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How to find the rotation direction(TRotateImage)
Posted:
September 10th, 2006, 1:25 pmby Donnie
I am using the RotateImage Component for my program. It is useful and powerful component for dealing with a picture. But a problem occured in these days. I don't know how to find the status of the rotation (CW or CCW) when the picture is operated. Can you give me some advice about it?
Posted:
September 11th, 2006, 9:51 amby Kambiz
Increasing angle, rotates the image in CCW.
Posted:
September 11th, 2006, 10:19 amby Donnie
I think it is difficult to know the direction if you just compare the original angle to the new angle (refer to below programe). You know the minus and plus value will be occured. Maybe, I don't understand your meaning very well. Could you explain it in detail for me. Thanks a lot.
if Dragging then
begin
if X = RotateImage1.Width / 2 then
if Y < RotateImage1.Height / 2 then
Theta := Pi / 2
else
Theta := -Pi / 2
else
Theta := ArcTan2(Y - RotateImage1.Height / 2, X - RotateImage1.Width / 2);
Angle := StartAngle + 180 * (StartTheta - Theta) / Pi;
TrackBar1.Position := Trunc(Angle * 10) mod 3600;
TrackBar1Change(Self);
end;