Added BlurShader API

Created BlurShader framework API along with
native implementation as an implementation of
the Shader wrapper that maps to either
SkShader or SkImageFilter

Bug: 143468037
Test: Added CTS test to verify BlurShader

Change-Id: I05fcf7ba79e9d552f8b0738f7382f7826cd94e21
diff --git a/libs/hwui/shader/BlurShader.cpp b/libs/hwui/shader/BlurShader.cpp
new file mode 100644
index 0000000..4d18cdd
--- /dev/null
+++ b/libs/hwui/shader/BlurShader.cpp
@@ -0,0 +1,38 @@
+/*
+ * 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 "BlurShader.h"
+#include "SkImageFilters.h"
+#include "SkRefCnt.h"
+#include "utils/Blur.h"
+
+namespace android::uirenderer {
+BlurShader::BlurShader(float radiusX, float radiusY, Shader* inputShader, const SkMatrix* matrix)
+    : Shader(matrix)
+    , skImageFilter(
+            SkImageFilters::Blur(
+                    Blur::convertRadiusToSigma(radiusX),
+                    Blur::convertRadiusToSigma(radiusY),
+                    inputShader ? inputShader->asSkImageFilter() : nullptr)
+            ) { }
+
+sk_sp<SkImageFilter> BlurShader::makeSkImageFilter() {
+    return skImageFilter;
+}
+
+BlurShader::~BlurShader() {}
+
+} // namespace android::uirenderer
\ No newline at end of file
diff --git a/libs/hwui/shader/BlurShader.h b/libs/hwui/shader/BlurShader.h
new file mode 100644
index 0000000..9eb22bd
--- /dev/null
+++ b/libs/hwui/shader/BlurShader.h
@@ -0,0 +1,42 @@
+/*
+ * 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
+#include "Shader.h"
+
+namespace android::uirenderer {
+
+/**
+ * Shader implementation that blurs another Shader instance or the source bitmap
+ */
+class BlurShader : public Shader {
+public:
+    /**
+     * Creates a BlurShader instance with the provided radius values to blur along the x and y
+     * axis accordingly.
+     *
+     * This will blur the contents of the provided input shader if it is non-null, otherwise
+     * the source bitmap will be blurred instead.
+     */
+    BlurShader(float radiusX, float radiusY, Shader* inputShader, const SkMatrix* matrix);
+    ~BlurShader() override;
+protected:
+    sk_sp<SkImageFilter> makeSkImageFilter() override;
+private:
+    sk_sp<SkImageFilter> skImageFilter;
+};
+
+} // namespace android::uirenderer
\ No newline at end of file
diff --git a/libs/hwui/shader/Shader.h b/libs/hwui/shader/Shader.h
index 3c0cdaa..6403e11 100644
--- a/libs/hwui/shader/Shader.h
+++ b/libs/hwui/shader/Shader.h
@@ -32,7 +32,9 @@
 class Shader: public SkRefCnt {
 public:
     /**
-     * Creates a Shader instance with an optional transformation matrix
+     * Creates a Shader instance with an optional transformation matrix. The transformation matrix
+     * is copied internally and ownership is unchanged. It is the responsibility of the caller to
+     * deallocate it appropriately.
      * @param matrix Optional matrix to transform the underlying SkShader or SkImageFilter
      */
     Shader(const SkMatrix* matrix);