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Commit d170532c authored by Roozbeh Pournader's avatar Roozbeh Pournader
Browse files

Add tests for line breaking that considers overhangs 

This adds tests as well as a test font that has large overhangs for
some letters.

Bug: 63938206
Test: bit FrameworksCoreTests:android.text.LineBreakingOverhangsTest
Change-Id: I94c3c03419e525ec10b5158e476a94a9e319891d
parent 8cf1ffec

core/tests/coretests/assets/fonts/LineBreakingOverhangsTestFont.ttf

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core/tests/coretests/assets/fonts/LineBreakingOverhangsTestFont.ttx

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<?xml version="1.0" encoding="UTF-8"?>

<!-- Copyright (C) 2017 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.

-->

<ttFont sfntVersion="\x00\x01\x00\x00" ttLibVersion="3.9">



  <GlyphOrder>

    <!-- The 'id' attribute is only for humans; it is ignored when parsed. -->

    <GlyphID id="0" name=".notdef"/>

    <GlyphID id="1" name="space"/>

    <GlyphID id="2" name="R"/>

    <GlyphID id="3" name="a"/>

    <GlyphID id="4" name="y"/>

  </GlyphOrder>



  <head>

    <!-- Most of this table will be recalculated by the compiler -->

    <tableVersion value="1.0"/>

    <fontRevision value="1.0"/>

    <checkSumAdjustment value="0x26d0d624"/>

    <magicNumber value="0x5f0f3cf5"/>

    <flags value="00000000 00000011"/>

    <unitsPerEm value="1000"/>

    <created value="Tue Oct  3 23:00:00 2017"/>

    <modified value="Tue Oct  3 23:33:15 2017"/>

    <xMin value="-1500"/>

    <yMin value="0"/>

    <xMax value="5000"/>

    <yMax value="1000"/>

    <macStyle value="00000000 00000000"/>

    <lowestRecPPEM value="7"/>

    <fontDirectionHint value="2"/>

    <indexToLocFormat value="0"/>

    <glyphDataFormat value="0"/>

  </head>



  <hhea>

    <tableVersion value="0x00010000"/>

    <ascent value="1000"/>

    <descent value="-200"/>

    <lineGap value="0"/>

    <advanceWidthMax value="1000"/>

    <minLeftSideBearing value="-1500"/>

    <minRightSideBearing value="-4000"/>

    <xMaxExtent value="5000"/>

    <caretSlopeRise value="1"/>

    <caretSlopeRun value="0"/>

    <caretOffset value="0"/>

    <reserved0 value="0"/>

    <reserved1 value="0"/>

    <reserved2 value="0"/>

    <reserved3 value="0"/>

    <metricDataFormat value="0"/>

    <numberOfHMetrics value="1"/>

  </hhea>



  <maxp>

    <!-- Most of this table will be recalculated by the compiler -->

    <tableVersion value="0x10000"/>

    <numGlyphs value="5"/>

    <maxPoints value="4"/>

    <maxContours value="1"/>

    <maxCompositePoints value="0"/>

    <maxCompositeContours value="0"/>

    <maxZones value="0"/>

    <maxTwilightPoints value="0"/>

    <maxStorage value="0"/>

    <maxFunctionDefs value="0"/>

    <maxInstructionDefs value="0"/>

    <maxStackElements value="0"/>

    <maxSizeOfInstructions value="0"/>

    <maxComponentElements value="0"/>

    <maxComponentDepth value="0"/>

  </maxp>



  <OS_2>

    <!-- The fields 'usFirstCharIndex' and 'usLastCharIndex'

         will be recalculated by the compiler -->

    <version value="3"/>

    <xAvgCharWidth value="594"/>

    <usWeightClass value="400"/>

    <usWidthClass value="5"/>

    <fsType value="00000000 00001000"/>

    <ySubscriptXSize value="650"/>

    <ySubscriptYSize value="600"/>

    <ySubscriptXOffset value="0"/>

    <ySubscriptYOffset value="75"/>

    <ySuperscriptXSize value="650"/>

    <ySuperscriptYSize value="600"/>

    <ySuperscriptXOffset value="0"/>

    <ySuperscriptYOffset value="350"/>

    <yStrikeoutSize value="50"/>

    <yStrikeoutPosition value="300"/>

    <sFamilyClass value="0"/>

    <panose>

      <bFamilyType value="0"/>

      <bSerifStyle value="0"/>

      <bWeight value="5"/>

      <bProportion value="0"/>

      <bContrast value="0"/>

      <bStrokeVariation value="0"/>

      <bArmStyle value="0"/>

      <bLetterForm value="0"/>

      <bMidline value="0"/>

      <bXHeight value="0"/>

    </panose>

    <ulUnicodeRange1 value="00000000 00000000 00000000 00000001"/>

    <ulUnicodeRange2 value="00000000 00000000 00000000 00000000"/>

    <ulUnicodeRange3 value="00000000 00000000 00000000 00000000"/>

    <ulUnicodeRange4 value="00000000 00000000 00000000 00000000"/>

    <achVendID value="UKWN"/>

    <fsSelection value="00000000 01000000"/>

    <usFirstCharIndex value="32"/>

    <usLastCharIndex value="121"/>

    <sTypoAscender value="800"/>

    <sTypoDescender value="-200"/>

    <sTypoLineGap value="200"/>

    <usWinAscent value="1000"/>

    <usWinDescent value="200"/>

    <ulCodePageRange1 value="00000000 00000000 00000000 00000001"/>

    <ulCodePageRange2 value="00000000 00000000 00000000 00000000"/>

    <sxHeight value="500"/>

    <sCapHeight value="700"/>

    <usDefaultChar value="0"/>

    <usBreakChar value="32"/>

    <usMaxContext value="0"/>

  </OS_2>



  <hmtx>

    <mtx name=".notdef" width="1000" lsb="0"/>

    <mtx name="R" width="1000" lsb="0"/>

    <mtx name="a" width="1000" lsb="0"/>

    <mtx name="space" width="1000" lsb="0"/>

    <mtx name="y" width="1000" lsb="-1500"/>

  </hmtx>



  <cmap>

    <tableVersion version="0"/>

    <cmap_format_12 platformID="3" platEncID="10" format="12" reserved="0" length="64" language="0" nGroups="4">

      <map code="0x20" name="space"/><!-- SPACE -->

      <map code="0x52" name="R"/><!-- LATIN CAPITAL LETTER R -->

      <map code="0x61" name="a"/><!-- LATIN SMALL LETTER A -->

      <map code="0x79" name="y"/><!-- LATIN SMALL LETTER Y -->

    </cmap_format_12>

  </cmap>



  <loca>

    <!-- The 'loca' table will be calculated by the compiler -->

  </loca>



  <glyf>



    <!-- The xMin, yMin, xMax and yMax values

         will be recalculated by the compiler. -->



    <TTGlyph name=".notdef"/><!-- contains no outline data -->



    <TTGlyph name="R" xMin="0" yMin="0" xMax="5000" yMax="1000">

      <contour>

        <pt x="0" y="0" on="1"/>

        <pt x="0" y="1000" on="1"/>

        <pt x="5000" y="1000" on="1"/>

        <pt x="5000" y="0" on="1"/>

      </contour>

      <instructions/>

    </TTGlyph>



    <TTGlyph name="a"/><!-- contains no outline data -->



    <TTGlyph name="space"/><!-- contains no outline data -->



    <TTGlyph name="y" xMin="-1500" yMin="0" xMax="1000" yMax="1000">

      <contour>

        <pt x="-1500" y="0" on="1"/>

        <pt x="-1500" y="1000" on="1"/>

        <pt x="1000" y="1000" on="1"/>

        <pt x="1000" y="0" on="1"/>

      </contour>

      <instructions/>

    </TTGlyph>



  </glyf>



  <name>

    <namerecord nameID="1" platformID="1" platEncID="0" langID="0x0" unicode="True">

      Font for LineBreakingOverhangsTest

    </namerecord>

    <namerecord nameID="2" platformID="1" platEncID="0" langID="0x0" unicode="True">

      Regular

    </namerecord>

    <namerecord nameID="4" platformID="1" platEncID="0" langID="0x0" unicode="True">

      Font for LineBreakingOverhangsTest

    </namerecord>

    <namerecord nameID="6" platformID="1" platEncID="0" langID="0x0" unicode="True">

      SampleFont-Regular

    </namerecord>

    <namerecord nameID="1" platformID="3" platEncID="1" langID="0x409">

      Sample Font

    </namerecord>

    <namerecord nameID="2" platformID="3" platEncID="1" langID="0x409">

      Regular

    </namerecord>

    <namerecord nameID="4" platformID="3" platEncID="1" langID="0x409">

      Sample Font

    </namerecord>

    <namerecord nameID="6" platformID="3" platEncID="1" langID="0x409">

      SampleFont-Regular

    </namerecord>

  </name>



  <post>

    <formatType value="3.0"/>

    <italicAngle value="0.0"/>

    <underlinePosition value="-75"/>

    <underlineThickness value="50"/>

    <isFixedPitch value="0"/>

    <minMemType42 value="0"/>

    <maxMemType42 value="0"/>

    <minMemType1 value="0"/>

    <maxMemType1 value="0"/>

  </post>



</ttFont>

core/tests/coretests/src/android/text/LineBreakingOverhangsTest.java

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/*

 * Copyright (C) 2012 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 android.text;



import static org.junit.Assert.assertEquals;



import android.annotation.NonNull;

import android.annotation.Nullable;

import android.graphics.Typeface;

import android.support.test.InstrumentationRegistry;

import android.support.test.filters.SmallTest;

import android.support.test.runner.AndroidJUnit4;



import org.junit.Test;

import org.junit.runner.RunWith;



@SmallTest

@RunWith(AndroidJUnit4.class)

public class LineBreakingOverhangsTest {

    private static final int EM = 100;  // Make 1em == 100px.

    private static final TextPaint sTextPaint = new TextPaint();



    static {

        // The test font has following coverage and overhangs.

        // All the characters have a width of 1em.

        // space: no overhangs

        // R: 4em overhang on the right

        // a: no overhang

        // y: 1.5em overhang on the left

        sTextPaint.setTypeface(Typeface.createFromAsset(

                  InstrumentationRegistry.getTargetContext().getAssets(),

                  "fonts/LineBreakingOverhangsTestFont.ttf"));

        sTextPaint.setTextSize(EM);

    }



    private static void layout(@NonNull CharSequence source, @NonNull int[] breaks, double width,

            @Nullable int[] leftPadding, @Nullable int[] rightPadding) {

        layout(source, breaks, width, leftPadding, rightPadding, null /* indents */);

    }



    private static void layout(@NonNull CharSequence source, @NonNull int[] breaks, double width,

            @Nullable int[] leftPadding, @Nullable int[] rightPadding, @Nullable int[] indents) {

        final StaticLayout staticLayout = StaticLayout.Builder

                .obtain(source, 0, source.length(), sTextPaint, (int) width)

                .setAvailablePaddings(leftPadding, rightPadding)

                .setIndents(indents, indents)

                .build();



        final int lineCount = breaks.length + 1;

        assertEquals("Number of lines", lineCount, staticLayout.getLineCount());



        for (int line = 0; line < lineCount; line++) {

            final int lineStart = staticLayout.getLineStart(line);

            final int lineEnd = staticLayout.getLineEnd(line);



            if (line == 0) {

                assertEquals("Line start for first line", 0, lineStart);

            } else {

                assertEquals("Line start for line " + line, breaks[line - 1], lineStart);

            }



            if (line == lineCount - 1) {

                assertEquals("Line end for last line", source.length(), lineEnd);

            } else {

                assertEquals("Line end for line " + line, breaks[line], lineEnd);

            }

        }

    }



    private static final int[] NO_BREAK = new int[] {};



    private static final int[] NO_PADDING = null;

    // Maximum needed for left side of 'y'.

    private static final int[] FULL_LEFT_PADDING = new int[] {(int) (1.5 * EM)};

    // Maximum padding needed for right side of 'R'.

    private static final int[] FULL_RIGHT_PADDING = new int[] {4 * EM};



    private static final int[] ONE_EM_PADDING = new int[] {1 * EM};

    private static final int[] HALF_EM_PADDING = new int[] {(int) (0.5 * EM)};

    private static final int[] QUARTER_EM_PADDING = new int[] {(int) (0.25 * EM)};



    @Test

    public void testRightOverhang() {

        // The advance of "aaa R" is 5em, but the right-side overhang of 'R' would need 4em more, so

        // we break the line if there's not enough overhang.



        // Enough right padding, so the whole line fits in 5em.

        layout("aaa R", NO_BREAK, 5 * EM, NO_PADDING, FULL_RIGHT_PADDING);



        // No right padding, so we'd need 9em to fit the advance and the right padding of 'R'.

        layout("aaa R", new int[] {4}, 8.9 * EM, NO_PADDING, NO_PADDING);

        layout("aaa R", NO_BREAK, 9 * EM, NO_PADDING, NO_PADDING);



        // 1em of right padding means we can fit the string in 8em.

        layout("aaa R", new int[] {4}, 7.9 * EM, NO_PADDING, ONE_EM_PADDING);

        layout("aaa R", NO_BREAK, 8 * EM, NO_PADDING, ONE_EM_PADDING);

    }



    @Test

    public void testLeftOverhang() {

        // The advance of "y a" is 3em, but the left-side overhang of 'y' would need 1.5em more, so

        // we break the line if there's not enough overhang.



        // Enough left padding, so the whole line fits in 3em.

        layout("y a", NO_BREAK, 3 * EM, FULL_LEFT_PADDING, NO_PADDING);



        // No right padding, so we'd need 4.5em to fit the advance and the left padding of 'y'.

        layout("y a", new int[] {2}, 4.4 * EM, NO_PADDING, NO_PADDING);

        layout("y a", NO_BREAK, 4.5 * EM, NO_PADDING, NO_PADDING);



        // 1em of left padding means we can fit the string in 3.5em.

        layout("y a", new int[] {2}, 3.4 * EM, ONE_EM_PADDING, NO_PADDING);

        layout("y a", NO_BREAK, 3.5 * EM, ONE_EM_PADDING, NO_PADDING);

    }



    @Test

    public void testBothSidesOverhang() {

        // The advance of "y a R" is 5em, but the left-side overhang of 'y' would need 1.5em more,

        // and the right side overhang or 'R' would need 4em more, so we break the line if there's

        // not enough overhang.



        // Enough padding, so the whole line fits in 5em.

        layout("y a R", NO_BREAK, 5 * EM, FULL_LEFT_PADDING, FULL_RIGHT_PADDING);



        // No padding, so we'd need 10.5em to fit the advance and the paddings.

        layout("y a R", new int[] {4}, 10.4 * EM, NO_PADDING, NO_PADDING);

        layout("y a R", NO_BREAK, 10.5 * EM, NO_PADDING, NO_PADDING);



        // 1em of padding on each side means we can fit the string in 8.5em.

        layout("y a R", new int[] {4}, 8.4 * EM, ONE_EM_PADDING, ONE_EM_PADDING);

        layout("y a R", NO_BREAK, 8.5 * EM, ONE_EM_PADDING, ONE_EM_PADDING);

    }



    @Test

    public void testIndentsDontAffectPaddings() {

        // This is identical to the previous test, except that it applies wide indents of 4em on

        // each side and thus needs an extra 8em of width. This test makes sure that indents and

        // paddings are independent.

        final int[] indents = new int[] {4 * EM};

        final int indentAdj = 8 * EM;



        // Enough padding, so the whole line fits in 5em.

        layout("y a R", NO_BREAK, 5 * EM + indentAdj, FULL_LEFT_PADDING, FULL_RIGHT_PADDING,

                indents);



        // No padding, so we'd need 10.5em to fit the advance and the paddings.

        layout("y a R", new int[] {4}, 10.4 * EM + indentAdj, NO_PADDING, NO_PADDING, indents);

        layout("y a R", NO_BREAK, 10.5 * EM + indentAdj, NO_PADDING, NO_PADDING, indents);



        // 1em of padding on each side means we can fit the string in 8.5em.

        layout("y a R", new int[] {4}, 8.4 * EM + indentAdj, ONE_EM_PADDING, ONE_EM_PADDING,

                indents);

        layout("y a R", NO_BREAK, 8.5 * EM + indentAdj, ONE_EM_PADDING, ONE_EM_PADDING, indents);

    }

}