/* * Copyright (c) Facebook, Inc. and its affiliates. * * 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.facebook.fbui.textlayoutbuilder.glyphwarmer; import android.annotation.SuppressLint; import android.graphics.Canvas; import android.graphics.Picture; import android.os.Handler; import android.os.HandlerThread; import android.os.Looper; import android.os.Message; import android.text.Layout; import androidx.annotation.VisibleForTesting; import com.facebook.fbui.textlayoutbuilder.GlyphWarmer; import com.facebook.fbui.textlayoutbuilder.util.LayoutMeasureUtil; /** * Default {@link GlyphWarmer} that runs a {@link HandlerThread} to draw a text {@link Layout} on a * {@link Picture}. This helps in warming up the FreeType cache in Android 4.0+. */ public class GlyphWarmerImpl implements GlyphWarmer { // Handler for the HandlerThread. private static WarmHandler sWarmHandler; @Override public void warmLayout(Layout layout) { WarmHandler handler = getWarmHandler(); handler.sendMessage(handler.obtainMessage(WarmHandler.NO_OP, layout)); } @VisibleForTesting Looper getWarmHandlerLooper() { return getWarmHandler().getLooper(); } @SuppressLint({ "BadMethodUse-android.os.HandlerThread._Constructor", "BadMethodUse-java.lang.Thread.start" }) private WarmHandler getWarmHandler() { if (sWarmHandler == null) { // A text warmer thread to render the the layout in the background. // This helps warm the layout cache in Android 4.0+ devices, // making large blurbs of text to draw in 0ms. HandlerThread warmerThread = new HandlerThread("GlyphWarmer"); warmerThread.start(); // Note: warmerThread.getLooper() can return null. sWarmHandler = new WarmHandler(warmerThread.getLooper()); } return sWarmHandler; } /** A handler to send messages to the GlyphWarmerImpl thread. */ private static class WarmHandler extends Handler { private static final int NO_OP = 1; private final Picture mPicture = new Picture(); WarmHandler(Looper looper) { super(looper); } @Override public void handleMessage(Message msg) { Layout layout = (Layout) msg.obj; try { Canvas canvas = mPicture.beginRecording( LayoutMeasureUtil.getWidth(layout), LayoutMeasureUtil.getHeight(layout)); layout.draw(canvas); mPicture.endRecording(); } catch (Exception e) { // Do nothing. } } } }