High speed image drawing method and apparatus therefor

An image drawing device comprising:

• an image display device having an image output region including a plurality of pixels arranged in an orthogonal X-Y matrix form;
• means, including an image screen buffer having a plurality of memory cell locations, each of which corresponds to a respective pixel in said image output region, for reaching out the content of said image screen buffer to transfer the content to said image display device;
• a plurality of registers for storing parameters required to draw a desired image;
• memory means for storing at least a program of a drawing procedure;
• and
• processor means connected to said image screen buffer, said register and said memory means, for executing said program by calculating the tangent of a tangential line at a position of said desired image corresponding to a position of a starting pixel from which a segment should be started;
• selecting a line of pixels along one of X-axis and Y-axis direction determined on the basis of the inclination indicated by said calculated tangent;
• determining an auxiliary line in parallel with the selected pixel line;
• determining a number of pixels in the selected pixel line so as to form a segment whose length is determined at an intersection of said auxiliary line with said desired image;
• writing image data of a plurality of segments thus obtained in said image screen buffer;
• and drawing said plurality of segments on said image display device on the basis of the image data as an approximation of said desired image.