知识大全 创建除三角形外的各种形状窗体

Posted 2022-07-21 知

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　　Is it possible to create forms with shapes other than the standard rectangular shape in Windows? 　　Sometimes it s just not enough to write applications that have the same boring rectangular forms over and over again Sometimes you need a change How about an elliptical form? Or maybe even a triangular form? Sound intriguing? It s not that hard to do

　　New in Win is something called a region The Win API Programmer s Reference defines a region as follows:

　　 a rectangle polygon or ellipse (or a bination of o or more of these shapes) that can be filled painted inverted framed and used to perform hit testing (testing for the cursor location)

　　From the definition the most notable thing about a region is that it can be manipulated in a variety of ways For our purposes we want to define a region to create a specific shape

　　I should point out that a region can be defined for just about any inControl descendant (not just forms) meaning you can apply a region to a TPanel or even a TEdit (though I strongly remend against it) But to alter the shape of a inControl descendant all you need to provide is a handle and employ some handy dandy shape change functions

　　To get a control to change its shape follow this o step process:

　　*　Define the boundaries of the region that represent a particular shape 　　*　Apply the boundaries you ve defined to a window 　　This is pretty simple However it s very important to refer to the help file and to have the source at hand I wouldn t be able to acplish many of my projects let alone write many of the articles I write here without those o resources at my disposal Especially with the Windows API calls having access to the Window PAS file is essential so I know what to pass into the functions Remember the WinAPI calls are really wrapper calls into the appropriate Windows DLLs and of course the help file is essential to getting background information on the topic you re interested in 　　With respect to this article look up the SetWindowRgn topic in Win Developer s Help and have it handy while you re putting together your program Pay particular attention to the Group hyperlink because it will give you a run down of all the procedures related to the region topic Let s move on! 　　Defining a Region s Boundary　　The first step to creating a form of a different shape is to define the shape itself For our discussion we ll use three WinAPI calls:

　　*　CreateEllipticRgn 　　This function will create an elliptically shaped region 　　*　CreateRoundRectRgn 　　This will create a rectangular region with rounded corners 　　*　CreatePolygonRgn 　　This will create just about any multi sided shape as long as the lines form a closed solid

　　These functions return a HRGN type which will then be used by a function called SetWindowRgn whose sole purpose in life it is to set the parameters defined by a particular region variable I ve encapsulated these functions in methods that are part of a demonstration form The functions are coded as follows:   Notice that all the functions are used in an assignment   operation to a variable called rgn This is a   private var that I declared for the form The private var is   accessible to all functions; I did this so that I could change the shape of   the form or a control on the form and use the same region

procedure TForm DrawEllipticRegion(wnd : HWND; rect : TRect);begin  rgn := CreateEllipticRgn(rect left rect top rect right rect bottom);  SetWindowRgn(wnd rgn TRUE);end;

procedure TForm DrawRndRectRegion(wnd : HWND; rect : TRect);begin  rgn := CreateRoundRectRgn(rect left rect top rect right rect bottom );  SetWindowRgn(wnd rgn TRUE);end;

procedure TForm DrawPolygonRegion(wnd : HWND; rect : TRect; NumPoints : Integer; DoStarShape : Boolean);const  RadConvert = PI/ ;  Degrees    = ;  MaxLines   = ;var  x y   xCenter   yCenter   radius   pts   I       : Integer;  angle   rotation: Extended;  arPts   : Array[ MaxLines] of TPoint;begin

  xCenter := (rect Right rect Left) div ;  yCenter := (rect Bottom rect Top) div ;  if DoStarShape then    begin      rotation := Degrees/( *NumPoints);      pts := * NumPoints;    end  else    begin      rotation := Degrees/NumPoints;             //get number of degrees to turn per point      pts := NumPoints    end;  radius := yCenter;

This loop defines the Cartesian points of the shape Notice I ve added degrees to the rotation angle This is so that shapes will stand up; otherwise they ll lie on their sides I had to brush up on my trigonometry to acplish this (fot all those sin and cos thingies) Many thanks to Terry Smithwick and David Ullrich for their assistance on CompuServe!   for I := to pts do begin    if DoStarShape then      if (I mod ) = then //which means that        radius := Round(radius/ )      else        radius := yCenter;

    angle := ((I * rotation) + ) * RadConvert;    x := xCenter + Round(cos(angle) * radius);    y := yCenter Round(sin(angle) * radius);    arPts[I] X := x;    arPts[I] Y := y;  end;

  rgn := CreatePolygonRgn(arPts pts WINDING);  SetWindowRgn(wnd rgn TRUE);end;

　　The first o functions are pretty simple just o liners All that s needed to create the appropriate shapes is a handle and a TRect structure For forms that structure would be taken from the ClientRect property; for other controls use the BoundsRect property

　　The DrawPolygonRegion method however is much more plex This is due in part to the fact that CreatePolygonRgn requires the vertices of the corners of the polygon to be passed as an array of TPoints and partly because I wanted to draw equilateral polygons based off points rotated around a mon center point For that I had to use some trigonometry

　　I wanted to not only draw polygon regions but stars as well Using rotational trig allowed me to do it The way the function works if the DrawStarShape parameter is set to True is that for every even value of I in the loop the radius of the circle is set to half its length and to maintain the number of points of the polygon I want to draw I double the number of points to acodate the contraction of the radius

　　At the very end of each function is a call to SetWindowRgn This function takes as parameters a window handle a rgn var and a Boolean value that specifies whether the window should be re drawn In all cases if you want to see the shape you ve made this must be always be set to True

　　Below is the listing for the entire source code of my test form On the form I ve dropped four TButtons (one for each of the shapes: ellipse round rectangle polygon and star); a TPanel to demonstrate the ability to set regions for inControl descendants other than TForm; and a SpinEdit used in conjunction with the Polygon and Star region buttons to define the number of points that ll be defining the shape Here s the code: unit regmain;

interface

uses  Windows Messages SysUtils Classes Graphics Controls Forms Dialogs   ExtCtrls StdCtrls Spin;

type  TForm = class(TForm)    Button : TButton;    Button : TButton;    Button : TButton;    SpinEdit : TSpinEdit;    Button : TButton;    Panel : TPanel;    Edit : TEdit;    procedure DrawRndRectRegion(wnd : HWND; rect : TRect);    procedure DrawEllipticRegion(wnd : HWND; rect : TRect);    procedure DrawPolygonRegion(wnd : HWND; rect : TRect; NumPoints : Integer; DoStarShape : Boolean);    procedure Button Click(Sender: TObject);    procedure Button Click(Sender: TObject);    procedure Button Click(Sender: TObject);    procedure Button Click(Sender: TObject);  private    Private declarations     rgn : HRGN;    rect : TRect;  public    Public declarations   end;

var  Form : TForm ;

implementation

$R * DFM

procedure TForm DrawRndRectRegion(wnd : HWND; rect : TRect);begin  rgn := CreateRoundRectRgn(rect left rect top rect right rect bottom );  SetWindowRgn(wnd rgn TRUE);end;

procedure TForm DrawEllipticRegion(wnd : HWND; rect : TRect);begin  rgn := CreateEllipticRgn(rect left rect top rect right rect bottom);  SetWindowRgn(wnd rgn TRUE);end;

procedure TForm DrawPolygonRegion(wnd : HWND; rect : TRect; NumPoints : Integer; DoStarShape : Boolean);const  RadConvert = PI/ ;  Degrees    = ;  MaxLines   = ;var  x y   xCenter   yCenter   radius   pts   I       : Integer;  angle   rotation: Extended;  arPts   : Array[ MaxLines] of TPoint;begin

  xCenter := (rect Right rect Left) div ;  yCenter := (rect Bottom rect Top) div ;  if DoStarShape then    begin      rotation := Degrees/( *NumPoints);      pts := * NumPoints;    end  else    begin      rotation := Degrees/NumPoints;             //get number of degrees to turn per point      pts := NumPoints    end;  radius := yCenter;

This loop defines the Cartesian points of the shape Again I ve added degrees to the rotation angle so the shapes will stand up rather than lie on their sides Thanks again to Terry Smithwick and David Ullrich for their trig help on CompuServe   for I := to pts do begin    if DoStarShape then      if (I mod ) = then //which means that        radius := Round(radius/ )      else        radius := yCenter;

    angle := ((I * rotation) + ) * RadConvert;    x := xCenter + Round(cos(angle) * radius);    y := yCenter Round(sin(angle) * radius);    arPts[I] X := x;    arPts[I] Y := y;  end;

  rgn := CreatePolygonRgn(arPts pts WINDING);  SetWindowRgn(wnd rgn TRUE);end;

procedure TForm Button Click(Sender: TObject);begin  DrawEllipticRegion(Form Handle Form ClientRect);end;

procedure TForm Button Click(Sender: TObject);begin  DrawPolygonRegion(Panel Handle Panel BoundsRect SpinEdit Value False);end;

procedure TForm Button Click(Sender: TObject);begin  DrawRndRectRegion(Form Handle Form ClientRect);end;

procedure TForm Button Click(Sender: TObject);begin  DrawPolygonRegion(Panel Handle Panel BoundsRect SpinEdit Value True);end;

end

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