1 files changed, 143 insertions, 0 deletions
diff --git a/weathereffects/src/com/google/android/wallpaper/weathereffects/rain/RainEffect.kt b/weathereffects/src/com/google/android/wallpaper/weathereffects/rain/RainEffect.kt
new file mode 100644
index 0000000..4aeb3c1
--- /dev/null
+++ b/weathereffects/src/com/google/android/wallpaper/weathereffects/rain/RainEffect.kt
@@ -0,0 +1,143 @@
+/*
+ * 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.rain
+
+import android.graphics.BitmapShader
+import android.graphics.Canvas
+import android.graphics.Paint
+import android.graphics.Shader
+import android.util.SizeF
+import com.google.android.torus.utils.extensions.getAspectRatio
+import com.google.android.wallpaper.weathereffects.WeatherEffect
+import com.google.android.wallpaper.weathereffects.utils.ImageCrop
+import kotlin.random.Random
+
+/** Defines and generates the rain weather effect animation. */
+class RainEffect(
+    /** The config of the rain effect. */
+    private val rainConfig: RainEffectConfig,
+    /** The initial size of the surface where the effect will be shown. */
+    surfaceSize: SizeF
+) : WeatherEffect {
+
+    private val rainPaint = Paint().also { it.shader = rainConfig.colorGradingShader }
+    private var elapsedTime: Float = 0f
+
+    init {
+        updateTextureUniforms()
+        adjustCropping(surfaceSize)
+        prepareColorGrading()
+    }
+
+    override fun resize(newSurfaceSize: SizeF) = adjustCropping(newSurfaceSize)
+
+    override fun update(deltaMillis: Long, frameTimeNanos: Long) {
+        elapsedTime += deltaMillis * MILLIS_TO_SECONDS
+        rainConfig.shader.setFloatUniform("time", elapsedTime)
+        rainConfig.colorGradingShader.setInputShader("texture", rainConfig.shader)
+    }
+
+    override fun draw(canvas: Canvas) {
+        canvas.drawPaint(rainPaint)
+    }
+
+    override fun reset() {
+        elapsedTime = Random.nextFloat() * 90f
+    }
+
+    override fun release() {
+        rainConfig.lut?.recycle()
+        rainConfig.blurredBackground.recycle()
+    }
+
+    private fun adjustCropping(surfaceSize: SizeF) {
+        val imageCropFgd = ImageCrop.centerCoverCrop(
+            surfaceSize.width,
+            surfaceSize.height,
+            rainConfig.foreground.width.toFloat(),
+            rainConfig.foreground.height.toFloat()
+        )
+        rainConfig.shader.setFloatUniform(
+            "uvOffsetFgd",
+            imageCropFgd.leftOffset,
+            imageCropFgd.topOffset
+        )
+        rainConfig.shader.setFloatUniform(
+            "uvScaleFgd",
+            imageCropFgd.horizontalScale,
+            imageCropFgd.verticalScale
+        )
+        val imageCropBgd = ImageCrop.centerCoverCrop(
+            surfaceSize.width,
+            surfaceSize.height,
+            rainConfig.background.width.toFloat(),
+            rainConfig.background.height.toFloat()
+        )
+        rainConfig.shader.setFloatUniform(
+            "uvOffsetBgd",
+            imageCropBgd.leftOffset,
+            imageCropBgd.topOffset
+        )
+        rainConfig.shader.setFloatUniform(
+            "uvScaleBgd",
+            imageCropBgd.horizontalScale,
+            imageCropBgd.verticalScale
+        )
+        rainConfig.shader.setFloatUniform("screenSize", surfaceSize.width, surfaceSize.height)
+        rainConfig.shader.setFloatUniform("screenAspectRatio", surfaceSize.getAspectRatio())
+    }
+
+    private fun updateTextureUniforms() {
+        rainConfig.shader.setInputBuffer(
+            "foreground",
+            BitmapShader(rainConfig.foreground, Shader.TileMode.MIRROR, Shader.TileMode.MIRROR)
+        )
+
+        rainConfig.shader.setInputBuffer(
+            "background",
+            BitmapShader(rainConfig.background, Shader.TileMode.MIRROR, Shader.TileMode.MIRROR)
+        )
+
+        rainConfig.shader.setInputBuffer(
+            "blurredBackground",
+            BitmapShader(
+                rainConfig.blurredBackground,
+                Shader.TileMode.MIRROR,
+                Shader.TileMode.MIRROR
+            )
+        )
+    }
+
+    private fun prepareColorGrading() {
+        rainConfig.colorGradingShader.setInputShader("texture", rainConfig.shader)
+        rainConfig.lut?.let {
+            rainConfig.colorGradingShader.setInputShader(
+                "lut",
+                BitmapShader(it, Shader.TileMode.MIRROR, Shader.TileMode.MIRROR)
+            )
+        }
+        rainConfig.colorGradingShader.setFloatUniform(
+            "intensity",
+            rainConfig.colorGradingIntensity
+        )
+    }
+
+    private companion object {
+
+        private const val MILLIS_TO_SECONDS = 1 / 1000f
+    }
+}