SurfaceView开发示波器<略>

最新推荐文章于 2024-12-17 02:44:11 发布

高锦湖

最新推荐文章于 2024-12-17 02:44:11 发布

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CC 4.0 BY-SA版权

本文链接：https://blog.youkuaiyun.com/blueshell001/article/details/51764090

本示例通过Android平台实现动态绘制正弦波和余弦波形，使用SurfaceView组件进行图形绘制，并通过按钮控制两种波形的切换。利用定时任务不断更新波形位置，实现了流畅的波形绘制效果。

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package com.test.tweenanimation;

import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Button;

import java.util.Timer;
import java.util.TimerTask;

public class ShowWaveActivity extends AppCompatActivity {
    private SurfaceHolder mHolder;
    Paint mPaint;
    int WIDTH = 800;
    int HEIGHT = 920;
    int X_OFFSET = 5;
    int cx = X_OFFSET;

    //实际y轴的位置
    int centerY = HEIGHT / 2;

    Timer mTimer = new Timer();
    TimerTask task = null;

    Button btnSin, btnCos;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_show_wave);

        SurfaceView surface = (SurfaceView) findViewById(R.id.surface);

        //初始化SurfaceHolder 对象
        mHolder = surface.getHolder();
        mPaint = new Paint();

        mPaint.setColor(Color.BLACK);
        mPaint.setStrokeWidth(30);

        btnSin = (Button) findViewById(R.id.btn_sin);
        btnCos = (Button) findViewById(R.id.btn_cos);

        View.OnClickListener listener = new View.OnClickListener() {
            @Override
            public void onClick(final View view) {
                drawBack(mHolder);
                cx = X_OFFSET;
                if (task != null) {
                    task.cancel();
                }
                task = new TimerTask() {
                    @Override
                    public void run() {
                        int cy = view.getId() == R.id.btn_sin ?
                                centerY - (int) (100 * Math.sin((cx - 5) * 2 * Math.PI / 150))
                                : centerY - (int) (100 * Math.cos((cx - 5) * 2 * Math.PI / 150));

                        Canvas canvas = mHolder.lockCanvas(new Rect(cx, cy - 2, cx + 2, cy + 2));
                        canvas.drawPoint(cx, cy, mPaint);
                        cx++;

                        if (cx > WIDTH) {
                            task.cancel();
                            task = null;
                        }
                        mHolder.unlockCanvasAndPost(canvas);

                    }
                };
                mTimer.schedule(task, 0, 30);
            }
        };
        btnSin.setOnClickListener(listener);
        btnCos.setOnClickListener(listener);

        mHolder.addCallback(new SurfaceHolder.Callback() {
            @Override
            public void surfaceCreated(SurfaceHolder holder) {

            }

            @Override
            public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
                drawBack(holder);
            }

            @Override
            public void surfaceDestroyed(SurfaceHolder holder) {
                mTimer.cancel();
            }
        });
    }

    private void drawBack(SurfaceHolder holder) {
        Canvas canvas = holder.lockCanvas();

        //绘制白色背景
        canvas.drawColor(Color.WHITE);

        Paint p = new Paint();
        p.setColor(Color.RED);

        p.setStrokeWidth(20);

        //绘制坐标
        canvas.drawLine(X_OFFSET, centerY, WIDTH, centerY, p);
        canvas.drawLine(X_OFFSET, 40, X_OFFSET, HEIGHT, p);

        holder.unlockCanvasAndPost(canvas);
        holder.lockCanvas(new Rect(0, 0, 0, 0));
        holder.unlockCanvasAndPost(canvas);
    }
}

布局文件

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

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:orientation="horizontal"
        >

        <Button
            android:id="@+id/btn_sin"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/sin"/>

        <Button
            android:id="@+id/btn_cos"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/cos"/>

    </LinearLayout>

    <SurfaceView
        android:id="@+id/surface"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>
</LinearLayout>