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#include <iostream></iostream>
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#include "perspectivesandboxview.h"
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PerspectiveSandBoxView::PerspectiveSandBoxView():
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persp_p0 (new View::Point( Vector2(-1, -1) )),
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persp_px (new View::Point( Vector2( 1, -1) )),
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persp_py (new View::Point( Vector2(-1, 1) )),
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persp_p1 (new View::Point( Vector2( 1, 1) )),
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bounds_p0 (new View::Point( Vector2(-2, -2) )),
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bounds_p1 (new View::Point( Vector2( 2, 2) ))
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{
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transform.scale(50, 50);
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points.push_back(persp_p0);
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points.push_back(persp_px);
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points.push_back(persp_py);
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points.push_back(persp_p1);
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points.push_back(bounds_p0);
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points.push_back(bounds_p1);
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}
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void
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PerspectiveSandBoxView::draw_grid(
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const Cairo::RefPtr<cairo::context> &context,</cairo::context>
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const Matrix &matrix,
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const Color &color )
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{
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const int count = 100;
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const int subcount = 10;
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const Real ps = get_pixel_size();
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for(int i = -count; i < count; ++i) {
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for(int j = -count; j < count; ++j) {
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Vector4 src(i/(Real)subcount, j/(Real)subcount, 0, 1);
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Vector4 dst = matrix*src;
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Real w = dst.w;
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if (w > real_precision) {
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Vector2 pos(dst.x/w, dst.y/w);
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Real ka = clamp(1/w, 0, 1);
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Real a = color.a*ka;
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Real r = 4*ps;
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if (i) r *= 0.5;
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if (j) r *= 0.5;
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if (i % 10) r *= 0.75;
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if (j % 10) r *= 0.75;
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context->set_source_rgba(color.r, color.g, color.b, a);
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context->arc(pos.x, pos.y, r, 0, 2.0*M_PI);
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context->fill();
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}
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}
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}
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}
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void
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PerspectiveSandBoxView::draw_line(
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const Cairo::RefPtr<cairo::context> &context,</cairo::context>
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const Pair2 &bounds,
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Real a,
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Real b,
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Real c,
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const Color &color )
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{
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// equatation of line is a*x + b*y = c
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int count = 0;
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Vector2 points[4];
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if (fabs(a) > real_precision) {
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Real x0 = (c - bounds.p0.y*b)/a;
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if ( x0 + real_precision >= bounds.p0.x
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&& x0 - real_precision <= bounds.p1.x )
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points[count++] = Vector2(x0, bounds.p0.y);
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Real x1 = (c - bounds.p1.y*b)/a;
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if ( x1 + real_precision >= bounds.p0.x
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&& x1 - real_precision <= bounds.p1.x )
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points[count++] = Vector2(x1, bounds.p1.y);
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}
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if (fabs(b) > real_precision) {
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Real y0 = (c - bounds.p0.x*a)/b;
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if ( y0 + real_precision >= bounds.p0.y
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&& y0 - real_precision <= bounds.p1.y )
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points[count++] = Vector2(bounds.p0.x, y0);
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Real y1 = (c - bounds.p1.x*a)/b;
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if ( y1 + real_precision >= bounds.p0.y
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&& y1 - real_precision <= bounds.p1.y )
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points[count++] = Vector2(bounds.p1.x, y1);
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}
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if (count >= 2) {
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context->set_source_rgba(color.r, color.g, color.b, color.a);
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context->move_to(points[0].x, points[0].y);
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context->line_to(points[1].x, points[1].y);
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context->stroke();
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}
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}
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void
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PerspectiveSandBoxView::draw_subdivisions(
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const Cairo::RefPtr<cairo::context> &context,</cairo::context>
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const Matrix &matrix,
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const Pair2 &bounds,
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const Color &color )
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{
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const Real ps = get_pixel_size();
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Vector4 a = matrix.row_x();
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Vector4 b = matrix.row_y();
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Vector4 c = matrix.row_w();
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// calc coefficient for equatation of "horizontal" line: A*x + B*y = C + D/w
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// equatation of line of horizon is: A*x + B*y = C
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Real A = a.y*b.w - a.w*b.y;
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Real B = a.w*b.x - a.x*b.w;
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Real C = a.y*b.x - a.x*b.y;
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Real D = a.w*(b.x*c.y - b.y*c.x) + b.w*(a.y*c.x - a.x*c.y) - C*c.w;
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if (D < 0) {
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A = -A;
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B = -B;
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C = -C;
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D = -D;
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}
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Real hd = ps*sqrt(A*A + B*B);
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if (hd <= real_precision)
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return; // orthogonal projection - no prespective - no subdiviosions
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hd = D/hd;
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Real horizonw = hd;
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Real horizonw2 = hd/4;
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Real maxw = -INFINITY, minw = INFINITY;
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Vector2 corners[] = {
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Vector2(bounds.p0.x, bounds.p0.y),
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Vector2(bounds.p1.x, bounds.p0.y),
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Vector2(bounds.p1.x, bounds.p1.y),
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Vector2(bounds.p0.x, bounds.p1.y) };
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for(int i = 0; i < 4; ++i) {
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Real w = A*corners[i].x + B*corners[i].y - C;
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if (fabs(w) > real_precision) {
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w = D/w;
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if (w < 0 || w > horizonw) w = horizonw;
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if (minw > w) minw = w;
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if (maxw < w) maxw = w;
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}
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}
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if (minw >= maxw - real_precision)
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return; // all bounds too thin
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Real maxw2 = maxw < horizonw2 ? maxw : horizonw2;
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// draw limits
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Color limits_color = color;
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limits_color.a *= 0.5;
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draw_line(context, get_bounds(), A, B, C + D/minw, limits_color);
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draw_line(context, get_bounds(), A, B, C + D/maxw, limits_color);
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// split
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int minlog = (int)ceil (log2(minw ) + real_precision);
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int maxlog = (int)floor(log2(maxw2) - real_precision);
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for(int i = minlog; i <= maxlog; ++i)
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draw_line(context, bounds, A, B, C + D/exp2(i), color);
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}
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void
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PerspectiveSandBoxView::on_draw_view(const Cairo::RefPtr<cairo::context> &context) {</cairo::context>
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context->save();
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const Real ps = get_pixel_size();
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context->set_line_width(ps);
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Vector2 p0 = persp_p0->position;
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Vector2 px = persp_px->position;
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Vector2 py = persp_py->position;
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Vector2 p1 = persp_p1->position;
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Pair2 bounds(bounds_p0->position, bounds_p1->position);
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// perspective matrix
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Matrix matrix;
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{
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Vector2 A = px - p1;
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Vector2 B = py - p1;
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Vector2 C = p0 + p1 - px - py;
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Real cw = A.y*B.x - A.x*B.y;
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Real aw = B.x*C.y - B.y*C.x;
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Real bw = A.y*C.x - A.x*C.y;
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if (cw < 0) {
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aw = -aw;
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bw = -bw;
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cw = -cw;
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}
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Vector2 c = p0*cw;
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Vector2 a = px*(cw + aw) - c;
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Vector2 b = py*(cw + bw) - c;
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matrix.row_x() = Vector4(a, 0, aw);
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matrix.row_y() = Vector4(b, 0, bw);
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matrix.row_w() = Vector4(c, 0, cw);
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}
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draw_grid(context, matrix, Color(0, 1, 0, 1));
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draw_subdivisions(context, matrix, bounds, Color(0, 0, 1, 1));
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// draw frames
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context->set_source_rgba(0, 0, 1, 0.75);
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context->move_to(p0.x, p0.y);
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context->line_to(px.x, px.y);
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context->line_to(p1.x, p1.y);
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context->line_to(py.x, py.y);
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context->close_path();
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context->stroke();
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context->move_to(bounds.p0.x, bounds.p0.y);
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context->line_to(bounds.p1.x, bounds.p0.y);
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context->line_to(bounds.p1.x, bounds.p1.y);
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context->line_to(bounds.p0.x, bounds.p1.y);
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context->close_path();
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context->stroke();
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context->restore();
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}
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