Get a transparent area of ​​the picture

(* //

Title: Make a picture of the picture

Description: Applicable to making complex irregularities

Design: zswang

Support: wjhu111@21cn.com

Date: 2004-03-10

// *)

(* / / ================================================================================================================================================================================ ===============================

Design Idea: ~~

It is a scan for the canvas and one line ~~

For pixels that are not transparent, they see a line segment ~~

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Use these line segments into irregular areas ~~

The line segment is to find the starting position and the end position.

The combination area is the time-spent place ~~

Reduce the frequency of the combination area to improve the speed of operation ~~

The combination of line segments is more than the point combination ~~

============================================================================================================================================================================================================= ========================== // *)

Function graphictorgn (Mgraphic: Tgraphic; MTRANSPOINT: TPOINT): HRGN;

VAR

I, J: Integer;

vStart: integer;

Vhandle: hrgn;

VTRANSCOLOR: TCOLOR;

Begin

Result: = 0;

IF NOT ASSIGNED (MGRAPHIC) THEN EXIT

Result: = CreateRectrGN (0, 0, 0, 0);

With Tbitmap.create Do Try

Width: = mgraphic.width;

Height: = mgraphic.height;

Canvas.draw (0, 0, mgraphic);

VTRANSCOLOR: = Canvas.pixels [MTRANSPOINT.X, MTRANSPOINT.Y];

For i: = 0 to Height - 1 Do Begin

vStart: = 0;

For j: = 0 to width do beginif (canvas.pixels [j, i] <> vTranscolor) and (j

IF vStart <0 THEN

vStart: = j

Else

Else if vStart> = 0 THEN Begin

vhandle: = CreateRectrGN (vStart, i, J, I 1);

Try

Combinergn (Result, Result, Vhandle, RGN_OR);

Finally

DeleteObject (vhandle);

END;

vStart: = -1;

END;

END;

END;

Finally

FREE;

END;

End; {graphictorgn}

// esample

Procedure TFORM1.BUTTON1CLICK (Sender: TOBJECT);

VAR

VRGN: hrgn

Begin

Borderstyle: = bsnone;

Image1.left: = 0;

Image1.top: = 0;

VRGN: = graphictorgn (image1.picture.graphic, point (0, 0));

Try

SetwindowRgn (Handle, VRGN, TRUE);

Finally

DeleteObject (VRGN);

END;

END;