gm/concavepaths.cpp

/*
 * Copyright 2015 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "gm/gm.h"
#include "include/core/SkCanvas.h"
#include "include/core/SkPaint.h"
#include "include/core/SkPath.h"
#include "include/core/SkScalar.h"

namespace {
// Concave test
void test_concave(SkCanvas* canvas, const SkPaint& paint) {
    SkPath path;
    canvas->translate(0, 0);
    path.moveTo(SkIntToScalar(20), SkIntToScalar(20))
        .lineTo(SkIntToScalar(80), SkIntToScalar(20))
        .lineTo(SkIntToScalar(30), SkIntToScalar(30))
        .lineTo(SkIntToScalar(20), SkIntToScalar(80));
    canvas->drawPath(path, paint);
}

// Reverse concave test
void test_reverse_concave(SkCanvas* canvas, const SkPaint& paint) {
    SkPath path;
    canvas->save();
    canvas->translate(100, 0);
    path.moveTo(SkIntToScalar(20), SkIntToScalar(20))
        .lineTo(SkIntToScalar(20), SkIntToScalar(80))
        .lineTo(SkIntToScalar(30), SkIntToScalar(30))
        .lineTo(SkIntToScalar(80), SkIntToScalar(20));
    canvas->drawPath(path, paint);
    canvas->restore();
}

// Bowtie (intersection)
void test_bowtie(SkCanvas* canvas, const SkPaint& paint) {
    SkPath path;
    canvas->save();
    canvas->translate(200, 0);
    path.moveTo(SkIntToScalar(20), SkIntToScalar(20))
        .lineTo(SkIntToScalar(80), SkIntToScalar(80))
        .lineTo(SkIntToScalar(80), SkIntToScalar(20))
        .lineTo(SkIntToScalar(20), SkIntToScalar(80));
    canvas->drawPath(path, paint);
    canvas->restore();
}

// "fake" bowtie (concave, but no intersection)
void test_fake_bowtie(SkCanvas* canvas, const SkPaint& paint) {
    SkPath path;
    canvas->save();
    canvas->translate(300, 0);
    path.moveTo(SkIntToScalar(20), SkIntToScalar(20))
        .lineTo(SkIntToScalar(50), SkIntToScalar(40))
        .lineTo(SkIntToScalar(80), SkIntToScalar(20))
        .lineTo(SkIntToScalar(80), SkIntToScalar(80))
        .lineTo(SkIntToScalar(50), SkIntToScalar(60))
        .lineTo(SkIntToScalar(20), SkIntToScalar(80));
    canvas->drawPath(path, paint);
    canvas->restore();
}

// Bowtie with a smaller right hand lobe. The outer vertex of the left hand
// lobe intrudes into the interior of the right hand lobe.
void test_intruding_vertex(SkCanvas* canvas, const SkPaint& paint) {
    SkPath path;
    canvas->save();
    canvas->translate(400, 0);
    path.setIsVolatile(true);
    path.moveTo(20, 20)
        .lineTo(50, 50)
        .lineTo(68, 20)
        .lineTo(68, 80)
        .lineTo(50, 50)
        .lineTo(20, 80);
    canvas->drawPath(path, paint);
    canvas->restore();
}

// A shape with an edge that becomes inverted on AA stroking and that also contains
// a repeated start/end vertex.
void test_inversion_repeat_vertex(SkCanvas* canvas, const SkPaint& paint) {
    SkPath path;
    canvas->save();
    canvas->translate(400, 100);
    path.setIsVolatile(true);
    path.moveTo(80,     50)
        .lineTo(40,     80)
        .lineTo(60,     20)
        .lineTo(20,     20)
        .lineTo(39.99f, 80)
        .lineTo(80,     50);
    canvas->drawPath(path, paint);
    canvas->restore();
}

// Fish test (intersection/concave)
void test_fish(SkCanvas* canvas, const SkPaint& paint) {
    SkPath path;
    canvas->save();
    canvas->translate(0, 100);
    path.moveTo(SkIntToScalar(20), SkIntToScalar(20))
        .lineTo(SkIntToScalar(80), SkIntToScalar(80))
        .lineTo(SkIntToScalar(70), SkIntToScalar(50))
        .lineTo(SkIntToScalar(80), SkIntToScalar(20))
        .lineTo(SkIntToScalar(20), SkIntToScalar(80))
        .lineTo(SkIntToScalar(0), SkIntToScalar(50));
    canvas->drawPath(path, paint);
    canvas->restore();
}

// Overlapping "Fast-forward" icon: tests coincidence of inner and outer
// vertices generated by intersection.
void test_fast_forward(SkCanvas* canvas, const SkPaint& paint) {
    SkPath path;
    canvas->save();
    canvas->translate(100, 100);
    path.moveTo(SkIntToScalar(20), SkIntToScalar(20))
        .lineTo(SkIntToScalar(60), SkIntToScalar(50))
        .lineTo(SkIntToScalar(20), SkIntToScalar(80))
        .moveTo(SkIntToScalar(40), SkIntToScalar(20))
        .lineTo(SkIntToScalar(40), SkIntToScalar(80))
        .lineTo(SkIntToScalar(80), SkIntToScalar(50));
    canvas->drawPath(path, paint);
    canvas->restore();
}

// Square polygon with a square hole.
void test_hole(SkCanvas* canvas, const SkPaint& paint) {
    SkPath path;
    canvas->save();
    canvas->translate(200, 100);
    path.addPoly({{20,20}, {80,20}, {80,80}, {20,80}}, false)
        .addPoly({{30,30}, {30,70}, {70,70}, {70,30}}, false);
    canvas->drawPath(path, paint);
    canvas->restore();
}

// Star test (self-intersecting)
void test_star(SkCanvas* canvas, const SkPaint& paint) {
    canvas->save();
    canvas->translate(300, 100);
    canvas->drawPath(SkPath().addPoly({{30,20}, {50,80}, {70,20}, {20,57}, {80,57}}, false),
                     paint);
    canvas->restore();
}

// Exercise a case where the intersection is below a bottom edge.
void test_twist(SkCanvas* canvas, const SkPaint& paint) {
    SkPath path;
    canvas->save();
    path.moveTo(                 0.5,                    6);
    path.lineTo(5.8070392608642578125, 6.4612660408020019531);
    path.lineTo(-2.9186885356903076172, 2.811046600341796875);
    path.lineTo(0.49999994039535522461, -1.4124038219451904297);
    canvas->translate(420, 220);
    canvas->scale(10, 10);
    canvas->drawPath(path, paint);
    canvas->restore();
}

// Stairstep with repeated vert (intersection)
void test_stairstep(SkCanvas* canvas, const SkPaint& paint) {
    SkPath path;
    canvas->save();
    canvas->translate(0, 200);
    path.moveTo(SkIntToScalar(50), SkIntToScalar(50));
    path.lineTo(SkIntToScalar(50), SkIntToScalar(20));
    path.lineTo(SkIntToScalar(80), SkIntToScalar(20));
    path.lineTo(SkIntToScalar(50), SkIntToScalar(50));
    path.lineTo(SkIntToScalar(20), SkIntToScalar(50));
    path.lineTo(SkIntToScalar(20), SkIntToScalar(80));
    canvas->drawPath(path, paint);
    canvas->restore();
}

void test_stairstep2(SkCanvas* canvas, const SkPaint& paint) {
    SkPath path;
    canvas->save();
    canvas->translate(100, 200);
    path.moveTo(20, 60);
    path.lineTo(35, 80);
    path.lineTo(50, 60);
    path.lineTo(65, 80);
    path.lineTo(80, 60);
    canvas->drawPath(path, paint);
    canvas->restore();
}

// Overlapping segments
void test_overlapping(SkCanvas* canvas, const SkPaint& paint) {
    SkPath path;
    canvas->save();
    canvas->translate(200, 200);
    path.moveTo(SkIntToScalar(20), SkIntToScalar(80));
    path.lineTo(SkIntToScalar(80), SkIntToScalar(80));
    path.lineTo(SkIntToScalar(80), SkIntToScalar(20));
    path.lineTo(SkIntToScalar(80), SkIntToScalar(30));
    canvas->drawPath(path, paint);
    canvas->restore();
}

// Two "island" triangles inside a containing rect.
// This exercises the partnering code in the tessellator.
void test_partners(SkCanvas* canvas, const SkPaint& paint) {
    SkPath path;
    canvas->save();
    canvas->translate(300, 200);
    path.moveTo(20, 80);
    path.lineTo(80, 80);
    path.lineTo(80, 20);
    path.lineTo(20, 20);
    path.moveTo(30, 30);
    path.lineTo(45, 50);
    path.lineTo(30, 70);
    path.moveTo(70, 30);
    path.lineTo(70, 70);
    path.lineTo(55, 50);
    canvas->drawPath(path, paint);
    canvas->restore();
}

// A split edge causes one half to be merged to zero winding (destroyed).
// Test that the other half of the split doesn't also get zero winding.
void test_winding_merged_to_zero(SkCanvas* canvas, const SkPaint& paint) {
    SkPath path;
    canvas->save();
    canvas->translate(400, 350);
    path.moveTo(20, 80);
    path.moveTo(70,  -0.000001f);
    path.lineTo(70,   0.0);
    path.lineTo(60, -30.0);
    path.lineTo(40,  20.0);
    path.moveTo(50,  50.0);
    path.lineTo(50, -50.0);
    path.lineTo(10,  50.0);
    canvas->drawPath(path, paint);
    canvas->restore();
}

// Monotone test 1 (point in the middle)
void test_monotone_1(SkCanvas* canvas, const SkPaint& paint) {
    SkPath path;
    canvas->save();
    canvas->translate(0, 300);
    path.moveTo(SkIntToScalar(20), SkIntToScalar(20));
    path.quadTo(SkIntToScalar(20), SkIntToScalar(50),
                SkIntToScalar(80), SkIntToScalar(50));
    path.quadTo(SkIntToScalar(20), SkIntToScalar(50),
                SkIntToScalar(20), SkIntToScalar(80));
    canvas->drawPath(path, paint);
    canvas->restore();
}

// Monotone test 2 (point at the top)
void test_monotone_2(SkCanvas* canvas, const SkPaint& paint) {
    SkPath path;
    canvas->save();
    canvas->translate(100, 300);
    path.moveTo(SkIntToScalar(20), SkIntToScalar(20));
    path.lineTo(SkIntToScalar(80), SkIntToScalar(30));
    path.quadTo(SkIntToScalar(20), SkIntToScalar(20),
                SkIntToScalar(20), SkIntToScalar(80));
    canvas->drawPath(path, paint);
    canvas->restore();
}

// Monotone test 3 (point at the bottom)
void test_monotone_3(SkCanvas* canvas, const SkPaint& paint) {
    SkPath path;
    canvas->save();
    canvas->translate(200, 300);
    path.moveTo(SkIntToScalar(20), SkIntToScalar(80));
    path.lineTo(SkIntToScalar(80), SkIntToScalar(70));
    path.quadTo(SkIntToScalar(20), SkIntToScalar(80),
                SkIntToScalar(20), SkIntToScalar(20));
    canvas->drawPath(path, paint);
    canvas->restore();
}

// Monotone test 4 (merging of two monotones)
void test_monotone_4(SkCanvas* canvas, const SkPaint& paint) {
    SkPath path;
    canvas->save();
    canvas->translate(300, 300);
    path.moveTo(80, 25);
    path.lineTo(50, 39);
    path.lineTo(20, 25);
    path.lineTo(40, 45);
    path.lineTo(70, 50);
    path.lineTo(80, 80);
    canvas->drawPath(path, paint);
    canvas->restore();
}

// Monotone test 5 (aborted merging of two monotones)
void test_monotone_5(SkCanvas* canvas, const SkPaint& paint) {
    SkPath path;
    canvas->save();
    canvas->translate(0, 400);
    path.moveTo(50, 20);
    path.lineTo(80, 80);
    path.lineTo(50, 50);
    path.lineTo(20, 80);
    canvas->drawPath(path, paint);
    canvas->restore();
}
// Degenerate intersection test
void test_degenerate(SkCanvas* canvas, const SkPaint& paint) {
    SkPath path;
    canvas->save();
    canvas->translate(100, 400);
    path.moveTo(50, 20);
    path.lineTo(70, 30);
    path.lineTo(20, 50);
    path.moveTo(50, 20);
    path.lineTo(80, 80);
    path.lineTo(50, 80);
    canvas->drawPath(path, paint);
    canvas->restore();
}
// Two triangles with a coincident edge.
void test_coincident_edge(SkCanvas* canvas, const SkPaint& paint) {
    SkPath path;
    canvas->save();
    canvas->translate(200, 400);

    path.moveTo(80, 20);
    path.lineTo(80, 80);
    path.lineTo(20, 80);

    path.moveTo(20, 20);
    path.lineTo(80, 80);
    path.lineTo(20, 80);

    canvas->drawPath(path, paint);
    canvas->restore();
}
// Bowtie with a coincident triangle (one triangle vertex coincident with the
// bowtie's intersection).
void test_bowtie_coincident_triangle(SkCanvas* canvas, const SkPaint& paint) {
    SkPath path;
    canvas->save();
    canvas->translate(300, 400);
    path.moveTo(SkIntToScalar(20), SkIntToScalar(20));
    path.lineTo(SkIntToScalar(80), SkIntToScalar(80));
    path.lineTo(SkIntToScalar(80), SkIntToScalar(20));
    path.lineTo(SkIntToScalar(20), SkIntToScalar(80));
    path.moveTo(SkIntToScalar(50), SkIntToScalar(50));
    path.lineTo(SkIntToScalar(80), SkIntToScalar(20));
    path.lineTo(SkIntToScalar(80), SkIntToScalar(80));
    canvas->drawPath(path, paint);
    canvas->restore();
}

// Collinear outer boundary edges. In the edge-AA codepath, this creates an overlap region
// which contains a boundary edge. It can't be removed, but it must have the correct winding.
void test_collinear_outer_boundary_edge(SkCanvas* canvas, const SkPaint& paint) {
    SkPath path;
    canvas->save();
    canvas->translate(400, 400);
    path.moveTo(20, 20);
    path.lineTo(20, 50);
    path.lineTo(50, 50);
    path.moveTo(80, 50);
    path.lineTo(50, 50);
    path.lineTo(80, 20);
    canvas->drawPath(path, paint);
    canvas->restore();
}

// Coincident edges (big ones first, coincident vert on top).
void test_coincident_edges_1(SkCanvas* canvas, const SkPaint& paint) {
    SkPath path;
    canvas->save();
    canvas->translate(0, 500);
    path.moveTo(SkIntToScalar(20), SkIntToScalar(20));
    path.lineTo(SkIntToScalar(80), SkIntToScalar(80));
    path.lineTo(SkIntToScalar(20), SkIntToScalar(80));
    path.moveTo(SkIntToScalar(20), SkIntToScalar(20));
    path.lineTo(SkIntToScalar(50), SkIntToScalar(50));
    path.lineTo(SkIntToScalar(20), SkIntToScalar(50));
    canvas->drawPath(path, paint);
    canvas->restore();
}
// Coincident edges (small ones first, coincident vert on top).
void test_coincident_edges_2(SkCanvas* canvas, const SkPaint& paint) {
    SkPath path;
    canvas->save();
    canvas->translate(100, 500);
    path.moveTo(SkIntToScalar(20), SkIntToScalar(20));
    path.lineTo(SkIntToScalar(50), SkIntToScalar(50));
    path.lineTo(SkIntToScalar(20), SkIntToScalar(50));
    path.moveTo(SkIntToScalar(20), SkIntToScalar(20));
    path.lineTo(SkIntToScalar(80), SkIntToScalar(80));
    path.lineTo(SkIntToScalar(20), SkIntToScalar(80));
    canvas->drawPath(path, paint);
    canvas->restore();
}
// Coincident edges (small ones first, coincident vert on bottom).
void test_coincident_edges_3(SkCanvas* canvas, const SkPaint& paint) {
    SkPath path;
    canvas->save();
    canvas->translate(200, 500);
    path.moveTo(SkIntToScalar(20), SkIntToScalar(80));
    path.lineTo(SkIntToScalar(20), SkIntToScalar(50));
    path.lineTo(SkIntToScalar(50), SkIntToScalar(50));
    path.moveTo(SkIntToScalar(20), SkIntToScalar(80));
    path.lineTo(SkIntToScalar(20), SkIntToScalar(20));
    path.lineTo(SkIntToScalar(80), SkIntToScalar(20));
    canvas->drawPath(path, paint);
    canvas->restore();
}
// Coincident edges (big ones first, coincident vert on bottom).
void test_coincident_edges_4(SkCanvas* canvas, const SkPaint& paint) {
    SkPath path;
    canvas->save();
    canvas->translate(300, 500);
    path.moveTo(SkIntToScalar(20), SkIntToScalar(80));
    path.lineTo(SkIntToScalar(20), SkIntToScalar(20));
    path.lineTo(SkIntToScalar(80), SkIntToScalar(20));
    path.moveTo(SkIntToScalar(20), SkIntToScalar(80));
    path.lineTo(SkIntToScalar(20), SkIntToScalar(50));
    path.lineTo(SkIntToScalar(50), SkIntToScalar(50));
    canvas->drawPath(path, paint);
    canvas->restore();
}

};

DEF_SIMPLE_GM(concavepaths, canvas, 500, 600) {
    SkPaint paint;

    paint.setAntiAlias(true);
    paint.setStyle(SkPaint::kFill_Style);

    test_concave(canvas, paint);
    test_reverse_concave(canvas, paint);
    test_bowtie(canvas, paint);
    test_fake_bowtie(canvas, paint);
    test_intruding_vertex(canvas, paint);
    test_fish(canvas, paint);
    test_fast_forward(canvas, paint);
    test_hole(canvas, paint);
    test_star(canvas, paint);
    test_twist(canvas, paint);
    test_inversion_repeat_vertex(canvas, paint);
    test_stairstep(canvas, paint);
    test_stairstep2(canvas, paint);
    test_overlapping(canvas, paint);
    test_partners(canvas, paint);
    test_winding_merged_to_zero(canvas, paint);
    test_monotone_1(canvas, paint);
    test_monotone_2(canvas, paint);
    test_monotone_3(canvas, paint);
    test_monotone_4(canvas, paint);
    test_monotone_5(canvas, paint);
    test_degenerate(canvas, paint);
    test_coincident_edge(canvas, paint);
    test_bowtie_coincident_triangle(canvas, paint);
    test_collinear_outer_boundary_edge(canvas, paint);
    test_coincident_edges_1(canvas, paint);
    test_coincident_edges_2(canvas, paint);
    test_coincident_edges_3(canvas, paint);
    test_coincident_edges_4(canvas, paint);
}