1 files changed, 41 insertions, 0 deletions
diff --git a/weathereffects/src/com/google/android/wallpaper/weathereffects/utils/MatrixUtils.kt b/weathereffects/src/com/google/android/wallpaper/weathereffects/utils/MatrixUtils.kt
new file mode 100644
index 0000000..b36b62a
--- /dev/null
+++ b/weathereffects/src/com/google/android/wallpaper/weathereffects/utils/MatrixUtils.kt
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2023 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.google.android.wallpaper.weathereffects.utils
+
+import android.graphics.Matrix
+import android.util.SizeF
+
+/** Helper functions for matrix operations. */
+object MatrixUtils {
+    /**
+     * Returns a [Matrix] that crops the image and centers to the screen.
+     */
+    fun centerCropMatrix(surfaceSize: SizeF, imageSize: SizeF): Matrix {
+        val widthScale = surfaceSize.width / imageSize.width
+        val heightScale = surfaceSize.height / imageSize.height
+        val scale = maxOf(widthScale, heightScale)
+
+        return Matrix(Matrix.IDENTITY_MATRIX).apply {
+            // Move the origin of the image to its center.
+            postTranslate(-imageSize.width / 2f, -imageSize.height / 2f)
+            // Apply scale.
+            postScale(scale, scale)
+            // Translate back to the center of the screen.
+            postTranslate(surfaceSize.width / 2f, surfaceSize.height / 2f)
+        }
+    }
+}