Compute correct bounds for DrawShadowRec.

Bug: skia:6880
Change-Id: Ia8b94e52eec3feb5104d2351bf7a7e6f99101deb
Reviewed-on: https://skia-review.googlesource.com/26370
Commit-Queue: Jim Van Verth <jvanverth@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>

1 files changed, 118 insertions, 0 deletions

diff --git a/tests/ShadowTest.cpp b/tests/ShadowTest.cpp
new file mode 100644
index 0000000000..8a921d8bc8
--- /dev/null
+++ b/tests/ShadowTest.cpp
@@ -0,0 +1,118 @@
+/*
+ * Copyright 2017 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkCanvas.h"
+#include "SkDrawShadowInfo.h"
+#include "SkPath.h"
+#include "SkShadowTessellator.h"
+#include "SkShadowUtils.h"
+#include "SkVertices.h"
+#include "Test.h"
+
+void tessellate_shadow(skiatest::Reporter* reporter, const SkPath& path, const SkMatrix& ctm,
+                       bool expectSuccess) {
+
+    auto heightParams = SkPoint3::Make(0, 0, 4);
+
+    auto verts = SkShadowTessellator::MakeAmbient(path, ctm, heightParams, true);
+    if (expectSuccess != SkToBool(verts)) {
+        ERRORF(reporter, "Expected shadow tessellation to %s but it did not.",
+               expectSuccess ? "succeed" : "fail");
+    }
+    verts = SkShadowTessellator::MakeAmbient(path, ctm, heightParams, false);
+    if (expectSuccess != SkToBool(verts)) {
+        ERRORF(reporter, "Expected shadow tessellation to %s but it did not.",
+               expectSuccess ? "succeed" : "fail");
+    }
+    verts = SkShadowTessellator::MakeSpot(path, ctm, heightParams, {0, 0, 128}, 128.f, false);
+    if (expectSuccess != SkToBool(verts)) {
+        ERRORF(reporter, "Expected shadow tessellation to %s but it did not.",
+               expectSuccess ? "succeed" : "fail");
+    }
+    verts = SkShadowTessellator::MakeSpot(path, ctm, heightParams, {0, 0, 128}, 128.f, false);
+    if (expectSuccess != SkToBool(verts)) {
+        ERRORF(reporter, "Expected shadow tessellation to %s but it did not.",
+               expectSuccess ? "succeed" : "fail");
+    }
+}
+
+DEF_TEST(ShadowUtils, reporter) {
+    SkCanvas canvas(100, 100);
+
+    SkPath path;
+    path.cubicTo(100, 50, 20, 100, 0, 0);
+    tessellate_shadow(reporter, path, canvas.getTotalMatrix(), true);
+
+    // This line segment has no area and no shadow.
+    path.reset();
+    path.lineTo(10.f, 10.f);
+    tessellate_shadow(reporter, path, canvas.getTotalMatrix(), false);
+
+    // A series of colinear line segments
+    path.reset();
+    for (int i = 0; i < 10; ++i) {
+        path.lineTo((SkScalar)i, (SkScalar)i);
+    }
+    tessellate_shadow(reporter, path, canvas.getTotalMatrix(), false);
+}
+
+void check_xformed_bounds(skiatest::Reporter* reporter, const SkPath& path, const SkMatrix& ctm) {
+    const SkDrawShadowRec rec = {
+        SkPoint3::Make(0, 0, 4),
+        SkPoint3::Make(100, 0, 600),
+        800.f,
+        0.035f,
+        0.25f,
+        SK_ColorBLACK,
+        0
+    };
+    SkRect bounds;
+    SkDrawShadowMetrics::GetLocalBounds(path, rec, ctm, &bounds);
+    ctm.mapRect(&bounds);
+
+    auto verts = SkShadowTessellator::MakeAmbient(path, ctm, rec.fZPlaneParams, true);
+    if (verts) {
+        REPORTER_ASSERT(reporter, bounds.contains(verts->bounds()));
+    }
+
+    SkPoint mapXY = ctm.mapXY(rec.fLightPos.fX, rec.fLightPos.fY);
+    SkPoint3 devLightPos = SkPoint3::Make(mapXY.fX, mapXY.fY, rec.fLightPos.fZ);
+    verts = SkShadowTessellator::MakeSpot(path, ctm, rec.fZPlaneParams, devLightPos,
+                                          rec.fLightRadius, false);
+    if (verts) {
+        REPORTER_ASSERT(reporter, bounds.contains(verts->bounds()));
+    }
+}
+
+void check_bounds(skiatest::Reporter* reporter, const SkPath& path) {
+    SkMatrix ctm;
+    ctm.setTranslate(100, 100);
+    check_xformed_bounds(reporter, path, ctm);
+    ctm.postScale(2, 2);
+    check_xformed_bounds(reporter, path, ctm);
+    ctm.preRotate(45);
+    check_xformed_bounds(reporter, path, ctm);
+    ctm.preSkew(40, -20);
+    check_xformed_bounds(reporter, path, ctm);
+    ctm[SkMatrix::kMPersp0] = 0.0001f;
+    ctm[SkMatrix::kMPersp1] = 12.f;
+    check_xformed_bounds(reporter, path, ctm);
+}
+
+DEF_TEST(ShadowBounds, reporter) {
+    SkPath path;
+    path.addRRect(SkRRect::MakeRectXY(SkRect::MakeLTRB(-50, -20, 40, 30), 4, 4));
+    check_bounds(reporter, path);
+
+    path.reset();
+    path.addOval(SkRect::MakeLTRB(300, 300, 900, 900));
+    check_bounds(reporter, path);
+
+    path.reset();
+    path.cubicTo(100, 50, 20, 100, 0, 0);
+    check_bounds(reporter, path);
+}