Generic "directory" viewer slide

This is a generalization of "skottie-dir", based on SkSG and operating
at the Slide API level.

For now it is only instantiated for Json slides, but could be used for
other slide "directories" in the future.

TBR=
NOTRY=true
Change-Id: If12429084bddeb172b234344f23eabcdadedcceb
Reviewed-on: https://skia-review.googlesource.com/108002
Commit-Queue: Florin Malita <fmalita@chromium.org>
Reviewed-by: Florin Malita <fmalita@chromium.org>

3 files changed, 254 insertions, 2 deletions

diff --git a/tools/viewer/SlideDir.cpp b/tools/viewer/SlideDir.cpp
new file mode 100644
index 0000000000..23f1a219f1
--- /dev/null
+++ b/tools/viewer/SlideDir.cpp
@@ -0,0 +1,189 @@
+/*
+ * 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 "SlideDir.h"
+
+#include "SkAnimTimer.h"
+#include "SkCanvas.h"
+#include "SkMakeUnique.h"
+#include "SkSGColor.h"
+#include "SkSGDraw.h"
+#include "SkSGGroup.h"
+#include "SkSGRenderNode.h"
+#include "SkSGScene.h"
+#include "SkSGText.h"
+#include "SkSGTransform.h"
+#include "SkTypeface.h"
+
+namespace {
+
+static constexpr float  kAspectRatio = 1.5f;
+static constexpr float  kLabelSize   = 12.0f;
+static constexpr SkSize kPadding     = { 12.0f, 24.0f };
+
+class SlideAdapter final : public sksg::RenderNode {
+public:
+    explicit SlideAdapter(sk_sp<Slide> slide)
+        : fSlide(std::move(slide)) {
+        SkASSERT(fSlide);
+    }
+
+    std::unique_ptr<sksg::Animator> makeForwardingAnimator() {
+        // Trivial sksg::Animator -> skottie::Animation tick adapter
+        class ForwardingAnimator final : public sksg::Animator {
+        public:
+            explicit ForwardingAnimator(sk_sp<SlideAdapter> adapter)
+                : fAdapter(std::move(adapter)) {}
+
+        protected:
+            void onTick(float t) override {
+                fAdapter->tick(SkScalarRoundToInt(t));
+            }
+
+        private:
+            sk_sp<SlideAdapter> fAdapter;
+        };
+
+        return skstd::make_unique<ForwardingAnimator>(sk_ref_sp(this));
+    }
+
+protected:
+    SkRect onRevalidate(sksg::InvalidationController* ic, const SkMatrix& ctm) override {
+        const auto isize = fSlide->getDimensions();
+        return SkRect::MakeIWH(isize.width(), isize.height());
+    }
+
+    void onRender(SkCanvas* canvas) const override {
+        fSlide->draw(canvas);
+    }
+
+private:
+    void tick(SkMSec t) {
+        fSlide->animate(SkAnimTimer(0, t * 1e6, SkAnimTimer::kRunning_State));
+        this->invalidate();
+    }
+
+    const sk_sp<Slide> fSlide;
+
+    using INHERITED = sksg::RenderNode;
+};
+
+} // namespace
+
+struct SlideDir::Rec {
+    sk_sp<sksg::Matrix> fMatrix;
+    SkRect              fRect;
+};
+
+SlideDir::SlideDir(const SkString& name, SkTArray<sk_sp<Slide>, true>&& slides, int columns)
+    : fSlides(std::move(slides))
+    , fColumns(columns) {
+    fName = name;
+}
+
+static sk_sp<sksg::RenderNode> MakeLabel(const SkString& txt, const SkRect& dst) {
+    auto text = sksg::Text::Make(nullptr, txt);
+    text->setFlags(SkPaint::kAntiAlias_Flag);
+    text->setSize(kLabelSize);
+    text->setAlign(SkPaint::kCenter_Align);
+    text->setPosition(SkPoint::Make(dst.centerX(), dst.bottom()));
+
+    return sksg::Draw::Make(std::move(text), sksg::Color::Make(SK_ColorBLACK));
+}
+
+void SlideDir::load(SkScalar winWidth, SkScalar winHeight) {
+    // Build a global scene using transformed animation fragments:
+    //
+    // [Group(root)]
+    //     [Transform]
+    //         [Group]
+    //             [AnimationWrapper]
+    //             [Draw]
+    //                 [Text]
+    //                 [Color]
+    //     [Transform]
+    //         [Group]
+    //             [AnimationWrapper]
+    //             [Draw]
+    //                 [Text]
+    //                 [Color]
+    //     ...
+    //
+
+    fSize = SkSize::Make(winWidth, winHeight).toCeil();
+
+    const auto  cellWidth =  winWidth / fColumns,
+               cellHeight = cellWidth / kAspectRatio;
+
+    sksg::AnimatorList sceneAnimators;
+    auto root = sksg::Group::Make();
+
+    for (int i = 0; i < fSlides.count(); ++i) {
+        const auto& slide     = fSlides[i];
+        slide->load(winWidth, winHeight);
+
+        const auto  slideSize = slide->getDimensions();
+        const auto  cell      = SkRect::MakeXYWH(cellWidth  * (i % fColumns),
+                                                 cellHeight * (i / fColumns),
+                                                 cellWidth,
+                                                 cellHeight),
+                    slideRect = cell.makeInset(kPadding.width(), kPadding.height());
+
+        auto matrix = sksg::Matrix::Make(
+            SkMatrix::MakeRectToRect(SkRect::MakeIWH(slideSize.width(), slideSize.height()),
+                                     slideRect,
+                                     SkMatrix::kCenter_ScaleToFit));
+
+        auto adapter  = sk_make_sp<SlideAdapter>(slide);
+        auto slideGrp = sksg::Group::Make();
+        slideGrp->addChild(sksg::Transform::Make(adapter, matrix));
+        slideGrp->addChild(MakeLabel(slide->getName(), cell));
+
+        sceneAnimators.push_back(adapter->makeForwardingAnimator());
+        root->addChild(std::move(slideGrp));
+
+        fRecs.push_back({ matrix, slideRect });
+    }
+
+    fScene = sksg::Scene::Make(std::move(root), std::move(sceneAnimators));
+}
+
+void SlideDir::unload() {
+    for (const auto& slide : fSlides) {
+        slide->unload();
+    }
+
+    fRecs.reset();
+    fScene.reset();
+    fTimeBase = 0;
+}
+
+SkISize SlideDir::getDimensions() const {
+    return fSize;
+}
+
+void SlideDir::draw(SkCanvas* canvas) {
+    fScene->render(canvas);
+}
+
+bool SlideDir::animate(const SkAnimTimer& timer) {
+    if (fTimeBase == 0) {
+        // Reset the animation time.
+        fTimeBase = timer.msec();
+    }
+    fScene->animate(timer.msec() - fTimeBase);
+
+    return true;
+}
+
+bool SlideDir::onChar(SkUnichar c) {
+    return false;
+}
+
+bool SlideDir::onMouse(SkScalar x, SkScalar y, sk_app::Window::InputState, uint32_t modifiers) {
+    return false;
+}
diff --git a/tools/viewer/SlideDir.h b/tools/viewer/SlideDir.h
new file mode 100644
index 0000000000..a4c5f6da0a
--- /dev/null
+++ b/tools/viewer/SlideDir.h
@@ -0,0 +1,53 @@
+/*
+ * Copyright 2018 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SlideDir_DEFINED
+#define SlideDir_DEFINED
+
+#include "Slide.h"
+
+#include "SkTArray.h"
+
+class SkString;
+
+namespace sksg { class Scene; }
+
+class SlideDir final : public Slide {
+public:
+    SlideDir(const SkString& name, SkTArray<sk_sp<Slide>, true>&&,
+             int columns = kDefaultColumnCount);
+
+protected:
+    void load(SkScalar winWidth, SkScalar winHeight) override;
+    void unload() override;
+
+    SkISize getDimensions() const override;
+
+    void draw(SkCanvas*) override;
+    bool animate(const SkAnimTimer&) override;
+
+    bool onChar(SkUnichar) override;
+    bool onMouse(SkScalar x, SkScalar y, sk_app::Window::InputState, uint32_t modifiers) override;
+
+private:
+    static constexpr int kDefaultColumnCount = 4;
+
+    struct Rec;
+
+    const SkTArray<sk_sp<Slide>, true> fSlides;
+    const int                          fColumns;
+
+    SkTArray<Rec, true>          fRecs;
+    std::unique_ptr<sksg::Scene> fScene;
+
+    SkISize                      fSize     = SkISize::MakeEmpty();
+    SkMSec                       fTimeBase = 0;
+
+    using INHERITED = Slide;
+};
+
+#endif // SlideDir_DEFINED
diff --git a/tools/viewer/Viewer.cpp b/tools/viewer/Viewer.cpp
index 2a58f2dc62..92741fea97 100644
--- a/tools/viewer/Viewer.cpp
+++ b/tools/viewer/Viewer.cpp
@@ -13,6 +13,7 @@
 #include "SampleSlide.h"
 #include "SkottieSlide.h"
 #include "SKPSlide.h"
+#include "SlideDir.h"
 
 #include "GrContext.h"
 #include "SkCanvas.h"
@@ -556,14 +557,23 @@ void Viewer::initSlides() {
     for (const auto& json : FLAGS_jsons) {
         fSlides.push_back(sk_make_sp<SkottieSlide2>(json));
 
+        SkTArray<sk_sp<Slide>, true> dirSlides;
+
         SkOSFile::Iter it(json.c_str(), ".json");
         SkString jsonName;
         while (it.next(&jsonName)) {
             if (SkCommandLineFlags::ShouldSkip(FLAGS_match, jsonName.c_str())) {
                 continue;
             }
-            fSlides.push_back(sk_make_sp<SkottieSlide>(jsonName, SkOSPath::Join(json.c_str(),
-                                                                                jsonName.c_str())));
+            auto slide = sk_make_sp<SkottieSlide>(jsonName, SkOSPath::Join(json.c_str(),
+                                                                           jsonName.c_str()));
+            dirSlides.push_back(slide);
+            fSlides.push_back(std::move(slide));
+        }
+
+        if (!dirSlides.empty()) {
+            fSlides.push_back(sk_make_sp<SlideDir>(SkStringPrintf("skottie-dir[%s]", json.c_str()),
+                                                   std::move(dirSlides)));
         }
     }
 }