Fix backdrop effect for prerotation

When doing prerotation the matrix math didn't work out due
to makeImageSnapshot() being rotated already, but then drawn
again into a rotating matrix. Fix this by having BackdropFilterDrawable
do everything in post-rotation space.

Bug: 353827335
Test: SilkFX view blur behind demo
Flag: EXEMPT bugfix
Change-Id: I7b41d95e7e5f15434f9c6481534c74ee998a83ef

5 files changed, 191 insertions, 4 deletions

diff --git a/libs/hwui/pipeline/skia/BackdropFilterDrawable.cpp b/libs/hwui/pipeline/skia/BackdropFilterDrawable.cpp
index e81cbfb508ae..b6d30b06dc5b 100644
--- a/libs/hwui/pipeline/skia/BackdropFilterDrawable.cpp
+++ b/libs/hwui/pipeline/skia/BackdropFilterDrawable.cpp
@@ -86,9 +86,17 @@ void BackdropFilterDrawable::onDraw(SkCanvas* canvas) {
         backdropImage = SkImages::MakeWithFilter(backdropImage, backdropFilter, imageSubset,
                                                  imageSubset, &mOutSubset, &mOutOffset);
     }
-    canvas->drawImageRect(backdropImage, SkRect::Make(mOutSubset), mDstBounds,
+
+    // backdropImage & mOutSubset are in post-pre-rotation space, whereas mDstBounds is in
+    // prerotation space. So map dst bounds to post-pre-rotation space & draw there
+    SkRect dst;
+    canvas->getTotalMatrix().mapRect(&dst, mDstBounds);
+    canvas->save();
+    canvas->resetMatrix();
+    canvas->drawImageRect(backdropImage, SkRect::Make(mOutSubset), dst,
                           SkSamplingOptions(SkFilterMode::kLinear), &mPaint,
-                          SkCanvas::kStrict_SrcRectConstraint);
+                          SkCanvas::kFast_SrcRectConstraint);
+    canvas->restore();
 }
 
 }  // namespace skiapipeline
diff --git a/libs/hwui/tests/unit/RenderNodeDrawableTests.cpp b/libs/hwui/tests/unit/RenderNodeDrawableTests.cpp
index ca540874833c..4b29100c55a6 100644
--- a/libs/hwui/tests/unit/RenderNodeDrawableTests.cpp
+++ b/libs/hwui/tests/unit/RenderNodeDrawableTests.cpp
@@ -1280,7 +1280,7 @@ RENDERTHREAD_TEST(BackdropFilterDrawable, drawing) {
     canvas->drawDrawable(&backdropDrawable);
     // the drawable is still visible, ok to draw.
     EXPECT_EQ(2, canvas->mDrawCounter);
-    EXPECT_EQ(SkRect::MakeLTRB(0, 0, CANVAS_WIDTH - 30, CANVAS_HEIGHT - 30), canvas->mDstBounds);
+    EXPECT_EQ(SkRect::MakeLTRB(30, 30, CANVAS_WIDTH, CANVAS_HEIGHT), canvas->mDstBounds);
 
     canvas->translate(CANVAS_WIDTH, CANVAS_HEIGHT);
     canvas->drawDrawable(&drawable);
diff --git a/tests/graphics/SilkFX/res/layout/view_blur_behind.xml b/tests/graphics/SilkFX/res/layout/view_blur_behind.xml
new file mode 100644
index 000000000000..83b1fa4b73cb
--- /dev/null
+++ b/tests/graphics/SilkFX/res/layout/view_blur_behind.xml
@@ -0,0 +1,148 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2024 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.
+  -->
+
+<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent">
+
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:orientation="vertical">
+
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:padding="8dp"
+            android:textSize="24dp"
+            android:text="~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~" />
+
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:padding="8dp"
+            android:textSize="24dp"
+            android:text="wowwowwowwowwowwowwowwowwowwowwowwowwowwowwow" />
+
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:padding="8dp"
+            android:textSize="24dp"
+            android:text="I'm a little teapot" />
+
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:padding="8dp"
+            android:textSize="24dp"
+            android:text="Something. Something." />
+
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:padding="8dp"
+            android:textSize="24dp"
+            android:text="/\\/\\/\\/\\/\\/\\/\\/\\/\\/" />
+
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:padding="8dp"
+            android:textSize="24dp"
+            android:text="^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^" />
+
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:padding="8dp"
+            android:textSize="24dp"
+            android:text="~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~" />
+
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:padding="8dp"
+            android:textSize="24dp"
+            android:text="wowwowwowwowwowwowwowwowwowwowwowwowwowwowwow" />
+
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:padding="8dp"
+            android:textSize="24dp"
+            android:text="I'm a little teapot" />
+
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:padding="8dp"
+            android:textSize="24dp"
+            android:text="Something. Something." />
+
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:padding="8dp"
+            android:textSize="24dp"
+            android:text="/\\/\\/\\/\\/\\/\\/\\/\\/\\/" />
+
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:padding="8dp"
+            android:textSize="24dp"
+            android:text="^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^.^" />
+
+    </LinearLayout>
+
+    <ScrollView
+        android:layout_width="match_parent"
+        android:layout_height="match_parent">
+
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:orientation="vertical">
+
+            <View
+                android:layout_width="match_parent"
+                android:layout_height="300dp" />
+
+            <com.android.test.silkfx.materials.BlurBehindContainer
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:background="#33AAAAAA"
+                android:padding="32dp">
+
+                <TextView
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:textSize="48dp"
+                    android:text="Blur!" />
+
+            </com.android.test.silkfx.materials.BlurBehindContainer>
+
+            <View
+                android:layout_width="match_parent"
+                android:layout_height="1024dp" />
+
+        </LinearLayout>
+
+    </ScrollView>
+
+</FrameLayout>
\ No newline at end of file
diff --git a/tests/graphics/SilkFX/src/com/android/test/silkfx/Main.kt b/tests/graphics/SilkFX/src/com/android/test/silkfx/Main.kt
index 59a6078376cf..6b6d3b8d3d12 100644
--- a/tests/graphics/SilkFX/src/com/android/test/silkfx/Main.kt
+++ b/tests/graphics/SilkFX/src/com/android/test/silkfx/Main.kt
@@ -61,7 +61,8 @@ private val AllDemos = listOf(
         )),
         DemoGroup("Materials", listOf(
                 Demo("Glass", GlassActivity::class),
-                Demo("Background Blur", BackgroundBlurActivity::class)
+                Demo("Background Blur", BackgroundBlurActivity::class),
+                Demo("View blur behind", R.layout.view_blur_behind, commonControls = false)
         ))
 )
 
diff --git a/tests/graphics/SilkFX/src/com/android/test/silkfx/materials/BlurBehindContainer.kt b/tests/graphics/SilkFX/src/com/android/test/silkfx/materials/BlurBehindContainer.kt
new file mode 100644
index 000000000000..ce6348e32969
--- /dev/null
+++ b/tests/graphics/SilkFX/src/com/android/test/silkfx/materials/BlurBehindContainer.kt
@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) 2024 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.
+ */
+package com.android.test.silkfx.materials
+
+import android.content.Context
+import android.graphics.RenderEffect
+import android.graphics.Shader
+import android.util.AttributeSet
+import android.widget.FrameLayout
+
+class BlurBehindContainer(context: Context, attributeSet: AttributeSet) : FrameLayout(context, attributeSet) {
+    override fun onFinishInflate() {
+        super.onFinishInflate()
+        setBackdropRenderEffect(
+            RenderEffect.createBlurEffect(16.0f, 16.0f, Shader.TileMode.CLAMP))
+    }
+}
\ No newline at end of file