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我在做捏操作以放大/縮小我的應用程序。當我捏的時候我想畫圓圈。我試着用下面的代碼。但有時它會畫1圈，有時候不是。我想按照我的手指運動繪製圓圈。我怎樣才能做到這一點？當手指在多點觸控上移動時畫圓圈
public class MainActivity extends Activity implements OnTouchListener {
String TAG="activity";
View view;
Bitmap bitmap /*newBitmap*/;
Canvas canvas;
Paint paintLine,paintCircle;
String direction;
float startX = 0, startY = 0, endX = 0, endY = 0, upx = 0, upy = 0;
private float scale = 1f;
final float MINIMUM_THRESHOLD=10;
boolean isZoomed=false,isMultitouch=false;
private ScaleGestureDetector SGD;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
//this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.activity_main);
view = (LinearLayout) findViewById(R.id.imageView1);
view.setOnTouchListener(this);
//detector=new GestureDetector(this);
DisplayMetrics currentDisplay = view.getContext().getResources().getDisplayMetrics();
float dw = currentDisplay.widthPixels;
float dh = currentDisplay.heightPixels;
SGD = new ScaleGestureDetector(this,new ScaleListener());
bitmap = Bitmap.createBitmap((int) dw, (int) dh,
Bitmap.Config.ARGB_8888);
//bitmap= BitmapFactory.decodeResource(getResources(), R.drawable.fish);
//newBitmap=bitmap.copy(Bitmap.Config.ARGB_8888, true);
canvas = new Canvas(bitmap);
paintLine = new Paint();
paintLine.setStyle(Paint.Style.STROKE);
paintLine.setStrokeCap(Paint.Cap.ROUND);
paintLine.setStrokeWidth(10);
paintLine.setColor(Color.GRAY);
view.setBackground(new BitmapDrawable(null, bitmap));
paintCircle=new Paint();
paintCircle.setStyle(Paint.Style.STROKE);
paintCircle.setStrokeWidth(5);
paintCircle.setColor(Color.WHITE);
}
@Override
public boolean onTouch(View v, MotionEvent event) {
// TODO Auto-generated method stub
switch (event.getActionMasked()) {
case MotionEvent.ACTION_POINTER_UP :
//hideDrawing(true);
SGD.onTouchEvent(event);
Log.v(TAG, "test:multitouch pointer up");
if(isZoomed){
Toast.makeText(MainActivity.this, "zoom in", Toast.LENGTH_SHORT).show();
}else{
Toast.makeText(MainActivity.this, "zoom out", Toast.LENGTH_SHORT).show();
}
return true;
case MotionEvent.ACTION_POINTER_DOWN:
//hideDrawing(true);
SGD.onTouchEvent(event);
Log.v(TAG, "test:multitouch pointer down");
return true;
case MotionEvent.ACTION_DOWN:
startX = event.getX();
startY = event.getY();
isMultitouch=false;
Log.v(TAG, "test:starting cords("+startX+","+startY+")");
break;
case MotionEvent.ACTION_MOVE:
upx = event.getX();
upy = event.getY();
if(event.getPointerCount()>1 || isMultitouch){
//hideDrawing(true);
float x1 = (event.getX(0) + event.getX(1))/2.0f;
float y1 = (event.getY(0) + event.getY(1))/2.0f;
double r = Math.sqrt(Math.pow(event.getX(1) - event.getX(0), 2.0f) + Math.pow(event.getY(1) - event.getY(0), 2.0f))/2.0f;
canvas.drawCircle(x1, y1, (float) r, paintCircle);
SGD.onTouchEvent(event);
Log.v(TAG, "test:multitouch :move");
return true;
}else if(event.getPointerCount()==1 && !isMultitouch){
Log.v(TAG, "test:singletouch : move");
if(Math.abs(upx-startX)>MINIMUM_THRESHOLD||Math.abs(upy-startY)>MINIMUM_THRESHOLD){
view.postDelayed(new Runnable() {
@Override
public void run() {
if(Math.abs(upx-startX)<Math.abs(upy-startY))
canvas.drawLine(startX, startY,startX, upy, paintLine);
else
canvas.drawLine(startX, startY,upx, startY, paintLine);
}
}, 300);
view.invalidate();
}
}
break;
case MotionEvent.ACTION_UP:
endX = event.getX();
endY = event.getY();
Log.v(TAG, "test:singletouch : up");
Log.v(TAG, "test:actual ending cords("+endX+","+endY+")");
if(!isMultitouch){
if(Math.abs(endX-startX)>MINIMUM_THRESHOLD||Math.abs(endY-startY)>MINIMUM_THRESHOLD){
if(Math.abs(endX-startX)<Math.abs(endY-startY))
endX=startX;
else
endY=startY;
Log.v(TAG, "test:edited ending cords("+endX+","+endY+")");
view.invalidate();
hideDrawing(false);
calculateDistanceAndDirection();
findDirection();
}
}
break;
}
return true;
}
private void hideDrawing(boolean immediate) {
if(immediate){
canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR);
view.invalidate();
}else{
view.postDelayed(new Runnable() {
@Override
public void run() {
canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR);
view.invalidate();
}
}, 500);
}
}
private void calculateDistanceAndDirection() {
double dist = Math.sqrt(Math.pow((startX - endX), 2)
+ Math.pow((startY - endY), 2));
//Toast.makeText(this, "cords is: ("+startX +","+startY+")("+endX+","+endY+")", Toast.LENGTH_LONG).show();
// Toast.makeText(this, "distance :"+dist, Toast.LENGTH_SHORT).show();
}
private void findDirection(){
if (startY < endY) {
direction="down";
Toast.makeText(this, direction, Toast.LENGTH_SHORT).show();
} else if (startY > endY){
direction="up";
Toast.makeText(this, direction, Toast.LENGTH_SHORT).show();
}else if (startX > endX){
direction="left";
Toast.makeText(this, direction, Toast.LENGTH_SHORT).show();
}else if (startX < endX){
direction="right";
Toast.makeText(this, direction, Toast.LENGTH_SHORT).show();
}
}
private class ScaleListener extends ScaleGestureDetector.
SimpleOnScaleGestureListener {
@Override
public boolean onScale(ScaleGestureDetector detector) {
scale *= detector.getScaleFactor();
scale = Math.max(0.1f, Math.min(scale, 5.0f));
isMultitouch=true;
// matrix.setScale(scale, scale);
// view.setImageMatrix(matrix);
if(detector.getScaleFactor()<1.0f)
isZoomed=false;
else
isZoomed=true;
return true;
}
}
}