求救！！！Image的"Canvas is not allow to drawing"错误！！！

christopher_hp 2004-09-18 12:22:01

我的form上有一个panel，panel是用来显示视频图象的（用的VFW），然后有个TIMAGE，是保存图象的，有个BYTE的数组保存image->Canvas->Pixels像素值，用来计算图象中圆的中心。
工作工程如下：接受一个指令，执行GetCaptruePicData函数，先停止视频显示，然后bitblt拷贝图象到image上面，然后取得像素值，然后掉用算法取得圆中心，然后把数据还回IMAGE并且保存图象文件，最后让视频采集。

bool __fastcall TMainForm::GetCaptruePicData()
{
float Cx, Cy, R;
bool result =true;
int i, j, l=0;
TColor RGB;
HDC hdc =NULL;
int width, height;
hdc =GetDC(Panel1->Handle);
//if(Set_GetFramePic())
//{
try
{
BitBlt(image->Canvas->Handle, 0, 0, image->Width, image->Height,
hdc, 0, 0, SRCCOPY);
image->Picture->SaveToFile("c:\\temp1.bmp");
//保存采集原始图象
image->Width =image->Picture->Bitmap->Width;
image->Height =image->Picture->Bitmap->Height;
if(lpBits)
delete lpBits;
lpBits =new BYTE[image->Width*image->Height];
//分配图象数据
}
__finally
{
for(i=0; i<image->Height; i++)
for(j=0; j<image->Width; j++)
{
RGB =image->Canvas->Pixels[j][i];
lpBits[l++] =(GetRValue(RGB) +GetGValue(RGB) +GetBValue(RGB))/3;

}
}
if(GetCirclePara(image->Width, image->Height, lpBits, 0, Cx,Cy,R, 20))
//取得圆心
{
l =0;
for(i=0; i<image->Height; i++)
for(j=0; j<image->Width; j++)
{
image->Canvas->Pixels[j][i] =(TColor)RGB(lpBits[l], lpBits[l], lpBits[l]);
l++;
}
image->Picture->SaveToFile("c:\\temp.bmp");
//保存画出圆心的图象
if(bFirstScale ==true)
ModiForm->newRadio =R;
if(m_bRevise ==true)
{
dx =Cx -gCapWidth/2;
dy =Cy -gCapHeight/2;
m_bRevise =false;
}
params[0] =(Cx -gCapWidth/2 +dx)*m_fModulus*1000/cos(m_fXDipRate*3.1415927/180)/m_fStepLengX;
params[1] =(Cy -gCapHeight/2 +dy)*m_fModulus*1000/cos(m_fYDipRate*3.1415927/180)/m_fStepLengY;
radio =R;
//ShowMessage(FloatToStr(R));
}
else
{
if(bFirstScale)
ModiForm->newRadio =0;
MessageBeep(0);
ShowMessage("error to get circle");
result =false;
}
//}
ReleaseDC(Panel1->Handle, hdc);
//Sleep(1000) //加了好象就不容易出错了
//Set_Preview();
return result;
}
请教为什么出错啊！？

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