From 0eddc5576c72c67ad068bccb3b906ca79de711f6 Mon Sep 17 00:00:00 2001 From: dvlierop2 Date: Fri, 4 May 2007 20:32:57 +0000 Subject: [PATCH] Refactoring of previous changes --- src/sp-item-transform.cpp | 55 +++++++++++++++++++-------------------- 1 file changed, 27 insertions(+), 28 deletions(-) diff --git a/src/sp-item-transform.cpp b/src/sp-item-transform.cpp index 2ad7758a4..93c3f5b7b 100644 --- a/src/sp-item-transform.cpp +++ b/src/sp-item-transform.cpp @@ -97,9 +97,9 @@ get_scale_transform_with_stroke (NR::Rect &bbox_param, gdouble strokewidth, bool NR::Matrix scale = NR::Matrix (NR::scale (1, 1)); // scale component NR::Matrix unbudge = NR::Matrix (NR::translate (0, 0)); // move component to compensate for the drift caused by stroke width change - gdouble w0 = bbox.extent(NR::X); + gdouble w0 = bbox.extent(NR::X); // will return a value >= 0, as required further down the road gdouble h0 = bbox.extent(NR::Y); - gdouble w1 = x1 - x0; + gdouble w1 = x1 - x0; // can have any sign gdouble h1 = y1 - y0; gdouble r0 = strokewidth; @@ -114,43 +114,42 @@ get_scale_transform_with_stroke (NR::Rect &bbox_param, gdouble strokewidth, bool return (p2o * direct * o2n); // can't solve the equation: one of the dimensions is equal to stroke width, so return the straightforward scaler } - // Flip when the width or height changes sign - int flip_x = ((w1 < 0) == (w0 < 0)) ? 1 : -1; - int flip_y = ((h1 < 0) == (h0 < 0)) ? 1 : -1; + int flip_x = (w1 > 0) ? 1 : -1; + int flip_y = (h1 > 0) ? 1 : -1; - // w1 and h1 can be negative, but if so then e.g. w1-r0 won't make sense - // therefore we should use fabs() all over the place - gdouble ratio_x = (fabs(w1) - fabs(r0)) / (fabs(w0) - fabs(r0)); - gdouble ratio_y = (fabs(h1) - fabs(r0)) / (fabs(h0) - fabs(r0)); + // w1 and h1 will be negative when mirroring, but if so then e.g. w1-r0 won't make sense + // Therefore we will use the absolute values from this point on + w1 = fabs(w1); + h1 = fabs(h1); + r0 = fabs(r0); + // w0 and h0 will always be positive due to the definition extent() + + gdouble ratio_x = (w1 - r0) / (w0 - r0); + gdouble ratio_y = (h1 - r0) / (h0 - r0); - NR::Matrix direct_constant_r = NR::Matrix (NR::scale(flip_x * ratio_x, flip_y*ratio_y)); + NR::Matrix direct_constant_r = NR::Matrix (NR::scale(flip_x * ratio_x, flip_y * ratio_y)); if (transform_stroke && r0 != 0 && r0 != NR_HUGE) { // there's stroke, and we need to scale it // These coefficients are obtained from the assumption that scaling applies to the // non-stroked "shape proper" and that stroke scale is scaled by the expansion of that - // matrix - // In fact, we're trying to solve this equation: + // matrix. We're trying to solve this equation: // r1 = r0 * sqrt (((w1-r0)/(w0-r0))*((h1-r1)/(h0-r0))) - // To make sense of this, the operant of the sqrt() should - // be positive, hence all the fabs() below - // (w1 and h1 will be negative when mirroring, w0 and h0 will probably never be negative) - gdouble A = -fabs(w0*h0) + fabs(r0)*(fabs(w0) + fabs(h0)); - gdouble B = -(fabs(w1) + fabs(h1)) * r0*r0; - gdouble C = fabs(w1 * h1 * r0*r0); + // The operant of the sqrt() must be positive, which is ensured by the fabs() a few lines above + gdouble A = -w0*h0 + r0*(w0 + h0); + gdouble B = -(w1 + h1) * r0*r0; + gdouble C = w1 * h1 * r0*r0; if (B*B - 4*A*C > 0) { - gdouble r1 = (-B - sqrt (B*B - 4*A*C))/(2*A); + gdouble r1 = fabs((-B - sqrt(B*B - 4*A*C))/(2*A)); //gdouble r2 = (-B + sqrt (B*B - 4*A*C))/(2*A); //std::cout << "r0" << r0 << " r1" << r1 << " r2" << r2 << "\n"; // - // I think r1 will always be positive if r0 is (mathematical proof?) - // but if w1 becomes negative, then the scale will be wrong if we just do + // If w1 < 0 then the scale will be wrong if we just do // gdouble scale_x = (w1 - r1)/(w0 - r0); - // gdouble scale_y = (h1 - r1)/(h0 - r0); - // So let's do it like this: Calculate the absolute scale - gdouble scale_x = (fabs(w1) - fabs(r1))/(fabs(w0) - fabs(r0)); - gdouble scale_y = (fabs(h1) - fabs(r1))/(fabs(h0) - fabs(r0)); - scale *= NR::scale(flip_x*scale_x, flip_y*scale_y); - unbudge *= NR::translate (-flip_x * 0.5 * (fabs(r0) * scale_x - fabs(r1)), -flip_y * 0.5 * (fabs(r0) * scale_y - fabs(r1))); + // Here we also need the absolute values of w0, w1, h0, h1, and r1 + gdouble scale_x = (w1 - r1)/(w0 - r0); + gdouble scale_y = (h1 - r1)/(h0 - r0); + scale *= NR::scale(flip_x * scale_x, flip_y * scale_y); + unbudge *= NR::translate (-flip_x * 0.5 * (r0 * scale_x - r1), -flip_y * 0.5 * (r0 * scale_y - r1)); } else { scale *= direct; } @@ -159,7 +158,7 @@ get_scale_transform_with_stroke (NR::Rect &bbox_param, gdouble strokewidth, bool scale *= direct; } else {// nonscaling strokewidth scale *= direct_constant_r; - unbudge *= NR::translate (flip_x * 0.5 * fabs(r0) * (1 - ratio_x), flip_y * 0.5 * fabs(r0) * (1 - ratio_y)); + unbudge *= NR::translate (flip_x * 0.5 * r0 * (1 - ratio_x), flip_y * 0.5 * r0 * (1 - ratio_y)); } } -- 2.30.2