Transfer SmartLengthInputFilter license to Tusky (#1384)

* Transfer SmartLengthInputFilter in-header license

Transfer license for file "SmartLengthInputFilter.java" from me (Diego Rossi) to Tusky and therefore also change it from the original Apache 2.0 to currently GPLv3. This was a mistake that has been sitting around for way too long.

* Rewrite SmartLengthInputFilter from Java to Kotlin

This has been done by hand, without the custom copy-paste tool.

* Fix bad references in Java files using SmartLengthInputFilter features

* Shorten code in Java classes referencing SmartLengthInputFilter instance

* Refactor SmartLengthInputFilter from class to singleton Kotlin object

* Move hasBadRatio to become a toplevel function

* Patch up all the files affected by SmartLengthInputFilter changes

* Length in SmartLengthInputFilter is const 500, simplify code accordingly

* More meaningful name for toplevel function for checking trimming ability

* Add missing license header

app/src/main/java/com/keylesspalace/tusky/components/conversation/ConversationEntity.kt

@@ -22,7 +22,7 @@ import androidx.room.Entity
 import androidx.room.TypeConverters
 import com.keylesspalace.tusky.db.Converters
 import com.keylesspalace.tusky.entity.*
-import com.keylesspalace.tusky.util.SmartLengthInputFilter
+import com.keylesspalace.tusky.util.shouldTrimStatus
 import java.util.*
 
 @Entity(primaryKeys = ["id","accountId"])
@@ -176,7 +176,7 @@ fun Status.toEntity() =
                 spoilerText, attachments, mentions,
                 false,
                 false,
-                !SmartLengthInputFilter.hasBadRatio(content, SmartLengthInputFilter.LENGTH_DEFAULT),
+                !shouldTrimStatus(content),
                 true,
                 poll
         )

app/src/main/java/com/keylesspalace/tusky/fragment/ViewThreadFragment.java

@@ -48,7 +48,7 @@ import com.keylesspalace.tusky.interfaces.StatusActionListener;
 import com.keylesspalace.tusky.network.MastodonApi;
 import com.keylesspalace.tusky.util.ListStatusAccessibilityDelegate;
 import com.keylesspalace.tusky.util.PairedList;
-import com.keylesspalace.tusky.util.SmartLengthInputFilter;
+import com.keylesspalace.tusky.util.SmartLengthInputFilterKt;
 import com.keylesspalace.tusky.util.ThemeUtils;
 import com.keylesspalace.tusky.util.ViewDataUtils;
 import com.keylesspalace.tusky.view.ConversationLineItemDecoration;
@@ -360,10 +360,7 @@ public final class ViewThreadFragment extends SFragment implements
         }
 
         StatusViewData.Concrete updatedStatus = new StatusViewData.Builder(status)
-                .setCollapsible(!SmartLengthInputFilter.hasBadRatio(
+                .setCollapsible(!SmartLengthInputFilterKt.shouldTrimStatus(status.getContent()))
-                        status.getContent(),
-                        SmartLengthInputFilter.LENGTH_DEFAULT
-                ))
                 .setCollapsed(isCollapsed)
                 .createStatusViewData();
         statuses.setPairedItem(position, updatedStatus);

app/src/main/java/com/keylesspalace/tusky/util/SmartLengthInputFilter.java

@@ -1,154 +0,0 @@
-/*
- * Copyright 2018 Diego Rossi (@_HellPie)
- *
- * 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.keylesspalace.tusky.util;
-
-import android.text.InputFilter;
-import android.text.SpannableStringBuilder;
-import android.text.Spanned;
-
-/**
- * A customized version of {@link android.text.InputFilter.LengthFilter} which allows smarter
- * constraints and adds better visuals such as:
- * <ul>
- *     <li>Ellipsis at the end of the constrained text to show continuation.</li>
- *     <li>Trimming of invisible characters (new lines, spaces, etc.) from the constrained text.</li>
- *     <li>Constraints end at the end of the last "word", before a whitespace.</li>
- *     <li>Expansion of the limit by up to 10 characters to facilitate the previous constraint.</li>
- *     <li>Constraints are not applied if the percentage of hidden content is too small.</li>
- * </ul>
- *
- * Some of these features are configurable through at instancing time.
- */
-public class SmartLengthInputFilter implements InputFilter {
-
-    /**
-     * Defines how many characters to extend beyond the limit to cut at the end of the word on the
-     * boundary of it rather than cutting at the word preceding that one.
-     */
-    private static final int RUNWAY = 10;
-
-    /**
-     * Default for maximum status length on Mastodon and default collapsing length on Pleroma.
-     */
-    public static final int LENGTH_DEFAULT = 500;
-
-    /**
-     * Stores a reusable singleton instance of a {@link SmartLengthInputFilter} already configured
-     * to the default maximum length of {@value #LENGTH_DEFAULT}.
-     */
-    public static final SmartLengthInputFilter INSTANCE = new SmartLengthInputFilter(LENGTH_DEFAULT);
-
-    private final int max;
-    private final boolean allowRunway;
-    private final boolean skipIfBadRatio;
-
-    /**
-     * Creates a new {@link SmartLengthInputFilter} instance with a predefined maximum length and
-     * all the smart constraint features this class supports.
-     *
-     * @param max The maximum length before trimming. May change based on other constraints.
-     */
-    public SmartLengthInputFilter(int max) {
-        this(max, true, true);
-    }
-
-    /**
-     * Fully configures a new {@link SmartLengthInputFilter} to fine tune the state of the supported
-     * smart constraints this class supports.
-     *
-     * @param max            The maximum length before trimming.
-     * @param allowRunway    Whether to extend {@param max} by an extra 10 characters
-     *                       and trim precisely at the end of the closest word.
-     * @param skipIfBadRatio Whether to skip trimming entirely if the trimmed content
-     *                       will be less than 25% of the shown content.
-     */
-    public SmartLengthInputFilter(int max, boolean allowRunway, boolean skipIfBadRatio) {
-        this.max = max;
-        this.allowRunway = allowRunway;
-        this.skipIfBadRatio = skipIfBadRatio;
-    }
-
-    /**
-     * Calculates if it's worth trimming the message at a specific limit or if the content that will
-     * be hidden will not be enough to justify the operation.
-     *
-     * @param message The message to trim.
-     * @param limit   The maximum length after trimming.
-     * @return        Whether the message should be trimmed or not.
-     */
-    public static boolean hasBadRatio(Spanned message, int limit) {
-        return (double) limit / message.length() > 0.75;
-    }
-
-    /** {@inheritDoc} */
-    @Override
-    public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
-        // Code originally imported from InputFilter.LengthFilter but heavily customized.
-        // https://android.googlesource.com/platform/frameworks/base/+/master/core/java/android/text/InputFilter.java#175
-
-        int sourceLength = source.length();
-        int keep = max - (dest.length() - (dend - dstart));
-        if (keep <= 0) return "";
-        if (keep >= end - start) return null; // keep original
-
-        keep += start;
-
-        // Enable skipping trimming if the ratio is not good enough
-        if (skipIfBadRatio && (double)keep / sourceLength > 0.75)
-            return null;
-
-        // Enable trimming at the end of the closest word if possible
-        if (allowRunway && Character.isLetterOrDigit(source.charAt(keep))) {
-            int boundary;
-
-            // Android N+ offer a clone of the ICU APIs in Java for better internationalization and
-            // unicode support. Using the ICU version of BreakIterator grants better support for
-            // those without having to add the ICU4J library at a minimum Api trade-off.
-            if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.N) {
-                android.icu.text.BreakIterator iterator = android.icu.text.BreakIterator.getWordInstance();
-                iterator.setText(source.toString());
-                boundary = iterator.following(keep);
-                if (keep - boundary > RUNWAY) boundary = iterator.preceding(keep);
-            } else {
-                java.text.BreakIterator iterator = java.text.BreakIterator.getWordInstance();
-                iterator.setText(source.toString());
-                boundary = iterator.following(keep);
-                if (keep - boundary > RUNWAY) boundary = iterator.preceding(keep);
-            }
-
-            keep = boundary;
-        } else {
-
-            // If no runway is allowed simply remove whitespaces if present
-            while (Character.isWhitespace(source.charAt(keep - 1))) {
-                --keep;
-                if (keep == start) return "";
-            }
-        }
-
-        if (Character.isHighSurrogate(source.charAt(keep - 1))) {
-            --keep;
-            if (keep == start) return "";
-        }
-
-        if (source instanceof Spanned) {
-            return new SpannableStringBuilder(source, start, keep).append("…");
-        } else {
-            return source.subSequence(start, keep) + "…";
-        }
-    }
-}

app/src/main/java/com/keylesspalace/tusky/util/SmartLengthInputFilter.kt

@@ -0,0 +1,111 @@
+/* Copyright 2019 Tusky contributors
+ *
+ * This file is a part of Tusky.
+ *
+ * This program is free software; you can redistribute it and/or modify it under the terms of the
+ * GNU General Public License as published by the Free Software Foundation; either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * Tusky is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
+ * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+ * Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with Tusky; if not,
+ * see <http://www.gnu.org/licenses>. */
+
+package com.keylesspalace.tusky.util
+
+import android.text.InputFilter
+import android.text.SpannableStringBuilder
+import android.text.Spanned
+
+/**
+ * Defines how many characters to extend beyond the limit to cut at the end of the word on the
+ * boundary of it rather than cutting at the word preceding that one.
+ */
+private const val RUNWAY = 10
+
+/**
+ * Default for maximum status length on Mastodon and default collapsing length on Pleroma.
+ */
+private const val LENGTH_DEFAULT = 500
+
+/**
+ * Calculates if it's worth trimming the message at a specific limit or if the content that will
+ * be hidden will not be enough to justify the operation.
+ *
+ * @param message The message to trim.
+ * @return        Whether the message should be trimmed or not.
+ */
+fun shouldTrimStatus(message: Spanned): Boolean {
+	return LENGTH_DEFAULT / message.length > 0.75
+}
+
+/**
+ * A customized version of {@link android.text.InputFilter.LengthFilter} which allows smarter
+ * constraints and adds better visuals such as:
+ * <ul>
+ *     <li>Ellipsis at the end of the constrained text to show continuation.</li>
+ *     <li>Trimming of invisible characters (new lines, spaces, etc.) from the constrained text.</li>
+ *     <li>Constraints end at the end of the last "word", before a whitespace.</li>
+ *     <li>Expansion of the limit by up to 10 characters to facilitate the previous constraint.</li>
+ *     <li>Constraints are not applied if the percentage of hidden content is too small.</li>
+ * </ul>
+ */
+object SmartLengthInputFilter : InputFilter {
+	/** {@inheritDoc} */
+	override fun filter(source: CharSequence, start: Int, end: Int, dest: Spanned, dstart: Int, dend: Int): CharSequence? {
+		// Code originally imported from InputFilter.LengthFilter but heavily customized and converted to Kotlin.
+		// https://android.googlesource.com/platform/frameworks/base/+/master/core/java/android/text/InputFilter.java#175
+
+		val sourceLength = source.length
+		var keep = LENGTH_DEFAULT - dest.length - dend - dstart
+		if (keep <= 0) return ""
+		if (keep >= end - start) return null // Keep original
+
+		keep += start
+
+		// Skip trimming if the ratio doesn't warrant it
+		if (keep.toDouble() / sourceLength > 0.75) return null
+
+		// Enable trimming at the end of the closest word if possible
+		if (source[keep].isLetterOrDigit()) {
+			var boundary: Int
+
+			// Android N+ offer a clone of the ICU APIs in Java for better internationalization and
+			// unicode support. Using the ICU version of BreakIterator grants better support for
+			// those without having to add the ICU4J library at a minimum Api trade-off.
+			if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.N) {
+				val iterator = android.icu.text.BreakIterator.getWordInstance()
+				iterator.setText(source.toString())
+				boundary = iterator.following(keep)
+				if (keep - boundary > RUNWAY) boundary = iterator.preceding(keep)
+			} else {
+				val iterator = java.text.BreakIterator.getWordInstance()
+				iterator.setText(source.toString())
+				boundary = iterator.following(keep)
+				if (keep - boundary > RUNWAY) boundary = iterator.preceding(keep)
+			}
+
+			keep = boundary
+		} else {
+
+			// If no runway is allowed simply remove whitespaces if present
+			while(source[keep - 1].isWhitespace()) {
+				--keep
+				if (keep == start) return ""
+			}
+		}
+
+		if (source[keep - 1].isHighSurrogate()) {
+			--keep
+			if (keep == start) return ""
+		}
+
+		return if (source is Spanned) {
+			SpannableStringBuilder(source, start, keep).append("…")
+		} else {
+			"${source.subSequence(start, keep)}…"
+		}
+	}
+}

app/src/main/java/com/keylesspalace/tusky/util/StatusExtensions.kt

@@ -18,6 +18,6 @@ package com.keylesspalace.tusky.util
 import com.keylesspalace.tusky.entity.Status
 
 fun Status.isCollapsible(): Boolean {
-    return !SmartLengthInputFilter.hasBadRatio(content, SmartLengthInputFilter.LENGTH_DEFAULT)
+    return !shouldTrimStatus(content)
 }
 

app/src/main/java/com/keylesspalace/tusky/util/StatusViewHelper.kt

@@ -310,7 +310,7 @@ class StatusViewHelper(private val itemView: View) {
     }
 
     companion object {
-        val COLLAPSE_INPUT_FILTER = arrayOf<InputFilter>(SmartLengthInputFilter.INSTANCE)
+        val COLLAPSE_INPUT_FILTER = arrayOf<InputFilter>(SmartLengthInputFilter)
         val NO_INPUT_FILTER = arrayOfNulls<InputFilter>(0)
     }
 }

app/src/main/java/com/keylesspalace/tusky/util/ViewDataUtils.java

@@ -58,10 +58,7 @@ public final class ViewDataUtils {
                 .setApplication(visibleStatus.getApplication())
                 .setStatusEmojis(visibleStatus.getEmojis())
                 .setAccountEmojis(visibleStatus.getAccount().getEmojis())
-                .setCollapsible(!SmartLengthInputFilter.hasBadRatio(
+                .setCollapsible(!SmartLengthInputFilterKt.shouldTrimStatus(visibleStatus.getContent()))
-                        visibleStatus.getContent(),
-                        SmartLengthInputFilter.LENGTH_DEFAULT
-                ))
                 .setCollapsed(true)
                 .setPoll(visibleStatus.getPoll())
                 .setCard(visibleStatus.getCard())