Lined EditText 底线消失答案

【问题标题】：Lined EditText bottom lines disappearsLined EditText 底线消失
【发布时间】：2021-03-03 13:28:18
【问题描述】：

我正在使用Lined EditText 在像记事本这样的安卓应用程序中显示垂直线。当我添加数据时，它会成功显示，但随着数据的增长，底线会消失。
我们将不胜感激。

代码：

    public class LinedEditText extends AppCompatEditText {

    private Rect mRect;
    private Paint mPaint;

    public LinedEditText(Context context, AttributeSet attrs) {
        super(context, attrs);
        mRect = new Rect();
        mPaint = new Paint();
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setColor(0xFF000000);
    }

    /**
     * This is called to draw the LinedEditText object
     *
     * @param canvas The canvas on which the background is drawn.
     */
    @Override
    protected void onDraw(Canvas canvas) {
        int height = canvas.getHeight();
        int curHeight = 0;
        Rect r = mRect;
        Paint paint = mPaint;
        int baseline = getLineBounds(0, r);
        for (curHeight = baseline + 1; curHeight < height;
             curHeight += getLineHeight()) {
            canvas.drawLine(r.left, curHeight, r.right, curHeight, paint);
        }
        super.onDraw(canvas);
    }
}

layout_file.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <com.g26app.LinedEditText
        android:id="@+id/note"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@android:color/transparent"
        android:gravity="top"
        android:textSize="22sp" />

</LinearLayout>

【问题讨论】：

标签： android android-layout android-edittext android-canvas

【解决方案1】：

这是你需要的基于max4ever的代码

@Override
protected void onDraw(Canvas canvas) {
    int height = getHeight();
    int line_height = getLineHeight();

    int count = height / line_height;

    if (getLineCount() > count)
        count = getLineCount();//for long text with scrolling

    Rect r = mRect;
    Paint paint = mPaint;
    int baseline = getLineBounds(0, r);//first line

    for (int i = 0; i < count; i++) {

        canvas.drawLine(r.left, baseline + 1, r.right, baseline + 1, paint);
        baseline += getLineHeight();//next line
    }

    super.onDraw(canvas);
}

【讨论】：

【解决方案2】：

我更新了LinedEditText 的onDraw，它工作正常：

public void onDraw(Canvas canvas) {
    int height = getHeight() / getLineHeight();
    if (getLineCount() > height) {
        height = getLineCount();
    }
    Rect rect = this.mRect;
    Paint paint = this.mPaint;
    int lineBounds = getLineBounds(0, rect);
    for (int i = 0; i < height; i++) {
        float f = (float) (lineBounds + 1);
        canvas.drawLine((float) rect.left, f, (float) rect.right, f, paint);
        lineBounds += getLineHeight();
    }
    super.onDraw(canvas);
}

【讨论】：