大家帮忙看看,到底错在那儿

[metalyt]

我想实现类似于幕后位图的功能.就是先构造一个位图对象，在它的画布上绘
制，然后将其拷贝到控件的画布上去.代码如下,究竟哪儿错了?



Graphics::TBitmap * backBitmap,* tempBitmap;
backBitmap = new Graphics::TBitmap;
tempBitmap = new Graphics::TBitmap;

tempBitmap->LoadFromFile("map.bmp");

backBitmap->PixelFormat=tempBitmap->PixelFormat;
backBitmap->Canvas->Draw(0,0,tempBitmap);

mapView->Canvas->Draw(0, 0, backBitmap);
// 直接用下面一句就可以
//mapView->Canvas->Draw(0, 0, tempBitmap);

delete tempBitmap;
delete backBitmap;

[c2y]

Graphics::TBitmap * backBitmap,* tempBitmap;
backBitmap = new Graphics::TBitmap;
tempBitmap = new Graphics::TBitmap;

tempBitmap->LoadFromFile("map.bmp");

backBitmap->PixelFormat=tempBitmap->PixelFormat;

//加上下面两句就OK，未指定位图大小，默认为0。
backBitmap->Height=tempBitmap->Height;
backBitmap->Width=tempBitmap->Width;


backBitmap->Canvas->Draw(0,0,tempBitmap);

mapView->Canvas->Draw(0, 0, backBitmap);
// 直接用下面一句就可以
//mapView->Canvas->Draw(0, 0, tempBitmap);

delete tempBitmap;
delete backBitmap;

[metalyt]

多谢, c2y(麻麻鱼)

[codecb]

啊！ 搞定了!
那就接点分 呵呵