void WinImage::slotBicubic() { _image = bicubicColor( _image, _a_number->value()); update(); QString message = "Test bicubic"; statusBar()->showMessage( message/*, 3000*/); }
void GrGLBicubicEffect::emitCode(EmitArgs& args) { const GrBicubicEffect& bicubicEffect = args.fFp.cast<GrBicubicEffect>(); GrGLSLUniformHandler* uniformHandler = args.fUniformHandler; fImageIncrementUni = uniformHandler->addUniform(kFragment_GrShaderFlag, kVec2f_GrSLType, kDefault_GrSLPrecision, "ImageIncrement"); const char* imgInc = uniformHandler->getUniformCStr(fImageIncrementUni); fColorSpaceHelper.emitCode(uniformHandler, bicubicEffect.colorSpaceXform()); GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder; SkString coords2D = fragBuilder->ensureCoords2D(args.fTransformedCoords[0]); /* * Filter weights come from Don Mitchell & Arun Netravali's 'Reconstruction Filters in Computer * Graphics', ACM SIGGRAPH Computer Graphics 22, 4 (Aug. 1988). * ACM DL: http://dl.acm.org/citation.cfm?id=378514 * Free : http://www.cs.utexas.edu/users/fussell/courses/cs384g/lectures/mitchell/Mitchell.pdf * * The authors define a family of cubic filters with two free parameters (B and C): * * { (12 - 9B - 6C)|x|^3 + (-18 + 12B + 6C)|x|^2 + (6 - 2B) if |x| < 1 * k(x) = 1/6 { (-B - 6C)|x|^3 + (6B + 30C)|x|^2 + (-12B - 48C)|x| + (8B + 24C) if 1 <= |x| < 2 * { 0 otherwise * * Various well-known cubic splines can be generated, and the authors select (1/3, 1/3) as their * favorite overall spline - this is now commonly known as the Mitchell filter, and is the * source of the specific weights below. * * This is GLSL, so the matrix is column-major (transposed from standard matrix notation). */ fragBuilder->codeAppend("mat4 kMitchellCoefficients = mat4(" " 1.0 / 18.0, 16.0 / 18.0, 1.0 / 18.0, 0.0 / 18.0," "-9.0 / 18.0, 0.0 / 18.0, 9.0 / 18.0, 0.0 / 18.0," "15.0 / 18.0, -36.0 / 18.0, 27.0 / 18.0, -6.0 / 18.0," "-7.0 / 18.0, 21.0 / 18.0, -21.0 / 18.0, 7.0 / 18.0);"); fragBuilder->codeAppendf("vec2 coord = %s - %s * vec2(0.5);", coords2D.c_str(), imgInc); // We unnormalize the coord in order to determine our fractional offset (f) within the texel // We then snap coord to a texel center and renormalize. The snap prevents cases where the // starting coords are near a texel boundary and accumulations of imgInc would cause us to skip/ // double hit a texel. fragBuilder->codeAppendf("coord /= %s;", imgInc); fragBuilder->codeAppend("vec2 f = fract(coord);"); fragBuilder->codeAppendf("coord = (coord - f + vec2(0.5)) * %s;", imgInc); fragBuilder->codeAppend("vec4 wx = kMitchellCoefficients * vec4(1.0, f.x, f.x * f.x, f.x * f.x * f.x);"); fragBuilder->codeAppend("vec4 wy = kMitchellCoefficients * vec4(1.0, f.y, f.y * f.y, f.y * f.y * f.y);"); fragBuilder->codeAppend("vec4 rowColors[4];"); for (int y = 0; y < 4; ++y) { for (int x = 0; x < 4; ++x) { SkString coord; coord.printf("coord + %s * vec2(%d, %d)", imgInc, x - 1, y - 1); SkString sampleVar; sampleVar.printf("rowColors[%d]", x); fDomain.sampleTexture(fragBuilder, args.fUniformHandler, args.fShaderCaps, bicubicEffect.domain(), sampleVar.c_str(), coord, args.fTexSamplers[0]); } fragBuilder->codeAppendf( "vec4 s%d = wx.x * rowColors[0] + wx.y * rowColors[1] + wx.z * rowColors[2] + wx.w * rowColors[3];", y); } SkString bicubicColor("(wy.x * s0 + wy.y * s1 + wy.z * s2 + wy.w * s3)"); if (fColorSpaceHelper.isValid()) { SkString xformedColor; fragBuilder->appendColorGamutXform(&xformedColor, bicubicColor.c_str(), &fColorSpaceHelper); bicubicColor.swap(xformedColor); } fragBuilder->codeAppendf("%s = %s * %s;", args.fOutputColor, bicubicColor.c_str(), args.fInputColor); }