1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/gfx/skia/trunk/src/core/SkScan_Hairline.cpp Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,417 @@
1.4 +
1.5 +/*
1.6 + * Copyright 2006 The Android Open Source Project
1.7 + *
1.8 + * Use of this source code is governed by a BSD-style license that can be
1.9 + * found in the LICENSE file.
1.10 + */
1.11 +
1.12 +
1.13 +#include "SkScan.h"
1.14 +#include "SkBlitter.h"
1.15 +#include "SkRasterClip.h"
1.16 +#include "SkFDot6.h"
1.17 +#include "SkLineClipper.h"
1.18 +
1.19 +static void horiline(int x, int stopx, SkFixed fy, SkFixed dy,
1.20 + SkBlitter* blitter) {
1.21 + SkASSERT(x < stopx);
1.22 +
1.23 + do {
1.24 + blitter->blitH(x, fy >> 16, 1);
1.25 + fy += dy;
1.26 + } while (++x < stopx);
1.27 +}
1.28 +
1.29 +static void vertline(int y, int stopy, SkFixed fx, SkFixed dx,
1.30 + SkBlitter* blitter) {
1.31 + SkASSERT(y < stopy);
1.32 +
1.33 + do {
1.34 + blitter->blitH(fx >> 16, y, 1);
1.35 + fx += dx;
1.36 + } while (++y < stopy);
1.37 +}
1.38 +
1.39 +#ifdef SK_DEBUG
1.40 +static bool canConvertFDot6ToFixed(SkFDot6 x) {
1.41 + const int maxDot6 = SK_MaxS32 >> (16 - 6);
1.42 + return SkAbs32(x) <= maxDot6;
1.43 +}
1.44 +#endif
1.45 +
1.46 +void SkScan::HairLineRgn(const SkPoint& pt0, const SkPoint& pt1,
1.47 + const SkRegion* clip, SkBlitter* blitter) {
1.48 + SkBlitterClipper clipper;
1.49 + SkRect r;
1.50 + SkIRect clipR, ptsR;
1.51 + SkPoint pts[2] = { pt0, pt1 };
1.52 +
1.53 + // We have to pre-clip the line to fit in a SkFixed, so we just chop
1.54 + // the line. TODO find a way to actually draw beyond that range.
1.55 + {
1.56 + SkRect fixedBounds;
1.57 + const SkScalar max = SkIntToScalar(32767);
1.58 + fixedBounds.set(-max, -max, max, max);
1.59 + if (!SkLineClipper::IntersectLine(pts, fixedBounds, pts)) {
1.60 + return;
1.61 + }
1.62 + }
1.63 +
1.64 + if (clip) {
1.65 + // Perform a clip in scalar space, so we catch huge values which might
1.66 + // be missed after we convert to SkFDot6 (overflow)
1.67 + r.set(clip->getBounds());
1.68 + if (!SkLineClipper::IntersectLine(pts, r, pts)) {
1.69 + return;
1.70 + }
1.71 + }
1.72 +
1.73 + SkFDot6 x0 = SkScalarToFDot6(pts[0].fX);
1.74 + SkFDot6 y0 = SkScalarToFDot6(pts[0].fY);
1.75 + SkFDot6 x1 = SkScalarToFDot6(pts[1].fX);
1.76 + SkFDot6 y1 = SkScalarToFDot6(pts[1].fY);
1.77 +
1.78 + SkASSERT(canConvertFDot6ToFixed(x0));
1.79 + SkASSERT(canConvertFDot6ToFixed(y0));
1.80 + SkASSERT(canConvertFDot6ToFixed(x1));
1.81 + SkASSERT(canConvertFDot6ToFixed(y1));
1.82 +
1.83 + if (clip) {
1.84 + // now perform clipping again, as the rounding to dot6 can wiggle us
1.85 + // our rects are really dot6 rects, but since we've already used
1.86 + // lineclipper, we know they will fit in 32bits (26.6)
1.87 + const SkIRect& bounds = clip->getBounds();
1.88 +
1.89 + clipR.set(SkIntToFDot6(bounds.fLeft), SkIntToFDot6(bounds.fTop),
1.90 + SkIntToFDot6(bounds.fRight), SkIntToFDot6(bounds.fBottom));
1.91 + ptsR.set(x0, y0, x1, y1);
1.92 + ptsR.sort();
1.93 +
1.94 + // outset the right and bottom, to account for how hairlines are
1.95 + // actually drawn, which may hit the pixel to the right or below of
1.96 + // the coordinate
1.97 + ptsR.fRight += SK_FDot6One;
1.98 + ptsR.fBottom += SK_FDot6One;
1.99 +
1.100 + if (!SkIRect::Intersects(ptsR, clipR)) {
1.101 + return;
1.102 + }
1.103 + if (clip->isRect() && clipR.contains(ptsR)) {
1.104 + clip = NULL;
1.105 + } else {
1.106 + blitter = clipper.apply(blitter, clip);
1.107 + }
1.108 + }
1.109 +
1.110 + SkFDot6 dx = x1 - x0;
1.111 + SkFDot6 dy = y1 - y0;
1.112 +
1.113 + if (SkAbs32(dx) > SkAbs32(dy)) { // mostly horizontal
1.114 + if (x0 > x1) { // we want to go left-to-right
1.115 + SkTSwap<SkFDot6>(x0, x1);
1.116 + SkTSwap<SkFDot6>(y0, y1);
1.117 + }
1.118 + int ix0 = SkFDot6Round(x0);
1.119 + int ix1 = SkFDot6Round(x1);
1.120 + if (ix0 == ix1) {// too short to draw
1.121 + return;
1.122 + }
1.123 +
1.124 + SkFixed slope = SkFixedDiv(dy, dx);
1.125 + SkFixed startY = SkFDot6ToFixed(y0) + (slope * ((32 - x0) & 63) >> 6);
1.126 +
1.127 + horiline(ix0, ix1, startY, slope, blitter);
1.128 + } else { // mostly vertical
1.129 + if (y0 > y1) { // we want to go top-to-bottom
1.130 + SkTSwap<SkFDot6>(x0, x1);
1.131 + SkTSwap<SkFDot6>(y0, y1);
1.132 + }
1.133 + int iy0 = SkFDot6Round(y0);
1.134 + int iy1 = SkFDot6Round(y1);
1.135 + if (iy0 == iy1) { // too short to draw
1.136 + return;
1.137 + }
1.138 +
1.139 + SkFixed slope = SkFixedDiv(dx, dy);
1.140 + SkFixed startX = SkFDot6ToFixed(x0) + (slope * ((32 - y0) & 63) >> 6);
1.141 +
1.142 + vertline(iy0, iy1, startX, slope, blitter);
1.143 + }
1.144 +}
1.145 +
1.146 +// we don't just draw 4 lines, 'cause that can leave a gap in the bottom-right
1.147 +// and double-hit the top-left.
1.148 +// TODO: handle huge coordinates on rect (before calling SkScalarToFixed)
1.149 +void SkScan::HairRect(const SkRect& rect, const SkRasterClip& clip,
1.150 + SkBlitter* blitter) {
1.151 + SkAAClipBlitterWrapper wrapper;
1.152 + SkBlitterClipper clipper;
1.153 + SkIRect r;
1.154 +
1.155 + r.set(SkScalarToFixed(rect.fLeft) >> 16,
1.156 + SkScalarToFixed(rect.fTop) >> 16,
1.157 + (SkScalarToFixed(rect.fRight) >> 16) + 1,
1.158 + (SkScalarToFixed(rect.fBottom) >> 16) + 1);
1.159 +
1.160 + if (clip.quickReject(r)) {
1.161 + return;
1.162 + }
1.163 + if (!clip.quickContains(r)) {
1.164 + const SkRegion* clipRgn;
1.165 + if (clip.isBW()) {
1.166 + clipRgn = &clip.bwRgn();
1.167 + } else {
1.168 + wrapper.init(clip, blitter);
1.169 + clipRgn = &wrapper.getRgn();
1.170 + blitter = wrapper.getBlitter();
1.171 + }
1.172 + blitter = clipper.apply(blitter, clipRgn);
1.173 + }
1.174 +
1.175 + int width = r.width();
1.176 + int height = r.height();
1.177 +
1.178 + if ((width | height) == 0) {
1.179 + return;
1.180 + }
1.181 + if (width <= 2 || height <= 2) {
1.182 + blitter->blitRect(r.fLeft, r.fTop, width, height);
1.183 + return;
1.184 + }
1.185 + // if we get here, we know we have 4 segments to draw
1.186 + blitter->blitH(r.fLeft, r.fTop, width); // top
1.187 + blitter->blitRect(r.fLeft, r.fTop + 1, 1, height - 2); // left
1.188 + blitter->blitRect(r.fRight - 1, r.fTop + 1, 1, height - 2); // right
1.189 + blitter->blitH(r.fLeft, r.fBottom - 1, width); // bottom
1.190 +}
1.191 +
1.192 +///////////////////////////////////////////////////////////////////////////////
1.193 +
1.194 +#include "SkPath.h"
1.195 +#include "SkGeometry.h"
1.196 +
1.197 +static int compute_int_quad_dist(const SkPoint pts[3]) {
1.198 + // compute the vector between the control point ([1]) and the middle of the
1.199 + // line connecting the start and end ([0] and [2])
1.200 + SkScalar dx = SkScalarHalf(pts[0].fX + pts[2].fX) - pts[1].fX;
1.201 + SkScalar dy = SkScalarHalf(pts[0].fY + pts[2].fY) - pts[1].fY;
1.202 + // we want everyone to be positive
1.203 + dx = SkScalarAbs(dx);
1.204 + dy = SkScalarAbs(dy);
1.205 + // convert to whole pixel values (use ceiling to be conservative)
1.206 + int idx = SkScalarCeilToInt(dx);
1.207 + int idy = SkScalarCeilToInt(dy);
1.208 + // use the cheap approx for distance
1.209 + if (idx > idy) {
1.210 + return idx + (idy >> 1);
1.211 + } else {
1.212 + return idy + (idx >> 1);
1.213 + }
1.214 +}
1.215 +
1.216 +typedef void (*LineProc)(const SkPoint&, const SkPoint&, const SkRegion*,
1.217 + SkBlitter*);
1.218 +
1.219 +static void hairquad(const SkPoint pts[3], const SkRegion* clip,
1.220 + SkBlitter* blitter, int level, LineProc lineproc) {
1.221 + if (level > 0) {
1.222 + SkPoint tmp[5];
1.223 +
1.224 + SkChopQuadAtHalf(pts, tmp);
1.225 + hairquad(tmp, clip, blitter, level - 1, lineproc);
1.226 + hairquad(&tmp[2], clip, blitter, level - 1, lineproc);
1.227 + } else {
1.228 + lineproc(pts[0], pts[2], clip, blitter);
1.229 + }
1.230 +}
1.231 +
1.232 +static void haircubic(const SkPoint pts[4], const SkRegion* clip,
1.233 + SkBlitter* blitter, int level, LineProc lineproc) {
1.234 + if (level > 0) {
1.235 + SkPoint tmp[7];
1.236 +
1.237 + SkChopCubicAt(pts, tmp, SK_Scalar1/2);
1.238 + haircubic(tmp, clip, blitter, level - 1, lineproc);
1.239 + haircubic(&tmp[3], clip, blitter, level - 1, lineproc);
1.240 + } else {
1.241 + lineproc(pts[0], pts[3], clip, blitter);
1.242 + }
1.243 +}
1.244 +
1.245 +#define kMaxCubicSubdivideLevel 6
1.246 +#define kMaxQuadSubdivideLevel 5
1.247 +
1.248 +static int compute_quad_level(const SkPoint pts[3]) {
1.249 + int d = compute_int_quad_dist(pts);
1.250 + /* quadratics approach the line connecting their start and end points
1.251 + 4x closer with each subdivision, so we compute the number of
1.252 + subdivisions to be the minimum need to get that distance to be less
1.253 + than a pixel.
1.254 + */
1.255 + int level = (33 - SkCLZ(d)) >> 1;
1.256 + // sanity check on level (from the previous version)
1.257 + if (level > kMaxQuadSubdivideLevel) {
1.258 + level = kMaxQuadSubdivideLevel;
1.259 + }
1.260 + return level;
1.261 +}
1.262 +
1.263 +static void hair_path(const SkPath& path, const SkRasterClip& rclip,
1.264 + SkBlitter* blitter, LineProc lineproc) {
1.265 + if (path.isEmpty()) {
1.266 + return;
1.267 + }
1.268 +
1.269 + SkAAClipBlitterWrapper wrap;
1.270 + const SkRegion* clip = NULL;
1.271 +
1.272 + {
1.273 + SkIRect ibounds;
1.274 + path.getBounds().roundOut(&ibounds);
1.275 + ibounds.inset(-1, -1);
1.276 +
1.277 + if (rclip.quickReject(ibounds)) {
1.278 + return;
1.279 + }
1.280 + if (!rclip.quickContains(ibounds)) {
1.281 + if (rclip.isBW()) {
1.282 + clip = &rclip.bwRgn();
1.283 + } else {
1.284 + wrap.init(rclip, blitter);
1.285 + blitter = wrap.getBlitter();
1.286 + clip = &wrap.getRgn();
1.287 + }
1.288 + }
1.289 + }
1.290 +
1.291 + SkPath::Iter iter(path, false);
1.292 + SkPoint pts[4];
1.293 + SkPath::Verb verb;
1.294 + SkAutoConicToQuads converter;
1.295 +
1.296 + while ((verb = iter.next(pts, false)) != SkPath::kDone_Verb) {
1.297 + switch (verb) {
1.298 + case SkPath::kMove_Verb:
1.299 + break;
1.300 + case SkPath::kLine_Verb:
1.301 + lineproc(pts[0], pts[1], clip, blitter);
1.302 + break;
1.303 + case SkPath::kQuad_Verb:
1.304 + hairquad(pts, clip, blitter, compute_quad_level(pts), lineproc);
1.305 + break;
1.306 + case SkPath::kConic_Verb: {
1.307 + // how close should the quads be to the original conic?
1.308 + const SkScalar tol = SK_Scalar1 / 4;
1.309 + const SkPoint* quadPts = converter.computeQuads(pts,
1.310 + iter.conicWeight(), tol);
1.311 + for (int i = 0; i < converter.countQuads(); ++i) {
1.312 + int level = compute_quad_level(quadPts);
1.313 + hairquad(quadPts, clip, blitter, level, lineproc);
1.314 + quadPts += 2;
1.315 + }
1.316 + break;
1.317 + }
1.318 + case SkPath::kCubic_Verb:
1.319 + haircubic(pts, clip, blitter, kMaxCubicSubdivideLevel, lineproc);
1.320 + break;
1.321 + case SkPath::kClose_Verb:
1.322 + break;
1.323 + case SkPath::kDone_Verb:
1.324 + break;
1.325 + }
1.326 + }
1.327 +}
1.328 +
1.329 +void SkScan::HairPath(const SkPath& path, const SkRasterClip& clip,
1.330 + SkBlitter* blitter) {
1.331 + hair_path(path, clip, blitter, SkScan::HairLineRgn);
1.332 +}
1.333 +
1.334 +void SkScan::AntiHairPath(const SkPath& path, const SkRasterClip& clip,
1.335 + SkBlitter* blitter) {
1.336 + hair_path(path, clip, blitter, SkScan::AntiHairLineRgn);
1.337 +}
1.338 +
1.339 +///////////////////////////////////////////////////////////////////////////////
1.340 +
1.341 +void SkScan::FrameRect(const SkRect& r, const SkPoint& strokeSize,
1.342 + const SkRasterClip& clip, SkBlitter* blitter) {
1.343 + SkASSERT(strokeSize.fX >= 0 && strokeSize.fY >= 0);
1.344 +
1.345 + if (strokeSize.fX < 0 || strokeSize.fY < 0) {
1.346 + return;
1.347 + }
1.348 +
1.349 + const SkScalar dx = strokeSize.fX;
1.350 + const SkScalar dy = strokeSize.fY;
1.351 + SkScalar rx = SkScalarHalf(dx);
1.352 + SkScalar ry = SkScalarHalf(dy);
1.353 + SkRect outer, tmp;
1.354 +
1.355 + outer.set(r.fLeft - rx, r.fTop - ry,
1.356 + r.fRight + rx, r.fBottom + ry);
1.357 +
1.358 + if (r.width() <= dx || r.height() <= dx) {
1.359 + SkScan::FillRect(outer, clip, blitter);
1.360 + return;
1.361 + }
1.362 +
1.363 + tmp.set(outer.fLeft, outer.fTop, outer.fRight, outer.fTop + dy);
1.364 + SkScan::FillRect(tmp, clip, blitter);
1.365 + tmp.fTop = outer.fBottom - dy;
1.366 + tmp.fBottom = outer.fBottom;
1.367 + SkScan::FillRect(tmp, clip, blitter);
1.368 +
1.369 + tmp.set(outer.fLeft, outer.fTop + dy, outer.fLeft + dx, outer.fBottom - dy);
1.370 + SkScan::FillRect(tmp, clip, blitter);
1.371 + tmp.fLeft = outer.fRight - dx;
1.372 + tmp.fRight = outer.fRight;
1.373 + SkScan::FillRect(tmp, clip, blitter);
1.374 +}
1.375 +
1.376 +void SkScan::HairLine(const SkPoint& p0, const SkPoint& p1,
1.377 + const SkRasterClip& clip, SkBlitter* blitter) {
1.378 + if (clip.isBW()) {
1.379 + HairLineRgn(p0, p1, &clip.bwRgn(), blitter);
1.380 + } else {
1.381 + const SkRegion* clipRgn = NULL;
1.382 + SkRect r;
1.383 + SkIRect ir;
1.384 + r.set(p0.fX, p0.fY, p1.fX, p1.fY);
1.385 + r.sort();
1.386 + r.inset(-SK_ScalarHalf, -SK_ScalarHalf);
1.387 + r.roundOut(&ir);
1.388 +
1.389 + SkAAClipBlitterWrapper wrap;
1.390 + if (!clip.quickContains(ir)) {
1.391 + wrap.init(clip, blitter);
1.392 + blitter = wrap.getBlitter();
1.393 + clipRgn = &wrap.getRgn();
1.394 + }
1.395 + HairLineRgn(p0, p1, clipRgn, blitter);
1.396 + }
1.397 +}
1.398 +
1.399 +void SkScan::AntiHairLine(const SkPoint& p0, const SkPoint& p1,
1.400 + const SkRasterClip& clip, SkBlitter* blitter) {
1.401 + if (clip.isBW()) {
1.402 + AntiHairLineRgn(p0, p1, &clip.bwRgn(), blitter);
1.403 + } else {
1.404 + const SkRegion* clipRgn = NULL;
1.405 + SkRect r;
1.406 + SkIRect ir;
1.407 + r.set(p0.fX, p0.fY, p1.fX, p1.fY);
1.408 + r.sort();
1.409 + r.roundOut(&ir);
1.410 + ir.inset(-1, -1);
1.411 +
1.412 + SkAAClipBlitterWrapper wrap;
1.413 + if (!clip.quickContains(ir)) {
1.414 + wrap.init(clip, blitter);
1.415 + blitter = wrap.getBlitter();
1.416 + clipRgn = &wrap.getRgn();
1.417 + }
1.418 + AntiHairLineRgn(p0, p1, clipRgn, blitter);
1.419 + }
1.420 +}
