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Add a StaticLayoutCompat class that supports Max Lines
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‎lib/java/com/google/android/material/internal/StaticLayoutBuilderCompat.java‎

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/*
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* Copyright (C) 2019 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.android.material.internal;
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import static androidx.core.util.Preconditions.checkNotNull;
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import android.os.Build;
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import android.os.Build.VERSION_CODES;
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import androidx.annotation.IntRange;
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import androidx.annotation.NonNull;
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import androidx.annotation.Nullable;
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import androidx.annotation.RestrictTo;
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import androidx.annotation.RestrictTo.Scope;
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import android.text.Layout;
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import android.text.Layout.Alignment;
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import android.text.StaticLayout;
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import android.text.TextDirectionHeuristic;
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import android.text.TextDirectionHeuristics;
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import android.text.TextPaint;
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import android.text.TextUtils;
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import java.lang.reflect.Constructor;
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/**
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* Class to create StaticLayout using StaticLayout.Builder on API23+ and a hidden StaticLayout
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* constructor before that.
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*
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* <p>Usage:
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*
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* <pre>{@code
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* StaticLayout staticLayout =
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* StaticLayoutBuilderCompat.obtain("Lorem Ipsum", new TextPaint(), 100)
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* .setAlignment(Alignment.ALIGN_NORMAL)
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* .build();
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* }</pre>
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*
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* @hide
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*/
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@RestrictTo(Scope.LIBRARY_GROUP)
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final class StaticLayoutBuilderCompat {
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private static final String TEXT_DIR_CLASS = "android.text.TextDirectionHeuristic";
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private static final String TEXT_DIRS_CLASS = "android.text.TextDirectionHeuristics";
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private static final String TEXT_DIR_FIRSTSTRONG_LTR = "FIRSTSTRONG_LTR";
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private static boolean initialized;
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@Nullable private static Constructor<StaticLayout> constructor;
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@Nullable private static Object textDirection;
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private final CharSequence source;
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private final TextPaint paint;
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private final int width;
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private int start;
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private int end;
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private Alignment alignment;
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private int maxLines;
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private boolean includePad;
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@Nullable private TextUtils.TruncateAt ellipsize;
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private StaticLayoutBuilderCompat(CharSequence source, TextPaint paint, int width) {
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this.source = source;
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this.paint = paint;
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this.width = width;
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this.start = 0;
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this.end = source.length();
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this.alignment = Alignment.ALIGN_NORMAL;
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this.maxLines = Integer.MAX_VALUE;
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this.includePad = true;
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this.ellipsize = null;
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}
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/**
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* Obtain a builder for constructing StaticLayout objects.
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*
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* @param source The text to be laid out, optionally with spans
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* @param paint The base paint used for layout
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* @param width The width in pixels
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* @return a builder object used for constructing the StaticLayout
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*/
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@NonNull
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public static StaticLayoutBuilderCompat obtain(
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@NonNull CharSequence source, @NonNull TextPaint paint, @IntRange(from = 0) int width) {
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return new StaticLayoutBuilderCompat(source, paint, width);
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}
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/**
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* Set the alignment. The default is {@link Layout.Alignment#ALIGN_NORMAL}.
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*
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* @param alignment Alignment for the resulting {@link StaticLayout}
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* @return this builder, useful for chaining
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*/
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@NonNull
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public StaticLayoutBuilderCompat setAlignment(@NonNull Alignment alignment) {
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this.alignment = alignment;
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return this;
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}
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/**
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* Set whether to include extra space beyond font ascent and descent (which is needed to avoid
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* clipping in some languages, such as Arabic and Kannada). The default is {@code true}.
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*
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* @param includePad whether to include padding
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* @return this builder, useful for chaining
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* @see android.widget.TextView#setIncludeFontPadding
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*/
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@NonNull
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public StaticLayoutBuilderCompat setIncludePad(boolean includePad) {
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this.includePad = includePad;
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return this;
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}
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/**
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* Set the index of the start of the text
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*
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* @return this builder, useful for chaining
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*/
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@NonNull
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public StaticLayoutBuilderCompat setStart(@IntRange(from = 0) int start) {
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this.start = start;
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return this;
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}
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/**
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* Set the index + 1 of the end of the text
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*
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* @return this builder, useful for chaining
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* @see android.widget.TextView#setIncludeFontPadding
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*/
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@NonNull
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public StaticLayoutBuilderCompat setEnd(@IntRange(from = 0) int end) {
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this.end = end;
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return this;
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}
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/**
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* Set maximum number of lines. This is particularly useful in the case of ellipsizing, where it
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* changes the layout of the last line. The default is unlimited.
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*
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* @param maxLines maximum number of lines in the layout
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* @return this builder, useful for chaining
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* @see android.widget.TextView#setMaxLines
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*/
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@NonNull
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public StaticLayoutBuilderCompat setMaxLines(@IntRange(from = 0) int maxLines) {
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this.maxLines = maxLines;
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return this;
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}
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/**
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* Set ellipsizing on the layout. Causes words that are longer than the view is wide, or exceeding
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* the number of lines (see #setMaxLines).
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*
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* @param ellipsize type of ellipsis behavior
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* @return this builder, useful for chaining
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* @see android.widget.TextView#setEllipsize
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*/
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@NonNull
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public StaticLayoutBuilderCompat setEllipsize(@Nullable TextUtils.TruncateAt ellipsize) {
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this.ellipsize = ellipsize;
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return this;
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}
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/** A method that allows to create a StaticLayout with maxLines on all supported API levels. */
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public StaticLayout build() throws StaticLayoutBuilderCompatException {
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if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
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// Marshmallow introduced StaticLayout.Builder which allows us not to use
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// the hidden constructor.
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StaticLayout.Builder builder = StaticLayout.Builder.obtain(source, start, end, paint, width);
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builder.setAlignment(alignment);
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builder.setIncludePad(includePad);
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if (ellipsize != null) {
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builder.setEllipsize(ellipsize);
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}
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builder.setMaxLines(maxLines);
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return builder.build();
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}
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createConstructorWithReflection();
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// Use the hidden constructor on older API levels.
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try {
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return checkNotNull(constructor)
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.newInstance(
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source,
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start,
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end,
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paint,
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width,
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alignment,
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checkNotNull(textDirection),
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1.0f,
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0.0f,
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includePad,
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ellipsize,
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width,
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maxLines);
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} catch (Exception cause) {
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throw new StaticLayoutBuilderCompatException(cause);
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}
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}
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/**
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* set constructor to this hidden {@link StaticLayout constructor.}
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*
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* <pre>{@code
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* StaticLayout(
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* CharSequence source,
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* int bufstart,
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* int bufend,
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* TextPaint paint,
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* int outerwidth,
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* Alignment align,
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* TextDirectionHeuristic textDir,
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* float spacingmult,
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* float spacingadd,
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* boolean includepad,
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* TextUtils.TruncateAt ellipsize,
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* int ellipsizedWidth,
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* int maxLines)
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* }</pre>
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*/
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private static void createConstructorWithReflection() throws StaticLayoutBuilderCompatException {
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if (initialized) {
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return;
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}
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try {
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final Class<?> textDirClass;
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if (Build.VERSION.SDK_INT >= VERSION_CODES.JELLY_BEAN_MR2) {
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textDirClass = TextDirectionHeuristic.class;
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textDirection = TextDirectionHeuristics.FIRSTSTRONG_LTR;
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} else {
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ClassLoader loader = StaticLayoutBuilderCompat.class.getClassLoader();
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textDirClass = loader.loadClass(TEXT_DIR_CLASS);
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Class<?> textDirsClass = loader.loadClass(TEXT_DIRS_CLASS);
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textDirection = textDirsClass.getField(TEXT_DIR_FIRSTSTRONG_LTR).get(textDirsClass);
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}
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final Class<?>[] signature =
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new Class<?>[] {
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CharSequence.class,
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int.class,
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int.class,
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TextPaint.class,
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int.class,
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Alignment.class,
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textDirClass,
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float.class,
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float.class,
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boolean.class,
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TextUtils.TruncateAt.class,
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int.class,
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int.class
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};
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constructor = StaticLayout.class.getDeclaredConstructor(signature);
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constructor.setAccessible(true);
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initialized = true;
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} catch (Exception cause) {
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throw new StaticLayoutBuilderCompatException(cause);
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}
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}
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static class StaticLayoutBuilderCompatException extends Exception {
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StaticLayoutBuilderCompatException(Throwable cause) {
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super("Error thrown initializing StaticLayout", cause);
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}
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}
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}

‎lib/javatests/com/google/android/material/internal/StaticLayoutBuilderCompatTest.java‎

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/*
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* Copyright (C) 2019 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.android.material.internal;
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import static android.os.Build.VERSION_CODES.LOLLIPOP;
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import static com.google.common.truth.Truth.assertThat;
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import android.os.Build.VERSION_CODES;
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import android.text.Layout.Alignment;
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import android.text.StaticLayout;
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import android.text.TextPaint;
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import android.text.TextUtils.TruncateAt;
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import org.junit.Test;
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import org.junit.runner.RunWith;
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import org.robolectric.RobolectricTestRunner;
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import org.robolectric.annotation.Config;
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/** Tests for {@link StaticLayoutBuilderCompat} */
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@RunWith(RobolectricTestRunner.class)
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public class StaticLayoutBuilderCompatTest {
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private static final String LONG_STRING =
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"Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Aenean commodo ligula eget dolor. "
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+ "Aenean massa. Cum sociis natoque penatibus et magnis dis parturient montes, nascetur "
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+ "ridiculus mus. Donec quam felis, ultricies nec, pellentesque eu, pretium quis, sem. "
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+ "Nulla consequat massa quis enim. Donec pede justo, fringilla vel, aliquet nec, "
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+ "vulputate eget, arcu. In enim justo, rhoncus ut, imperdiet a";
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@Config(minSdk = LOLLIPOP, maxSdk = VERSION_CODES.P)
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@Test
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public void createStaticLayout_withMaxLines_LongString() throws Exception {
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int maxLines = 3;
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StaticLayout staticLayout =
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StaticLayoutBuilderCompat.obtain(LONG_STRING, new TextPaint(), 100)
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.setAlignment(Alignment.ALIGN_NORMAL)
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.setIncludePad(true)
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.setEllipsize(TruncateAt.END)
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.setMaxLines(maxLines)
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.build();
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assertThat(staticLayout).isNotNull();
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}
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}

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