Patent Application
20050248794
Host-based printer drivers are software applications that process print data (i.e., data to be sent to a printer) on a host device, such as a personal computer. By processing the print data on the host device, the printer driver allows the host device to cooperate with printers having minimal processing capability (and, thus, a lower cost) while yielding superior print quality.
However, because such low-capability printers cannot process object-oriented graphics (e.g., vector graphics and associated text fonts), the printer driver typically converts object-oriented images into raster (bitmap) data before the printer can print the images. Unfortunately, such data conversion often places high demands on the processing resources of the host device, and thus can detract from the performance of applications simultaneously running on the host device.
According to an embodiment of the invention, a system includes a controller operable to receive a first data set comprising data in a first format type, the first-format-type data representing an image. The system further includes a circuit coupled to the controller, the circuit operable to produce a second data set in a second format type, the second data set based on the first-format-type data, the second data set representing the image.
Most modern personal computers (PCs) are equipped with video cards (aka video adapters) that have high-level 2D and 3D graphics processing capabilities. Conventionally, PCs employ such video card processing capability solely to process data to be rendered by a video display. According to an embodiment of the invention, a host-based printer driver leverages this video card capability to process print data.
In operation, the application 90 issues a print request, with associated print data representing an image (e.g., graphics or text), to the driver 100 through defined interfaces associated with the OS 80. The print data received by the driver 100 can be in a variety of known application-specific formats, such as, for example, bitmapped graphics, bitmapped text fonts, vector-graphics text fonts and/or vector graphics. The driver 100 converts any non-raster print data to raster data so that the printer 30 can print the associated image.
The driver 100 translates the vector-graphics-based print data into a set of executable commands. The driver 100 communicates these commands to the video card 60 for execution. In one embodiment, the driver 100 is configured to employ a high-level cross platform API 110, such as OpenGL® or DirectX, in order to communicate with the video card 60. Of course, the driver 100 can be configured to utilize other custom APIs as well.
In executing the commands received from the driver 100, the video card 60 produces bitmapped images of points, arcs, lines, text and other shapes corresponding to the vector graphics, and thus to the associated image. The commands may further instruct the video card 60 to fill, as appropriate, the rendered bitmapped shapes in a manner and with colors specified by the commands. For example, at the direction of the driver 100, the video card 60 may render overlapping objects, only a topmost object, or blended objects in the case of semi-transparent objects.
In a case where the print data includes both vector graphics and bitmap data, the driver 100 may pass the bitmap data, along-with the commands, to the video card 60. The video card 60 may cache this bitmap data in a memory (not shown) of the video card 60, and later place the bitmap data in an appropriate location of the image rendered by the video card 60.
Once the video card 60 has rendered into bitmap format the image (or portion thereof) associated with the print data, the video card 60 communicates the bitmapped image to the memory 40. The driver 100 may then employ the CPU 50 to perform any necessary post processing of the rendered image before providing the image to the printer 30, via the interface 31, for printing.
As discussed above, video cards are conventionally used to process data for display on video monitors. Standard video monitors are capable of displaying far fewer pixels than can be displayed on a printed page. If a particular print-data set represents an image that, when in bitmap format, requires a large number of pixels, the video card 60 may not be able to render the entire image.
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In an alternative embodiment, the driver 100 may allocate a subset of the data portions 200 to the video card 60 for processing. The driver 100 itself may then process the data portions 200 not allocated to the video card 60 to produce corresponding bitmap portions 210. The processing by the driver 100 of data portions 200 may or may not be simultaneous with processing by the video card 60 of data portions 200.
The preceding discussion is presented to enable a person skilled in the art to make and use the invention. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the generic principles herein may be applied to other embodiments and applications without departing from the spirit and scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein.
