b4c37e50df
git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@3912 42af7a65-404d-4744-a932-0658087f49c3
338 lines
11 KiB
C
338 lines
11 KiB
C
/****************************************************************************
|
|
* graphics/nxglib/nxglib_splitline.c
|
|
*
|
|
* Copyright (C) 2011 Gregory Nutt. All rights reserved.
|
|
* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
*
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in
|
|
* the documentation and/or other materials provided with the
|
|
* distribution.
|
|
* 3. Neither the name NuttX nor the names of its contributors may be
|
|
* used to endorse or promote products derived from this software
|
|
* without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
|
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
|
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
|
|
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
|
|
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
|
|
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
|
|
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
|
|
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
|
|
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
|
|
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
* POSSIBILITY OF SUCH DAMAGE.
|
|
*
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Included Files
|
|
****************************************************************************/
|
|
|
|
#include <nuttx/config.h>
|
|
|
|
#include <string.h>
|
|
#include <errno.h>
|
|
|
|
#include <nuttx/nx/nxglib.h>
|
|
|
|
/****************************************************************************
|
|
* Pre-Processor Definitions
|
|
****************************************************************************/
|
|
|
|
#define SMALL_SIN 1966 /* 1966/65536 = 0.03 */
|
|
|
|
/****************************************************************************
|
|
* Private Types
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Private Data
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Public Data
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Private Functions
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Public Functions
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Name: nxgl_splitline
|
|
*
|
|
* Description:
|
|
* In the general case, a line with width can be represented as a
|
|
* parallelogram with a triangle at the top and bottom. Triangles and
|
|
* parallelograms are both degenerate versions of a trapeziod. This
|
|
* function breaks a wide line into triangles and trapezoids. This
|
|
* function also detects other degenerate cases:
|
|
*
|
|
* 1. If y1 == y2 then the line is horizontal and is better represented
|
|
* as a rectangle.
|
|
* 2. If x1 == x2 then the line is vertical and also better represented
|
|
* as a rectangle.
|
|
* 3. If the width of the line is 1, then there are no triangles at the
|
|
* top and bottome (this may also be the case if the width is narrow
|
|
* and the line is near vertical).
|
|
* 4. If the line is oriented is certain angles, it may consist only of
|
|
* the upper and lower triangles with no trapezoid in between. In
|
|
* this case, 3 trapezoids will be returned, but traps[1] will be
|
|
* degenerate.
|
|
*
|
|
* Input parameters:
|
|
* vector - A pointer to the vector described the line to be drawn.
|
|
* traps - A pointer to a array of trapezoids (size 3).
|
|
* rect - A pointer to a rectangle.
|
|
*
|
|
* Returned value:
|
|
* 0: Line successfully broken up into three trapezoids. Values in
|
|
* traps[0], traps[1], and traps[2] are valid.
|
|
* 1: Line successfully represented by one trapezoid. Value in traps[1]
|
|
* is valid.
|
|
* 2: Line successfully represented by one rectangle. Value in rect is
|
|
* valid
|
|
* <0: On errors, a negated errno value is returned.
|
|
*
|
|
****************************************************************************/
|
|
|
|
int nxgl_splitline(FAR struct nxgl_vector_s *vector,
|
|
FAR struct nxgl_trapezoid_s *traps,
|
|
FAR struct nxgl_rect_s *rect,
|
|
nxgl_coord_t linewidth)
|
|
{
|
|
struct nxgl_vector_s line;
|
|
nxgl_coord_t iheight;
|
|
nxgl_coord_t iwidth;
|
|
nxgl_coord_t iy;
|
|
nxgl_coord_t triheight;
|
|
nxgl_coord_t halfheight;
|
|
b16_t adjwidth;
|
|
b16_t xoffset;
|
|
b16_t halfoffset;
|
|
b16_t angle;
|
|
b16_t sinangle;
|
|
b16_t b16x;
|
|
|
|
/* First, check the linewidth */
|
|
|
|
if (linewidth < 1)
|
|
{
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* Then make sure that the start position of the line is above the end
|
|
* position of the line... in raster order.
|
|
*/
|
|
|
|
if (vector->pt1.y < vector->pt2.y)
|
|
{
|
|
/* Vector is already in raster order */
|
|
|
|
memcpy(&line, vector, sizeof(struct nxgl_vector_s));
|
|
}
|
|
else if (vector->pt1.y > vector->pt2.y)
|
|
{
|
|
/* Swap the top and bottom */
|
|
|
|
line.pt1.x = vector->pt2.x;
|
|
line.pt1.y = vector->pt2.y;
|
|
line.pt2.x = vector->pt1.x;
|
|
line.pt2.y = vector->pt1.y;
|
|
}
|
|
else
|
|
{
|
|
/* First degenerate case: The line is horizontal. */
|
|
|
|
if (vector->pt1.x < vector->pt2.x)
|
|
{
|
|
rect->pt1.x = vector->pt1.x;
|
|
rect->pt2.x = vector->pt2.x;
|
|
}
|
|
else
|
|
{
|
|
rect->pt1.x = vector->pt2.x;
|
|
rect->pt2.x = vector->pt1.x;
|
|
}
|
|
|
|
/* The height of the rectangle is the width of the line, half above
|
|
* and half below.
|
|
*/
|
|
|
|
rect->pt1.y = vector->pt1.y - (linewidth >> 1);
|
|
rect->pt2.y = rect->pt1.y + linewidth - 1;
|
|
return 2;
|
|
}
|
|
|
|
/* Check if the line is vertical */
|
|
|
|
if (line.pt1.x == line.pt2.x)
|
|
{
|
|
/* Second degenerate case: The line is vertical. */
|
|
|
|
rect->pt1.y = line.pt1.y;
|
|
rect->pt2.y = line.pt2.y;
|
|
|
|
rect->pt1.x = line.pt1.x - (linewidth >> 1);
|
|
rect->pt2.x = rect->pt1.x + linewidth - 1;
|
|
return 2;
|
|
}
|
|
|
|
/* The final degenerate case */
|
|
|
|
if (linewidth == 1)
|
|
{
|
|
/* A line of width 1 is basically a single parallelogram of width 1 */
|
|
|
|
traps[1].top.x1 = itob16(line.pt1.x);
|
|
traps[1].top.x2 = traps[1].top.x1;
|
|
traps[1].top.y = line.pt1.y;
|
|
|
|
traps[1].bot.x1 = itob16(line.pt2.x);
|
|
traps[1].bot.x2 = traps[1].bot.x1;
|
|
traps[1].bot.y = line.pt2.y;
|
|
return 1;
|
|
}
|
|
|
|
/* Okay, then what remains is interesting.
|
|
*
|
|
* iheight = |y2 - y1|
|
|
* iwidth = |x2 - x1|
|
|
*/
|
|
|
|
iheight = line.pt2.y - line.pt1.y + 1;
|
|
if (line.pt1.x < line.pt2.x)
|
|
{
|
|
iwidth = line.pt2.x - line.pt1.x + 1;
|
|
}
|
|
else
|
|
{
|
|
iwidth = line.pt1.x - line.pt2.x + 1;
|
|
}
|
|
|
|
/* Triangle height: linewidth * cosA
|
|
* Adjusted width: triheight / sinA
|
|
* X offset : linewidth * linewidth / adjusted line width
|
|
*/
|
|
|
|
angle = b16atan2(itob16(iheight), itob16(iwidth));
|
|
triheight = b16toi(linewidth * b16cos(angle) + b16HALF);
|
|
halfheight = (triheight >> 1);
|
|
|
|
/* If the sine of the angle is tiny (i.e., the line is nearly horizontal),
|
|
* then we cannot compute the adjusted width. In this case, just use
|
|
* the width of the line bounding box.
|
|
*/
|
|
|
|
sinangle = b16sin(angle);
|
|
if (sinangle < SMALL_SIN)
|
|
{
|
|
adjwidth = itob16(iwidth);
|
|
xoffset = 0;
|
|
}
|
|
else
|
|
{
|
|
adjwidth = b16divb16(itob16(linewidth), sinangle);
|
|
xoffset = itob16(linewidth * linewidth);
|
|
xoffset = b16divb16(xoffset, adjwidth);
|
|
}
|
|
|
|
halfoffset = (xoffset >> 1);
|
|
|
|
/* Return the top triangle (if there is one). NOTE that the horizontal
|
|
* (z) positions are represented with 16 bits of fraction. The vertical
|
|
* (y) positions, on the other hand, are integer.
|
|
*/
|
|
|
|
if (triheight > 0)
|
|
{
|
|
if (line.pt1.x < line.pt2.x)
|
|
{
|
|
/* Line is going "south east" */
|
|
|
|
b16x = itob16(line.pt1.x) - halfoffset;
|
|
iy = line.pt1.y + halfheight;
|
|
|
|
traps[0].top.x1 = b16x + xoffset;
|
|
traps[0].top.x2 = traps[0].top.x1;
|
|
traps[0].top.y = iy - triheight + 1;
|
|
traps[0].bot.x1 = b16x;
|
|
traps[0].bot.x2 = b16x + adjwidth - b16ONE;
|
|
traps[0].bot.y = iy;
|
|
|
|
b16x = itob16(line.pt2.x) + halfoffset;
|
|
iy = line.pt2.y - halfheight;
|
|
|
|
traps[2].top.x1 = b16x - adjwidth + b16ONE;
|
|
traps[2].top.x2 = b16x;
|
|
traps[2].top.y = iy;
|
|
traps[2].bot.x1 = b16x - xoffset;
|
|
traps[2].bot.x2 = traps[2].bot.x1;
|
|
traps[2].bot.y = iy + triheight - 1;
|
|
}
|
|
else
|
|
{
|
|
/* Line is going "south west" */
|
|
|
|
b16x = itob16(line.pt1.x) + halfoffset;
|
|
iy = line.pt1.y + halfheight;
|
|
|
|
traps[0].top.x1 = b16x - xoffset;
|
|
traps[0].top.x2 = traps[0].top.x1;
|
|
traps[0].top.y = iy - triheight + 1;
|
|
traps[0].bot.x1 = b16x - adjwidth + b16ONE;
|
|
traps[0].bot.x2 = b16x;
|
|
traps[0].bot.y = iy;
|
|
|
|
b16x = itob16(line.pt2.x) - halfoffset;
|
|
iy = line.pt2.y - halfheight;
|
|
|
|
traps[2].top.x1 = b16x;
|
|
traps[2].top.x2 = b16x + adjwidth - b16ONE;
|
|
traps[2].top.y = iy;
|
|
traps[2].bot.x1 = b16x + xoffset;
|
|
traps[2].bot.x2 = traps[2].bot.x1;
|
|
traps[2].bot.y = iy + triheight - 1;
|
|
}
|
|
|
|
/* The center parallelogram is the horizontal edge of each triangle.
|
|
* Note the minor inefficency: that horizontal edges are drawn twice.
|
|
*/
|
|
|
|
traps[1].top.x1 = traps[0].bot.x1;
|
|
traps[1].top.x2 = traps[0].bot.x2;
|
|
traps[1].top.y = traps[0].bot.y;
|
|
|
|
traps[1].bot.x1 = traps[2].top.x1;
|
|
traps[1].bot.x2 = traps[2].top.x2;
|
|
traps[1].bot.y = traps[2].top.y;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* The line is too vertical to have any significant triangular top or
|
|
* bottom. Just return the center parallelogram.
|
|
*/
|
|
|
|
traps[1].top.x1 = itob16(line.pt1.x) - halfoffset;
|
|
traps[1].top.x2 = traps[1].top.x1 + adjwidth - 1;
|
|
traps[1].top.y = line.pt1.y;
|
|
|
|
traps[1].bot.x1 = itob16(line.pt2.x) - halfoffset;
|
|
traps[1].bot.x2 = traps[1].bot.x1 + adjwidth - 1;
|
|
traps[1].bot.y = line.pt2.y;
|
|
return 1;
|
|
}
|