Resurrect pathfinder in viewer and rename to "bisect"

Bug: skia:
Change-Id: If8d2f46b8f27fefc3a0f983eb649654e0fb4afcb
Reviewed-on: https://skia-review.googlesource.com/108685
Commit-Queue: Chris Dalton <csmartdalton@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
diff --git a/tools/viewer/BisectSlide.cpp b/tools/viewer/BisectSlide.cpp
new file mode 100644
index 0000000..63e69d2
--- /dev/null
+++ b/tools/viewer/BisectSlide.cpp
@@ -0,0 +1,130 @@
+/*
+ * Copyright 2018 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "BisectSlide.h"
+
+#include "SkDOM.h"
+#include "SkOSPath.h"
+#include "SkPicture.h"
+#include "SkStream.h"
+#include "../experimental/svg/model/SkSVGDOM.h"
+
+sk_sp<BisectSlide> BisectSlide::Create(const char filepath[]) {
+    SkFILEStream stream(filepath);
+    if (!stream.isValid()) {
+        SkDebugf("BISECT: invalid input file at \"%s\"\n", filepath);
+        return nullptr;
+    }
+
+    sk_sp<BisectSlide> bisect(new BisectSlide(filepath));
+    if (bisect->fFilePath.endsWith(".svg")) {
+        SkDOM xml;
+        if (!xml.build(stream)) {
+            SkDebugf("BISECT: XML parsing failed: \"%s\"\n", filepath);
+            return nullptr;
+        }
+        sk_sp<SkSVGDOM> svg = SkSVGDOM::MakeFromDOM(xml);
+        if (!svg) {
+            SkDebugf("BISECT: couldn't load svg at \"%s\"\n", filepath);
+            return nullptr;
+        }
+        svg->setContainerSize(SkSize::Make(bisect->getDimensions()));
+        svg->render(bisect.get());
+    } else {
+        sk_sp<SkPicture> skp = SkPicture::MakeFromStream(&stream);
+        if (!skp) {
+            SkDebugf("BISECT: couldn't load skp at \"%s\"\n", filepath);
+            return nullptr;
+        }
+        skp->playback(bisect.get());
+    }
+
+    return bisect;
+}
+
+BisectSlide::BisectSlide(const char filepath[])
+        : SkCanvas(4096, 4096, nullptr)
+        , fFilePath(filepath) {
+    const char* basename = strrchr(fFilePath.c_str(), SkOSPath::SEPARATOR);
+    fName.printf("BISECT_%s", basename ? basename + 1 : fFilePath.c_str());
+}
+
+// Called through SkPicture::playback only during creation.
+void BisectSlide::onDrawPath(const SkPath& path, const SkPaint& paint) {
+    SkRect bounds;
+    SkIRect ibounds;
+    this->getTotalMatrix().mapRect(&bounds, path.getBounds());
+    bounds.roundOut(&ibounds);
+    fDrawBounds.join(ibounds);
+    fFoundPaths.push_back() = {path, paint, this->getTotalMatrix()};
+}
+
+bool BisectSlide::onChar(SkUnichar c) {
+    switch (c) {
+        case 'X':
+            if (!fTossedPaths.empty()) {
+                SkTSwap(fFoundPaths, fTossedPaths);
+                if ('X' == fTrail.back()) {
+                    fTrail.pop_back();
+                } else {
+                    fTrail.push_back('X');
+                }
+            }
+            return true;
+
+        case 'x':
+            if (fFoundPaths.count() > 1) {
+                int midpt = (fFoundPaths.count() + 1) / 2;
+                fPathHistory.emplace(fFoundPaths, fTossedPaths);
+                fTossedPaths.reset(fFoundPaths.begin() + midpt, fFoundPaths.count() - midpt);
+                fFoundPaths.resize_back(midpt);
+                fTrail.push_back('x');
+            }
+            return true;
+
+        case 'Z': {
+            if (!fPathHistory.empty()) {
+                fFoundPaths = fPathHistory.top().first;
+                fTossedPaths = fPathHistory.top().second;
+                fPathHistory.pop();
+                char ch;
+                do {
+                    ch = fTrail.back();
+                    fTrail.pop_back();
+                } while (ch != 'x');
+            }
+            return true;
+        }
+
+        case 'D':
+            SkDebugf("viewer --bisect %s", fFilePath.c_str());
+            if (!fTrail.empty()) {
+                SkDebugf(" ");
+                for (char ch : fTrail) {
+                    SkDebugf("%c", ch);
+                }
+            }
+            SkDebugf("\n");
+            for (const FoundPath& foundPath : fFoundPaths) {
+                foundPath.fPath.dump();
+            }
+            return true;
+    }
+
+    return false;
+}
+
+void BisectSlide::draw(SkCanvas* canvas) {
+    SkAutoCanvasRestore acr(canvas, true);
+    canvas->translate(-fDrawBounds.left(), -fDrawBounds.top());
+
+    for (const FoundPath& path : fFoundPaths) {
+        SkAutoCanvasRestore acr(canvas, true);
+        canvas->concat(path.fViewMatrix);
+        canvas->drawPath(path.fPath, path.fPaint);
+    }
+}