/************************************************************************* * * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * Copyright 2008 by Sun Microsystems, Inc. * * OpenOffice.org - a multi-platform office productivity suite * * $RCSfile: clippedlinerenderer.hxx,v $ * $Revision: 1.10 $ * * This file is part of OpenOffice.org. * * OpenOffice.org is free software: you can redistribute it and/or modify * it under the terms of the GNU Lesser General Public License version 3 * only, as published by the Free Software Foundation. * * OpenOffice.org 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 Lesser General Public License version 3 for more details * (a copy is included in the LICENSE file that accompanied this code). * * You should have received a copy of the GNU Lesser General Public License * version 3 along with OpenOffice.org. If not, see * * for a copy of the LGPLv3 License. * ************************************************************************/ #ifndef INCLUDED_BASEBMP_CLIPPEDLINERENDERER_HXX #define INCLUDED_BASEBMP_CLIPPEDLINERENDERER_HXX #include #include #include #include #include namespace basebmp { // factored-out bresenham setup code, which is used from two different // places in renderClippedLine() below. Admittedly messy for the long // parameter list... inline bool prepareClip( sal_Int32 a1, sal_Int32 a2, sal_Int32 b1, sal_Int32 da, sal_Int32 db, sal_Int32& o_as, sal_Int32& o_bs, int sa, int sb, sal_Int32& io_rem, int& o_n, sal_uInt32 clipCode1, sal_uInt32 clipCount1, sal_uInt32 clipCode2, sal_uInt32 clipCount2, sal_Int32 aMin, sal_uInt32 aMinFlag, sal_Int32 aMax, sal_uInt32 aMaxFlag, sal_Int32 bMin, sal_uInt32 bMinFlag, sal_Int32 bMax, sal_uInt32 bMaxFlag, bool bRoundTowardsPt2 ) { int ca(0), cb(0); if( clipCode1 ) { if( clipCode1 & aMinFlag ) { ca = 2*db*(aMin - a1); o_as = aMin; } else if( clipCode1 & aMaxFlag ) { ca = 2*db*(a1 - aMax); o_as = aMax; } if( clipCode1 & bMinFlag ) { cb = 2*da*(bMin - b1); o_bs = bMin; } else if( clipCode1 & bMaxFlag ) { cb = 2*da*(b1 - bMax); o_bs = bMax; } if( clipCount1 == 2 ) clipCode1 &= (ca + da < cb + !bRoundTowardsPt2) ? ~(aMinFlag|aMaxFlag) : ~(bMinFlag|bMaxFlag); if( clipCode1 & (aMinFlag|aMaxFlag) ) { cb = (ca + da - !bRoundTowardsPt2) / (2*da); if( sb >= 0 ) { o_bs = b1 + cb; if( o_bs > bMax ) return false; } else { o_bs = b1 - cb; if( o_bs < bMin ) return false; } io_rem += ca - 2*da*cb; } else { ca = (cb - da + 2*db - bRoundTowardsPt2) / (2*db); if( sa >= 0 ) { o_as = a1 + ca; if( o_as > aMax ) return false; } else { o_as = a1 - ca; if( o_as < aMin ) return false; } io_rem += 2*db*ca - cb; } } else { o_as = a1; o_bs = b1; } bool bRetVal = false; if( clipCode2 ) { if( clipCount2 == 2 ) { ca = 2*db*((clipCode2 & aMinFlag) ? a1 - aMin : aMax - a1); cb = 2*da*((clipCode2 & bMinFlag) ? b1 - bMin : bMax - b1); clipCode2 &= (cb + da < ca + bRoundTowardsPt2) ? ~(aMinFlag|aMaxFlag) : ~(bMinFlag|bMaxFlag); } if( clipCode2 & (aMinFlag|aMaxFlag) ) o_n = (clipCode2 & aMinFlag) ? o_as - aMin : aMax - o_as; else { o_n = (clipCode2 & bMinFlag) ? o_bs - bMin : bMax - o_bs; bRetVal = true; } } else o_n = (a2 >= o_as) ? a2 - o_as : o_as - a2; return bRetVal; } /** Render line to image iterators, clip against given rectangle This method renders a line from aPt1 to aPt2, clipped against rClipRect (the clipping will take place pixel-perfect, i.e. as if the original bresenham-rendered line would have been clipped each pixel individually. No slight shifts compared to unclipped lines). @param aPt1 Start point of the line @param aPt2 End point of the line @param rClipRect Rectangle to clip against @param color Color value to render the line with @param begin left-top image iterator @param end right-bottom image iterator @param acc Image accessor @param bRoundTowardsPt2 Rounding mode to use. Giving false here results in line pixel tend towards pt1, i.e. when a pixel exactly hits the middle between two pixel, the pixel closer to pt1 will be chosen. Giving true here makes renderClippedLine() choose pt2 in those cases. */ template< class Iterator, class Accessor > void renderClippedLine( basegfx::B2IPoint aPt1, basegfx::B2IPoint aPt2, const basegfx::B2IRange& rClipRect, typename Accessor::value_type color, Iterator begin, Accessor acc, bool bRoundTowardsPt2=false ) { // Algorithm according to Steven Eker's 'Pixel-perfect line clipping', // Graphics Gems V, pp. 314-322 sal_uInt32 clipCode1 = basegfx::tools::getCohenSutherlandClipFlags(aPt1, rClipRect); sal_uInt32 clipCode2 = basegfx::tools::getCohenSutherlandClipFlags(aPt2, rClipRect); if( clipCode1 & clipCode2 ) return; // line fully clipped away sal_uInt32 clipCount1 = basegfx::tools::getNumberOfClipPlanes(clipCode1); sal_uInt32 clipCount2 = basegfx::tools::getNumberOfClipPlanes(clipCode2); if( (clipCode1 != 0 && clipCode2 == 0) || (clipCount1 == 2 && clipCount2 == 1) ) { std::swap(clipCount2,clipCount1); std::swap(clipCode2,clipCode1); std::swap(aPt1,aPt2); bRoundTowardsPt2 = !bRoundTowardsPt2; } const sal_Int32 x1 = aPt1.getX(); const sal_Int32 x2 = aPt2.getX(); const sal_Int32 y1 = aPt1.getY(); const sal_Int32 y2 = aPt2.getY(); // TODO(E1): This might overflow sal_Int32 adx = x2 - x1; int sx = 1; if( adx < 0 ) { adx *= -1; sx = -1; } // TODO(E1): This might overflow sal_Int32 ady = y2 - y1; int sy = 1; if( ady < 0 ) { ady *= -1; sy = -1; } int n = 0; sal_Int32 xs = x1; sal_Int32 ys = y1; if( adx >= ady ) { // semi-horizontal line sal_Int32 rem = 2*ady - adx - !bRoundTowardsPt2; const bool bUseAlternateBresenham( prepareClip(x1, x2, y1, adx, ady, xs, ys, sx, sy, rem, n, clipCode1, clipCount1, clipCode2, clipCount2, rClipRect.getMinX(), basegfx::tools::RectClipFlags::LEFT, rClipRect.getMaxX(), basegfx::tools::RectClipFlags::RIGHT, rClipRect.getMinY(), basegfx::tools::RectClipFlags::TOP, rClipRect.getMaxY(), basegfx::tools::RectClipFlags::BOTTOM, bRoundTowardsPt2 )); Iterator currIter( begin + vigra::Diff2D(0,ys) ); typename vigra::IteratorTraits::row_iterator rowIter( currIter.rowIterator() + xs ); adx *= 2; ady *= 2; if( bUseAlternateBresenham ) { while(true) { acc.set(color, rowIter); if( rem >= 0 ) { if( --n < 0 ) break; ys += sy; xs += sx; rem -= adx; currIter.y += sy; rowIter = currIter.rowIterator() + xs; } else { xs += sx; rowIter += sx; } rem += ady; } } else { while(true) { acc.set(color, rowIter); if( --n < 0 ) break; if( rem >= 0 ) { ys += sy; xs += sx; rem -= adx; currIter.y += sy; rowIter = currIter.rowIterator() + xs; } else { xs += sx; rowIter += sx; } rem += ady; } } } else { // semi-vertical line sal_Int32 rem = 2*adx - ady - !bRoundTowardsPt2; const bool bUseAlternateBresenham( prepareClip(y1, y2, x1, ady, adx, ys, xs, sy, sx, rem, n, clipCode1, clipCount1, clipCode2, clipCount2, rClipRect.getMinY(), basegfx::tools::RectClipFlags::TOP, rClipRect.getMaxY(), basegfx::tools::RectClipFlags::BOTTOM, rClipRect.getMinX(), basegfx::tools::RectClipFlags::LEFT, rClipRect.getMaxX(), basegfx::tools::RectClipFlags::RIGHT, bRoundTowardsPt2 )); Iterator currIter( begin + vigra::Diff2D(xs,0) ); typename vigra::IteratorTraits::column_iterator colIter( currIter.columnIterator() + ys ); adx *= 2; ady *= 2; if( bUseAlternateBresenham ) { while(true) { acc.set(color, colIter); if( rem >= 0 ) { if( --n < 0 ) break; xs += sx; ys += sy; rem -= ady; currIter.x += sx; colIter = currIter.columnIterator() + ys; } else { ys += sy; colIter += sy; } rem += adx; } } else { while(true) { acc.set(color, colIter); if( --n < 0 ) break; if( rem >= 0 ) { xs += sx; ys += sy; rem -= ady; currIter.x += sx; colIter = currIter.columnIterator() + ys; } else { ys += sy; colIter += sy; } rem += adx; } } } } } // namespace basebmp #endif /* INCLUDED_BASEBMP_CLIPPEDLINERENDERER_HXX */