Revert "Revert "try resolver pattern""

This reverts commit 2bafb64.

Change-Id: I46f29284546a8978fd0005a0937e28410e5ac0da
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/220518
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Florin Malita <fmalita@chromium.org>

Author: reed-at-google

BUILD.gn

@@ -21,6 +21,7 @@ declare_args() {
   skia_use_angle = false
   skia_use_egl = false
   skia_use_expat = true
+  skia_use_experimental_xform = false
   skia_use_ffmpeg = false
   skia_use_fontconfig = is_linux
   skia_use_fonthost_mac = is_mac
@@ -1724,8 +1725,8 @@ if (skia_enable_tools) {
       ":skia",
       ":skvm_builders",
       ":tool_utils",
-      "modules/skshaper",
       "modules/skparagraph:bench",
+      "modules/skshaper",
     ]
   }
 
@@ -1763,6 +1764,17 @@ if (skia_enable_tools) {
     }
   }
 
+  test_lib("experimental_xform") {
+    sources = [
+      "experimental/xform/SkShape.cpp",
+      "experimental/xform/SkXform.cpp",
+      "experimental/xform/XContext.cpp",
+    ]
+    deps = [
+      ":skia",
+    ]
+  }
+
   if (skia_use_lua) {
     test_lib("lua") {
       sources = [
@@ -1937,8 +1949,8 @@ if (skia_enable_tools) {
       ":skia",
       ":tool_utils",
       ":trace",
-      "modules/sksg",
       "modules/skparagraph:bench",
+      "modules/sksg",
       "modules/skshaper",
     ]
   }
@@ -2394,6 +2406,10 @@ if (skia_enable_tools) {
       "modules/sksg:samples",
       "//third_party/imgui",
     ]
+    if (skia_use_experimental_xform) {
+      deps += [ ":experimental_xform" ]
+      sources += [ "gm/xform.cpp" ]
+    }
   }
 
   if (!skia_use_angle && (is_linux || is_win || is_mac)) {

experimental/xform/SkShape.cpp

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2019 Google LLC.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "experimental/xform/SkShape.h"
+#include "experimental/xform/SkXform.h"
+#include "include/core/SkCanvas.h"
+
+void GeoShape::draw(XContext* ctx) {
+    ctx->drawRect(fRect, fPaint, this->xform());
+}
+
+void GroupShape::draw(XContext* ctx) {
+    if (fArray.count() == 0) {
+        return;
+    }
+
+    ctx->push(this->xform());
+    for (auto s : fArray) {
+        s->draw(ctx);
+    }
+    ctx->pop();
+}

experimental/xform/SkShape.h

@@ -0,0 +1,104 @@
+/*
+ * Copyright 2019 Google LLC.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkShape_DEFINED
+#define SkShape_DEFINED
+
+#include "experimental/xform/SkXform.h"
+#include "include/core/SkPaint.h"
+
+class SkCanvas;
+
+class XContext {
+public:
+    virtual ~XContext() {}
+
+    void push(Xform* parentXform) { this->onPush(parentXform); }
+    void pop() { this->onPop(); }
+
+    void drawRect(const SkRect&, const SkPaint&, Xform* localXform);
+
+    static std::unique_ptr<XContext> Make(SkCanvas*);
+
+protected:
+    virtual void onPush(Xform*) = 0;
+    virtual void onPop() = 0;
+
+    virtual void onDrawRect(const SkRect&, const SkPaint&, Xform*) = 0;
+};
+
+class Shape : public SkRefCnt {
+    sk_sp<Xform>    fXform;
+
+public:
+    Shape(sk_sp<Xform> x = nullptr) : fXform(std::move(x)) {}
+
+    Xform* xform() const { return fXform.get(); }
+    void setXform(sk_sp<Xform> x) {
+        fXform = std::move(x);
+    }
+
+    virtual void draw(XContext*) {}
+};
+
+class GeoShape : public Shape {
+    SkRect  fRect;
+    SkPaint fPaint;
+
+    GeoShape(sk_sp<Xform> x, const SkRect& r, SkColor c) : Shape(std::move(x)), fRect(r) {
+        fPaint.setColor(c);
+    }
+
+public:
+    static sk_sp<Shape> Make(sk_sp<Xform> x, const SkRect& r, SkColor c) {
+        return sk_sp<Shape>(new GeoShape(std::move(x), r, c));
+    }
+
+    void draw(XContext*) override;
+};
+
+class GroupShape : public Shape {
+    SkTDArray<Shape*> fArray;
+
+    GroupShape(sk_sp<Xform> x) : Shape(std::move(x)) {}
+
+public:
+    static sk_sp<GroupShape> Make(sk_sp<Xform> x = nullptr) {
+        return sk_sp<GroupShape>(new GroupShape(std::move(x)));
+    }
+
+    static sk_sp<GroupShape> Make(sk_sp<Xform> x, sk_sp<Shape> s) {
+        auto g = sk_sp<GroupShape>(new GroupShape(std::move(x)));
+        g->append(std::move(s));
+        return g;
+    }
+
+    ~GroupShape() override {
+        fArray.unrefAll();
+    }
+
+    int count() const { return fArray.count(); }
+    Shape* get(int index) const { return fArray[index]; }
+    void set(int index, sk_sp<Shape> s) {
+        fArray[index] = s.release();
+    }
+
+    void append(sk_sp<Shape> s) {
+        *fArray.append() = s.release();
+    }
+    void insert(int index, sk_sp<Shape> s) {
+        *fArray.insert(index) = s.release();
+    }
+    void remove(int index) {
+        SkSafeUnref(fArray[index]);
+        fArray.remove(index);
+    }
+
+    void draw(XContext*) override ;
+};
+
+#endif

experimental/xform/SkXform.cpp

@@ -0,0 +1,87 @@
+/*
+ * Copyright 2019 Google LLC.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "experimental/xform/SkXform.h"
+
+static std::atomic<uint32_t> gGenID{1};
+Xform::GenID Xform::NextGenID() {
+    return gGenID++;
+}
+
+#ifdef SK_DEBUG
+void Xform::debugValidate() const {
+    if (this->isCached() && fParent) {
+        SkASSERT(fParent->isCached());
+    }
+    for (auto c : fChildren) {
+        SkASSERT(c->parent() == this);
+        c->debugValidate();
+    }
+}
+#endif
+
+void Xform::setParent(sk_sp<Xform> parent) {
+    if (parent == fParent) {
+        return;
+    }
+
+    if (fParent) {
+        fParent->internalRemoveChild(this);
+    }
+    if (parent) {
+        parent->internalAddChild(this);
+    }
+    fParent = std::move(parent);
+
+    // Potentially we could skip this if knew that our old and new parents
+    // were both cached, and they started us in the same state...
+    // For now, we conservatively always inval
+    this->invalidateCaches();
+
+    this->debugValidate();
+}
+
+void Xform::internalAddChild(Xform* child) {
+    SkASSERT(fChildren.find(child) < 0);
+    fChildren.push_back(child);
+}
+
+void Xform::internalRemoveChild(Xform* child) {
+    int index = fChildren.find(child);
+    SkASSERT(index >= 0);
+    fChildren.removeShuffle(index);
+}
+
+void Xform::invalidateCaches() {
+    fGenID = 0;
+    if (this->isCached()) {
+        this->internalInvalidateCaches();
+        for (auto c : fChildren) {
+            c->invalidateCaches();
+        }
+    }
+}
+
+void Xform::visit(XformResolver* resolver) {
+    this->onVisit(resolver);
+}
+
+void Xform::setCache(const SkMatrix& ctm, sk_sp<ClipCache> clip) {
+    fCTM = ctm;
+    fClip = std::move(clip);
+    fGenID = NextGenID();
+}
+
+//////////////////////////////////////////////////////////////////////////////////////////////////
+
+void MatrixXF::onVisit(XformResolver* resolver) {
+    resolver->concat(fLocalMatrix);
+}
+
+void ClipXF::onVisit(XformResolver* resolver) {
+    resolver->clipRect(fRect, fOp);
+}