Function write_device_prim_blocks 

pub fn write_device_prim_blocks(
    builder: &mut GpuBufferBuilderImpl<GpuBufferBlockF>,
    prim_rect: &DeviceRect,
    clip_rect: &DeviceRect,
    pattern_base_color: ColorF,
    pattern_texture_input: RenderTaskId,
    segments: &[QuadSegment],
    pattern_scale_offset: ScaleOffset,
) -> GpuBufferAddress

Write the gpu blocks for a primitive in device space.