Android App开发手机阅读中贝塞尔曲线的原理讲解及实现波浪起伏动画实战（附源码和演示视频 可直接使用）

package com.example.ebook;
import androidx.annotation.RequiresApi;
import androidx.appcompat.app.AppCompatActivity;
import android.graphics.ImageDecoder;
import android.graphics.drawable.Animatable;
import android.graphics.drawable.Drawable;
import android.os.Build;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.Spinner;
@RequiresApi(api = Build.VERSION_CODES.P)
public class BezierCurveActivity extends AppCompatActivity {
    private ImageView iv_curve; // 声明一个图像视图对象
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_bezier_curve);
        iv_curve = findViewById(R.id.iv_curve);
        initCurveSpinner(); // 初始化曲线类型下拉框
    }
    private String[] mCurveArray = {"一次贝塞尔曲线", "二次贝塞尔曲线", "三次贝塞尔曲线" };
    private int[] mDrawableArray = {R.drawable.bezier_first_order, R.drawable.bezier_second_order, R.drawable.bezier_third_order };
    // 初始化曲线类型下拉框
    private void initCurveSpinner() {
        ArrayAdapter<String> curveAdapter = new ArrayAdapter<>(this,
                R.layout.item_select, mCurveArray);
        Spinner sp_curve = findViewById(R.id.sp_curve);
        sp_curve.setPrompt("请选择曲线类型");
        sp_curve.setAdapter(curveAdapter);
        sp_curve.setOnItemSelectedListener(new CurveSelectedListener());
        sp_curve.setSelection(0);
    }
    private class CurveSelectedListener implements AdapterView.OnItemSelectedListener {
        public void onItemSelected(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
            showBezierCurve(arg2); // 显示贝塞尔曲线的演示动图
        }
        public void onNothingSelected(AdapterView<?> arg0) {}
    }
    // 显示贝塞尔曲线的演示动图
    private void showBezierCurve(int order) {
        int drawableId = mDrawableArray[order];
        try {
            // 利用Android 9.0新增的ImageDecoder读取图片
            ImageDecoder.Source source = ImageDecoder.createSource(getResources(), drawableId);
            // 从数据源解码得到图形信息
            Drawable drawable = ImageDecoder.decodeDrawable(source);
            iv_curve.setImageDrawable(drawable); // 设置图像视图的图形对象
            if (drawable instanceof Animatable) { // 如果是动画图形，则开始播放动画
                ((Animatable) iv_curve.getDrawable()).start();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="40dp">
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:paddingLeft="5dp"
            android:gravity="center"
            android:text="请选择曲线类型"
            android:textColor="@color/black"
            android:textSize="17sp" />
        <Spinner
            android:id="@+id/sp_curve"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:gravity="center"
            android:spinnerMode="dialog" />
    </LinearLayout>
    <ImageView
        android:id="@+id/iv_curve"
        android:layout_width="match_parent"
        android:layout_height="150dp" />
</LinearLayout>

package com.example.ebook;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import androidx.appcompat.app.AppCompatActivity;
import com.example.ebook.widget.WaveView;
public class BezierWaveActivity extends AppCompatActivity {
    private Button btn_start;
    private WaveView wv_wave; // 声明一个波浪视图对象
    private boolean isPlaying = false; // 是否正在播放动画
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_bezier_wave);
        wv_wave = findViewById(R.id.wv_wave);
        btn_start = findViewById(R.id.btn_start);
        btn_start.setOnClickListener(v -> {
            if (!isPlaying) {
                wv_wave.startAnim(); // 开始播放波浪动画
            } else {
                wv_wave.stopAnim(); // 停止播放波浪动画
            }
            isPlaying = !isPlaying;
            btn_start.setText(isPlaying?"停止播放动画":"开始播放动画");
        });
    }
}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <Button
        android:id="@+id/btn_start"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="开始播放动画"
        android:textColor="@color/black"
        android:textSize="17sp" />
    <com.example.ebook.widget.WaveView
        android:id="@+id/wv_wave"
        android:layout_width="match_parent"
        android:layout_height="120dp" />
</LinearLayout>