Introduce CanvasFrontend
Add a front-end to convert between "stateful" canvas
and "semi-statelss" CanvasOps. Handles tracking
save/restores, clips, and transforms, and injects
the transform on all draw ops.
Test: CanvasFrontend unit tests
Change-Id: Ifbcd14600690f10717047c50954ab54b4fc27aee
diff --git a/libs/hwui/canvas/CanvasFrontend.h b/libs/hwui/canvas/CanvasFrontend.h
new file mode 100644
index 0000000..5fccccb
--- /dev/null
+++ b/libs/hwui/canvas/CanvasFrontend.h
@@ -0,0 +1,200 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+// TODO: Can we get the dependencies scoped down more?
+#include "CanvasOps.h"
+#include "CanvasOpBuffer.h"
+#include <SaveFlags.h>
+
+#include <SkRasterClip.h>
+#include <ui/FatVector.h>
+
+#include <optional>
+
+namespace android::uirenderer {
+
+// Exists to avoid forcing all this common logic into the templated class
+class CanvasStateHelper {
+protected:
+ CanvasStateHelper(int width, int height);
+ ~CanvasStateHelper() = default;
+
+ struct SaveEntry {
+ bool clip : 1 = false;
+ bool matrix : 1 = false;
+ bool layer : 1 = false;
+ };
+
+ constexpr SaveEntry saveEntryForLayer() {
+ return {
+ .clip = true,
+ .matrix = true,
+ .layer = true,
+ };
+ }
+
+ constexpr SaveEntry flagsToSaveEntry(SaveFlags::Flags flags) {
+ return SaveEntry {
+ .clip = static_cast<bool>(flags & SaveFlags::Clip),
+ .matrix = static_cast<bool>(flags & SaveFlags::Matrix),
+ .layer = false
+ };
+ }
+
+ bool internalSave(SaveEntry saveEntry);
+ bool internalSave(SaveFlags::Flags flags) {
+ return internalSave(flagsToSaveEntry(flags));
+ }
+ void internalSaveLayer(const SkCanvas::SaveLayerRec& layerRec) {
+ internalSave({
+ .clip = true,
+ .matrix = true,
+ .layer = true
+ });
+ internalClipRect(*layerRec.fBounds, SkClipOp::kIntersect);
+ }
+
+ bool internalRestore();
+
+ void internalClipRect(const SkRect& rect, SkClipOp op);
+ void internalClipPath(const SkPath& path, SkClipOp op);
+
+ SkIRect mInitialBounds;
+ FatVector<SaveEntry, 6> mSaveStack;
+ FatVector<SkMatrix, 6> mTransformStack;
+ FatVector<SkConservativeClip, 6> mClipStack;
+
+ size_t mCurrentTransformIndex;
+ size_t mCurrentClipIndex;
+
+ const SkConservativeClip& clip() const {
+ return mClipStack[mCurrentClipIndex];
+ }
+
+ SkConservativeClip& clip() {
+ return mClipStack[mCurrentClipIndex];
+ }
+
+public:
+ int saveCount() const { return mSaveStack.size(); }
+
+ SkRect getClipBounds() const;
+ bool quickRejectRect(float left, float top, float right, float bottom) const;
+ bool quickRejectPath(const SkPath& path) const;
+
+ const SkMatrix& transform() const {
+ return mTransformStack[mCurrentTransformIndex];
+ }
+
+ SkMatrix& transform() {
+ return mTransformStack[mCurrentTransformIndex];
+ }
+
+ // For compat with existing HWUI Canvas interface
+ void getMatrix(SkMatrix* outMatrix) const {
+ *outMatrix = transform();
+ }
+
+ void setMatrix(const SkMatrix& matrix) {
+ transform() = matrix;
+ }
+
+ void concat(const SkMatrix& matrix) {
+ transform().preConcat(matrix);
+ }
+
+ void rotate(float degrees) {
+ SkMatrix m;
+ m.setRotate(degrees);
+ concat(m);
+ }
+
+ void scale(float sx, float sy) {
+ SkMatrix m;
+ m.setScale(sx, sy);
+ concat(m);
+ }
+
+ void skew(float sx, float sy) {
+ SkMatrix m;
+ m.setSkew(sx, sy);
+ concat(m);
+ }
+
+ void translate(float dx, float dy) {
+ transform().preTranslate(dx, dy);
+ }
+};
+
+// Front-end canvas that handles queries, up-front state, and produces CanvasOp<> output downstream
+template <typename CanvasOpReceiver>
+class CanvasFrontend final : public CanvasStateHelper {
+public:
+ template<class... Args>
+ CanvasFrontend(int width, int height, Args&&... args) : CanvasStateHelper(width, height),
+ mReceiver(std::forward<Args>(args)...) { }
+ ~CanvasFrontend() = default;
+
+ void save(SaveFlags::Flags flags = SaveFlags::MatrixClip) {
+ if (internalSave(flagsToSaveEntry(flags))) {
+ submit<CanvasOpType::Save>({});
+ }
+ }
+
+ void restore() {
+ if (internalRestore()) {
+ submit<CanvasOpType::Restore>({});
+ }
+ }
+
+ template <CanvasOpType T>
+ void draw(CanvasOp<T>&& op) {
+ // The front-end requires going through certain front-doors, which these aren't.
+ static_assert(T != CanvasOpType::Save, "Must use CanvasFrontend::save() call instead");
+ static_assert(T != CanvasOpType::Restore, "Must use CanvasFrontend::restore() call instead");
+
+ if constexpr (T == CanvasOpType::SaveLayer) {
+ internalSaveLayer(op.saveLayerRec);
+ }
+ if constexpr (T == CanvasOpType::SaveBehind) {
+ // Don't use internalSaveLayer as this doesn't apply clipping, it's a "regular" save
+ // But we do want to flag it as a layer, such that restore is Definitely Required
+ internalSave(saveEntryForLayer());
+ }
+ if constexpr (T == CanvasOpType::ClipRect) {
+ internalClipRect(op.rect, op.op);
+ }
+ if constexpr (T == CanvasOpType::ClipPath) {
+ internalClipPath(op.path, op.op);
+ }
+
+ submit(std::move(op));
+ }
+
+ const CanvasOpReceiver& receiver() const { return mReceiver; }
+
+private:
+ CanvasOpReceiver mReceiver;
+
+ template <CanvasOpType T>
+ void submit(CanvasOp<T>&& op) {
+ mReceiver.push_container(CanvasOpContainer(std::move(op), transform()));
+ }
+};
+
+} // namespace android::uirenderer