1 /* 2 * Copyright (C) 2024 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.systemui.surfaceeffects 18 19 import android.graphics.Paint 20 import android.graphics.RenderEffect 21 22 /** 23 * A callback with a [Paint] object that contains shader info, which is triggered every frame while 24 * animation is playing. Note that the [Paint] object here is always the same instance. 25 * 26 * This approach is more performant than other ones because [RenderEffect] forces an intermediate 27 * render pass of the View to a texture to feed into it. 28 * 29 * The usage of this callback is as follows: 30 * <pre>{@code 31 * private var paint: Paint? = null 32 * // Override [View.onDraw]. 33 * override fun onDraw(canvas: Canvas) { 34 * // RuntimeShader requires hardwareAcceleration. 35 * if (!canvas.isHardwareAccelerated) return 36 * 37 * paint?.let { canvas.drawPaint(it) } 38 * } 39 * 40 * // Given that this is called [PaintDrawCallback.onDraw] 41 * fun draw(paint: Paint) { 42 * this.paint = paint 43 * 44 * // Must call invalidate to trigger View#onDraw 45 * invalidate() 46 * } 47 * }</pre> 48 * 49 * Please refer to [RenderEffectDrawCallback] for alternative approach. 50 */ 51 interface PaintDrawCallback { onDrawnull52 fun onDraw(paint: Paint) 53 } 54