View实现涂鸦、撤销以及重做功能

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.Bitmap.CompressFormat;
import android.os.Environment;
import android.view.MotionEvent;
import android.view.View;

/**
 * View实现涂鸦、撤销以及重做功能
 */

public class TuyaView extends View {

    private Bitmap mBitmap;
    private Canvas mCanvas;
    private Path mPath;
    private Paint mBitmapPaint;// 画布的画笔
    private Paint mPaint;// 真实的画笔
    private float mX, mY;// 临时点坐标
    private static final float TOUCH_TOLERANCE = 4;

    // 保存Path路径的集合,用List集合来模拟栈
    private static List<DrawPath> savePath;
    // 记录Path路径的对象
    private DrawPath dp;

    private int screenWidth, screenHeight;

    private class DrawPath {
        public Path path;// 路径
        public Paint paint;// 画笔
    }

    public TuyaView(Context context, int w, int h) {
        super(context);
        screenWidth = w;
        screenHeight = h;

        mBitmap = Bitmap.createBitmap(screenWidth, screenHeight, Bitmap.Config.ARGB_8888);
        // 保存一次一次绘制出来的图形
        mCanvas = new Canvas(mBitmap);

        mBitmapPaint = new Paint(Paint.DITHER_FLAG);
        mPaint = new Paint();
        mPaint.setAntiAlias(true);
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setStrokeJoin(Paint.Join.ROUND);// 设置外边缘
        mPaint.setStrokeCap(Paint.Cap.ROUND);// 形状
        mPaint.setStrokeWidth(5);// 画笔宽度

        savePath = new ArrayList<DrawPath>();
    }

    @Override
    public void onDraw(Canvas canvas) {
        canvas.drawColor(0xFFAAAAAA);
        // 将前面已经画过得显示出来
        canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);
        if (mPath != null) {
            // 实时的显示
            canvas.drawPath(mPath, mPaint);
        }
    }

    private void touch_start(float x, float y) {
        mPath.moveTo(x, y);
        mX = x;
        mY = y;
    }

    private void touch_move(float x, float y) {
        float dx = Math.abs(x - mX);
        float dy = Math.abs(mY - y);
        if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
            // 从x1,y1到x2,y2画一条贝塞尔曲线，更平滑(直接用mPath.lineTo也是可以的)
            mPath.quadTo(mX, mY, (x + mX) / 2, (y + mY) / 2);
            mX = x;
            mY = y;
        }
    }

    private void touch_up() {
        mPath.lineTo(mX, mY);
        mCanvas.drawPath(mPath, mPaint);
        //将一条完整的路径保存下来(相当于入栈操作)
        savePath.add(dp);
        mPath = null;// 重新置空
    }
    /**
     * 撤销的核心思想就是将画布清空，
     * 将保存下来的Path路径最后一个移除掉，
     * 重新将路径画在画布上面。
     */
    public void undo() {
        if (savePath != null && savePath.size() > 0) {
            savePath.remove(savePath.size() - 1);
            redrawOnBitmap();
        }
    }
    /**
     * 重做
     */
    public void redo(){
        if (savePath != null && savePath.size() > 0) {
            savePath.clear();
            redrawOnBitmap();
        }
    }

    private void redrawOnBitmap(){
        mBitmap = Bitmap.createBitmap(screenWidth, screenHeight,
                Bitmap.Config.ARGB_8888);
        mCanvas.setBitmap(mBitmap);// 重新设置画布，相当于清空画布
        Iterator<DrawPath> iter = savePath.iterator();
        while (iter.hasNext()) {
            DrawPath drawPath = iter.next();
            mCanvas.drawPath(drawPath.path, drawPath.paint);
        }
        invalidate();// 刷新
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        float x = event.getX();
        float y = event.getY();

        switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN:
            // 每次down下去重新new一个Path
            mPath = new Path();
            //每一次记录的路径对象是不一样的
            dp = new DrawPath();
            dp.path = mPath;
            dp.paint = mPaint;
            touch_start(x, y);
            invalidate();
            break;
        case MotionEvent.ACTION_MOVE:
            touch_move(x, y);
            invalidate();
            break;
        case MotionEvent.ACTION_UP:
            touch_up();
            invalidate();
            break;
        }
        return true;
    }

    public void saveToSDCard(){
        String fileUrl = Environment.getExternalStorageDirectory()
                .toString() + "/android/data/test.png";
        try {
            FileOutputStream fos = new FileOutputStream(new File(fileUrl));
            mBitmap.compress(CompressFormat.PNG, 100, fos);
            fos.flush();
            fos.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

import android.app.Activity;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.KeyEvent;

public class TuyaActivity extends Activity {

    private TuyaView tuyaView = null;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        DisplayMetrics dm = new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(dm);

        tuyaView = new TuyaView(this, dm.widthPixels, dm.heightPixels);
        setContentView(tuyaView);
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_BACK) {// 返回键
            tuyaView.undo();
            return true;
        }else if(keyCode == KeyEvent.KEYCODE_MENU){//MENU
            tuyaView.redo();
            return true;
        }
        return super.onKeyDown(keyCode, event);
    }

}

 

• Tuya.rar (234.4 KB)
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• 描述: 附送一个画图软件
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