Artifact used: androidx.appcompat:appcompat:1.1.0-alpha04
Version used: 28
Theme used: Theme.AppCompat.Light.DarkActionBar
Devices/Android versions reproduced on: Emulator Nexus 5 API 28

We notice that, during targetSdkVersion 28, androidx.appcompat.widget.AppCompatEditText will tend to "slightly push down" the line after input, when non-English unicode (Like Chinese, Japanese, ...) is being entered.

Such behavior doesn't happen, when the code is targetSdkVersion 27 or below.

Use targetSdkVersion 27, run on emulator API 28
======================================

(Before input non-English unicode) - before-27.png
(After input non-English unicode) - after-27.png
(Confirm spacing is OK) - compare-27.png

Use targetSdkVersion 28, run on emulator API 28
======================================

(Before input non-English unicode) - before-28.png
(After input non-English unicode) - after-28.png
(Confirm spacing is problematic. Lines after input are being pushed down) - compare-28.png

This is the XML and code used by us. We inherit from `androidx.appcompat.widget.AppCompatEditText`, to paint the lines, to make the problem more obvious.

<com.yocto.wenote.note.LinedEditText
android:id="@+id/body_edit_text"
android:gravity="top"
android:paddingLeft="16dp"
android:paddingRight="16dp"
android:layout_marginBottom="12dp"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@android:color/transparent"
android:scrollbars="vertical"
android:textSize="18sp"
android:singleLine="false"
android:lineSpacingMultiplier="1.4"
android:inputType="textMultiLine|textCapSentences"
android:textCursorDrawable="?attr/shorterCursor" />

package com.yocto.wenote.note;

import android.content.Context;
import android.content.res.Resources;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.util.TypedValue;

import com.yocto.wenote.R;

/**
* Created by yccheok on 24/3/2018.
*/

public class LinedEditText extends androidx.appcompat.widget.AppCompatEditText {
private final Paint mPaint = new Paint();
private int noteLineColor;
private static final float DEFAULT_LINE_SPACING_EXTRA = 0.0f;
private static final float DEFAULT_LINE_SPACING_MULTIPLIER = 1.4f;

private void initResource() {
Context context = getContext();
TypedValue typedValue = new TypedValue();
Resources.Theme theme = context.getTheme();
theme.resolveAttribute(R.attr.noteLineColor, typedValue, true);
noteLineColor = typedValue.data;
}

public LinedEditText(Context context) {
super(context);
initResource();
initPaint();
}

public void setNoteLineColor(int noteLineColor) {
this.noteLineColor = noteLineColor;
}

public LinedEditText(Context context, AttributeSet attrs) {
super(context, attrs);
initResource();
initPaint();
}

public LinedEditText(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
initResource();
initPaint();
}

private void initPaint() {
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setColor(noteLineColor);
mPaint.setStrokeWidth(1);
}

@Override
protected void onDraw(Canvas canvas) {
int left = getLeft();
int right = getRight();
int paddingTop = getPaddingTop();
int paddingBottom = getPaddingBottom();
int paddingLeft = getPaddingLeft();
int paddingRight = getPaddingRight();
final int heightWithScrollY = getHeight() + getScrollY();
int lineHeight = getLineHeight();
int count = (heightWithScrollY-paddingTop-paddingBottom) / lineHeight;

mPaint.setColor(noteLineColor);
mPaint.setTypeface(this.getTypeface());

final float originalLineHeight;
if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.JELLY_BEAN) {
originalLineHeight = lineHeight / getLineSpacingMultiplier();
} else {
originalLineHeight = lineHeight / DEFAULT_LINE_SPACING_MULTIPLIER;
}

for (int i = 0; i < count; i++) {
float baseline = lineHeight * (i + 1) + paddingTop - mPaint.descent() - (lineHeight - originalLineHeight);
canvas.drawLine(
left + paddingLeft,
baseline,
right - paddingRight,
baseline,
mPaint
);
}

super.onDraw(canvas);
}

// https://stackoverflow.com/questions/49467579/workaround-for-edittext-ignoring-linespacingmultiplier
@Override
protected void onTextChanged(CharSequence text, int start, int lengthBefore, int lengthAfter) {
super.onTextChanged(text, start, lengthBefore, lengthAfter);

if (lengthBefore != lengthAfter) {
float add;
float mul;

if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.JELLY_BEAN) {
add = getLineSpacingExtra();
mul = getLineSpacingMultiplier();
} else {
add = DEFAULT_LINE_SPACING_EXTRA;
mul = DEFAULT_LINE_SPACING_MULTIPLIER;
}

setLineSpacing(0f, 1f);
setLineSpacing(add, mul);
}
}

}

Take note that, if you use `targetSdkVersion` 28, BUT run on emulator API 27, this problem will not occur too.

This issue also posted at https://stackoverflow.com/questions/55845977/incorrect-edittext-line-spacing-behavior-in-target-api-28-when-dealing-with-non

Thank you.

Issue 131284662

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