External memory access exacts considerable timing and energy burdens from portable devices. However, most hardware accelerators for rendering two-dimensional (2D) vector graphics draw images in a path-based (path-by-path) manner, which frequently causes excessive external memory traffic. This paper proposes a scanline-based method for rendering 2D vector graphics in portable devices. The proposed method processes all paths spanning a scanline at a time, enabling the use of a scanline-sized internal frame buffer (FB). Using the internal FB, the accelerator can avoid repeated accesses to the external FB and reduce external memory access considerably for images in which many objects overlap with one another. Keywords: vector graphics, rendering, hardware accelerator, memory access Classification: Electron devices, circuits, and systems References

In rendering two-dimensional (2D) vector graphics, edge lists are often so large that their handling hinders the desired operation of portable devices. This paper proposes and evaluates an efficient edge-list handling method for a 2D vector graphics hardware accelerator. The proposed method selects edges that span the next scanline from among those spanning the current scanline and stores them in a small list in the internal memory. An edge list is assigned to each scanline and it stores only those edges that have not appeared in previous edge lists. Given that most active edges span only a few scanlines, the internal list can be small and implemented in the accelerator, whereas the edge lists are held in the external memory. Experimental results show that the proposed method can reduce external memory access by 23.4%À76.6% for the benchmark images considered compared to the prior methods.