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Diffstat (limited to 'include/basegfx/tools/gradienttools.hxx')
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diff --git a/include/basegfx/tools/gradienttools.hxx b/include/basegfx/tools/gradienttools.hxx new file mode 100644 index 000000000000..aa7479d2c369 --- /dev/null +++ b/include/basegfx/tools/gradienttools.hxx @@ -0,0 +1,405 @@ +/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */ +/* + * This file is part of the LibreOffice project. + * + * This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. + * + * This file incorporates work covered by the following license notice: + * + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed + * with this work for additional information regarding copyright + * ownership. The ASF licenses this file to you under the Apache + * License, Version 2.0 (the "License"); you may not use this file + * except in compliance with the License. You may obtain a copy of + * the License at http://www.apache.org/licenses/LICENSE-2.0 . + */ + +#ifndef _BGFX_TOOLS_GRADIENTTOOLS_HXX +#define _BGFX_TOOLS_GRADIENTTOOLS_HXX + +#include <basegfx/point/b2dpoint.hxx> +#include <basegfx/range/b2drange.hxx> +#include <basegfx/vector/b2dvector.hxx> +#include <basegfx/matrix/b2dhommatrix.hxx> +#include <basegfx/numeric/ftools.hxx> +#include <basegfx/basegfxdllapi.h> + +#include <vector> +#include <algorithm> + +namespace basegfx +{ + /** Gradient definition as used in ODF 1.2 + + This struct collects all data necessary for rendering ODF + 1.2-compatible gradients. Use the createXXXODFGradientInfo() + methods below for initializing from ODF attributes. + */ + struct BASEGFX_DLLPUBLIC ODFGradientInfo + { + /** transformation mapping from [0,1]^2 texture coordinate + space to [0,1]^2 shape coordinate space + */ + B2DHomMatrix maTextureTransform; + + /** transformation mapping from [0,1]^2 shape coordinate space + to [0,1]^2 texture coordinate space. This is the + transformation commonly used to create gradients from a + scanline rasterizer (put shape u/v coordinates into it, get + texture s/t coordinates out of it) + */ + B2DHomMatrix maBackTextureTransform; + + /** Aspect ratio of the gradient. Only used in drawinglayer + for generating nested gradient polygons currently. Already + catered for in the transformations above. + */ + double mfAspectRatio; + + /** Requested gradient steps to render. See the + implementations of the getXXXGradientAlpha() methods below, + the semantic differs slightly for the different gradient + types. + */ + sal_uInt32 mnSteps; + }; + + namespace tools + { + /** Create matrix for ODF's linear gradient definition + + Note that odf linear gradients are varying in y direction. + + @param o_rGradientInfo + Receives the calculated texture transformation matrix (for + use with standard [0,1]x[0,1] texture coordinates) + + @param rTargetArea + Output area, needed for aspect ratio calculations and + texture transformation + + @param nSteps + Number of gradient steps (from ODF) + + @param fBorder + Width of gradient border (from ODF) + + @param fAngle + Gradient angle (from ODF) + */ + BASEGFX_DLLPUBLIC ODFGradientInfo& createLinearODFGradientInfo(ODFGradientInfo& o_rGradientInfo, + const B2DRange& rTargetArea, + sal_uInt32 nSteps, + double fBorder, + double fAngle); + + /** Calculate linear gradient blend value + + This method generates you the lerp alpha value for + blending linearly between gradient start and end color, + according to the formula (startCol*(1.0-alpha) + endCol*alpha) + + @param rUV + Current uv coordinate. Values outside [0,1] will be + clamped. Assumes gradient color varies along the y axis. + + @param rGradInfo + Gradient info, for transformation and number of steps + */ + inline double getLinearGradientAlpha(const B2DPoint& rUV, + const ODFGradientInfo& rGradInfo ) + { + const B2DPoint aCoor(rGradInfo.maBackTextureTransform * rUV); + const double t(clamp(aCoor.getY(), 0.0, 1.0)); + const sal_uInt32 nSteps(rGradInfo.mnSteps); + + if(nSteps > 2L && nSteps < 128L) + return floor(t * nSteps) / double(nSteps + 1L); + + return t; + } + + /** Create matrix for ODF's axial gradient definition + + Note that odf axial gradients are varying in y + direction. Note further that you can map the axial + gradient to a linear gradient (in case you want or need to + avoid an extra gradient renderer), by using + createLinearODFGradientInfo() instead, shifting the + resulting texture transformation by 0.5 to the top and + appending the same stop colors again, but mirrored. + + @param o_rGradientInfo + Receives the calculated texture transformation matrix (for + use with standard [0,1]x[0,1] texture coordinates) + + @param rTargetArea + Output area, needed for aspect ratio calculations and + texture transformation + + @param nSteps + Number of gradient steps (from ODF) + + @param fBorder + Width of gradient border (from ODF) + + @param fAngle + Gradient angle (from ODF) + */ + BASEGFX_DLLPUBLIC ODFGradientInfo& createAxialODFGradientInfo(ODFGradientInfo& o_rGradientInfo, + const B2DRange& rTargetArea, + sal_uInt32 nSteps, + double fBorder, + double fAngle); + + /** Calculate axial gradient blend value + + This method generates you the lerp alpha value for + blending linearly between gradient start and end color, + according to the formula (startCol*(1.0-alpha) + endCol*alpha) + + @param rUV + Current uv coordinate. Values outside [0,1] will be + clamped. Assumes gradient color varies along the y axis. + + @param rGradInfo + Gradient info, for transformation and number of steps + */ + inline double getAxialGradientAlpha(const B2DPoint& rUV, + const ODFGradientInfo& rGradInfo ) + { + const B2DPoint aCoor(rGradInfo.maBackTextureTransform * rUV); + const double t(clamp(fabs(aCoor.getY()), 0.0, 1.0)); + const sal_uInt32 nSteps(rGradInfo.mnSteps); + const double fInternalSteps((nSteps * 2L) - 1L); + + if(nSteps > 2L && nSteps < 128L) + return floor(((t * fInternalSteps) + 1.0) / 2.0) / double(nSteps - 1L); + + return t; + } + + /** Create matrix for ODF's radial gradient definition + + @param o_rGradientInfo + Receives the calculated texture transformation matrix (for + use with standard [0,1]x[0,1] texture coordinates) + + @param rTargetArea + Output area, needed for aspect ratio calculations and + texture transformation + + @param rOffset + Gradient offset value (from ODF) + + @param nSteps + Number of gradient steps (from ODF) + + @param fBorder + Width of gradient border (from ODF) + + @param fAngle + Gradient angle (from ODF) + */ + BASEGFX_DLLPUBLIC ODFGradientInfo& createRadialODFGradientInfo(ODFGradientInfo& o_rGradientInfo, + const B2DRange& rTargetArea, + const B2DVector& rOffset, + sal_uInt32 nSteps, + double fBorder); + + /** Calculate radial gradient blend value + + This method generates you the lerp alpha value for + blending linearly between gradient start and end color, + according to the formula (startCol*(1.0-alpha) + endCol*alpha) + + @param rUV + Current uv coordinate. Values outside [0,1] will be + clamped. + + @param rGradInfo + Gradient info, for transformation and number of steps + */ + inline double getRadialGradientAlpha(const B2DPoint& rUV, + const ODFGradientInfo& rGradInfo ) + { + const B2DPoint aCoor(rGradInfo.maBackTextureTransform * rUV); + const double fDist( + clamp(aCoor.getX() * aCoor.getX() + aCoor.getY() * aCoor.getY(), + 0.0, + 1.0)); + + const double t(1.0 - sqrt(fDist)); + const sal_uInt32 nSteps(rGradInfo.mnSteps); + + if(nSteps > 2L && nSteps < 128L) + return floor(t * nSteps) / double(nSteps - 1L); + + return t; + } + + /** Create matrix for ODF's elliptical gradient definition + + @param o_rGradientInfo + Receives the calculated texture transformation matrix (for + use with standard [0,1]x[0,1] texture coordinates) + + @param rTargetArea + Output area, needed for aspect ratio calculations and + texture transformation + + @param rOffset + Gradient offset value (from ODF) + + @param nSteps + Number of gradient steps (from ODF) + + @param fBorder + Width of gradient border (from ODF) + + @param fAngle + Gradient angle (from ODF) + */ + BASEGFX_DLLPUBLIC ODFGradientInfo& createEllipticalODFGradientInfo(ODFGradientInfo& o_rGradientInfo, + const B2DRange& rTargetArea, + const B2DVector& rOffset, + sal_uInt32 nSteps, + double fBorder, + double fAngle); + + /** Calculate elliptical gradient blend value + + This method generates you the lerp alpha value for + blending linearly between gradient start and end color, + according to the formula (startCol*(1.0-alpha) + endCol*alpha) + + @param rUV + Current uv coordinate. Values outside [0,1] will be + clamped. + + @param rGradInfo + Gradient info, for transformation and number of steps + */ + inline double getEllipticalGradientAlpha(const B2DPoint& rUV, + const ODFGradientInfo& rGradInfo ) + { + return getRadialGradientAlpha(rUV,rGradInfo); // only matrix setup differs + } + + /** Create matrix for ODF's square gradient definition + + @param o_rGradientInfo + Receives the calculated texture transformation matrix (for + use with standard [0,1]x[0,1] texture coordinates) + + @param rTargetArea + Output area, needed for aspect ratio calculations and + texture transformation + + @param rOffset + Gradient offset value (from ODF) + + @param nSteps + Number of gradient steps (from ODF) + + @param fBorder + Width of gradient border (from ODF) + + @param fAngle + Gradient angle (from ODF) + */ + BASEGFX_DLLPUBLIC ODFGradientInfo& createSquareODFGradientInfo(ODFGradientInfo& o_rGradientInfo, + const B2DRange& rTargetArea, + const B2DVector& rOffset, + sal_uInt32 nSteps, + double fBorder, + double fAngle); + + /** Calculate square gradient blend value + + This method generates you the lerp alpha value for + blending linearly between gradient start and end color, + according to the formula (startCol*(1.0-alpha) + endCol*alpha) + + @param rUV + Current uv coordinate. Values outside [0,1] will be + clamped. + + @param rGradInfo + Gradient info, for transformation and number of steps + */ + inline double getSquareGradientAlpha(const B2DPoint& rUV, + const ODFGradientInfo& rGradInfo ) + { + const B2DPoint aCoor(rGradInfo.maBackTextureTransform * rUV); + const double fAbsX(fabs(aCoor.getX())); + const double fAbsY(fabs(aCoor.getY())); + + if(fTools::moreOrEqual(fAbsX, 1.0) || fTools::moreOrEqual(fAbsY, 1.0)) + return 0.0; + + const double t(1.0 - (fAbsX > fAbsY ? fAbsX : fAbsY)); + const sal_uInt32 nSteps(rGradInfo.mnSteps); + + if(nSteps > 2L && nSteps < 128L) + return floor(t * nSteps) / double(nSteps - 1L); + + return t; + } + + /** Create matrix for ODF's rectangular gradient definition + + @param o_rGradientInfo + Receives the calculated texture transformation matrix (for + use with standard [0,1]x[0,1] texture coordinates) + + @param rTargetArea + Output area, needed for aspect ratio calculations and + texture transformation + + @param rOffset + Gradient offset value (from ODF) + + @param nSteps + Number of gradient steps (from ODF) + + @param fBorder + Width of gradient border (from ODF) + + @param fAngle + Gradient angle (from ODF) + */ + BASEGFX_DLLPUBLIC ODFGradientInfo& createRectangularODFGradientInfo(ODFGradientInfo& o_rGradientInfo, + const B2DRange& rTargetArea, + const B2DVector& rOffset, + sal_uInt32 nSteps, + double fBorder, + double fAngle); + + /** Calculate rectangular gradient blend value + + This method generates you the lerp alpha value for + blending linearly between gradient start and end color, + according to the formula (startCol*(1.0-alpha) + endCol*alpha) + + @param rUV + Current uv coordinate. Values outside [0,1] will be + clamped. + + @param rGradInfo + Gradient info, for transformation and number of steps + */ + inline double getRectangularGradientAlpha(const B2DPoint& rUV, + const ODFGradientInfo& rGradInfo ) + { + return getSquareGradientAlpha(rUV, rGradInfo); // only matrix setup differs + } + } +} + +#endif + +/* vim:set shiftwidth=4 softtabstop=4 expandtab: */ |