取消内部间距的 TextView

package com.alibaba.genie.panel.basic.widget;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Rect;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v7.widget.AppCompatTextView;
import android.util.AttributeSet;

/**
 * 取消内部间距的 TextView
 *
 * @author YouMingKun
 * @since 2023-08-07
 */
public final class NoPaddingTextView extends AppCompatTextView {

    public NoPaddingTextView(@NonNull Context context) {
        super(context);
    }

    public NoPaddingTextView(@NonNull Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }

    public NoPaddingTextView(@NonNull Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    private Rect minRect;

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        if (minRect == null) {
            // minRect 用来获取文字显示所需要最小区域的左上角和右下角坐标
            // 该坐标是以（0,0）为基准的矩形坐标
            minRect = new Rect();
        }
        getPaint().getTextBounds(getText().toString(), 0, getText().length(), minRect);
        final int width = minRect.width();
        final int height = minRect.height();
        // 这里不使用测量的 width 否则会导致 MaxEms 属性失效
        setMeasuredDimension(getMeasuredWidthAndState(), height);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        final String text = getText().toString();
        final int left = minRect.left;
        final int top = minRect.top;
        Paint paint = getPaint();
        paint.setColor(getCurrentTextColor());

        // 此时文字的基线在（0,0），要达到刚好包裹文字的效果，相当于把以(0,0)为基线的minRect 移动到合适的位置
        // x轴上由于左边内边距的存在，所以需要左移minRect.left距离
        // y轴上相当于把mingRect的顶点向下移动minRect.top距离
        canvas.drawText(text, -left, -top, paint);
    }
}