getDeviceNBitmap
Get a raw bitmap for one DeviceN color channel.
getDeviceNBitmap([in] int channelIdx,
[out] int *width, [out] int *height, [out] int *stride, [out, retval] HGLOBAL *data)
This function retrieves a raw bitmap for the specified channel
generated by the last call to
convertPageToDeviceNImage. It is
identical to getDeviceNPicture, except that it returns a raw
bitmap instead of an OLE IPicture object.
The bitmap will be an 8-bit grayscale bitmap, indicating the level of the specific colorant at each pixel.
width, height, and stride are
output arguments that provide the bitmap width, height, and stride
(bytes per row).
The channel bitmaps returned by getDeviceNBitmap will
all have the same width and height.
NB: The returned value is an HGLOBAL (i.e.,
XpdfRasterizer allocates it with GlobalAlloc), and the
caller is responsible for calling GlobalFree
(or Marshal.FreeHGBlobal) to free it.
C#:
rast.convertPageToDeviceNImage(page, dpi);
nChannels = rast.getNumDeviceNChannels();
for (int i = 0; i < nChannels; ++i) {
int width, height, stride;
IntPtr bitmapData = rast.getDeviceNBitmap(i, out width, out height, out stride);
Bitmap bmp = new Bitmap(width, height, stride, PixelFormat.Format8bppIndexed, bitmapData);
// ... use bmp ...
Marshal.FreeHGlobal(bitmapData);
}
rast.clearDeviceNImage();