Java代码 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(); } } } Java代码 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); } }
//原文地址：http://www.cnblogs.com/top5/archive/2012/04/09/2439626.html