引言: 你的程式沒貼好 為什麼有這行 bmbuf -= ImageHeight * ImageWidth * 3 ; 第一次看到這種指標減法 不知道這樣合法嗎？ 我跑了一下 錯的好像是這行 delete[] bmbuf; ～剩下的就交給帥氣了～

   for (i=0;i＜ImageHeight;i  ){
      for (j=0;j＜ImageWidth;j  ,bmbuf =3){
        *(bmbuf 2) = IMatrixGray[i][j];
        *(bmbuf 1) = IMatrixGray[i][j];
        *(bmbuf)= IMatrixGray[i][j];
      }
      ProgressBar1->Position  ;
   }
   bmbuf -= ImageHeight * ImageWidth * 3 ;

引言: 這是將一張存在IMatrixGray二維陣列中的圖片放到Image2..只要一按 Buttom1就會執行..執行結果也很好..但是我發現只要我按三次以上這按鈕. setbitmapbit就會出錯..後來我把delete pBitmap拿掉就可以解決這問題.. 可是這樣似乎會導致記憶體一直無法被釋放..這問題該怎麼解決呢? 請板上高手幫忙一下..謝謝. :) --

void __fastcall TForm1::Button1Click(TObject *Sender)
{
   //Graphics::TBitmap *pBitmap = new Graphics::TBitmap();
   Graphics::TBitmap *pBitmap = new Graphics::TBitmap();
   pBitmap->Height = ImageHeight;
   pBitmap->Width = ImageWidth;
   pBitmap->PixelFormat = pf24bit;
   Byte *temp;
   Byte *bmbuf = new Byte[ImageHeight * ImageWidth *3];       for (i=0;i〈ImageHeight;i  ){
      for (j=0;j〈ImageWidth;j  ,bmbuf =3){
        *(bmbuf 2) = IMatrixGray[i][j];
        *(bmbuf 1) = IMatrixGray[i][j];
        *(bmbuf)= IMatrixGray[i][j];
      }
      ProgressBar1->Position  ;
   }
   bmbuf -= ImageHeight * ImageWidth * 3 ;
   if (SetBitmapBits(pBitmap->Handle, ImageHeight * ImageWidth * 3, bmbuf) == 0)
        ShowMessage("Wrong");
   Image2->Visible = true;
   Image2->Picture->Assign(pBitmap);
   ProgressBar1->Position =0;
   delete[] bmbuf;
   delete pBitmap;  // 就是神秘的這一行!!
}

發表人 - yuwenyang 於 2003/04/04 01:58:39

// 請您新增個 Application，加入兩個TButton 一個 TEdit 一個 TImage，並指示好如下的事件：
void __fastcall TForm1::Button1Click(TObject *Sender)
{
  Image1->Width=Edit1->Text.ToIntDef(499);
  int ImageHeight=Image1->Height;
  int ImageWidth=Image1->Width;
  Graphics::TBitmap *pBitmap = new Graphics::TBitmap();
  pBitmap->Height = ImageHeight;
  pBitmap->Width = ImageWidth;
  pBitmap->PixelFormat = pf24bit;
  Byte *bmbuf = new Byte[ImageHeight * ImageWidth *3];
  for (int i=0;i<ImageHeight;i  )
  {
    for (int j=0;j<ImageWidth;j  ,bmbuf =3)
    {
      *(bmbuf 2) = i j;    // IMatrixGray[i][j];
      *(bmbuf 1) = 4*i j;  // IMatrixGray[i][j];
      *(bmbuf)   = 4*j i;  // IMatrixGray[i][j];
    }
  }
  bmbuf -= ImageHeight * ImageWidth * 3 ;
  if (SetBitmapBits(pBitmap->Handle, ImageHeight * ImageWidth * 3, bmbuf) == 0)
  { // 我的測試，會有錯的是這個 SetBitmapBits()！！
    ShowMessage("Wrong");
  }
  Image1->Visible = true;
  Image1->Picture->Assign(pBitmap);
  delete[] bmbuf;
  delete pBitmap;
}
//----------------------------------------------------------------------------//
void __fastcall TForm1::Button2Click(TObject *Sender)
{
  Image1->Width=Edit1->Text.ToIntDef(499);
  int ImageHeight=Image1->Height;
  int ImageWidth=Image1->Width;
  Graphics::TBitmap *pBitmap = new Graphics::TBitmap();
  pBitmap->Height = ImageHeight;
  pBitmap->Width = ImageWidth;
  pBitmap->PixelFormat = pf24bit;
  for (int i=0;i<ImageHeight;i  )
  {
    for (int j=0;j<ImageWidth;j  )
    {
      ((Byte*)pBitmap->ScanLine[i])[j*3 2]=i j;    // IMatrixGray[i][j];
      ((Byte*)pBitmap->ScanLine[i])[j*3 1]=4*i j;  // IMatrixGray[i][j];
      ((Byte*)pBitmap->ScanLine[i])[j*3]  =4*j i;  // IMatrixGray[i][j];
    }
  }
  Image1->Visible = true;
  Image1->Picture->Assign(pBitmap);
  delete pBitmap;
}
//----------------------------------------------------------------------------//
void __fastcall TForm1::Edit1Exit(TObject *Sender)
{
  int Value=Edit1->Text.ToIntDef(499);
  Edit1->Text=IntToStr(Value);
}
//----------------------------------------------------------------------------//

Byte *bmbuf = new Byte[ImageHeight * ImageWidth *3];
Byte *temp=bmbuf;
for (i=0;i<ImageHeight;i  )
{      
  for (j=0;j<ImageWidth;j  ,temp =3)
  {        
    *(temp 2) = IMatrixGray[i][j];        
    *(temp 1) = IMatrixGray[i][j];        
    *(temp)= IMatrixGray[i][j];      
  }      
  ProgressBar1->Position  ;   
}
if (SetBitmapBits(pBitmap->Handle, ImageHeight * ImageWidth * 3, bmbuf) == 0)
...
delete[] bmbuf;
...

引言: 但我發現使用 Scanline 的處理顯示速度沒有 SetBitmapBits() 的方式快。 不過，按 BCB5 所附的 MSHelp 中提到 SetBitmapBits() 是舊的方法，最好不要使用，而且在以上的 code 中，我故意將 ImageWidth 設為 499 時，發現 SetBitmapBits() 與 Scanline[] 的結果不同，而很明顯可以看出是 SetBitmapBits() 錯誤！！而寬度為 512 時，則相同，表示 SetBitmapBits 只適用於 Width 是 8 的倍數，或是有一定的限制。除非您的應用中，可以很確定 SetBitmapBits() 不會有問題，否則最好別用。 這樣，就不會有人被 bmbuf -= ImageHeight * ImageWidth * 3; 嚇到。 沒空更新的網頁... http://dllee.ktop.com.tw C及指標教學,計算機概論,資訊管理導論... http://big5.to/吃軟也吃硬 http://coolsite.to/ushells 介紹Shells,LiteStep,GeoShell.... 發表人 - dllee 於 2003/04/04 13:05:59

The SetDIBits function sets the pixels in a bitmap using the color 
data found in the specified device-independent bitmap (DIB).     int SetDIBits(        HDC hdc,        // handle of device context 
    HBITMAP hbmp,        // handle of bitmap 
    UINT uStartScan,        // starting scan line 
    UINT cScanLines,        // number of scan lines 
    CONST VOID *lpvBits,        // array of bitmap bits 
    CONST BITMAPINFO *lpbmi,        // address of structure with bitmap data 
    UINT fuColorUse         // type of color indices to use 
   );        
     Parameters    hdc    Identifies a device context.     hbmp    Identifies the bitmap that is to be altered using the color data from 
the specified DIB.     uStartScan    Specifies the starting scan line for the device-independent color data in the array pointed to by the lpvBits parameter.     cScanLines    Specifies the number of scan lines found in the array containing 
device-independent color data.     lpvBits    Points to the DIB color data, stored as an array of bytes. The format 
of the bitmap values depends on the biBitCount member of the 
BITMAPINFO structure pointed to by the lpbmi parameter.     lpbmi    Points to a BITMAPINFO data structure that contains information about the DIB.    fuColorUse    Specifies whether the bmiColors member of the BITMAPINFO structure 
was provided and, if so, whether bmiColors contains explicit red, 
green, blue (RGB) values or palette indices. The fuColorUse parameter 
must be one of the following values:     Value        Meaning
DIB_PAL_COLORS        The color table consists of an array of 16-bit
 indices into the logical palette of the device context identified by 
the hdc parameter.
DIB_RGB_COLORS        The color table is provided and contains literal 
RGB values.    Return Values    If the function succeeds, the return value is the number of scan lines copied.
If the function fails, the return value is zero. 

void __fastcall TForm1::Gray1Click(TObject *Sender)
{
        BITMAPINFOHEADER bmih = {
          sizeof(BITMAPINFOHEADER), // biSize
          ImageWidth,            // biWidth
          -1 *ImageHeight,           // biHeight, *** note this is top-down ***
          1,                        // biPlanes
          24,                       // biBitCount
          BI_RGB,                   // biCompression
          0,                        // biSizeImage (not reqd. in this case)
          0,                        // biXPelsPerMeter (not reqd.)
          0,                        // biYPelsPerMeter (not reqd.)
          0,                        // biClrUsed
          0                         // biClrImportant
          };
        RGBQUAD rgb0 = {0,0,0,0};
        BITMAPINFO bmi;
        bmi.bmiHeader = bmih;
        bmi.bmiColors[0] = rgb0;    // no palette
        // Create array of BYTE to hold 24 bit rgb values
        int RowSize = ((((ImageWidth   1) * 3) / 4) * 4);
                                    // round up each row to 4 byte boundary
        BYTE *Bits = new BYTE[RowSize * ImageHeight];
        BYTE *BitsPtr;
        for (int y=0; y〈ImageHeight; y  ){
          BitsPtr = Bits   (RowSize * y);
          for (int x=0; x〈ImageWidth; x  ){
            *BitsPtr   = (BYTE)IMatrixGray[y][x];   // Blue 'noise'
            *BitsPtr   = (BYTE)IMatrixGray[y][x];   // Green
            *BitsPtr   = (BYTE)IMatrixGray[y][x];   // Red
            }
          }
        Image2->Picture->Bitmap->Width = ImageWidth;
        Image2->Picture->Bitmap->Height = ImageWidth;
        HBITMAP hbmp = Image2->Picture->Bitmap->Handle;
        HDC hdc = Image2->Canvas->Handle;
        SetDIBits (
          hdc,
          hbmp,
          0,
          ImageHeight,
          Bits,
          &bmi,
          DIB_RGB_COLORS
        );
        delete[] Bits;
        Image2->Visible = true;
        Image2->Repaint();    }