📄 第2章 图象的几何变换.htm
字号:
v:shapes="_x0000_i1035"> </SUB></SPAN></P>
<P style="LINE-HEIGHT: 18pt; TEXT-ALIGN: right" align=right><SPAN
lang=EN-US>(2.9)</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN
style="FONT-FAMILY: 宋体">这样，对于新图中的每一点，我们就可以根据公式</SPAN><SPAN
lang=EN-US>(2.9)</SPAN><SPAN
style="FONT-FAMILY: 宋体">求出对应原图中的点，得到它的灰度。如果超出原图范围，则填成白色。要注意的是，由于有浮点运算，计算出来点的坐标可能不是整数，采用取整处理，即找最接近的点，这样会带来一些误差</SPAN><SPAN
lang=EN-US>(</SPAN><SPAN style="FONT-FAMILY: 宋体">图象可能会出现锯齿</SPAN><SPAN
lang=EN-US>)</SPAN><SPAN
style="FONT-FAMILY: 宋体">。更精确的方法是采用插值，将在图象缩放时介绍。</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN style="FONT-FAMILY: 宋体">源程序如下：</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-US>#define PI 3.1415926535</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-US>#define RADIAN(angle)
((angle)*PI/180.0) //</SPAN><SPAN style="FONT-FAMILY: 宋体">角度到弧度转化的宏</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-US>BOOL Rotation(HWND
hWnd)</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-US>{</SPAN></P>
<P style="LINE-HEIGHT: 18pt">DLGPROC
dlgInputBox = NULL;</P>
<P style="LINE-HEIGHT: 18pt">DWORD
OffBits,SrcBufSize,DstBufSize,DstLineBytes;</P>
<P style="LINE-HEIGHT: 18pt">LPBITMAPINFOHEADER lpImgData;</P>
<P
style="LINE-HEIGHT: 18pt">LPSTR
lpPtr;</P>
<P style="LINE-HEIGHT: 18pt">HLOCAL
hTempImgData;</P>
<P style="LINE-HEIGHT: 18pt">LPBITMAPINFOHEADER lpTempImgData;</P>
<P style="LINE-HEIGHT: 18pt">LPSTR
lpTempPtr;</P>
<P
style="LINE-HEIGHT: 18pt">float
SrcX1,SrcY1,SrcX2,SrcY2;</P>
<P
style="LINE-HEIGHT: 18pt">float
SrcX3,SrcY3,SrcX4,SrcY4;</P>
<P
style="LINE-HEIGHT: 18pt">float
DstX1,DstY1,DstX2,DstY2;</P>
<P
style="LINE-HEIGHT: 18pt">float
DstX3,DstY3,DstX4,DstY4;</P>
<P
style="LINE-HEIGHT: 18pt">DWORD
Wold,Hold,Wnew,Hnew;</P>
<P
style="LINE-HEIGHT: 18pt">HDC
hDc;</P>
<P
style="LINE-HEIGHT: 18pt">HFILE
hf;</P>
<P
style="LINE-HEIGHT: 18pt">DWORD
x0,y0,x1,y1;</P>
<P
style="LINE-HEIGHT: 18pt">float
cosa,sina; //cos(a),sin(a);</P>
<P
style="LINE-HEIGHT: 18pt">float
num1,num2;</P>
<P style="LINE-HEIGHT: 18pt">BITMAPFILEHEADER
DstBf;</P>
<P
style="LINE-HEIGHT: 18pt">BITMAPINFOHEADER
DstBi;</P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-US>//</SPAN><SPAN
style="FONT-FAMILY: 宋体">出现对话框，输入旋转角度</SPAN><SPAN lang=EN-US>(</SPAN><SPAN
style="FONT-FAMILY: 宋体">顺时针方向</SPAN><SPAN lang=EN-US>)</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-US>dlgInputBox = (DLGPROC)
MakeProcInstance ( (FARPROC)InputBox,ghInst );</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-US>DialogBox (ghInst, "INPUTBOX",
hWnd, dlgInputBox);</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-US>FreeProcInstance ( (FARPROC)
dlgInputBox );</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-US>//</SPAN><SPAN
style="FONT-FAMILY: 宋体">角度到弧度的转化</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN
lang=EN-US>RotateAngle=(float)RADIAN(RotateAngle);</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN
lang=EN-US>cosa=(float)cos((double)RotateAngle);</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN
lang=EN-US>sina=(float)sin((double)RotateAngle);</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-US>//</SPAN><SPAN
style="FONT-FAMILY: 宋体">原图的宽度和高度</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-US>Wold=bi.biWidth;</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-US>Hold=bi.biHeight;</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-US>//</SPAN><SPAN
style="FONT-FAMILY: 宋体">原图的四个角的坐标</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN
lang=EN-US>SrcX1=(float)(-0.5*Wold);</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN
lang=EN-US>SrcY1=(float)(0.5*Hold);</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN
lang=EN-US>SrcX2=(float)(0.5*Wold);</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN
lang=EN-US>SrcY2=(float)(0.5*Hold);</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN
lang=EN-US>SrcX3=(float)(-0.5*Wold);</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN
lang=EN-US>SrcY3=(float)(-0.5*Hold);</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN
lang=EN-US>SrcX4=(float)(0.5*Wold);</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN
lang=EN-US>SrcY4=(float)(-0.5*Hold);</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-US>//</SPAN><SPAN
style="FONT-FAMILY: 宋体">新图四个角的坐标</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN
lang=EN-US>DstX1=cosa*SrcX1+sina*SrcY1;</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN
lang=EN-US>DstY1=-sina*SrcX1+cosa*SrcY1;</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN
lang=EN-US>DstX2=cosa*SrcX2+sina*SrcY2;</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN
lang=EN-US>DstY2=-sina*SrcX2+cosa*SrcY2;</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN
lang=EN-US>DstX3=cosa*SrcX3+sina*SrcY3;</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN
lang=EN-US>DstY3=-sina*SrcX3+cosa*SrcY3;</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN
lang=EN-US>DstX4=cosa*SrcX4+sina*SrcY4;</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN
lang=EN-US>DstY4=-sina*SrcX4+cosa*SrcY4;</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-US>//</SPAN><SPAN
style="FONT-FAMILY: 宋体">计算新图的宽度，高度</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-US>Wnew =
(DWORD)(max(fabs(DstX4-DstX1), fabs(DstX3-DstX2))+0.5);</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-US>Hnew =
(DWORD)(max(fabs(DstY4-DstY1), fabs(DstY3-DstY2))+0.5);</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-US>//</SPAN><SPAN
style="FONT-FAMILY: 宋体">计算矩阵</SPAN><SPAN lang=EN-US>(2.9)</SPAN><SPAN
style="FONT-FAMILY: 宋体">中的两个常数，这样不用以后每次都计算了</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-US>num1=(float)(
-0.5*Wnew*cosa-0.5*Hnew*sina+0.5*Wold);</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN
lang=EN-US>num2=(float)(0.5*Wnew*sina-0.5*Hnew*cosa+0.5*Hold);</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-US>//OffBits</SPAN><SPAN
style="FONT-FAMILY: 宋体">为</SPAN><SPAN lang=EN-US>BITMAPINFOHEADER</SPAN><SPAN
style="FONT-FAMILY: 宋体">结构长度加调色板的大小</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN
lang=EN-US>OffBits=bf.bfOffBits-sizeof(BITMAPFILEHEADER);</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN
lang=EN-US>SrcBufSize=OffBits+bi.biHeight*LineBytes;</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-US>//</SPAN><SPAN
style="FONT-FAMILY: 宋体">显示时，采用新图的宽度和高度，</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-US>ImgWidth=Wnew;</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-US>ImgHeight=Hnew;</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-US>//</SPAN><SPAN
style="FONT-FAMILY: 宋体">新图每行占用的字节</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN
lang=EN-US>DstLineBytes=(DWORD)WIDTHBYTES(Wnew*bi.biBitCount);</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN
lang=EN-US>DstBufSize=(DWORD)(sizeof(BITMAPINFOHEADER)+</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN
lang=EN-US>NumColors*sizeof(RGBQUAD)+</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-US>(DWORD)DstLineBytes*Hnew);
//</SPAN><SPAN style="FONT-FAMILY: 宋体">要开的缓冲区的大小</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-US>//</SPAN><SPAN
style="FONT-FAMILY: 宋体">为新产生的位图分配缓冲区内存</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN
lang=EN-US>if((hTempImgData=LocalAlloc(LHND,DstBufSize))==NULL)</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-US>{</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-US>MessageBox(hWnd,"Error alloc
memory!","Error Message",</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN
lang=EN-US>MB_OK|MB_ICONEXCLAMATION);</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-US>return FALSE; //</SPAN><SPAN
style="FONT-FAMILY: 宋体">失败，返回</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-US>}</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><A name=OLE_LINK2></A><SPAN
lang=EN-US>//lpImgData</SPAN><SPAN
style="FONT-FAMILY: 宋体">为指向原来位图数据的指针</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN
lang=EN-US>lpImgData=(LPBITMAPINFOHEADER)GlobalLock(hImgData); </SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-⌨️ 快捷键说明
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