📄 chap02.htm
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"Times New Roman"'>，图象区域的</span><span lang=EN-US>y</span><span
style='font-family:宋体;"Times New Roman"'>范围从</span><span lang=EN-US>0</span><span style='font-family:
宋体;"Times New Roman"'>到</span><span
lang=EN-US>height-|t<sub>y</sub>|,</span><span style='font-family:宋体;
"Times New Roman"'>对应原图的范围从</span><span
lang=EN-US>|t<sub>y</sub>|</span><span style='font-family:宋体;"Times New Roman";"Times New Roman"'>到</span><span
lang=EN-US>height</span><span style='font-family:宋体;
"Times New Roman"'>；</span></p>
<p style='line-height:18.0pt;
'> <span
lang=EN-US>(3)<span style='font:7.0pt "Times New Roman"'> </span></span>
<span
lang=EN-US>0<t<sub>y</sub><height </span><span style='font-family:宋体;
"Times New Roman"'>，图象区域的</span><span
lang=EN-US>y</span><span style='font-family:宋体;
"Times New Roman"'>范围从</span><span lang=EN-US>t<sub>y</sub></span><span
style='font-family:宋体;"Times New Roman"'>到</span><span lang=EN-US>height,</span><span
style='font-family:宋体;"Times New Roman"'>对应原图的范围从</span><span lang=EN-US>0</span><span
style='font-family:宋体;"Times New Roman"'>到</span><span lang=EN-US>height-t<sub>y</sub></span><span
style='font-family:宋体;"Times New Roman"'>；</span></p>
<p style='line-height:18.0pt;
'> <span
lang=EN-US>(4)<span style='font:7.0pt "Times New Roman"'> </span></span>
<span
lang=EN-US>t<sub>y</sub></span><span style='font-family:宋体;"Times New Roman";"Times New Roman"'>≥</span><span
lang=EN-US>height</span><span style='font-family:宋体;
"Times New Roman"'>，图象完全移出了屏幕，不用做任何处理。</span></p>
<p style='line-height:18.0pt'><span
style='font-family:宋体;"Times New Roman"'>这种做法利用了位图存储的连续性，即同一行的象素在内存中是相邻的。利用</span><span lang=EN-US>memcpy</span><span
style='font-family:宋体;"Times New Roman"'>函数，从</span><span lang=EN-US>(x<sub>0</sub>,y<sub>0</sub>)</span><span
style='font-family:宋体;"Times New Roman"'>点开始，一次可以拷贝一整行</span><span lang=EN-US>(</span><span
style='font-family:宋体;"Times New Roman"'>宽度为</span><span lang=EN-US>x<sub>1</sub></span><span
style='font-family:宋体;"Times New Roman"'>－</span><span lang=EN-US>x<sub>0</sub>)</span><span
style='font-family:宋体;"Times New Roman"'>，然后将内存指针移到</span><span lang=EN-US>(x<sub>0</sub>,y<sub>0</sub>+1)</span><span
style='font-family:宋体;"Times New Roman"'>处，拷贝下一行。这样拷贝</span><span lang=EN-US>(y<sub>1</sub>-y<sub>0</sub>)</span><span
style='font-family:宋体;"Times New Roman"'>行就完成了全部操作，避免了一个一个象素的计算，提高了效率。</span><span lang=EN-US>Translation</span><span
style='font-family:宋体;"Times New Roman"'>的源代码如下：</span></p>
<p style='line-height:18.0pt'>int xOffset=0,yOffset=0;</p>
<p style='line-height:18.0pt'><span lang=EN-US>BOOL Translation(HWND hWnd)</span></p>
<p style='line-height:18.0pt'><span lang=EN-US>{</span></p>
<p style='line-height:18.0pt'>DLGPROC
dlgInputBox = NULL;</p>
<p style='line-height:18.0pt'>DWORD
OffBits,BufSize;</p>
<p style='line-height:18.0pt'>LPBITMAPINFOHEADER lpImgData;</p>
<p style='line-height:18.0pt'>LPSTR
lpPtr;</p>
<p style='line-height:18.0pt'>HLOCAL
hTempImgData;</p>
<p style='line-height:18.0pt'>LPBITMAPINFOHEADER lpTempImgData;</p>
<p style='line-height:18.0pt'>LPSTR
lpTempPtr;</p>
<p style='line-height:18.0pt'>int
SrcX0,SrcY0,SrcX1,SrcY1;</p>
<p style='line-height:18.0pt'>int
DstX0,DstY0,DstX1,DstY1;</p>
<p style='line-height:18.0pt'>int
RectWidth,RectHeight;</p>
<p style='line-height:18.0pt'>BOOL
xVisible,yVisible;</p>
<p style='line-height:18.0pt'>HDC
hDc;</p>
<p style='line-height:18.0pt'>HFILE
hf;</p>
<p style='line-height:18.0pt'>int
i;</p>
<p style='line-height:18.0pt'><span
lang=EN-US>//</span><span style='font-family:宋体;
"Times New Roman"'>出现对话框，输入</span><span lang=EN-US>x</span><span
style='font-family:宋体;"Times New Roman"'>偏移量</span><span lang=EN-US>xOffset</span><span
style='font-family:宋体;"Times New Roman"'>，和</span><span lang=EN-US>y</span><span style='font-family:
宋体;"Times New Roman"'>偏移量</span><span
lang=EN-US>yOffset</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>dlgInputBox = (DLGPROC) MakeProcInstance ( (FARPROC)InputBox,ghInst
);</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>DialogBox (ghInst, "INPUTBOX", hWnd, dlgInputBox);</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>FreeProcInstance ( (FARPROC) dlgInputBox );</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>//OffBits</span><span style='font-family:宋体;"Times New Roman";"Times New Roman"'>为</span><span
lang=EN-US>BITMAPINFOHEADER</span><span style='font-family:宋体;"Times New Roman";"Times New Roman"'>结构长度加调色板的大小</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>OffBits=bf.bfOffBits-sizeof(BITMAPFILEHEADER); </span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>BufSize=OffBits+bi.biHeight*LineBytes;//</span><span
style='font-family:宋体;"Times New Roman"'>要开的缓冲区的大小</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>//</span><span style='font-family:宋体;
"Times New Roman"'>为新产生的位图分配缓冲区内存</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>if((hTempImgData=LocalAlloc(LHND,BufSize))==NULL)</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>{</span></p>
<p style='line-height:
18.0pt'><span lang=EN-US>MessageBox(hWnd,"Error alloc memory!","Error
Message",MB_OK|</span></p>
<p style='line-height:
18.0pt'><span lang=EN-US>MB_ICONEXCLAMATION);</span></p>
<p style='line-height:
18.0pt'><span lang=EN-US>return FALSE; //</span><span style='font-family:宋体;
"Times New Roman"'>失败，返回</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>}</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>//lpImgData</span><span style='font-family:宋体;"Times New Roman";"Times New Roman"'>为指向原来位图数据的指针</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>lpImgData=(LPBITMAPINFOHEADER)GlobalLock(hImgData);</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>//lpTempImgData</span><span style='font-family:宋体;"Times New Roman";"Times New Roman"'>为指向新产生位图数据的指针</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>lpTempImgData=(LPBITMAPINFOHEADER)LocalLock(hTempImgData);</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>lpPtr=(char *)lpImgData;</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>lpTempPtr=(char *)lpTempImgData;</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>//</span><span style='font-family:宋体;
"Times New Roman"'>将新的缓冲区中的每个字节都填成</span><span
lang=EN-US>255</span><span style='font-family:宋体;
"Times New Roman"'>，这样以后未处理的象素就是白色</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>memset(lpTempPtr,(BYTE)255,BufSize);</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>//</span><span style='font-family:宋体;
"Times New Roman"'>两幅图之间的头信息，包括调色板都是相同的，所以直接拷贝头和调色板</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>memcpy(lpTempPtr,lpPtr,OffBits);</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>//xVisible</span><span style='font-family:宋体;"Times New Roman";"Times New Roman"'>为</span><span
lang=EN-US>FALSE</span><span style='font-family:宋体;
"Times New Roman"'>时，表示</span><span lang=EN-US>x</span><span
style='font-family:宋体;"Times New Roman"'>方向已经移出了可显示的范围</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>xVisible=TRUE; </span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>if( xOffset<= -bi.biWidth )</span></p>
<p style='line-height:
18.0pt'><span lang=EN-US>xVisible=FALSE; </span></p>
<p style='line-height:
18.0pt'><span lang=EN-US>else if( xOffset<=0){</span></p>
<p style='line-height:
18.0pt'>DstX0=0; //<span style='font-family:宋体;
"Times New Roman"'>表示移动后，有图区域的左上角点的</span><span
lang=EN-US>x</span><span style='font-family:宋体;
"Times New Roman"'>坐标</span></p>
<p style='line-height:
18.0pt'><span lang=EN-US>DstX1=bi.biWidth+xOffset; //</span><span
style='font-family:宋体;"Times New Roman"'>表示移动后，有图区域的右下角点的</span><span lang=EN-US>x</span><span
style='font-family:宋体;"Times New Roman"'>坐标</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>}</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>else if ( xOffset<bi.biWidth){</span></p>
<p style='line-height:
18.0pt'><span lang=EN-US>DstX0=xOffset;</span></p>
<p style='line-height:
18.0pt'><span lang=EN-US>DstX1=bi.biWidth;</span></p>
<p style='line-height:
18.0pt'><span lang=EN-US>}</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>else</span></p>
<p style='line-height:
18.0pt'><span lang=EN-US>xVisible=FALSE;</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>SrcX0=DstX0-xOffset; //</span><span style='font-family:宋体;
"Times New Roman"'>对应</span><span
lang=EN-US>DstX0</span><span style='font-family:宋体;
"Times New Roman"'>在原图中的</span><span lang=EN-US>x</span><span
style='font-family:宋体;"Times New Roman"'>坐标</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>SrcX1=DstX1-xOffset; //</span><span style='font-family:宋体;
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