Description > Bitmaps

There are currently two ways to perform bitmap marking: legacy mode with DevicePixelLine and raster mode with RasterPixelLine, which is only available with USC-2.

DevicePixelLine:

When using DevicePixelLine, marking is performed with the currently set marking speed, and the output frequency results from the pixel vector length. You have to adjust the speed yourself if a particular pixel vector would result in an illegal frequency setting.

Steps for DevicePixelLine:

•position the scanner at the start of a line

•output the line with DevicePixelLine

•repeat until finished

	•DevicePixelLine

RasterPixelLine:

In raster mode, marking of a bitmap is encapsulated in raster start and raster end calls, similar to stream start and end. Each line is marked with RasterPixelLine, but movement is performed by the SAM library. In contrast to legacy mode, raster mode takes the pixel vector length and a user specified pixel period and calculates the corresponding marking speed itself.

Steps for RasterPixelLine:

•enable scComStandardDeviceStyleFlagEnablePixelOutput

•signal bitmap start and pass parameters with ScSCIRasterStart or ScSetDeviceData

•output all lines

•signal bitmap end

Raster start is signaled using a sc_com_raster_info structure that is passed to the ScSetDeviceData function with scComStandardDeviceDataIDRasterStart ID. The direct dll interface provides the function ScSCIStartRaster that offers the same functionality. The structure contains the following members:

Member	Type	Description
m_version	long	struct version, set to 1
m_origin_x	double	start point x coordinate
m_origin_y	double	start point y coordinate
m_dir_x	double	x component of direction vector
m_dir_y	double	y component of direction vector
m_pixel_step	double	width of one pixel
m_line_step	double	distance between bitmap lines
m_acceleration_time	double	time until scanner achieves desired speed
m_deceleration_time	double	time to compensate tracking offset on line end
m_line_offset	double	time offset to compensate acceleration_time and tracking offset
m_jump_speed	double	speed used when jumping between lines
m_wait_delay_0	double	delay after jump
m_limit_value	double	value used to determine if a pixel is blank - currently unused
m_mode_flags	long	0, or any combination of scComStandardDeviceRasterModeFlagBiDir and scComStandardDeviceRasterModeFlagJumpOverBlankPixels

Table 5: Bitmap RasterPixelLine members

m_acceleration_time - m_line_offset should equal the tracking offset of your scanner.

The following image illustrates the various parameters. The left part shows the theoretical output with no acceleration/deceleration and offset, the right part shows the influence of these parameters. Both parts assume scComStandardDeviceRasterModeFlagBiDir is enabled.

RasterImage

Figure 2: Illustration of Bitmap RasterPixelLine

note

•RasterPixelLine

•Start/EndRaster

•SetDeviceData