raphics(Canvas->Handle);
g->DrawImage(newBmp, 0, 0);
delete g;
delete source;
delete dest;
delete newBmp;
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Button3Click(TObject *Sender)
{
BitmapData data, dst, src;
// 建立新图像
Gdiplus::Bitmap *newBmp = new Gdiplus::Bitmap(768, 256, PixelFormat32bppARGB);
LockBitmap(newBmp, &data);
// 合成目标到新图左边
Gdiplus::Bitmap *dest = new Gdiplus::Bitmap(L"d:\\xmas_011.png");
LockBitmap(dest, &dst);
ImageMixer(&data, 0, 0, &dst, 255);
// 合成源图到新图中间
Gdiplus::Bitmap *source = new Gdiplus::Bitmap(L"d:\\Apple.png");
LockBitmap(source, &src);
ImageMixer(&data, dest->GetWidth(), 0, &src, 255);
// 目标图与源图混合
ImageMixer(&dst, &src, 192);
// 混合后的目标图合成到新图右边
ImageMixer(&data, dest->GetWidth() << 1, 0, &dst, 255);
UnlockBitmap(source, &src);
UnlockBitmap(dest, &dst);
UnlockBitmap(newBmp, &data);
// 显示拼接后的图像
Gdiplus::Graphics *g = new Gdiplus::Graphics(Canvas->Handle);
g->DrawImage(newBmp, 0, 0);
delete g;
delete source;
delete dest;
delete newBmp;
}
//---------------------------------------------------------------------------
运行效果截图如下：
运行效果与《图像（层）正常混合模式详解（上）》例子运行效果截图是一样的（其实就是同一张图片），但含义却是不一样的：《图像（层）正常混合模式详解（上）》例子是分多次在窗口上显示，而上面例子却是将源图和目标图拼接（多次混合）到一张图上，然后再显示。
其实，上面的ImageMixer函数没有对源图进行混合坐标定位，也是不太完善的，不过有了GetSubBitmapData函数，对源图进行坐标定位是很简单的。
下面再应用ImageMixer函数实现图像显示功能，代码如下：
VOID GetBitmapInfoHeader(CONST BitmapData *data, CONST PBITMAPINFO pbi)
{
pbi->bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
pbi->bmiHeader.biWidth = data->Width;
pbi->bmiHeader.biHeight = data->Height;
pbi->bmiHeader.biPlanes = 1;
pbi->bmiHeader.biBitCount = (data->PixelFormat >> 8) & 0xff;
pbi->bmiHeader.biCompression = BI_RGB;
}
//---------------------------------------------------------------------------
VOID GetDCImageData(HDC DC, INT x, INT y, BitmapData *data, PBITMAPINFO pbi)
{
HBITMAP bitmap = CreateCompatibleBitmap(DC, data->Width, data->Height);
HDC memDC = CreateCompatibleDC(DC);
HBITMAP saveBitmap = (HBITMAP)SelectObject(memDC, bitmap);
BitBlt(memDC, 0, 0, data->Width, data->Height, DC, x, y, SRCCOPY);
SelectObject(memDC, saveBitmap);
DeleteDC(memDC);
GetDIBits(DC, bitmap, 0, data->Height, data->Scan0, pbi, DIB_RGB_COLORS);
DeleteObject(bitmap);
}
//---------------------------------------------------------------------------
VOID BitBltImageData(HDC DC, INT x, INT y, CONST BitmapData *data, PBITMAPINFO pbi)
{
HBITMAP bitmap = CreateDIBitmap(DC, &pbi->bmiHeader, CBM_INIT, data->Scan0, pbi, DIB_RGB_COLORS);
HDC memDC = CreateCompatibleDC(DC);
HBITMAP saveBitmap = (HBITMAP)SelectObject(memDC, bitmap);
BitBlt(DC, x, y, data->Width, data->Height, memDC, 0, 0, SRCCOPY);
SelectObject(memDC, saveBitmap);
DeleteDC(memDC);
DeleteObject(bitmap);
}
//---------------------------------------------------------------------------
VOID ImageDraw(HDC DC, INT x, INT y, CONST BitmapData *data, float alpha = 1.0f)
{
BITMAPINFO bi;
RECT r;
INT alphaI;
LPVOID scan0;
BitmapData dst, src, tmp;
// 获取DC可见矩形
if (GetClipBox(DC, &r) <= NULLREGION)
return;
alphaI = (INT)(alpha * 255);
// 如果alpha=1，同时data不含alpha信息，同时d