Question

我有这个代码，我在这里看到了pan + zoom功能。我在模拟器中测试它，但我只能在模拟器中单击，所以我不知道它是否真的有效。我该如何检查？

import android.content.Context;
import android.graphics.Canvas;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.widget.ImageView;

public class MyImageView extends ImageView {
private static final int INVALID_POINTER_ID = -1;

private float mPosX;
private float mPosY;

private float mLastTouchX;
private float mLastTouchY;
private float mLastGestureX;
private float mLastGestureY;
private int mActivePointerId = INVALID_POINTER_ID;

private ScaleGestureDetector mScaleDetector;
private float mScaleFactor = 1.f;

public MyImageView(Context context, AttributeSet attrs) {
    this(context, attrs, 0);
    mScaleDetector = new ScaleGestureDetector(getContext(), new ScaleListener());
}

public MyImageView(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
    mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
}

@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: {
            if (!mScaleDetector.isInProgress()) {
                final float x = ev.getX();
                final float y = ev.getY();

                mLastTouchX = x;
                mLastTouchY = y;
                mActivePointerId = ev.getPointerId(0);
            }
            break;
        }
        case MotionEvent.ACTION_POINTER_1_DOWN: {
            if (mScaleDetector.isInProgress()) {
                final float gx = mScaleDetector.getFocusX();
                final float gy = mScaleDetector.getFocusY();
                mLastGestureX = gx;
                mLastGestureY = gy;
            }
            break;
        }
        case MotionEvent.ACTION_MOVE: {

            // Only move if the ScaleGestureDetector isn't processing a gesture.
            if (!mScaleDetector.isInProgress()) {
                final int pointerIndex = ev.findPointerIndex(mActivePointerId);
                final float x = ev.getX(pointerIndex);
                final float y = ev.getY(pointerIndex);

                final float dx = x - mLastTouchX;
                final float dy = y - mLastTouchY;

                mPosX += dx;
                mPosY += dy;

                invalidate();

                mLastTouchX = x;
                mLastTouchY = y;
            }
            else{
                final float gx = mScaleDetector.getFocusX();
                final float gy = mScaleDetector.getFocusY();

                final float gdx = gx - mLastGestureX;
                final float gdy = gy - mLastGestureY;

                mPosX += gdx;
                mPosY += gdy;

                invalidate();

                mLastGestureX = gx;
                mLastGestureY = gy;
            }

            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);
            }
            else{
                final int tempPointerIndex = ev.findPointerIndex(mActivePointerId);
                mLastTouchX = ev.getX(tempPointerIndex);
                mLastTouchY = ev.getY(tempPointerIndex);
            }

            break;
        }
    }

    return true;
}

@Override
public void onDraw(Canvas canvas) {

    canvas.save();

    canvas.translate(mPosX, mPosY);

    if (mScaleDetector.isInProgress()) {
        canvas.scale(mScaleFactor, mScaleFactor, mScaleDetector.getFocusX(), mScaleDetector.getFocusY());
    }
    else{
        canvas.scale(mScaleFactor, mScaleFactor, mLastGestureX, mLastGestureY);
    }
    super.onDraw(canvas);
    canvas.restore();
}

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;
    }
}

}

Answer 1

Android模拟器不支持多点触控，除非您有可用于提供触摸点的实际设备。

从sdk-r20开始，您可以在模拟器中使用real phone connected to computer进行多点触控。

测试Android模拟器上的触摸功能

1 个答案: