android代码绘制函数,android – 如何在canvas画面中实现UNDO函数后更改绘制颜色/笔触...

在我的Paint App中,我实现了UNDO功能,并且工作正常.但是如果更改了画笔颜色(或)画笔描边,那么我以前绘制的所有路径都会更改为新的颜色.代码如下：

public class CustomView extends View implements OnTouchListener {

public Canvas mCanvas;

private Path mPath;

public Paint mPaint, mBitmapPaint;

Bitmap mBitmap;

Canvas canvas;

public ArrayList paths = new ArrayList();

public ArrayList undonePaths = new ArrayList();

private Bitmap im;

public CustomView(Context context) {

super(context);

setFocusable(true);

setFocusableInTouchMode(true);

setOnTouchListener(this);

mPaint = new Paint();

mPaint.setAntiAlias(true);

mPaint.setDither(true);

mPaint.setColor(0xFFFFFFFF);

mPaint.setStyle(Paint.Style.STROKE);

mPaint.setStrokeJoin(Paint.Join.ROUND);

mPaint.setStrokeCap(Paint.Cap.ROUND);

mPaint.setStrokeWidth(6);

mCanvas = new Canvas();

mPath = new Path();

im = BitmapFactory.decodeResource(context.getResources(), R.drawable.ic_launcher);

DisplayMetrics metrics = getContext().getResources().getDisplayMetrics();

int w = metrics.widthPixels;

int h = metrics.heightPixels;

mBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);

mBitmapPaint = new Paint(Paint.DITHER_FLAG);

// mBitmapPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC));

}

@Override

protected void onSizeChanged(int w, int h, int oldw, int oldh) {

super.onSizeChanged(w, h, oldw, oldh);

}

@Override

protected void onDraw(Canvas canvas) {

// mPath = new Path();

// canvas.drawPath(mPath, mPaint);

canvas.drawColor(Color.TRANSPARENT);

canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);

for (Path p : paths) {

canvas.drawPath(p, mPaint);

}

canvas.drawPath(mPath, mPaint);

}

private float mX, mY;

private static final float TOUCH_TOLERANCE = 4;

private void touch_start(float x, float y) {

undonePaths.clear();

mPath.reset();

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(y - mY);

if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {

mPath.quadTo(mX, mY, (x + mX) / 2, (y + mY) / 2);

mX = x;

mY = y;

}

}

private void touch_up() {

mPath.lineTo(mX, mY);

// commit the path to our offscreen

mCanvas.drawPath(mPath, mPaint);

// kill this so we don't double draw

paths.add(mPath);

mPath = new Path();

}

public void onClickUndo() {

if (paths.size() > 0) {

undonePaths.add(paths.remove(paths.size() - 1));

invalidate();

} else {

}

// toast the user

}

public void onClickRedo() {

if (undonePaths.size() > 0) {

paths.add(undonePaths.remove(undonePaths.size() - 1));

invalidate();

} else {

}

// toast the user

}

@Override

public boolean onTouch(View arg0, MotionEvent event) {

float x = event.getX();

float y = event.getY();

switch (event.getAction()) {

case MotionEvent.ACTION_DOWN:

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;

}

}