Operating system independent method and apparatus for graphical remote access having improved latency

A method for scanning video graphics data, comprising the acts of:

• (a) dividing a screen into a number of rows and columns of blocks, each of the blocks having contents, wherein each pixel within each of the blocks is identifiable by a respective X-Y coordinate;
• (b) scanning a first row of blocks to read the contents of each one of the blocks in the first row;
• (c) checking a first register to determine whether an indication of a change in the contents of one of the pixels of one of the blocks having a minimum X-Y coordinate has been stored in the first register;
• (d) checking a second register to determine whether an indication of a change in the contents of one of the pixels of one of the blocks having a maximum X-Y coordinate has been stored in the a second register;
• (e) if the respective indications have not been stored in the respective first and second registers, scanning a successive row of blocks to read the contents of each one of the blocks in the successive row, and repeating acts (c) and (d);
• (f) if the respective indications have been stored in the respective first and second registers, determining whether a rectangle can be formed having the block having the pixel having the minimum X-Y coordinate in one corner and having the block having the pixel having the maximum X-Y coordinate in an opposite corner;
• (g) if the rectangle cannot be formed, scanning the successive row of blocks to read the contents of each one of the blocks in the successive row, and repeating acts (c) through (f);
• (h) if a rectangle can be formed, determining whether the rectangle exceeds a given size threshold;
• (i) if the rectangle does not exceed the size threshold, scanning only the blocks defined by and within the rectangle;
• and
• (j) if the rectangle does exceed the size threshold, scanning the successive row of blocks to read the contents of each one of the blocks in the successive row, and repeating acts (c) through (j).

An apparatus for scanning video graphics data, comprising:

• a video graphics controller having a frame buffer;
• and
• a remote management controller having a first register and a second register, the remote management controller coupled to the video graphics controller to:
• (a) divide the frame buffer into a number of rows and columns of blocks, each of the blocks having contents, wherein each pixel within each of the blocks is identifiable by a respective X-Y coordinate;
• (b) scan a first row of blocks to read the contents of each one of the blocks in the first row;
• (c) check the first register to determine whether an indication of a change in the contents of one of the pixels within one of the blocks having a minimum X-Y coordinate has been stored in the first register;
• (d) check the second register to determine whether an indication of a change in the contents of one of the pixels within one of the blocks having a maximum X-Y coordinate has been stored in the a second register;
• (e) if the respective indications have not been stored in the respective first and second registers, scan a successive row of blocks to read the contents of each one of the blocks in the successive row, and repeat acts (c) and (d);
• (f) if the respective indications have been stored in the respective first and second registers, determine whether a rectangle can be formed having the block having the pixel having the minimum X-Y coordinate in one corner and having the block having the pixel having the maximum X-Y coordinate in an opposite corner;
• (g) if the rectangle cannot be formed, scan the successive row of blocks to read the contents of each one of the blocks in the successive row, and repeat acts (c) through (f);
• (h) if a rectangle can be formed, determine whether the rectangle exceeds a given size threshold;
• (i) if the rectangle does not exceed the size threshold, scan only the blocks defined by and within the rectangle;
• and
• (j) if the rectangle does exceed the size threshold, scan the successive row of blocks to read the contents of each one of the blocks in the successive row, and repeat acts (c) through (j).