JDK14/Java14源码在线阅读
/*
* Copyright (c) 2000, 2001, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
#include "GraphicsPrimitiveMgr.h"
#include "LineUtils.h"
#include "sun_java2d_loops_DrawLine.h"
#define OUTCODE_TOP 1
#define OUTCODE_BOTTOM 2
#define OUTCODE_LEFT 4
#define OUTCODE_RIGHT 8
static void
RefineBounds(SurfaceDataBounds *bounds, jint x1, jint y1, jint x2, jint y2)
{
jint min, max;
if (x1 < x2) {
min = x1;
max = x2;
} else {
min = x2;
max = x1;
}
max++;
if (max <= min) {
/* integer overflow */
max--;
}
if (bounds->x1 < min) bounds->x1 = min;
if (bounds->x2 > max) bounds->x2 = max;
if (y1 < y2) {
min = y1;
max = y2;
} else {
min = y2;
max = y1;
}
max++;
if (max <= min) {
/* integer overflow */
max--;
}
if (bounds->y1 < min) bounds->y1 = min;
if (bounds->y2 > max) bounds->y2 = max;
}
#define _out(v, vmin, vmax, cmin, cmax) \
((v < vmin) ? cmin : ((v > vmax) ? cmax : 0))
#define outcode(x, y, xmin, ymin, xmax, ymax) \
(_out(y, ymin, ymax, OUTCODE_TOP, OUTCODE_BOTTOM) | \
_out(x, xmin, xmax, OUTCODE_LEFT, OUTCODE_RIGHT))
/*
* "Small" math here will be done if the coordinates are less
* than 15 bits in range (-16384 => 16383). This could be
* expanded to 16 bits if we rearrange some of the math in
* the normal version of SetupBresenham.
* "Big" math here will be done with coordinates with 30 bits
* of total range - 2 bits less than a jint holds.
* Intermediate calculations for "Big" coordinates will be
* done using jlong variables.
*/
#define OverflowsSmall(v) ((v) != (((v) << 17) >> 17))
#define OverflowsBig(v) ((v) != (((v) << 2) >> 2))
#define BIG_MAX ((1 << 29) - 1)
#define BIG_MIN (-(1 << 29))
#define SETUP_BRESENHAM(CALC_TYPE, ORIGX1, ORIGY1, ORIGX2, ORIGY2, SHORTEN) \
do { \
jint X1 = ORIGX1, Y1 = ORIGY1, X2 = ORIGX2, Y2 = ORIGY2; \
jint dx, dy, ax, ay; \
jint cxmin, cymin, cxmax, cymax; \
jint outcode1, outcode2; \
jboolean xmajor; \
jint errminor, errmajor; \
jint error; \
jint steps; \
\
dx = X2 - X1; \
dy = Y2 - Y1; \
ax = (dx < 0) ? -dx : dx; \
ay = (dy < 0) ? -dy : dy; \
\
cxmin = pBounds->x1; \
cymin = pBounds->y1; \
cxmax = pBounds->x2 - 1; \
cymax = pBounds->y2 - 1; \
xmajor = (ax >= ay); \
\
outcode1 = outcode(X1, Y1, cxmin, cymin, cxmax, cymax); \
outcode2 = outcode(X2, Y2, cxmin, cymin, cxmax, cymax); \
while ((outcode1 | outcode2) != 0) { \
CALC_TYPE xsteps, ysteps; \
if ((outcode1 & outcode2) != 0) { \
return JNI_FALSE; \
} \
if (outcode1 != 0) { \
if (outcode1 & (OUTCODE_TOP | OUTCODE_BOTTOM)) { \
if (outcode1 & OUTCODE_TOP) { \
Y1 = cymin; \
} else { \
Y1 = cymax; \
} \
ysteps = Y1 - ORIGY1; \
if (ysteps < 0) { \
ysteps = -ysteps; \
} \
xsteps = 2 * ysteps * ax + ay; \
if (xmajor) { \
xsteps += ay - ax - 1; \
} \
xsteps = xsteps / (2 * ay); \
if (dx < 0) { \
xsteps = -xsteps; \
} \
X1 = ORIGX1 + (jint) xsteps; \
} else if (outcode1 & (OUTCODE_LEFT | OUTCODE_RIGHT)) { \
if (outcode1 & OUTCODE_LEFT) { \
X1 = cxmin; \
} else { \
X1 = cxmax; \
} \
xsteps = X1 - ORIGX1; \
if (xsteps < 0) { \
xsteps = -xsteps; \
} \
ysteps = 2 * xsteps * ay + ax; \
if (!xmajor) { \
ysteps += ax - ay - 1; \
} \
ysteps = ysteps / (2 * ax); \
if (dy < 0) { \
ysteps = -ysteps; \
} \
Y1 = ORIGY1 + (jint) ysteps; \
} \
outcode1 = outcode(X1, Y1, cxmin, cymin, cxmax, cymax); \
} else { \
if (outcode2 & (OUTCODE_TOP | OUTCODE_BOTTOM)) { \
if (outcode2 & OUTCODE_TOP) { \
Y2 = cymin; \
} else { \
Y2 = cymax; \
} \
ysteps = Y2 - ORIGY2; \
if (ysteps < 0) { \
ysteps = -ysteps; \
} \
xsteps = 2 * ysteps * ax + ay; \
if (xmajor) { \
xsteps += ay - ax; \
} else { \
xsteps -= 1; \
} \
xsteps = xsteps / (2 * ay); \
if (dx > 0) { \
xsteps = -xsteps; \
} \
X2 = ORIGX2 + (jint) xsteps; \
} else if (outcode2 & (OUTCODE_LEFT | OUTCODE_RIGHT)) { \
if (outcode2 & OUTCODE_LEFT) { \
X2 = cxmin; \
} else { \
X2 = cxmax; \
} \
xsteps = X2 - ORIGX2; \
if (xsteps < 0) { \
xsteps = -xsteps; \
} \
ysteps = 2 * xsteps * ay + ax; \
if (xmajor) { \
ysteps -= 1; \
} else { \
ysteps += ax - ay; \
} \
ysteps = ysteps / (2 * ax); \
if (dy > 0) { \
ysteps = -ysteps; \
} \
Y2 = ORIGY2 + (jint) ysteps; \
} \
outcode2 = outcode(X2, Y2, cxmin, cymin, cxmax, cymax); \
} \
} \
*pStartX = X1; \
*pStartY = Y1; \
\
if (xmajor) { \
errmajor = ay * 2; \
errminor = ax * 2; \
*pBumpMajorMask = (dx < 0) ? BUMP_NEG_PIXEL : BUMP_POS_PIXEL; \
*pBumpMinorMask = (dy < 0) ? BUMP_NEG_SCAN : BUMP_POS_SCAN; \
ax = -ax; /* For clipping adjustment below */ \
steps = X2 - X1; \
if (X2 != ORIGX2) { \
SHORTEN = 0; \
} \
} else { \
errmajor = ax * 2; \
errminor = ay * 2; \
*pBumpMajorMask = (dy < 0) ? BUMP_NEG_SCAN : BUMP_POS_SCAN; \
*pBumpMinorMask = (dx < 0) ? BUMP_NEG_PIXEL : BUMP_POS_PIXEL; \
ay = -ay; /* For clipping adjustment below */ \
steps = Y2 - Y1; \
if (Y2 != ORIGY2) { \
SHORTEN = 0; \
} \
} \
if ((steps = ((steps >= 0) ? steps : -steps) + 1 - SHORTEN) == 0) { \
return JNI_FALSE; \
} \
error = - (errminor / 2); \
if (Y1 != ORIGY1) { \
jint ysteps = Y1 - ORIGY1; \
if (ysteps < 0) { \
ysteps = -ysteps; \
} \
error += ysteps * ax * 2; \
} \
if (X1 != ORIGX1) { \
jint xsteps = X1 - ORIGX1; \
if (xsteps < 0) { \
xsteps = -xsteps; \
} \
error += xsteps * ay * 2; \
} \
error += errmajor; \
errminor -= errmajor; \
\
*pSteps = steps; \
*pError = error; \
*pErrMajor = errmajor; \
*pErrMinor = errminor; \
} while (0)
static jboolean
LineUtils_SetupBresenhamBig(jint _x1, jint _y1, jint _x2, jint _y2,
jint shorten,
SurfaceDataBounds *pBounds,
jint *pStartX, jint *pStartY,
jint *pSteps, jint *pError,
jint *pErrMajor, jint *pBumpMajorMask,
jint *pErrMinor, jint *pBumpMinorMask)
{
/*
* Part of calculating the Bresenham parameters for line stepping
* involves being able to store numbers that are twice the magnitude
* of the biggest absolute difference in coordinates. Since we
* want the stepping parameters to be stored in jints, we then need
* to avoid any absolute differences more than 30 bits. Thus, we
* need to preprocess the coordinates to reduce their range to 30
* bits regardless of clipping. We need to cut their range back
* before we do the clipping because the Bresenham stepping values
* need to be calculated based on the "unclipped" coordinates.
*
* Thus, first we perform a "pre-clipping" stage to bring the
* coordinates within the 30-bit range and then we proceed to the
* regular clipping procedure, pretending that these were the
* original coordinates all along. Since this operation occurs
* based on a constant "pre-clip" rectangle of +/- 30 bits without
* any consideration for the final clip, the rounding errors that
* occur here will depend only on the line coordinates and be
* invariant with respect to the particular device/user clip
* rectangles in effect at the time. Thus, rendering a given
* large-range line will be consistent under a variety of
* clipping conditions.
*/
if (OverflowsBig(_x1) || OverflowsBig(_y1) ||
OverflowsBig(_x2) || OverflowsBig(_y2))
{
/*
* Use doubles to get us into range for "Big" arithmetic.
*
* The math of adjusting an endpoint for clipping can involve
* an intermediate result with twice the number of bits as the
* original coordinate range. Since we want to maintain as
* much as 30 bits of precision in the resulting coordinates,
* we will get roundoff here even using IEEE double-precision
* arithmetic which cannot carry 60 bits of mantissa. Since
* the rounding errors will be consistent for a given set
* of input coordinates the potential roundoff error should
* not affect the consistency of our rendering.
*/
double X1d = _x1;
double Y1d = _y1;
double X2d = _x2;
double Y2d = _y2;
double DXd = X2d - X1d;
double DYd = Y2d - Y1d;
if (_x1 < BIG_MIN) {
Y1d = _y1 + (BIG_MIN - _x1) * DYd / DXd;
X1d = BIG_MIN;
} else if (_x1 > BIG_MAX) {
Y1d = _y1 - (_x1 - BIG_MAX) * DYd / DXd;
X1d = BIG_MAX;
}
/* Use Y1d instead of _y1 for testing now as we may have modified it */
if (Y1d < BIG_MIN) {
X1d = _x1 + (BIG_MIN - _y1) * DXd / DYd;
Y1d = BIG_MIN;
} else if (Y1d > BIG_MAX) {
X1d = _x1 - (_y1 - BIG_MAX) * DXd / DYd;
Y1d = BIG_MAX;
}
if (_x2 < BIG_MIN) {
Y2d = _y2 + (BIG_MIN - _x2) * DYd / DXd;
X2d = BIG_MIN;
} else if (_x2 > BIG_MAX) {
Y2d = _y2 - (_x2 - BIG_MAX) * DYd / DXd;
X2d = BIG_MAX;
}
/* Use Y2d instead of _y2 for testing now as we may have modified it */
if (Y2d < BIG_MIN) {
X2d = _x2 + (BIG_MIN - _y2) * DXd / DYd;
Y2d = BIG_MIN;
} else if (Y2d > BIG_MAX) {
X2d = _x2 - (_y2 - BIG_MAX) * DXd / DYd;
Y2d = BIG_MAX;
}
_x1 = (int) X1d;
_y1 = (int) Y1d;
_x2 = (int) X2d;
_y2 = (int) Y2d;
}
SETUP_BRESENHAM(jlong, _x1, _y1, _x2, _y2, shorten);
return JNI_TRUE;
}
jboolean
LineUtils_SetupBresenham(jint _x1, jint _y1, jint _x2, jint _y2,
jint shorten,
SurfaceDataBounds *pBounds,
jint *pStartX, jint *pStartY,
jint *pSteps, jint *pError,
jint *pErrMajor, jint *pBumpMajorMask,
jint *pErrMinor, jint *pBumpMinorMask)
{
if (OverflowsSmall(_x1) || OverflowsSmall(_y1) ||
OverflowsSmall(_x2) || OverflowsSmall(_y2))
{
return LineUtils_SetupBresenhamBig(_x1, _y1, _x2, _y2, shorten,
pBounds,
pStartX, pStartY,
pSteps, pError,
pErrMajor, pBumpMajorMask,
pErrMinor, pBumpMinorMask);
}
SETUP_BRESENHAM(jint, _x1, _y1, _x2, _y2, shorten);
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