Initial data commit

Task/Bitmap-Bresenhams-line-algorithm/Fortran/bitmap-bresenhams-line-algorithm-1.f

@@ -0,0 +1,70 @@
+module RCImagePrimitive
+  use RCImageBasic
+
+  implicit none
+
+  type point
+     integer :: x, y
+  end type point
+
+  private :: swapcoord
+
+contains
+
+  subroutine swapcoord(p1, p2)
+    integer, intent(inout) :: p1, p2
+    integer :: t
+
+    t = p2
+    p2 = p1
+    p1 = t
+  end subroutine swapcoord
+
+  subroutine draw_line(img, from, to, color)
+    type(rgbimage), intent(inout) :: img
+    type(point), intent(in) :: from, to
+    type(rgb), intent(in) :: color
+
+    type(point) :: rfrom, rto
+    integer :: dx, dy, error, ystep, x, y
+    logical :: steep
+
+    rfrom = from
+    rto = to
+    steep = (abs(rto%y - rfrom%y) > abs(rto%x - rfrom%x))
+    if ( steep ) then
+       call swapcoord(rfrom%x, rfrom%y)
+       call swapcoord(rto%x, rto%y)
+    end if
+    if ( rfrom%x > rto%x ) then
+       call swapcoord(rfrom%x, rto%x)
+       call swapcoord(rfrom%y, rto%y)
+    end if
+
+    dx = rto%x - rfrom%x
+    dy = abs(rto%y - rfrom%y)
+    error = dx / 2
+    y = rfrom%y
+
+    if ( rfrom%y < rto%y ) then
+       ystep = 1
+    else
+       ystep = -1
+    end if
+
+    do x = rfrom%x, rto%x
+       if ( steep ) then
+          call put_pixel(img, y, x, color)
+       else
+          call put_pixel(img, x, y, color)
+       end if
+       error = error - dy
+       if ( error < 0 ) then
+          y = y + ystep
+          error = error + dx
+       end if
+    end do
+
+  end subroutine draw_line
+
+end module RCImagePrimitive