346 lines
10 KiB
C++
346 lines
10 KiB
C++
/* libs/graphics/sgl/SkScan_Hairline.cpp
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**
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** Copyright 2006, The Android Open Source Project
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**
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** Licensed under the Apache License, Version 2.0 (the "License");
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** you may not use this file except in compliance with the License.
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** You may obtain a copy of the License at
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**
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** http://www.apache.org/licenses/LICENSE-2.0
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**
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** Unless required by applicable law or agreed to in writing, software
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** distributed under the License is distributed on an "AS IS" BASIS,
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** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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** See the License for the specific language governing permissions and
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** limitations under the License.
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*/
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#include "SkScan.h"
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#include "SkBlitter.h"
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#include "SkRegion.h"
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#include "SkFDot6.h"
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static void horiline(int x, int stopx, SkFixed fy, SkFixed dy, SkBlitter* blitter)
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{
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SkASSERT(x < stopx);
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do {
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blitter->blitH(x, fy >> 16, 1);
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fy += dy;
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} while (++x < stopx);
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}
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static void vertline(int y, int stopy, SkFixed fx, SkFixed dx, SkBlitter* blitter)
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{
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SkASSERT(y < stopy);
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do {
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blitter->blitH(fx >> 16, y, 1);
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fx += dx;
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} while (++y < stopy);
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}
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void SkScan::HairLine(const SkPoint& pt0, const SkPoint& pt1, const SkRegion* clip, SkBlitter* blitter)
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{
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SkBlitterClipper clipper;
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SkFDot6 x0 = SkScalarToFDot6(pt0.fX);
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SkFDot6 y0 = SkScalarToFDot6(pt0.fY);
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SkFDot6 x1 = SkScalarToFDot6(pt1.fX);
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SkFDot6 y1 = SkScalarToFDot6(pt1.fY);
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if (clip)
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{
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SkRect r;
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SkIRect ir;
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SkPoint pts[2];
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pts[0] = pt0;
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pts[1] = pt1;
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r.set(pts, 2);
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r.roundOut(&ir);
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// if we're given a horizontal or vertical line
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// this rect could be empty (in area), in which case
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// clip->quickReject() will always return true.
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// hence we bloat the rect to avoid that case
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if (ir.width() == 0)
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ir.fRight += 1;
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if (ir.height() == 0)
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ir.fBottom += 1;
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if (clip->quickReject(ir))
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return;
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if (clip->quickContains(ir))
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clip = NULL;
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else
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{
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blitter = clipper.apply(blitter, clip);
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}
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}
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SkFDot6 dx = x1 - x0;
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SkFDot6 dy = y1 - y0;
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if (SkAbs32(dx) > SkAbs32(dy)) // mostly horizontal
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{
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if (x0 > x1) // we want to go left-to-right
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{
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SkTSwap<SkFDot6>(x0, x1);
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SkTSwap<SkFDot6>(y0, y1);
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}
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int ix0 = SkFDot6Round(x0);
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int ix1 = SkFDot6Round(x1);
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if (ix0 == ix1) // too short to draw
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return;
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SkFixed slope = SkFixedDiv(dy, dx);
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SkFixed startY = SkFDot6ToFixed(y0) + (slope * ((32 - x0) & 63) >> 6);
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horiline(ix0, ix1, startY, slope, blitter);
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}
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else // mostly vertical
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{
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if (y0 > y1) // we want to go top-to-bottom
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{
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SkTSwap<SkFDot6>(x0, x1);
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SkTSwap<SkFDot6>(y0, y1);
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}
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int iy0 = SkFDot6Round(y0);
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int iy1 = SkFDot6Round(y1);
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if (iy0 == iy1) // too short to draw
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return;
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SkFixed slope = SkFixedDiv(dx, dy);
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SkFixed startX = SkFDot6ToFixed(x0) + (slope * ((32 - y0) & 63) >> 6);
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vertline(iy0, iy1, startX, slope, blitter);
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}
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}
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// we don't just draw 4 lines, 'cause that can leave a gap in the bottom-right
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// and double-hit the top-left.
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void SkScan::HairRect(const SkRect& rect, const SkRegion* clip, SkBlitter* blitter)
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{
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SkBlitterClipper clipper;
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SkIRect r;
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r.set(SkScalarToFixed(rect.fLeft) >> 16,
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SkScalarToFixed(rect.fTop) >> 16,
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(SkScalarToFixed(rect.fRight) >> 16) + 1,
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(SkScalarToFixed(rect.fBottom) >> 16) + 1);
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if (clip)
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{
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if (clip->quickReject(r))
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return;
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if (!clip->quickContains(r))
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blitter = clipper.apply(blitter, clip);
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}
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int width = r.width();
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int height = r.height();
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if ((width | height) == 0)
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return;
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if (width <= 2 || height <= 2)
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{
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blitter->blitRect(r.fLeft, r.fTop, width, height);
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return;
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}
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// if we get here, we know we have 4 segments to draw
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blitter->blitH(r.fLeft, r.fTop, width); // top
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blitter->blitRect(r.fLeft, r.fTop + 1, 1, height - 2); // left
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blitter->blitRect(r.fRight - 1, r.fTop + 1, 1, height - 2); // right
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blitter->blitH(r.fLeft, r.fBottom - 1, width); // bottom
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}
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/////////////////////////////////////////////////////////////////////////////////////////////////
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#include "SkPath.h"
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#include "SkGeometry.h"
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static bool quad_too_curvy(const SkPoint pts[3])
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{
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return true;
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}
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static int compute_int_quad_dist(const SkPoint pts[3]) {
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// compute the vector between the control point ([1]) and the middle of the
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// line connecting the start and end ([0] and [2])
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SkScalar dx = SkScalarHalf(pts[0].fX + pts[2].fX) - pts[1].fX;
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SkScalar dy = SkScalarHalf(pts[0].fY + pts[2].fY) - pts[1].fY;
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// we want everyone to be positive
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dx = SkScalarAbs(dx);
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dy = SkScalarAbs(dy);
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// convert to whole pixel values (use ceiling to be conservative)
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int idx = SkScalarCeil(dx);
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int idy = SkScalarCeil(dy);
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// use the cheap approx for distance
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if (idx > idy) {
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return idx + (idy >> 1);
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} else {
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return idy + (idx >> 1);
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}
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}
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static void hairquad(const SkPoint pts[3], const SkRegion* clip, SkBlitter* blitter, int level,
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void (*lineproc)(const SkPoint&, const SkPoint&, const SkRegion* clip, SkBlitter*))
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{
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#if 1
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if (level > 0 && quad_too_curvy(pts))
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{
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SkPoint tmp[5];
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SkChopQuadAtHalf(pts, tmp);
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hairquad(tmp, clip, blitter, level - 1, lineproc);
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hairquad(&tmp[2], clip, blitter, level - 1, lineproc);
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}
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else
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lineproc(pts[0], pts[2], clip, blitter);
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#else
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int count = 1 << level;
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const SkScalar dt = SkFixedToScalar(SK_Fixed1 >> level);
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SkScalar t = dt;
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SkPoint prevPt = pts[0];
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for (int i = 1; i < count; i++) {
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SkPoint nextPt;
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SkEvalQuadAt(pts, t, &nextPt);
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lineproc(prevPt, nextPt, clip, blitter);
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t += dt;
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prevPt = nextPt;
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}
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// draw the last line explicitly to 1.0, in case t didn't match that exactly
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lineproc(prevPt, pts[2], clip, blitter);
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#endif
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}
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static bool cubic_too_curvy(const SkPoint pts[4])
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{
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return true;
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}
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static void haircubic(const SkPoint pts[4], const SkRegion* clip, SkBlitter* blitter, int level,
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void (*lineproc)(const SkPoint&, const SkPoint&, const SkRegion*, SkBlitter*))
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{
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if (level > 0 && cubic_too_curvy(pts))
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{
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SkPoint tmp[7];
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SkChopCubicAt(pts, tmp, SK_Scalar1/2);
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haircubic(tmp, clip, blitter, level - 1, lineproc);
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haircubic(&tmp[3], clip, blitter, level - 1, lineproc);
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}
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else
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lineproc(pts[0], pts[3], clip, blitter);
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}
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#define kMaxCubicSubdivideLevel 6
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#define kMaxQuadSubdivideLevel 5
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static void hair_path(const SkPath& path, const SkRegion* clip, SkBlitter* blitter,
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void (*lineproc)(const SkPoint&, const SkPoint&, const SkRegion*, SkBlitter*))
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{
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if (path.isEmpty())
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return;
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const SkIRect* clipR = NULL;
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if (clip)
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{
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SkRect bounds;
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SkIRect ibounds;
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path.computeBounds(&bounds, SkPath::kFast_BoundsType);
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bounds.roundOut(&ibounds);
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ibounds.inset(-1, -1);
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if (clip->quickReject(ibounds))
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return;
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if (clip->quickContains(ibounds))
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clip = NULL;
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else
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clipR = &clip->getBounds();
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}
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SkPath::Iter iter(path, false);
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SkPoint pts[4];
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SkPath::Verb verb;
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while ((verb = iter.next(pts)) != SkPath::kDone_Verb)
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{
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switch (verb) {
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case SkPath::kLine_Verb:
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lineproc(pts[0], pts[1], clip, blitter);
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break;
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case SkPath::kQuad_Verb: {
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int d = compute_int_quad_dist(pts);
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/* quadratics approach the line connecting their start and end points
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4x closer with each subdivision, so we compute the number of
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subdivisions to be the minimum need to get that distance to be less
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than a pixel.
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*/
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int level = (33 - SkCLZ(d)) >> 1;
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// SkDebugf("----- distance %d computedLevel %d\n", d, computedLevel);
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// sanity check on level (from the previous version)
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if (level > kMaxQuadSubdivideLevel) {
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level = kMaxQuadSubdivideLevel;
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}
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hairquad(pts, clip, blitter, level, lineproc);
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break;
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}
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case SkPath::kCubic_Verb:
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haircubic(pts, clip, blitter, kMaxCubicSubdivideLevel, lineproc);
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break;
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default:
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break;
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}
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}
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}
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void SkScan::HairPath(const SkPath& path, const SkRegion* clip, SkBlitter* blitter)
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{
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hair_path(path, clip, blitter, SkScan::HairLine);
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}
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void SkScan::AntiHairPath(const SkPath& path, const SkRegion* clip, SkBlitter* blitter)
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{
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hair_path(path, clip, blitter, SkScan::AntiHairLine);
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}
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////////////////////////////////////////////////////////////////////////////////
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void SkScan::FrameRect(const SkRect& r, SkScalar diameter, const SkRegion* clip, SkBlitter* blitter)
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{
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SkASSERT(diameter > 0);
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if (r.isEmpty())
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return;
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SkScalar radius = diameter / 2;
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SkRect outer, tmp;
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outer.set( r.fLeft - radius, r.fTop - radius,
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r.fRight + radius, r.fBottom + radius);
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if (r.width() <= diameter || r.height() <= diameter)
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{
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SkScan::FillRect(outer, clip, blitter);
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return;
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}
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tmp.set(outer.fLeft, outer.fTop, outer.fRight, outer.fTop + diameter);
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SkScan::FillRect(tmp, clip, blitter);
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tmp.fTop = outer.fBottom - diameter;
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tmp.fBottom = outer.fBottom;
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SkScan::FillRect(tmp, clip, blitter);
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tmp.set(outer.fLeft, outer.fTop + diameter, outer.fLeft + diameter, outer.fBottom - diameter);
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SkScan::FillRect(tmp, clip, blitter);
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tmp.fLeft = outer.fRight - diameter;
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tmp.fRight = outer.fRight;
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SkScan::FillRect(tmp, clip, blitter);
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}
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