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.cpp b/libs/hwui/canvas/CanvasFrontend.cpp
new file mode 100644
index 0000000..2c839b0
--- /dev/null
+++ b/libs/hwui/canvas/CanvasFrontend.cpp
@@ -0,0 +1,117 @@
+/*
+ * 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.
+ */
+
+#include "CanvasFrontend.h"
+#include "CanvasOps.h"
+#include "CanvasOpBuffer.h"
+
+namespace android::uirenderer {
+
+CanvasStateHelper::CanvasStateHelper(int width, int height) {
+ mInitialBounds = SkIRect::MakeWH(width, height);
+ mSaveStack.emplace_back();
+ mClipStack.emplace_back().setRect(mInitialBounds);
+ mTransformStack.emplace_back();
+ mCurrentClipIndex = 0;
+ mCurrentTransformIndex = 0;
+}
+
+bool CanvasStateHelper::internalSave(SaveEntry saveEntry) {
+ mSaveStack.push_back(saveEntry);
+ if (saveEntry.matrix) {
+ // We need to push before accessing transform() to ensure the reference doesn't move
+ // across vector resizes
+ mTransformStack.emplace_back() = transform();
+ mCurrentTransformIndex += 1;
+ }
+ if (saveEntry.clip) {
+ // We need to push before accessing clip() to ensure the reference doesn't move
+ // across vector resizes
+ mClipStack.emplace_back() = clip();
+ mCurrentClipIndex += 1;
+ return true;
+ }
+ return false;
+}
+
+// Assert that the cast from SkClipOp to SkRegion::Op is valid
+static_assert(static_cast<int>(SkClipOp::kDifference) == SkRegion::Op::kDifference_Op);
+static_assert(static_cast<int>(SkClipOp::kIntersect) == SkRegion::Op::kIntersect_Op);
+static_assert(static_cast<int>(SkClipOp::kUnion_deprecated) == SkRegion::Op::kUnion_Op);
+static_assert(static_cast<int>(SkClipOp::kXOR_deprecated) == SkRegion::Op::kXOR_Op);
+static_assert(static_cast<int>(SkClipOp::kReverseDifference_deprecated) == SkRegion::Op::kReverseDifference_Op);
+static_assert(static_cast<int>(SkClipOp::kReplace_deprecated) == SkRegion::Op::kReplace_Op);
+
+void CanvasStateHelper::internalClipRect(const SkRect& rect, SkClipOp op) {
+ clip().opRect(rect, transform(), mInitialBounds, (SkRegion::Op)op, false);
+}
+
+void CanvasStateHelper::internalClipPath(const SkPath& path, SkClipOp op) {
+ clip().opPath(path, transform(), mInitialBounds, (SkRegion::Op)op, true);
+}
+
+bool CanvasStateHelper::internalRestore() {
+ // Prevent underflows
+ if (saveCount() <= 1) {
+ return false;
+ }
+
+ SaveEntry entry = mSaveStack[mSaveStack.size() - 1];
+ mSaveStack.pop_back();
+ bool needsRestorePropagation = entry.layer;
+ if (entry.matrix) {
+ mTransformStack.pop_back();
+ mCurrentTransformIndex -= 1;
+ }
+ if (entry.clip) {
+ // We need to push before accessing clip() to ensure the reference doesn't move
+ // across vector resizes
+ mClipStack.pop_back();
+ mCurrentClipIndex -= 1;
+ needsRestorePropagation = true;
+ }
+ return needsRestorePropagation;
+}
+
+SkRect CanvasStateHelper::getClipBounds() const {
+ SkIRect ibounds = clip().getBounds();
+
+ if (ibounds.isEmpty()) {
+ return SkRect::MakeEmpty();
+ }
+
+ SkMatrix inverse;
+ // if we can't invert the CTM, we can't return local clip bounds
+ if (!transform().invert(&inverse)) {
+ return SkRect::MakeEmpty();
+ }
+
+ SkRect ret = SkRect::MakeEmpty();
+ inverse.mapRect(&ret, SkRect::Make(ibounds));
+ return ret;
+}
+
+bool CanvasStateHelper::quickRejectRect(float left, float top, float right, float bottom) const {
+ // TODO: Implement
+ return false;
+}
+
+bool CanvasStateHelper::quickRejectPath(const SkPath& path) const {
+ // TODO: Implement
+ return false;
+}
+
+} // namespace android::uirenderer