6. The system of claim 5 , wherein the first network computer is further to compress the GDI document, and outputting the compressed GDI document to the second network computer; the second network computer is further to receive the compressed GDI document sent from the first network computer and decompress the GDI document.
5. A system for transmitting a sharing document containing only text and pictures over a network, comprising: a first network computer including a processor coupled to a memory storing instructions for execution by the processor, to convert GDI (Graph Device Interface) functions corresponding to a sharing document to be transmitted into GDI instructions, form a GDI document by synthesizing the GDI instructions, and send the GDI document to the second network computer over the network; a second network computer including a processor coupled to a memory storing instructions for execution by the processor, to receive the GDI document from the first network computer, restore the GDI document, and contents of the restored GDI document being same as that of the sharing document; the first network computer comprises a document sender and a virtual printing module, and an application sharing document on the document sender is to: open the interface for interacting with the virtual printer module and start to perform virtual printing of the sharing document; determine whether the virtual printing should be terminated, if the virtual printing should be terminated, terminate the virtual printing of the sharing document by sending a GDI function indicating the end of the sharing document to the virtual printer module and terminate current procedure for generating the GDI document; if the virtual printing should not be terminated, send, based on the contents of the sharing document and b calling print driver GDI transfer interface function, a GDI function to the virtual printer module; receive a result of converting the received GDI function into a GDI instruction from the virtual printer module; determine, based on the result received from the virtual printer module, whether the conversion is successful, and if the conversion is successful, start to deal with the next GDI function and cycle back to the step of determining whether the virtual print should be terminated; if the conversion is unsuccessful, terminate the virtual printing of the sharing document by sending a GDI function indicating the end of the sharing document to the virtual printer module and terminate the procedure for generating the GDI document; and the virtual printer module is to convert the received GDI function into a GDI instruction and return the result of the conversion to the application of the sharing document; and the GDI instruction comprises at least: the name of GDI function, number of GDI function and serial number of GDI performance; the virtual module is to: after the application of sharing document calls the print driver GDI transfer interface function, determine, whether the received GDI function is a GDI function indicating start of virtual printing of the sharing document, if the received GDI function is a GDI function indicating start of virtual printing of the sharing document, acquire a corresponding table of names and numbers of GDI functions from a GDI subsystem, initialize the variable of the serial number of GDI performance to 0, establish and open an empty GDI document, and generate an initialization variable indicating the completion situation of the initialization; if the received GDI function is not a GDI function indicating start of virtual printing of the sharing document, determine, based on the initialization variable, whether the initialization has been completed, and if the initialization has been completed, determine whether the received GDI function is a GDI function indicating end of the virtual printing of the sharing document, if the received GDI function is a GDI function indicating end of the virtual printing of the sharing document, close the GDI document, and return the result of the conversion to the application of the sharing document; if the received GDI function is not a GDI function indicating end of the virtual print of the sharing document, determine whether the number of GDI function corresponding to the current GDI function is found, and if the number of GDI function corresponding to the current GDI function is found, add 1 to the variable of the serial number of GDI performance, encode the name of GDI function, the variable of the serial number of GDI performance and the GDI function based on the format of GDI instruction stream so as to venerate a GDI instruction, and write the GDI instruction into the GDI document; and if the number of GDS function correspond to the current GDI function is not found, return the result of the conversion to the application of the sharing document; and if initialization has not been completed, cycle back to the step of acquiring the corresponding table of names and numbers of GDI functions from the GDI subsystem, initializing the variable of the serial number of GDI performance to 0, establishing and opening the empty GDI document, and generating the initialization variable indicating the completion situation of the initialization.