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我正在使用Android项目。我无法理解如何使用ScaleDetector和Canvas。如何计算Android中缩放画布的坐标
我有名为printTable与矩形列表。我在onDraw（）方法的屏幕上绘制每个Rectangle。 然后我有第二个名为listpointer与矩形和id的矩形。我正在检查屏幕上绘制的矩形的onTouchEvent列表。如果矩形包含X，Y我打印有关点击矩形的ID的信息。
问题是如何计算我的X，Y当我移动画布或缩放它时？
public class Painter extends View {
//
private static final int INVALID_POINTER_ID = -1;
private float mPosX;
private float mPosY;
private float mLastTouchX;
private float mLastTouchY;
private int mActivePointerId = INVALID_POINTER_ID;
private ScaleGestureDetector mScaleDetector;
private float mScaleFactor = 1.f;
//
Paint paint = new Paint();
List<Table> printTable = new ArrayList<Table>(); // lista wyświetlanych stolików
//
List<Pointer> listPointer = new ArrayList<Pointer>();
//
public Painter(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public Painter(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
}
private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {
@Override
public boolean onScale(ScaleGestureDetector detector) {
mScaleFactor *= detector.getScaleFactor();
// Don't let the object get too small or too large.
mScaleFactor = Math.max(0.1f, Math.min(mScaleFactor, 10.0f));
invalidate();
return true;
}
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
// Let the ScaleGestureDetector inspect all events.
mScaleDetector.onTouchEvent(ev);
final int action = ev.getAction();
switch (action & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN: {
final float x = ev.getX();
final float y = ev.getY();
mLastTouchX = x;
mLastTouchY = y;
mActivePointerId = ev.getPointerId(0);
for(int i = 0; i<listPointer.size(); i++)
{
if(listPointer.get(i).getRectangle().contains((int)(Math.round(x)), (int)(Math.round(y))))
{
if(listPointer.get(i).getIsItTable())
{
Log.e("Exc", "Stolik "+listPointer.get(i).getId());
}
else
{
Log.e("Exc", "Button "+listPointer.get(i).getId());
}
}
}
break;
}
case MotionEvent.ACTION_MOVE: {
final int pointerIndex = ev.findPointerIndex(mActivePointerId);
final float x = ev.getX(pointerIndex);
final float y = ev.getY(pointerIndex);
// Only move if the ScaleGestureDetector isn't processing a gesture.
if (!mScaleDetector.isInProgress()) {
final float dx = x - mLastTouchX;
final float dy = y - mLastTouchY;
mPosX += dx;
mPosY += dy;
invalidate();
}
mLastTouchX = x;
mLastTouchY = y;
break;
}
case MotionEvent.ACTION_UP: {
mActivePointerId = INVALID_POINTER_ID;
break;
}
case MotionEvent.ACTION_CANCEL: {
mActivePointerId = INVALID_POINTER_ID;
break;
}
case MotionEvent.ACTION_POINTER_UP: {
final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK)
>> MotionEvent.ACTION_POINTER_INDEX_SHIFT;
final int pointerId = ev.getPointerId(pointerIndex);
if (pointerId == mActivePointerId) {
// This was our active pointer going up. Choose a new
// active pointer and adjust accordingly.
final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
mLastTouchX = ev.getX(newPointerIndex);
mLastTouchY = ev.getY(newPointerIndex);
mActivePointerId = ev.getPointerId(newPointerIndex);
}
break;
}
}
return true;
}
//
public Painter(Context context) {
this(context, null, 0);
paint.setColor(Color.BLACK);
List<Table> printTable = Bridge.getTables(getContext());
}
@SuppressLint("DrawAllocation")
@Override
public void onDraw(Canvas canvas) {
super.onDraw(canvas);
Rect rect = null;
RectF rectF = null;
// czyszczenie tablicy
listPointer.clear();
for(int j = 0; j<printTable.size(); j++)
{
Table item = printTable.get(j);
// Obsługa rozciągania
canvas.save();
Log.d("DEBUG", "X: "+mPosX+" Y: "+mPosY);
canvas.translate(mPosX, mPosY);
canvas.scale(mScaleFactor, mScaleFactor);
// dodaje do tablicy stołów
paint.setColor(getResources().getColor(R.color.green));
rect = new Rect(item.getX1(), item.getY1(), item.getX2(), item.getY2());
rectF = new RectF(rect);
canvas.drawRoundRect(rectF, 0,0, paint);
listPointer.add(new Pointer(rect, true, j));
canvas.restore();
}
}