先写段代码再说。 procedure RotateImage(Bitmap:TBitmap;Angle:Real); {Bitmap： 要旋转的图像。 Angle: 要旋转的角度(弧度)。 } var tx0,ty1,x0,y0,x1,x2,y1,y2,r:Integer; tmpBitmap:TBitmap; x,y:Integer; begin tmpBitmap:=TBitmap.Create; x0:=Round(Bitmap.Width/2); y0:=Round(Biymap.Height/2); r:=Round(sqrt(x0*x0+y0*y0)); tx1:=Round(abs(r*Cos(Angle))); ty1:=Round(abs(r*Sin(Angle))); tmpBitmap.Width:=2*tx1; tmpBitmap.Height:=2*ty1; for y:=0 to Bitmap.Height-1 do begin for x:=0 to Bitmap.Width-1 do begin x1:=x-x0; y1:=y-y0; x2:=Round(x1*cos(Angle)-y1*sin(Angle))+tx1; y2:=Round(y1*sin(Angle)+x1*cos(Angle))+ty1; tmpBitmap.Canvas.Pixels[x2,y2]:=Bitmap.Canvas.Pixels[x,y]; end; end; Bitmap.Assign(tmpBitmap); tmpBitmap.Free; end; 由于在网吧上网，没有开发工具，无法调试，只是人为编译通过. ^_^;
明白你的意思了，如果在NT下，有现成API可用。PlgBltThe PlgBlt function performs a bit-block transfer of the bits of color data from the specified rectangle in the source device context to the specified parallelogram in the destination device context. If the given bitmask handle identifies a valid monochrome bitmap, the function uses this bitmap to mask the bits of color data from the source rectangle. BOOL PlgBlt( HDC hdcDest, // handle to destination DC CONST POINT *lpPoint, // destination vertices HDC hdcSrc, // handle to source DC int nXSrc, // x-coord of source upper-left corner int nYSrc, // y-coord of source upper-left corner int nWidth, // width of source rectangle int nHeight, // height of source rectangle HBITMAP hbmMask, // handle to bitmask int xMask, // x-coord of bitmask upper-left corner int yMask // y-coord of bitmask upper-left corner ); Parameters hdcDest [in] Handle to the destination device context. lpPoint [in] Pointer to an array of three points in logical space that identify three corners of the destination parallelogram. The upper-left corner of the source rectangle is mapped to the first point in this array, the upper-right corner to the second point in this array, and the lower-left corner to the third point. The lower-right corner of the source rectangle is mapped to the implicit fourth point in the parallelogram. hdcSrc [in] Handle to the source device context. nXSrc [in] Specifies the x-coordinate, in logical units, of the upper-left corner of the source rectangle. nYSrc [in] Specifies the y-coordinate, in logical units, of the upper-left corner of the source rectangle. nWidth [in] Specifies the width, in logical units, of the source rectangle. nHeight [in] Specifies the height, in logical units, of the source rectangle. hbmMask [in] Handle to an optional monochrome bitmap that is used to mask the colors of the source rectangle. xMask [in] Specifies the x-coordinate, in logical units, of the upper-left corner of the monochrome bitmap. yMask [in] Specifies the y-coordinate, in logical units, of the upper-left corner of the monochrome bitmap. Return Values If the function succeeds, the return value is nonzero.If the function fails, the return value is zero. Windows NT/2000/XP: To get extended error information, call GetLastError. Res The PlgBlt function works with device-dependent bitmaps.The fourth vertex of the parallelogram (D) is defined by treating the first three points (A, B, and C) as vectors and computing D = B + C A. If the bitmask exists, a value of one in the mask indicates that the source pixel color should be copied to the destination. A value of zero in the mask indicates that the destination pixel color is not to be changed. If the mask rectangle is smaller than the source and destination rectangles, the function replicates the mask pattern. Scaling, translation, and reflection transformations are allowed in the source device context; however, rotation and shear transformations are not. If the mask bitmap is not a monochrome bitmap, an error occurs. The stretching mode for the destination device context is used to determine how to stretch or compress the pixels, if that is necessary. When an enhanced metafile is being recorded, an error occurs if the source device context identifies an enhanced-metafile device context. The destination coordinates are transformed according to the destination device context; the source coordinates are transformed according to the source device context. If the source transformation has a rotation or shear, an error is returned. If the destination and source rectangles do not have the same color format, PlgBlt converts the source rectangle to match the destination rectangle. Not all devices support the PlgBlt function. For more information, see the description of the RC_BITBLT raster capability in the GetDeviceCaps function. If the source and destination device contexts represent incompatible devices, PlgBlt returns an error. Windows 2000/XP: When used in a multiple monitor system, both hdcSrc and hdcDest must refer to the same device or the function will fail. To transfer data between DCs for different devices, convert the memory bitmap to a DIB by calling GetDIBits. To display the DIB to the second device, call SetDIBits or StretchDIBits.Requirements Windows NT/2000/XP: Included in Windows NT 3.1 and later. Windows 95/98/Me: Unsupported. Header: Declared in Wingdi.h; include Windows.h. Library: Use Gdi32.lib.
procedure RotateImage(Bitmap:TBitmap;Angle:Real);
{Bitmap： 要旋转的图像。
Angle: 要旋转的角度(弧度)。
}
var
tx0,ty1,x0,y0,x1,x2,y1,y2,r:Integer;
tmpBitmap:TBitmap;
x,y:Integer;
begin
tmpBitmap:=TBitmap.Create;
x0:=Round(Bitmap.Width/2);
y0:=Round(Biymap.Height/2);
r:=Round(sqrt(x0*x0+y0*y0));
tx1:=Round(abs(r*Cos(Angle)));
ty1:=Round(abs(r*Sin(Angle)));
tmpBitmap.Width:=2*tx1;
tmpBitmap.Height:=2*ty1;
for y:=0 to Bitmap.Height-1 do
begin
for x:=0 to Bitmap.Width-1 do
begin
x1:=x-x0;
y1:=y-y0;
x2:=Round(x1*cos(Angle)-y1*sin(Angle))+tx1;
y2:=Round(y1*sin(Angle)+x1*cos(Angle))+ty1;
tmpBitmap.Canvas.Pixels[x2,y2]:=Bitmap.Canvas.Pixels[x,y];
end;
end;
Bitmap.Assign(tmpBitmap);
tmpBitmap.Free;
end;
由于在网吧上网，没有开发工具，无法调试，只是人为编译通过. ^_^;
to:： miky(miky) :我是这样想的，图片旋转后只显示菱形内的东西，而不会遮住底下的文字,它的角只存在上、下，和左、右。
｛角｝
/\asdfsdfasdf
/ 角 / 内 \｛角｝
\ /
\ /
\/
角
HDC hdcDest, // handle to destination DC
CONST POINT *lpPoint, // destination vertices
HDC hdcSrc, // handle to source DC
int nXSrc, // x-coord of source upper-left corner
int nYSrc, // y-coord of source upper-left corner
int nWidth, // width of source rectangle
int nHeight, // height of source rectangle
HBITMAP hbmMask, // handle to bitmask
int xMask, // x-coord of bitmask upper-left corner
int yMask // y-coord of bitmask upper-left corner
);
Parameters
hdcDest
[in] Handle to the destination device context.
lpPoint
[in] Pointer to an array of three points in logical space that identify three corners of the destination parallelogram. The upper-left corner of the source rectangle is mapped to the first point in this array, the upper-right corner to the second point in this array, and the lower-left corner to the third point. The lower-right corner of the source rectangle is mapped to the implicit fourth point in the parallelogram.
hdcSrc
[in] Handle to the source device context.
nXSrc
[in] Specifies the x-coordinate, in logical units, of the upper-left corner of the source rectangle.
nYSrc
[in] Specifies the y-coordinate, in logical units, of the upper-left corner of the source rectangle.
nWidth
[in] Specifies the width, in logical units, of the source rectangle.
nHeight
[in] Specifies the height, in logical units, of the source rectangle.
hbmMask
[in] Handle to an optional monochrome bitmap that is used to mask the colors of the source rectangle.
xMask
[in] Specifies the x-coordinate, in logical units, of the upper-left corner of the monochrome bitmap.
yMask
[in] Specifies the y-coordinate, in logical units, of the upper-left corner of the monochrome bitmap.
Return Values
If the function succeeds, the return value is nonzero.If the function fails, the return value is zero. Windows NT/2000/XP: To get extended error information, call GetLastError. Res
The PlgBlt function works with device-dependent bitmaps.The fourth vertex of the parallelogram (D) is defined by treating the first three points (A, B, and C) as vectors and computing D = B + C A. If the bitmask exists, a value of one in the mask indicates that the source pixel color should be copied to the destination. A value of zero in the mask indicates that the destination pixel color is not to be changed. If the mask rectangle is smaller than the source and destination rectangles, the function replicates the mask pattern. Scaling, translation, and reflection transformations are allowed in the source device context; however, rotation and shear transformations are not. If the mask bitmap is not a monochrome bitmap, an error occurs. The stretching mode for the destination device context is used to determine how to stretch or compress the pixels, if that is necessary. When an enhanced metafile is being recorded, an error occurs if the source device context identifies an enhanced-metafile device context. The destination coordinates are transformed according to the destination device context; the source coordinates are transformed according to the source device context. If the source transformation has a rotation or shear, an error is returned. If the destination and source rectangles do not have the same color format, PlgBlt converts the source rectangle to match the destination rectangle. Not all devices support the PlgBlt function. For more information, see the description of the RC_BITBLT raster capability in the GetDeviceCaps function. If the source and destination device contexts represent incompatible devices, PlgBlt returns an error. Windows 2000/XP: When used in a multiple monitor system, both hdcSrc and hdcDest must refer to the same device or the function will fail. To transfer data between DCs for different devices, convert the memory bitmap to a DIB by calling GetDIBits. To display the DIB to the second device, call SetDIBits or StretchDIBits.Requirements
Windows NT/2000/XP: Included in Windows NT 3.1 and later.
Windows 95/98/Me: Unsupported.
Header: Declared in Wingdi.h; include Windows.h.
Library: Use Gdi32.lib.