AndroidStudio：设计一个能在图片上涂鸦的程序

一内容：设计一个能在图片上涂鸦的程序

二实现

①布局文件activity_main.xml

②主控文件MainActivity.java

package com.example.asus.test442;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {
    private HandWrite handWrite = null;
    Button clear = null;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        handWrite = (HandWrite)findViewById(R.id.hw); //关联view组件
        clear = (Button)findViewById(R.id.btn);
        clear.setOnClickListener(new click());
    }

    private class click implements View.OnClickListener {
        @Override
        public void onClick(View view) {
            handWrite.clear();
        }
    }
}

3记录在屏幕上滑动的轨迹，实现在图片上涂鸦的功能 HandWrite.java

package com.example.asus.test442;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

public class HandWrite extends View {
    Paint paint = null;  //定义画笔
    Bitmap origBit = null;  //存放原始图像
    Bitmap new_1Bit = null;   //存放从原始图像复制的位图图像
    Bitmap new_2Bit = null;      //存放处理后的图像
    float startX = 0,startY = 0;   //画线的起点坐标
    float clickX = 0, clickY = 0;   //画线的终点坐标
    boolean isMove = true;   //设置是否画线的标记
    boolean isClear = false;    //设置是否清除涂鸦的标记
    int color = Color.BLUE;    //设置画笔的颜色
    float strokeWidth = 2.0f;    //设置画笔的宽度
    public HandWrite(Context context, AttributeSet attrs) {
        super(context, attrs);
        // 从资源中获取原始图像
        origBit = BitmapFactory.decodeResource(getResources(),R.drawable.p1).copy(Bitmap.Config.ARGB_8888,true);
        // 建立原始图像的位图
        new_1Bit = Bitmap.createBitmap(origBit);
    }

    // 清除涂鸦
    public void clear() {
        isClear = true;
        new_2Bit = Bitmap.createBitmap(origBit);
        invalidate();
    }

    public void setSyle(float strokeWidth) {
        this.strokeWidth = strokeWidth;
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawBitmap(HandWriting(new_1Bit),0,0,null);
    }

    private Bitmap HandWriting(Bitmap newBit) {  //记录绘制图形
        Canvas canvas = null;  // 定义画布
        if (isClear) {  // 创建绘制新图形的画布
            canvas = new Canvas(new_2Bit);
        }
        else {
            canvas = new Canvas(newBit);  //创建绘制原图形的画布
        }

        paint = new Paint();
        paint.setStyle(Paint.Style.STROKE);
        paint.setAntiAlias(true);
        paint.setColor(color);
        paint.setStrokeWidth(strokeWidth);

        if (isMove){
            canvas.drawLine(startX,startY,clickX,clickY,paint);  // 在画布上画线条
        }
        startX = clickX;
        startY = clickY;

        if (isClear){
            return new_2Bit;  // 返回新绘制的图像
        }
        return newBit;  // 若清屏，则返回原图像
    }

    // 定义触摸屏事件
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        clickX = event.getX();  // 获取触摸坐标位置
        clickY = event.getY();
        if (event.getAction() == MotionEvent.ACTION_DOWN) {  // 按下屏幕时无绘图
            isMove = false;
            invalidate();
            return true;
        } else if (event.getAction() == MotionEvent.ACTION_MOVE) {  // 记录在屏幕上划动的轨迹
            isMove = true;
            invalidate();
            return true;
        }
        return super.onTouchEvent(event);
    }
}

三效果