?? 第2章 圖象的幾何變換.htm
字號:
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: 宋體">這樣，對于新圖中的每一點，我們就可以根據公式</SPAN><SPAN
lang=EN-US>(2.9)</SPAN><SPAN
style="FONT-FAMILY: 宋體">求出對應原圖中的點，得到它的灰度。如果超出原圖范圍，則填成白色。要注意的是，由于有浮點運算，計算出來點的坐標可能不是整數，采用取整處理，即找最接近的點，這樣會帶來一些誤差</SPAN><SPAN
lang=EN-US>(</SPAN><SPAN style="FONT-FAMILY: 宋體">圖象可能會出現鋸齒</SPAN><SPAN
lang=EN-US>)</SPAN><SPAN
style="FONT-FAMILY: 宋體">。更精確的方法是采用插值，將在圖象縮放時介紹。</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN style="FONT-FAMILY: 宋體">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: 宋體">角度到弧度轉化的宏</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: 宋體">出現對話框，輸入旋轉角度</SPAN><SPAN lang=EN-US>(</SPAN><SPAN
style="FONT-FAMILY: 宋體">順時針方向</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: 宋體">角度到弧度的轉化</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: 宋體">原圖的寬度和高度</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: 宋體">原圖的四個角的坐標</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: 宋體">新圖四個角的坐標</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: 宋體">計算新圖的寬度，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: 宋體">計算矩陣</SPAN><SPAN lang=EN-US>(2.9)</SPAN><SPAN
style="FONT-FAMILY: 宋體">中的兩個常數，這樣不用以后每次都計算了</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: 宋體">為</SPAN><SPAN lang=EN-US>BITMAPINFOHEADER</SPAN><SPAN
style="FONT-FAMILY: 宋體">結構長度加調色板的大小</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: 宋體">顯示時，采用新圖的寬度和高度，</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: 宋體">新圖每行占用的字節</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: 宋體">要開的緩沖區的大小</SPAN></P>
<P style="LINE-HEIGHT: 18pt"><SPAN lang=EN-US>//</SPAN><SPAN
style="FONT-FAMILY: 宋體">為新產生的位圖分配緩沖區內存</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: 宋體">失敗，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: 宋體">為指向原來位圖數據的指針</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-?? 快捷鍵說明
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