我在画布相关的应用程序中工作，除了清除所有功能外，一切正常。
我已经使用此代码创建画布，它也有擦除操作但手动擦除。
public class CharactersCanvas extends Activity {
public int width;
public int height;
public Arrays paths1;
private Bitmap mBitmap;
private Canvas mCanvas;
private Path mPath;
private Paint mBitmapPaint;
Context context;
private Paint circlePaint;
private Path circlePath;
static List<Integer> listFlag;
/* MyView mv; */
DrawingPanel dp;
AlertDialog dialog;
private ArrayList<Path> undonePaths = new ArrayList<Path>();
public ArrayList<Path> paths = new ArrayList<Path>();
private ArrayList<String> step = new ArrayList<String>();
FrameLayout frmLayout;
Canvas canvas;
protected static ImageView imageView;
private Integer frameIndex = 0;
public int res;
@SuppressLint("NewApi")
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.canvas_screen);
dp = new DrawingPanel(this);
frmLayout = (FrameLayout) findViewById(R.id.frameLayout1);
imageView=(ImageView) findViewById(R.id.imageView5);
frmLayout.addView(dp);
Bundle bundle = this.getIntent().getExtras();
res = bundle.getInt("resourseInt");
imageView.setImageResource(res);
frameIndex = (bundle != null && bundle.getInt("image") != 0) ? HomeScreen.characters.indexOf(bundle.getInt("image")) : frameIndex;
System.out.println(" Blank " + frameIndex);
frmLayout.setBackgroundResource((int)HomeScreen.characters.get(frameIndex));
/*
* if(){ dp.setBackgroundResource(R.drawable.atemplate); }
*/
((Button) findViewById(R.id.clear_buttonn))
.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
paths = new ArrayList<Path>();
if (paths != null)
paths.clear();
if(dp !=null)
dp.invalidate();
}
});
((Button) findViewById(R.id.next_buttonn))
.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
paths = new ArrayList<Path>();
if (frameIndex < (HomeScreen.characters.size() - 1)) {
if (paths != null)
paths.clear();
if (dp != null)
dp.invalidate();
System.out.println(" Size is "
+ HomeScreen.characters.size());
frmLayout
.setBackgroundResource((int) HomeScreen.characters
.get(frameIndex != HomeScreen.characters
.size() ? ++frameIndex
: frameIndex));
}
}
});
((Button) findViewById(R.id.previous_buttonn))
.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if (frameIndex >= 0) {
paths = new ArrayList<Path>();
if (paths != null)
paths.clear();
if (dp != null)
dp.invalidate();
frmLayout
.setBackgroundResource((int) HomeScreen.characters
.get(frameIndex == 0 ? frameIndex
: --frameIndex));
}
}
});
((Button) findViewById(R.id.letters_buttonn))
.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
MediaPlayer mPlayer = MediaPlayer.create(
CharactersCanvas.this, R.raw.one_sound);
mPlayer.start();
Intent intent = new Intent(getApplicationContext(),
CharactersGridView.class);
intent.putExtra("resourseInt", res);
// integerList is
// ArrayList<Integer>
startActivity(intent);
/*
* startActivity(new Intent(CharactersCanvas.this,
* CharactersGridView.class));
*/
}
});
((Button) findViewById(R.id.home_buttonn))
.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
MediaPlayer mPlayer = MediaPlayer.create(
CharactersCanvas.this, R.raw.one_sound);
mPlayer.start();
startActivity(new Intent(CharactersCanvas.this,
HomeScreen.class));
finish();
}
});
}
private Paint mPaint;
private MaskFilter mEmboss;
private MaskFilter mBlur;
public class DrawingPanel extends View implements OnTouchListener {
private Canvas mCanvas;
private Path mPath;
private Paint mPaint, circlePaint, outercirclePaint;
// private ArrayList<Path> undonePaths = new ArrayList<Path>();
private float xleft, xright, xtop, xbottom;
public DrawingPanel(Context context) {
super(context);
setFocusable(true);
setFocusableInTouchMode(true);
this.setOnTouchListener(this);
circlePaint = new Paint();
mPaint = new Paint();
outercirclePaint = new Paint();
outercirclePaint.setAntiAlias(false);
circlePaint.setAntiAlias(false);
mPaint.setAntiAlias(false);
mPaint.setColor(0xFFFF0000);
outercirclePaint.setColor(0x44FFF000);
circlePaint.setColor(0xF57F35);
outercirclePaint.setStyle(Paint.Style.FILL_AND_STROKE);
circlePaint.setStyle(Paint.Style.FILL);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.MITER);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeWidth(10);
outercirclePaint.setStrokeWidth(10);
mCanvas = new Canvas();
mPath = new Path();
paths.add(mPath);
}
public void colorChanged(int color) {
mPaint.setColor(color);
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
}
@Override
protected void onDraw(Canvas canvas) {
if (paths != null && paths.size() > 0) {
for (Path p : paths) {
canvas.drawPath(p, mPaint);
}
}
}
private float mX, mY;
private static final float TOUCH_TOLERANCE = 0;
private void touch_start(float x, float y) {
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
mPath = new Path();
paths.add(mPath);
}
@Override
public boolean onTouch(View arg0, MotionEvent event) {
float x = event.getX();
float y = event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
// if (x <= cx+circleRadius+5 && x>= cx-circleRadius-5) {
// if (y<= cy+circleRadius+5 && cy>= cy-circleRadius-5){
// paths.clear();
// return true;
// }
// }
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;
}
}
}
我想用一个按钮清除所有的抄写。如何做到这一点？任何想法都会非常有用。
答案 0 :(得分：1)
清除画布的内容，你可以画一种颜色，
canvas.drawColor(Color.TRANSPARENT)
。