个人练习代码库/自制TextView

最新推荐文章于 2024-03-30 09:47:51 发布

原创最新推荐文章于 2024-03-30 09:47:51 发布 · 265 阅读

0 ·

CC 4.0 BY-SA版权

代码库（个人练习）专栏收录该内容

19 篇文章

订阅专栏

本文介绍了一种自定义Android TextView的方法，通过实现MyTextView类，使用LinearGradient为文本背景添加渐变效果，并通过Matrix实现渐变动画。文章展示了如何设置不同颜色的矩形背景以及如何在绘制时进行坐标平移来显示文本。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.LinearGradient;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Shader;
import android.support.annotation.Nullable;
import android.support.v4.content.ContextCompat;
import android.support.v7.widget.AppCompatTextView;
import android.util.AttributeSet;

/**
 * Created by YRC on 2017/4/18.
 */

public class MyTextView extends AppCompatTextView {
    private int mViewWidth;
    private Paint mPaint1=new Paint(),mPaint2=new Paint();
    private Matrix mGradientMatrix;
    private int mTranslate=0;
    private LinearGradient mLinearGradient;



    public MyTextView(Context context) {
        super(context);
    }

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

    public MyTextView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);


    }
    @Override
    protected void onDraw(Canvas canvas) {
        mPaint1.setColor(ContextCompat.getColor(getContext(),R.color.holo_blue_light));
        mPaint1.setStyle(Paint.Style.FILL);
        mPaint2.setColor(Color.YELLOW);
        mPaint2.setStyle(Paint.Style.FILL);
        //绘制外层矩形
        canvas.drawRect(0,0,getMeasuredWidth(),getMeasuredHeight(),mPaint1);
        //绘制内层矩形
        canvas.drawRect(10,10,getMeasuredWidth()-10,getMeasuredHeight()-10,mPaint2);
        canvas.save();
        //绘制文字前平移10像素
        canvas.translate(10,0);
        super.onDraw(canvas);
        //用于从上次保存调用后删除对矩阵/剪辑状态的所有修改
        canvas.restore();

        if (mGradientMatrix!=null){
            mTranslate+= mViewWidth / 5;
            if (mTranslate>2*mViewWidth){
                mTranslate=-mViewWidth;
            }
            mGradientMatrix.setTranslate(mTranslate,0);
            mLinearGradient.setLocalMatrix(mGradientMatrix);
            postInvalidateDelayed(100);
        }

    }


    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        if (mViewWidth==0){
            mViewWidth=getMeasuredWidth();
            if (mViewWidth>0){
                Paint mPaint=getPaint();
                mLinearGradient=new LinearGradient(0,0,mViewWidth,0,new int[]{
                        Color.BLUE,0xffffffff,Color.BLUE
                },null, Shader.TileMode.CLAMP);
                mPaint.setShader(mLinearGradient);
                mGradientMatrix=new Matrix();
            }
        }
    }
}