我只是为了好玩而使用虚拟桌面与朋友一起玩Magic The Gathering 。我使用的是 Delphi 2010。卡片在应用程序中由TImage组件表示（加载从数据库加载的卡片的 PNG 文件）。这里的重点是，在 MTG 中，一个非常常见的做法是点击一张牌（将其向右旋转 90 度）。有一种简单的方法可以做到这一点吗？我真的不需要“动画”，只需单击旋转一次的卡片（动画会很好）。游戏应该与许多卡片同时工作，并且它们可以在表格中的任何位置移动。我正在考虑在数据库中点击和取消点击卡片的图像，但如果有一种很好且有效的方式来旋转卡片，这可能是一种矫枉过正的做法。
有任何想法吗？
这样做的老式方法是使用PlgBlt。
procedure RotateBitmap90CW(b1,b2:TBitmap);
var
x,y:integer;
p:array[0..2] of TPoint;
begin
x:=b1.Width;
y:=b1.Height;
b2.Width:=y;
b2.Height:=x;
p[0].X:=y;
p[0].Y:=0;
p[1].X:=y;
p[1].Y:=x;
p[2].X:=0;
p[2].Y:=0;
PlgBlt(b2.Canvas.Handle,p,b1.Canvas.Handle,0,0,x,y,0,0,0);
end;
或者您可以离开TImage并使用例如TPaintBox和 GDI+ 库。GDI+ 有 RotateFlip直接执行此操作的方法。使用GDI+ Library for Delphi它看起来像：
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, ExtCtrls, ActiveX, GDIPOBJ, GDIPAPI;
type
TForm1 = class(TForm)
Button1: TButton;
PaintBox1: TPaintBox;
procedure FormCreate(Sender: TObject);
procedure FormDestroy(Sender: TObject);
procedure Button1Click(Sender: TObject);
procedure PaintBox1Paint(Sender: TObject);
private
FImage: TGPImage;
public
{ Public declarations }
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
procedure TForm1.FormCreate(Sender: TObject);
var
Stream: IStream;
BlobStream: TMemoryStream;
begin
BlobStream := TMemoryStream.Create;
try
// assuming the BlobStream here has a valid image loaded from a database
Stream := TStreamAdapter.Create(BlobStream);
FImage := TGPImage.Create(Stream);
finally
BlobStream.Free;
end;
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
FImage.Free;
end;
procedure TForm1.Button1Click(Sender: TObject);
begin
FImage.RotateFlip(Rotate90FlipNone);
PaintBox1.Invalidate;
end;
procedure TForm1.PaintBox1Paint(Sender: TObject);
begin
with TGPGraphics.Create(PaintBox1.Canvas.Handle) do
try
DrawImage(FImage, 0, 0);
finally
Free;
end;
end;
end.
如此矫枉过正，不是吗:-？
您可以使用 TPaintBox 而不是 TImage 并使用带有旋转矩阵的 SetWorldTransform 来绘制被点击的卡片。我为此使用 StretchDrawRotated：
procedure XForm_SetRotation(out AXForm: TXForm; AAngle: Extended; ACenter: TPoint);
var
SinA, CosA: Extended;
begin
SinCos(AAngle, SinA, CosA);
AXForm.eM11 := CosA;
AXForm.eM12 := SinA;
AXForm.eM21 := -SinA;
AXForm.eM22 := CosA;
AXForm.eDx := (ACenter.X - (CosA * ACenter.X)) + ((SinA * ACenter.Y));
AXForm.eDy := (ACenter.Y - (SinA * ACenter.X)) - ((CosA * ACenter.Y));
end;
procedure StretchDrawRotated(ACanvas: TCanvas; const ARect: TRect; AAngle: Extended; ACenter: TPoint; AGraphic: TGraphic);
var
XForm, XFormOld: TXForm;
GMode: Integer;
begin
GMode := SetGraphicsMode(ACanvas.Handle, GM_ADVANCED);
try
if GetWorldTransform(ACanvas.Handle, XFormOld) then
try
XForm_SetRotation(XForm, AAngle, ACenter);
SetWorldTransform(ACanvas.Handle, XForm);
ACanvas.StretchDraw(ARect, AGraphic);
finally
SetWorldTransform(ACanvas.Handle, XFormOld);
end;
finally
SetGraphicsMode(ACanvas.Handle, GMode);
end;
end;
您还可以使用 Graphics32 库或我前段时间从 CodeCentral 获取的这个函数：
{by Gustavo Daud (Submited on 21 May 2006 )
Use this method to rotate RGB and RGB Alpha 'Portable Network Graphics' Images using a smooth antialiased algorithm in order to get much better results.
Note: Part of this code was based on JansFreeware code [http://jansfreeware.com/]
This is only possible when using the 1.56 library version.}
{Smooth rotate a png object}
procedure SmoothRotate(var aPng: TPNGImage; Angle: Extended);
{Supporting functions}
function TrimInt(i, Min, Max: Integer): Integer;
begin
if i>Max then Result:=Max
else if i<Min then Result:=Min
else Result:=i;
end;
function IntToByte(i:Integer):Byte;
begin
if i>255 then Result:=255
else if i<0 then Result:=0
else Result:=i;
end;
function Min(A, B: Double): Double;
begin
if A < B then Result := A else Result := B;
end;
function Max(A, B: Double): Double;
begin
if A > B then Result := A else Result := B;
end;
function Ceil(A: Double): Integer;
begin
Result := Integer(Trunc(A));
if Frac(A) > 0 then
Inc(Result);
end;
{Calculates the png new size}
function newsize: tsize;
var
fRadians: Extended;
fCosine, fSine: Double;
fPoint1x, fPoint1y, fPoint2x, fPoint2y, fPoint3x, fPoint3y: Double;
fMinx, fMiny, fMaxx, fMaxy: Double;
begin
{Convert degrees to radians}
fRadians := (2 * PI * Angle) / 360;
fCosine := abs(cos(fRadians));
fSine := abs(sin(fRadians));
fPoint1x := (-apng.Height * fSine);
fPoint1y := (apng.Height * fCosine);
fPoint2x := (apng.Width * fCosine - apng.Height * fSine);
fPoint2y := (apng.Height * fCosine + apng.Width * fSine);
fPoint3x := (apng.Width * fCosine);
fPoint3y := (apng.Width * fSine);
fMinx := min(0,min(fPoint1x,min(fPoint2x,fPoint3x)));
fMiny := min(0,min(fPoint1y,min(fPoint2y,fPoint3y)));
fMaxx := max(fPoint1x,max(fPoint2x,fPoint3x));
fMaxy := max(fPoint1y,max(fPoint2y,fPoint3y));
Result.cx := ceil(fMaxx-fMinx);
Result.cy := ceil(fMaxy-fMiny);
end;
type
TFColor = record b,g,r:Byte end;
var
Top, Bottom, Left, Right, eww,nsw, fx,fy, wx,wy: Extended;
cAngle, sAngle: Double;
xDiff, yDiff, ifx,ify, px,py, ix,iy, x,y, cx, cy: Integer;
nw,ne, sw,se: TFColor;
anw,ane, asw,ase: Byte;
P1,P2,P3:Pbytearray;
A1,A2,A3: pbytearray;
dst: TPNGImage;
IsAlpha: Boolean;
new_colortype: Integer;
begin
{Only allows RGB and RGBALPHA images}
if not (apng.Header.ColorType in [COLOR_RGBALPHA, COLOR_RGB]) then
raise Exception.Create('Only COLOR_RGBALPHA and COLOR_RGB formats' +
' are supported');
IsAlpha := apng.Header.ColorType in [COLOR_RGBALPHA];
if IsAlpha then new_colortype := COLOR_RGBALPHA else
new_colortype := COLOR_RGB;
{Creates a copy}
dst := tpngobject.Create;
with newsize do
dst.createblank(new_colortype, 8, cx, cy);
cx := dst.width div 2; cy := dst.height div 2;
{Gather some variables}
Angle:=angle;
Angle:=-Angle*Pi/180;
sAngle:=Sin(Angle);
cAngle:=Cos(Angle);
xDiff:=(Dst.Width-apng.Width)div 2;
yDiff:=(Dst.Height-apng.Height)div 2;
{Iterates over each line}
for y:=0 to Dst.Height-1 do
begin
P3:=Dst.scanline[y];
if IsAlpha then A3 := Dst.AlphaScanline[y];
py:=2*(y-cy)+1;
{Iterates over each column}
for x:=0 to Dst.Width-1 do
begin
px:=2*(x-cx)+1;
fx:=(((px*cAngle-py*sAngle)-1)/ 2+cx)-xDiff;
fy:=(((px*sAngle+py*cAngle)-1)/ 2+cy)-yDiff;
ifx:=Round(fx);
ify:=Round(fy);
{Only continues if it does not exceed image boundaries}
if(ifx>-1)and(ifx<apng.Width)and(ify>-1)and(ify<apng.Height)then
begin
{Obtains data to paint the new pixel}
eww:=fx-ifx;
nsw:=fy-ify;
iy:=TrimInt(ify+1,0,apng.Height-1);
ix:=TrimInt(ifx+1,0,apng.Width-1);
P1:=apng.scanline[ify];
P2:=apng.scanline[iy];
if IsAlpha then A1 := apng.alphascanline[ify];
if IsAlpha then A2 := apng.alphascanline[iy];
nw.r:=P1[ifx*3];
nw.g:=P1[ifx*3+1];
nw.b:=P1[ifx*3+2];
if IsAlpha then anw:=A1[ifx];
ne.r:=P1[ix*3];
ne.g:=P1[ix*3+1];
ne.b:=P1[ix*3+2];
if IsAlpha then ane:=A1[ix];
sw.r:=P2[ifx*3];
sw.g:=P2[ifx*3+1];
sw.b:=P2[ifx*3+2];
if IsAlpha then asw:=A2[ifx];
se.r:=P2[ix*3];
se.g:=P2[ix*3+1];
se.b:=P2[ix*3+2];
if IsAlpha then ase:=A2[ix];
{Defines the new pixel}
Top:=nw.b+eww*(ne.b-nw.b);
Bottom:=sw.b+eww*(se.b-sw.b);
P3[x*3+2]:=IntToByte(Round(Top+nsw*(Bottom-Top)));
Top:=nw.g+eww*(ne.g-nw.g);
Bottom:=sw.g+eww*(se.g-sw.g);
P3[x*3+1]:=IntToByte(Round(Top+nsw*(Bottom-Top)));
Top:=nw.r+eww*(ne.r-nw.r);
Bottom:=sw.r+eww*(se.r-sw.r);
P3[x*3]:=IntToByte(Round(Top+nsw*(Bottom-Top)));
{Only for alpha}
if IsAlpha then
begin
Top:=anw+eww*(ane-anw);
Bottom:=asw+eww*(ase-asw);
A3[x]:=IntToByte(Round(Top+nsw*(Bottom-Top)));
end;
end;
end;
end;
apng.assign(dst);
dst.free;
end;
上面已经提到了 Graphics32 库。
我想再提一个好的图书馆，Vampyre Imaging