Simple implementation of drawing curve in Window drawing program
Below is a very prior program, mimic the drawing curve in the drawing program of Windows. In fact, the principle is simple, it is a Polybezier function. That interested can be packaged into a class, which is convenient to use .unit unit1;
Interface
Uses Windows, Messages, Sysutils, Variants, Classes, Graphics, Controls, Forms, Dialogs, Stdctrls;
type TStep = (sStartEnd, sCtrl1, sCtrl2); TForm1 = class (TForm) Button1: TButton; procedure FormCreate (Sender: TObject); procedure FormMouseDown (Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer) ; procedure FormMouseMove (Sender: TObject; Shift: TShiftState; X, Y: Integer); procedure FormMouseUp (Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer); procedure FormPaint (Sender: TObject); private {Private Declarations}}: boolean; osok: boolean; // Identify whether the reach of the Bezier line completes Step: tstep; / / indication StartP: tpoint; // The following is the four point coordinate ENDP: TPOINT; CTRP1 : Tpoint; ctrp2: tpoint; public {public declarations}
Var Form1: TFORM1;
IMPLEMENTATION
{$ R * .dfm}
Procedure TForm1.FormCreate (Sender: TOBJECT); begin self.doublebuffered: = true; isdown: = false; step: = sstartend; isok: = false;
procedure TForm1.FormMouseDown (Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer); begin isDown: = true; if Button = mbLeft then begin if (Step = sStartEnd) then begin StartP.X: = X Startp.y: = Y; ENDP: = Point (x, y); ISOK: = false; end else if (step = sctrl1) THEN BEGIN CTRP1: = Point (x, y); ctrp2: = Point (x, Y); ELSE IF (Step = sctrl2) THEN BEGIN CTRP2: = POINT (X, Y); END; END;
Procedure TForm1.FormMousemove (Sender: Tobject; Shift: TshiftState; x, y: integer); begin if isdown and (shift = [ssleft) THEN BEGIN ENDP.X: = X; ENDP. Y: = Y; Else if step = sctr1 the begin Ctrp1: = Point (x, y); ctrp2: = Point (x, y); end else if (step = sctrl2) Then Begin Ctrp2: = Point (x, Y); end; self.Invalidate; end; end; procedure TForm1.FormMouseUp (Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer); begin if isDown and (Button = mbLeft) then begin isDown: = False; if step: = sctrl1 else if step = sctrl1 dam: = sctrl2 else if step = sctrl2 The begin: = SSTARTEND; ISOK: = TRUE; END; END;
Procedure TForm1.FormPaint (Sender: TOBJECT); Begin if not isok the beginning of step = sstartnd the beginning, self.canvas.moveto (startp.x, startp.y); self.canvas.lineto (Endp.x, endp.y ); Else Begin Self.canvas.Polybezier ([StartP, CTRP1, CTRP2, ENDP]); End; Else Begin Self.canvas.Polybezier ([StartP, CTRP1, CTRP2, ENDP]); END;
End.
Author Blog:
http://blog.9cbs.net/linzhenngqun/
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