Rotate Function for Component Drawed with Canvas Lazarus - freepascal

Question

I need a function in Lazarus that with it I can rotate some components instead of rewrite them (swapping x with y and viceversa)
for example:
i am using a class developed by another user
with this class i had to define the name of the component with properties and after a procedure NameComponent.Draw
the motedi engine draw the components reading this Draw procedure.
i save the components on a file sch (with also wires junction resistors etc)
when i load a circuit ...my software creates components (also wires junction) with saved properties (include points of connection where wire is attached)
wires has also node property
my software creates the netlist etc
procedure SW.Draw;
var angle:extended;
begin
if (self.Orientamento = '') or (self.Orientamento = '1') then
begin
v2d.setpen(pssolid,1,clBlue);
v2d.SetBrush(clwhite);
v2d.Line(x,y+30,x+100,y+30);
v2d.line(x,y+30,x,y+120);
v2d.line(x,y+120,x+100,y+120);
v2d.line(x+100,y+30,x+100,y+120);
v2d.line(x+20,y+30,x+20,y+10); // nc-
v2d.line(x+80,y+30,x+80,y+10); // nc+
v2d.line(x+20,y+120,x+20,y+140); // n-
v2d.line(x+80,y+120,x+80,y+140); // n+
// interruttore dentro
v2d.line(x+20,y+120,x+20,y+80); // a
v2d.line(x+80,y+120,x+80,y+80); // b
v2d.line(x+20,y+80,x+40,y+80); // c
v2d.line(x+60,y+80,x+80,y+80); // d
if (self.State = 'OFF') then
begin
v2d.setpen(pssolid,2,clGreen);
v2d.line(x+40,y+80,x+63,y+72); // e
end
else
begin
v2d.setpen(pssolid,2,clGreen);
v2d.line(x+40,y+80,x+60,y+80);
end;
v2d.setpen(pssolid,1,clBlue);
v2d.SetText(clRed, 6,'', true);
v2d.Texto(X+82, Y +110, 'N+');
v2d.Texto(X+74, Y +35, 'NC+');
v2d.SetText(clBlack, 6,'', true);
v2d.Texto(X+22, Y +110, 'N-');
v2d.Texto(X+15, Y +35, 'NC-');
v2d.SetText(clBlack, 8,'', true);
v2d.Texto(x+104,y+35, self.Nome);
v2d.Texto(x+104,y+50, self.VT);
v2d.Texto(x+104,y+65, self.VH);
v2d.Texto(x+104,y+80, self.RON);
v2d.Texto(x+104,y+95, self.ROFF);
end;
if (self.Orientamento = '2') then
begin
v2d.setpen(pssolid,1,clBlue);
v2d.SetBrush(clwhite);
v2d.line(x+30,y,x+30,y+100);
v2d.line(x+30,y,x+120,y);
v2d.line(x+120,y,x+120,y+100);
v2d.line(x+30,y+100,x+120,y+100);
v2d.line(x+30,y+20,x+10,y+20); // nc-
v2d.line(x+30,y+80,x+10,y+80); // nc +
v2d.line(x+120,y+20, x+140,y+20); // n-
v2d.line(x+120,y+80,x+140,y+80); // n+
v2d.line(x+120, y+20, x+80, y+20);
v2d.line(x+120,y+80,x+80,y+80);
v2d.line(x+80, y+20, x+80, y+40);
v2d.line(x+80, y+60, x+80, y+80);
if (self.State = 'OFF') then
begin
v2d.setpen(pssolid,2,clGreen);
// v2d.line(x+80, y+40, x+72, y+63);
v2d.line(x+80, y+60, x+72, y+37);
end
else
begin
v2d.setpen(pssolid,2,clGreen);
v2d.line(x+80,y+60, x+80, y+40);
// v2d.line(x+80, y+40, x+80, y+60);
end;
v2d.setpen(pssolid,1,clBlue);
v2d.SetText(clBlack, 6,'', true);
v2d.texto(x+110, y+82, 'N-');
v2d.texto(x+35, y+74, 'NC-');
v2d.SetText(clRed, 6,'', true);
v2d.Texto(x+110, y+22, 'N+');
v2d.Texto(x+35, y+15, 'NC+');
end;
inherited;
end;

Answer 1

In case you're asking for code, that's supports degrees instead of pre-defined values, here's an example, which uses Math PI to perform sectoral rotation of a point on 2-dimensional space:
function findCenter(Width, Height: Integer): TPoint;
begin
// Specify rotation center
Result := TPoint.Create(Width DIV 2, Height DIV 2);
end;
function Rotate(What, Center: TPoint; Angle: Double): TPoint; overload;
begin
if Angle > 0 then
begin
// Perform rotation
Result.X :=
ROUND(
Center.X + (What.X - Center.X)* COS(Angle)
- (What.Y - Center.Y)* SIN(Angle) );
Result.Y :=
ROUND(
Center.X + (What.X - Center.X)* SIN(Angle)
+ (What.Y - Center.Y)* COS(Angle) );
end
else
Result := TPoint.Create(What);
end;
function Rotate(What, Center: TPoint; Degrees: Integer): TPoint; overload;
var RotationAngle: Double;
begin
// Convert Degress to Radians
RotationAngle := Degrees * PI/180;
Result := Rotate(What, Center, RotationAngle);
end;
function Rotate(What: TPoint; Degrees: Integer): TPoint; overload;
var RotationAngle: Double;
begin
RotationAngle := Degrees * PI/180;
Result := Rotate(What, TPoint.Create(0,0), RotationAngle);
end;
Use the function Rotate() to rotate the location of your elements, for each of them you need to specify also a center of an element (Width and Height of parent element, divided by 2), information to get the center of element for text you can gather from WinAPI ( CalcTextWidth or CalcTextRect either )
The actual height of the text is the Font.Size - 1, so you can get Height value without external functions.
Note, that this probably won't work, if you're resizing your polygons, to resize them you need to calculate relations between every point or to split polygons to the triangles and do it for them (every n-heighted polygon can be splitted to triangles, the exception is ellipse, which has its own sizing technique - modifying the diameter ).
Also, be aware, that you must calculate new area sizes and positions offsets in order to keep final picture in field of view.