw arrows
+  for(const std::string arrow: gs.arrows){
+    std::uint8_t sfile = arrow[0]-'a';
+    std::uint8_t srank = arrow[1]-'1';
+    std::uint8_t dfile = arrow[2]-'a';
+    std::uint8_t drank = arrow[3]-'1';
+    if (!black_side) {
+      srank = 7 - srank;
+      sfile = 7 - sfile;
+      drank = 7 - drank;
+      dfile = 7 - dfile;
+    }
+    std::uint32_t sx = boardX + (7 - sfile) * square_width + square_width/2;
+    std::uint32_t sy = boardY + srank * square_width + square_width/2;
+    std::uint32_t dx = boardX + (7 - dfile) * square_width + square_width/2;
+    std::uint32_t dy = boardY + drank * square_width + square_width/2;
+
+    if(((abs(drank-srank) == 2) && (abs(dfile-sfile) == 1))||
+    ((abs(drank-srank) == 1) && (abs(dfile-sfile) == 2))){
+      if(abs(drank-srank) == 1){
+        DrawLArrow(dc,sx,sy,dx,dy);
+      }
+      else {
+        DrawLArrow(dc,sx,sy,dx,dy,true);
+      }
+    } else {
+      DrawArrow(dc,sx,sy,dx,dy);
+    }
+  }
 }
 
 void BoardCanvas::MouseEvent(wxMouseEvent &event) {
@@ -472,7 +504,7 @@ void BoardCanvas::SetClockTime(short hours, short min, short sec,
 void BoardCanvas::DrawArrow(wxDC &dc, int xsrc, int ysrc, int xdst, int ydst){
   // Compute arrow length and angle
   wxPoint vect(xdst-xsrc,ydst-ysrc);
-  double length=sqrt(pow(vect.x,2)+pow(vect.y,2));
+  double length=ceil(sqrt(pow(vect.x,2)+pow(vect.y,2)));
   double angle=acos(vect.x/length);
 
   // Compute metrics
@@ -481,9 +513,8 @@ void BoardCanvas::DrawArrow(wxDC &dc, int xsrc, int ysrc, int xdst, int ydst){
   std::uint32_t tail_length=length-tip_height;
 
   // Setup transform matrix
-  wxAffineMatrix2D rot_m,trans_m;
+  wxAffineMatrix2D rot_m;
-  rot_m.Rotate(angle);
+  rot_m.Rotate(-angle);
-  trans_m.Translate(xsrc,ysrc);
 
   // Init polygons
   wxPoint tip[]={wxPoint(tail_length,-thickness/2),wxPoint(tail_length,thickness/2),wxPoint(tail_length+tip_height,0)};
@@ -499,3 +530,58 @@ void BoardCanvas::DrawArrow(wxDC &dc, int xsrc, int ysrc, int xdst, int ydst){
   dc.DrawPolygon(3,tip);
   dc.DrawPolygon(4,tail);
 }
+
+void BoardCanvas::DrawLArrow(wxDC &dc, int xsrc, int ysrc, int xdst, int ydst, bool flip){
+  double X=xdst-xsrc;
+  double Y=ydst-ysrc;
+
+  // Check if L arrows are required
+  if(X==0 || Y==0){
+    DrawArrow(dc, xsrc, ysrc, xdst, ydst);
+    return;
+  }
+
+  if(flip){
+    // Compute metrics
+    std::uint8_t thickness=50;
+    double tip_height=sqrt(3)/2*thickness;
+    double yoffset=Y<0 ? -thickness/4 : thickness/4; // Y tail should be longer to form a right angle (corner of tail joins)
+    if(X<0){tip_height=-tip_height;}
+    wxPoint tip[]={wxPoint(X-tip_height,-thickness/2+Y),wxPoint(X,Y),wxPoint(X-tip_height,thickness/2+Y)};
+    wxPoint tail1[]={wxPoint(-thickness/4,0),wxPoint(thickness/4,0),wxPoint(thickness/4,Y+yoffset),wxPoint(-thickness/4,Y+yoffset)};
+    wxPoint tail2[]={wxPoint(0,Y-thickness/4),wxPoint(X-tip_height,Y-thickness/4),wxPoint(X-tip_height,Y+thickness/4),wxPoint(0,Y+thickness/4)};
+
+    // Apply transforms
+    TRANS2(tip[0]);TRANS2(tip[1]);TRANS2(tip[2]);
+    TRANS2(tail1[0]);TRANS2(tail1[1]);TRANS2(tail1[2]);TRANS2(tail1[3]);
+    TRANS2(tail2[0]);TRANS2(tail2[1]);TRANS2(tail2[2]);TRANS2(tail2[3]);
+
+    // Draw
+    dc.SetPen(wxNullPen);
+    dc.SetBrush(wxColour(255,0,0));
+    dc.DrawPolygon(4,tail1);
+    dc.DrawPolygon(4,tail2);
+    dc.DrawPolygon(3,tip);
+  } else {
+    // Compute metrics
+    std::uint8_t thickness=50;
+    double tip_height=sqrt(3)/2*thickness;
+    double xoffset=X<0 ? -thickness/4 : thickness/4; // Y tail should be longer to form a right angle (corner of tail joins)
+    if(Y<0){tip_height=-tip_height;}
+    wxPoint tip[]={wxPoint(-thickness/2 + X,Y-tip_height),wxPoint(thickness/2 + X ,Y-tip_height),wxPoint(X,Y)};
+    wxPoint tail1[]={wxPoint(0,-thickness/4),wxPoint(X+xoffset,-thickness/4),wxPoint(X+xoffset,thickness/4),wxPoint(0,thickness/4)};
+    wxPoint tail2[]={wxPoint(X-thickness/4,0),wxPoint(X+thickness/4,0),wxPoint(X+thickness/4,Y-tip_height),wxPoint(X-thickness/4,Y-tip_height)};
+
+    // Apply transforms
+    TRANS2(tip[0]);TRANS2(tip[1]);TRANS2(tip[2]);
+    TRANS2(tail1[0]);TRANS2(tail1[1]);TRANS2(tail1[2]);TRANS2(tail1[3]);
+    TRANS2(tail2[0]);TRANS2(tail2[1]);TRANS2(tail2[2]);TRANS2(tail2[3]);
+
+    // Draw
+    dc.SetPen(wxNullPen);
+    dc.SetBrush(wxColour(255,0,0));
+    dc.DrawPolygon(4,tail1);
+    dc.DrawPolygon(4,tail2);
+    dc.DrawPolygon(3,tip);
+  }
+}

src/game_tab/left_panel/board/BoardCanvas.hpp

@@ -64,6 +64,7 @@ typedef struct GameState {
   std::string board;
   std::map<char, std::uint8_t> captures;
   std::vector<std::string> squares_hl;
+  std::vector<std::string> arrows;
   bool is_black_turn;
   bool mat_black;
   bool mat_white;
@@ -93,6 +94,8 @@ class BoardCanvas : public wxPanel {
 
   /// @brief Draw an arrow from a source point to a destination point on DC
   void DrawArrow(wxDC &dc, int xsrc, int ysrc, int xdst, int ydst);
+  /// @brief Draw an arrow with a L shape (such as knight moves)
+  void DrawLArrow(wxDC &dc, int xsrc, int ysrc, int xdst, int ydst, bool flip=false);
 
 public:
   BoardCanvas(wxFrame *parent);