[sksg] Initial text support

Use the new node type for SkottieSlide2 labels.

TBR=

Change-Id: Icd6a4faf1c281bd83a2331c0072d1a6ed71acc09
Reviewed-on: https://skia-review.googlesource.com/102441
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Florin Malita <fmalita@chromium.org>

10 files changed, 209 insertions, 41 deletions

diff --git a/BUILD.gn b/BUILD.gn
index 18d16ded01..f48c62e2a6 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -1401,6 +1401,7 @@ if (skia_enable_tools) {
       "experimental/sksg/geometry/SkSGMerge.cpp",
       "experimental/sksg/geometry/SkSGPath.cpp",
       "experimental/sksg/geometry/SkSGRect.cpp",
+      "experimental/sksg/geometry/SkSGText.cpp",
       "experimental/sksg/geometry/SkSGTrimEffect.cpp",
       "experimental/sksg/paint/SkSGColor.cpp",
       "experimental/sksg/paint/SkSGGradient.cpp",
diff --git a/experimental/sksg/geometry/SkSGGeometryTransform.h b/experimental/sksg/geometry/SkSGGeometryTransform.h
index ea990c6f29..fe7e026031 100644
--- a/experimental/sksg/geometry/SkSGGeometryTransform.h
+++ b/experimental/sksg/geometry/SkSGGeometryTransform.h
@@ -50,7 +50,7 @@ private:
     const sk_sp<Matrix>       fMatrix;
     SkPath                    fTransformed;
 
-    typedef GeometryNode INHERITED;
+    using INHERITED = GeometryNode;
 };
 
 }
diff --git a/experimental/sksg/geometry/SkSGMerge.h b/experimental/sksg/geometry/SkSGMerge.h
index 69f824e011..54924d6475 100644
--- a/experimental/sksg/geometry/SkSGMerge.h
+++ b/experimental/sksg/geometry/SkSGMerge.h
@@ -55,6 +55,8 @@ private:
     std::vector<sk_sp<GeometryNode>> fGeos;
     SkPath                           fMerged;
     Mode                             fMode;
+
+    using INHERITED = GeometryNode;
 };
 
 } // namespace sksg
diff --git a/experimental/sksg/geometry/SkSGPath.h b/experimental/sksg/geometry/SkSGPath.h
index 6dd259394b..a398e2f0a4 100644
--- a/experimental/sksg/geometry/SkSGPath.h
+++ b/experimental/sksg/geometry/SkSGPath.h
@@ -38,6 +38,8 @@ private:
     explicit Path(const SkPath&);
 
     SkPath fPath;
+
+    using INHERITED = GeometryNode;
 };
 
 } // namespace sksg
diff --git a/experimental/sksg/geometry/SkSGRect.h b/experimental/sksg/geometry/SkSGRect.h
index a99c76ab98..f5fcb962c6 100644
--- a/experimental/sksg/geometry/SkSGRect.h
+++ b/experimental/sksg/geometry/SkSGRect.h
@@ -42,6 +42,8 @@ private:
     explicit Rect(const SkRect&);
 
     SkRect fRect;
+
+    using INHERITED = GeometryNode;
 };
 
 /**
@@ -65,6 +67,8 @@ private:
     explicit RRect(const SkRRect&);
 
     SkRRect fRRect;
+
+    using INHERITED = GeometryNode;
 };
 
 } // namespace sksg
diff --git a/experimental/sksg/geometry/SkSGText.cpp b/experimental/sksg/geometry/SkSGText.cpp
new file mode 100644
index 0000000000..c149390023
--- /dev/null
+++ b/experimental/sksg/geometry/SkSGText.cpp
@@ -0,0 +1,77 @@
+/*
+ * 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 "SkSGText.h"
+
+#include "SkCanvas.h"
+#include "SkPaint.h"
+#include "SkPath.h"
+#include "SkTArray.h"
+#include "SkTextBlob.h"
+#include "SkTypeface.h"
+
+namespace sksg {
+
+sk_sp<Text> Text::Make(sk_sp<SkTypeface> tf, const SkString& text) {
+    return sk_sp<Text>(new Text(std::move(tf), text));
+}
+
+Text::Text(sk_sp<SkTypeface> tf, const SkString& text)
+    : fTypeface(std::move(tf))
+    , fText(text) {}
+
+Text::~Text() = default;
+
+SkRect Text::onRevalidate(InvalidationController*, const SkMatrix&) {
+    // TODO: we could potentially track invals which don't require rebuilding the blob.
+
+    SkPaint font;
+    font.setFlags(fFlags);
+    font.setTypeface(fTypeface);
+    font.setTextSize(fSize);
+    font.setTextScaleX(fScaleX);
+    font.setTextSkewX(fSkewX);
+    font.setTextAlign(fAlign);
+    font.setHinting(fHinting);
+
+    // First, convert to glyphIDs.
+    font.setTextEncoding(SkPaint::kUTF8_TextEncoding);
+    SkSTArray<256, SkGlyphID, true> glyphs;
+    glyphs.reset(font.textToGlyphs(fText.c_str(), fText.size(), nullptr));
+    SkAssertResult(font.textToGlyphs(fText.c_str(), fText.size(), glyphs.begin()) == glyphs.count());
+    font.setTextEncoding(SkPaint::kGlyphID_TextEncoding);
+
+    // Next, build the cached blob.
+    SkTextBlobBuilder builder;
+    const auto& buf = builder.allocRun(font, glyphs.count(), 0, 0, nullptr);
+    if (!buf.glyphs) {
+        fBlob.reset();
+        return SkRect::MakeEmpty();
+    }
+
+    memcpy(buf.glyphs, glyphs.begin(), glyphs.count() * sizeof(SkGlyphID));
+
+    fBlob = builder.make();
+    return fBlob
+        ? fBlob->bounds().makeOffset(fPosition.x(), fPosition.y())
+        : SkRect::MakeEmpty();
+}
+
+void Text::onDraw(SkCanvas* canvas, const SkPaint& paint) const {
+    canvas->drawTextBlob(fBlob, fPosition.x(), fPosition.y(), paint);
+}
+
+SkPath Text::onAsPath() const {
+    // TODO
+    return SkPath();
+}
+
+void Text::onClip(SkCanvas* canvas, bool antiAlias) const {
+    canvas->clipPath(this->asPath(), antiAlias);
+}
+
+} // namespace sksg
diff --git a/experimental/sksg/geometry/SkSGText.h b/experimental/sksg/geometry/SkSGText.h
new file mode 100644
index 0000000000..eb43337a10
--- /dev/null
+++ b/experimental/sksg/geometry/SkSGText.h
@@ -0,0 +1,69 @@
+/*
+ * 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 SkSGText_DEFINED
+#define SkSGText_DEFINED
+
+#include "SkSGGeometryNode.h"
+
+#include "SkPaintDefaults.h"
+#include "SkPoint.h"
+#include "SkString.h"
+
+class SkCanvas;
+class SkPaint;
+class SkTextBlob;
+class SkTypeface;
+
+namespace sksg {
+
+/**
+ * Concrete Geometry node, wrapping a (shaped) SkTextBlob.
+ */
+class Text final : public GeometryNode {
+public:
+    static sk_sp<Text> Make(sk_sp<SkTypeface> tf, const SkString& text);
+    ~Text() override;
+
+    SG_ATTRIBUTE(Text    , SkString      , fText    )
+    SG_ATTRIBUTE(Flags   , uint32_t      , fFlags   )
+    SG_ATTRIBUTE(Position, SkPoint       , fPosition)
+    SG_ATTRIBUTE(Size    , SkScalar      , fSize    )
+    SG_ATTRIBUTE(ScaleX  , SkScalar      , fScaleX  )
+    SG_ATTRIBUTE(SkewX   , SkScalar      , fSkewX   )
+    SG_ATTRIBUTE(Align   , SkPaint::Align, fAlign   )
+
+    // TODO: add shaping functionality.
+
+protected:
+    void onClip(SkCanvas*, bool antiAlias) const override;
+    void onDraw(SkCanvas*, const SkPaint&) const override;
+
+    SkRect onRevalidate(InvalidationController*, const SkMatrix&) override;
+    SkPath onAsPath() const override;
+
+private:
+    explicit Text(sk_sp<SkTypeface>, const SkString&);
+
+    const sk_sp<SkTypeface> fTypeface;
+    SkString                fText;
+    uint32_t                fFlags    = SkPaintDefaults_Flags;
+    SkPoint                 fPosition = SkPoint::Make(0, 0);
+    SkScalar                fSize     = SkPaintDefaults_TextSize;
+    SkScalar                fScaleX   = 1;
+    SkScalar                fSkewX    = 0;
+    SkPaint::Align          fAlign    = SkPaint::kLeft_Align;
+    SkPaint::Hinting        fHinting  = SkPaintDefaults_Hinting;
+
+    sk_sp<SkTextBlob> fBlob; // cached text blob
+
+    using INHERITED = GeometryNode;
+};
+
+} // namespace sksg
+
+#endif // SkSGText_DEFINED
diff --git a/experimental/sksg/geometry/SkSGTrimEffect.h b/experimental/sksg/geometry/SkSGTrimEffect.h
index 860cfafc25..e86ede83e6 100644
--- a/experimental/sksg/geometry/SkSGTrimEffect.h
+++ b/experimental/sksg/geometry/SkSGTrimEffect.h
@@ -47,6 +47,8 @@ private:
     SkScalar                  fStart  = 0, // starting t
                               fEnd    = 1, // ending t
                               fOffset = 0; // t offset
+
+    using INHERITED = GeometryNode;
 };
 
 } // namespace sksg
diff --git a/tools/viewer/SkottieSlide.h b/tools/viewer/SkottieSlide.h
index f573c2ed09..44929d7be5 100644
--- a/tools/viewer/SkottieSlide.h
+++ b/tools/viewer/SkottieSlide.h
@@ -50,13 +50,13 @@ public:
     void draw(SkCanvas*) override;
     bool animate(const SkAnimTimer&) override;
     bool onMouse(SkScalar x, SkScalar y, sk_app::Window::InputState, uint32_t modifiers) override;
+
 private:
     class AnimationWrapper;
 
     struct Rec {
         sk_sp<AnimationWrapper>             fWrapper;
         SkMSec                              fTimeBase = 0;
-        SkString                            fName;
         bool                                fShowAnimationInval = false;
 
         explicit Rec(sk_sp<AnimationWrapper>);
diff --git a/tools/viewer/SkottieSlide2.cpp b/tools/viewer/SkottieSlide2.cpp
index 7a9854031d..7b2c7c25a1 100644
--- a/tools/viewer/SkottieSlide2.cpp
+++ b/tools/viewer/SkottieSlide2.cpp
@@ -12,11 +12,17 @@
 #include "Skottie.h"
 #include "SkOSFile.h"
 #include "SkOSPath.h"
+#include "SkSGColor.h"
+#include "SkSGDraw.h"
 #include "SkSGGroup.h"
 #include "SkSGRenderNode.h"
 #include "SkSGScene.h"
+#include "SkSGText.h"
 #include "SkSGTransform.h"
 #include "SkStream.h"
+#include "SkTypeface.h"
+
+#include <cmath>
 
 static constexpr int CELL_WIDTH  = 240;
 static constexpr int CELL_HEIGHT = 160;
@@ -65,38 +71,64 @@ SkottieSlide2::SkottieSlide2(const SkString& path)
     fName.set("skottie-dir");
 }
 
+// Build a global scene using tranformed animation fragments:
+//
+// [Group(root)]
+//     [Transform]
+//         [Group]
+//             [AnimationWrapper]
+//             [Draw]
+//                 [Text]
+//                 [Color]
+//     [Transform]
+//         [Group]
+//             [AnimationWrapper]
+//             [Draw]
+//                 [Text]
+//                 [Color]
+//     ...
+//
+// Note: for now animation wrappers are also tracked externally in fAnims, for tick dispatching.
+
+static sk_sp<sksg::RenderNode> MakeLabel(const SkString& txt,
+                                         const SkRect& src,
+                                         const SkMatrix& dstXform) {
+    auto text = sksg::Text::Make(nullptr, txt);
+    text->setFlags(SkPaint::kAntiAlias_Flag);
+    text->setSize(12 / std::sqrt(dstXform.getScaleX() * dstXform.getScaleY()));
+    text->setAlign(SkPaint::kCenter_Align);
+    text->setPosition(SkPoint::Make(src.width() / 2, src.height() + text->getSize()));
+
+    return sksg::Draw::Make(std::move(text), sksg::Color::Make(SK_ColorBLACK));
+}
+
 void SkottieSlide2::load(SkScalar, SkScalar) {
     SkString name;
     SkOSFile::Iter iter(fPath.c_str(), "json");
 
     int x = 0, y = 0;
 
-    // Build a global scene using tranformed animation fragments:
-    //
-    // [Group]
-    //     [Transform]
-    //         [AnimationWrapper]
-    //     [Transform]
-    //         [AnimationWrapper]
-    //     ...
-    //
-    // Note: for now animation wrappers are also tracked externally in fAnims, for tick dispatching.
     auto scene_root = sksg::Group::Make();
 
     while (iter.next(&name)) {
         SkString path = SkOSPath::Join(fPath.c_str(), name.c_str());
         if (auto anim  = skottie::Animation::MakeFromFile(path.c_str())) {
-            const SkRect src = SkRect::MakeSize(anim->size()),
-                         dst = SkRect::MakeXYWH(MARGIN + x * (CELL_WIDTH + SPACER_X),
-                                                MARGIN + y * (CELL_HEIGHT + SPACER_Y),
-                                                CELL_WIDTH, CELL_HEIGHT);
+            const auto src = SkRect::MakeSize(anim->size()),
+                       dst = SkRect::MakeXYWH(MARGIN + x * (CELL_WIDTH + SPACER_X),
+                                              MARGIN + y * (CELL_HEIGHT + SPACER_Y),
+                                              CELL_WIDTH, CELL_HEIGHT);
+            const auto   m = SkMatrix::MakeRectToRect(src, dst, SkMatrix::kCenter_ScaleToFit);
+
             auto wrapper = sk_make_sp<AnimationWrapper>(std::move(anim));
-            auto matrix  = sksg::Matrix::Make(
-                SkMatrix::MakeRectToRect(src, dst, SkMatrix::kCenter_ScaleToFit));
-            auto xform   = sksg::Transform::Make(wrapper, std::move(matrix));
+
+            auto group   = sksg::Group::Make();
+            group->addChild(wrapper);
+            group->addChild(MakeLabel(name, src, m));
+
+            auto xform   = sksg::Transform::Make(std::move(group), m);
 
             scene_root->addChild(xform);
-            fAnims.emplace_back(std::move(wrapper)).fName = name;
+            fAnims.emplace_back(std::move(wrapper));
 
             if (++x == COL_COUNT) {
                 x = 0;
@@ -123,27 +155,6 @@ SkISize SkottieSlide2::getDimensions() const {
 
 void SkottieSlide2::draw(SkCanvas* canvas) {
     fScene->render(canvas);
-
-    // TODO: this is all only to draw labels; replace with sksg::Text nodes, when available.
-    SkPaint paint;
-    paint.setTextSize(12);
-    paint.setAntiAlias(true);
-    paint.setTextAlign(SkPaint::kCenter_Align);
-
-    const SkRect dst = SkRect::MakeIWH(CELL_WIDTH, CELL_HEIGHT);
-    int x = 0, y = 0;
-
-    canvas->translate(MARGIN, MARGIN);
-    for (const auto& rec : fAnims) {
-        SkAutoCanvasRestore acr(canvas, true);
-        canvas->translate(x * (CELL_WIDTH + SPACER_X), y * (CELL_HEIGHT + SPACER_Y));
-        canvas->drawText(rec.fName.c_str(), rec.fName.size(),
-                         dst.centerX(), dst.bottom() + paint.getTextSize(), paint);
-        if (++x == COL_COUNT) {
-            x = 0;
-            y += 1;
-        }
-    }
 }
 
 bool SkottieSlide2::animate(const SkAnimTimer& timer) {