Android ImageView缩放和翻译问题

Question

我正在开发一个Android应用程序（API 19 4.4），我遇到了ImageViews的一些问题。 我有一个SurfaceView，我在其中动态添加我想对触摸事件做出反应的ImageViews。 到目前为止，我已经成功地使ImageView移动并且平滑地缩放，但是我有一个讨厌的行为。

当我将图像缩小到一定限度时（我会说原始尺寸的一半）并且我尝试移动它，图像闪烁。 经过简短的分析，它似乎是围绕屏幕上的手指点对称地切换其位置，累积距离，最后看不见（所有这些都发生得非常快（<1s）。 我想我错过了触摸事件对ImageView / SurfaceView的相对价值的东西，但我是一个相当的菜鸟而且我被困了......

这是我的代码

public class MyImageView extends ImageView {
private ScaleGestureDetector mScaleDetector ;
private static final int MAX_SIZE = 1024;

private static final String TAG = "MyImageView";
PointF DownPT = new PointF(); // Record Mouse Position When Pressed Down
PointF StartPT = new PointF(); // Record Start Position of 'img'

public MyImageView(Context context) {
    super(context);
    mScaleDetector = new ScaleGestureDetector(context,new MySimpleOnScaleGestureListener());
    setBackgroundColor(Color.RED);
    setScaleType(ScaleType.MATRIX);
    setAdjustViewBounds(true);
    RelativeLayout.LayoutParams lp = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT);

    lp.setMargins(-MAX_SIZE, -MAX_SIZE, -MAX_SIZE, -MAX_SIZE);
    this.setLayoutParams(lp);
    this.setX(MAX_SIZE);
    this.setY(MAX_SIZE);

}

int firstPointerID;
boolean inScaling=false;
@Override
public boolean onTouchEvent(MotionEvent event) {
    // get pointer index from the event object
    int pointerIndex = event.getActionIndex();
    // get pointer ID
    int pointerId = event.getPointerId(pointerIndex);
    //First send event to scale detector to find out, if it's a scale
    boolean res = mScaleDetector.onTouchEvent(event);

    if (!mScaleDetector.isInProgress()) {
        int eid = event.getAction();
        switch (eid & MotionEvent.ACTION_MASK)
        {
        case MotionEvent.ACTION_MOVE :
            if(pointerId == firstPointerID) {

                PointF mv = new PointF( (int)(event.getX() - DownPT.x), (int)( event.getY() - DownPT.y));

                this.setX((int)(StartPT.x+mv.x));
                this.setY((int)(StartPT.y+mv.y));
                StartPT = new PointF( this.getX(), this.getY() );

            }
            break;
        case MotionEvent.ACTION_DOWN : {
            firstPointerID = pointerId;
            DownPT.x = (int) event.getX();
            DownPT.y = (int) event.getY();
            StartPT = new PointF( this.getX(), this.getY() );
            break;
        }
        case MotionEvent.ACTION_POINTER_DOWN: {
            break;
        }
        case MotionEvent.ACTION_UP:
        case MotionEvent.ACTION_POINTER_UP:
        case MotionEvent.ACTION_CANCEL: {
            firstPointerID = -1;
            break;
        }
        default :
            break;
        }
        return true;
    }
    return true;

}

public boolean onScaling(ScaleGestureDetector detector) {

    this.setScaleX(this.getScaleX()*detector.getScaleFactor());
    this.setScaleY(this.getScaleY()*detector.getScaleFactor());
    invalidate();
    return true;
}

private class MySimpleOnScaleGestureListener extends SimpleOnScaleGestureListener {


    @Override
    public boolean onScale(ScaleGestureDetector detector) {
        return onScaling(detector);
    }

    @Override
    public boolean onScaleBegin(ScaleGestureDetector detector) {
        Log.d(TAG, "onScaleBegin");
        return true;
    }

    @Override
    public void onScaleEnd(ScaleGestureDetector arg0) {
        Log.d(TAG, "onScaleEnd");
    }
}

}

我还有另外一个关于轮换的问题。我该如何实现呢？ 我可以以某种方式使用ScalegestureDetector，还是让我在视图触摸事件中使用它？我希望能够以相同的手势进行缩放和旋转（并在另一个手势中移动）。

感谢帮助我，我真的很感激！

抱歉我的英文

Answer 1

这是两个手指移动/缩放/旋转的工作示例（注意：由于使用了智能检测器，代码很短 - 请参阅MatrixGestureDetector）：

class ViewPort extends View {
    List<Layer> layers = new LinkedList<Layer>();
    int[] ids = {R.drawable.layer0, R.drawable.layer1, R.drawable.layer2};

    public ViewPort(Context context) {
        super(context);
        Resources res = getResources();
        for (int i = 0; i < ids.length; i++) {
            Layer l = new Layer(context, this, BitmapFactory.decodeResource(res, ids[i]));
            layers.add(l);
        }
    }

    @Override
    protected void onDraw(Canvas canvas) {
        for (Layer l : layers) {
            l.draw(canvas);
        }
    }

    private Layer target;

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        if (event.getAction() == MotionEvent.ACTION_DOWN) {
            target = null;
            for (int i = layers.size() - 1; i >= 0; i--) {
                Layer l = layers.get(i);
                if (l.contains(event)) {
                    target = l;
                    layers.remove(l);
                    layers.add(l);
                    invalidate();
                    break;
                }
            }
        }
        if (target == null) {
            return false;
        }
        return target.onTouchEvent(event);
    }
}

class Layer implements MatrixGestureDetector.OnMatrixChangeListener {
    Matrix matrix = new Matrix();
    Matrix inverse = new Matrix();
    RectF bounds;
    View parent;
    Bitmap bitmap;
    MatrixGestureDetector mgd = new MatrixGestureDetector(matrix, this);

    public Layer(Context ctx, View p, Bitmap b) {
        parent = p;
        bitmap = b;
        bounds = new RectF(0, 0, b.getWidth(), b.getHeight());
        matrix.postTranslate(50 + (float) Math.random() * 50, 50 + (float) Math.random() * 50);
    }

    public boolean contains(MotionEvent event) {
        matrix.invert(inverse);
        float[] pts = {event.getX(), event.getY()};
        inverse.mapPoints(pts);
        if (!bounds.contains(pts[0], pts[1])) {
            return false;
        }
        return Color.alpha(bitmap.getPixel((int) pts[0], (int) pts[1])) != 0;
    }

    public boolean onTouchEvent(MotionEvent event) {
        mgd.onTouchEvent(event);
        return true;
    }

    @Override
    public void onChange(Matrix matrix) {
        parent.invalidate();
    }

    public void draw(Canvas canvas) {
        canvas.drawBitmap(bitmap, matrix, null);
    }
}

class MatrixGestureDetector {
    private static final String TAG = "MatrixGestureDetector";

    private int ptpIdx = 0;
    private Matrix mTempMatrix = new Matrix();
    private Matrix mMatrix;
    private OnMatrixChangeListener mListener;
    private float[] mSrc = new float[4];
    private float[] mDst = new float[4];
    private int mCount;

    interface OnMatrixChangeListener {
        void onChange(Matrix matrix);
    }

    public MatrixGestureDetector(Matrix matrix, MatrixGestureDetector.OnMatrixChangeListener listener) {
        this.mMatrix = matrix;
        this.mListener = listener;
    }

    public void onTouchEvent(MotionEvent event) {
        if (event.getPointerCount() > 2) {
            return;
        }

        int action = event.getActionMasked();
        int index = event.getActionIndex();

        switch (action) {
            case MotionEvent.ACTION_DOWN:
            case MotionEvent.ACTION_POINTER_DOWN:
                int idx = index * 2;
                mSrc[idx] = event.getX(index);
                mSrc[idx + 1] = event.getY(index);
                mCount++;
                ptpIdx = 0;
                break;

            case MotionEvent.ACTION_MOVE:
                for (int i = 0; i < mCount; i++) {
                    idx = ptpIdx + i * 2;
                    mDst[idx] = event.getX(i);
                    mDst[idx + 1] = event.getY(i);
                }
                mTempMatrix.setPolyToPoly(mSrc, ptpIdx, mDst, ptpIdx, mCount);
                mMatrix.postConcat(mTempMatrix);
                if(mListener != null) {
                    mListener.onChange(mMatrix);
                }
                System.arraycopy(mDst, 0, mSrc, 0, mDst.length);
                break;

            case MotionEvent.ACTION_UP:
            case MotionEvent.ACTION_POINTER_UP:
                if (event.getPointerId(index) == 0) ptpIdx = 2;
                mCount--;
                break;
        }
    }
}

Answer 2

我终于使用了这个（间距用于计算两个手指之间的距离），我在缩放后偏移了imageview以使其保持居中，现在工作正常：

    float newDist = spacing(event);
            float scale = newDist / oldDist;

            int oldH =getLayoutParams().height;
            int oldW =getLayoutParams().width;

            int newH =(int) (getLayoutParams().height*scale);
            int newW =(int) (getLayoutParams().width*scale);

            if(newH<MAX_SIZE && newW<MAX_SIZE){
                //scale the height and width of the view
                getLayoutParams().height = newH;
                getLayoutParams().width = newW;

                //calculate the X and Y offset to apply after scaling to keep the image centered
                int xOffset = (int)(getLayoutParams().height - oldH)/2;
                int yOffset = (int)(getLayoutParams().width - oldW)/2;

                setX(getX()-xOffset);
                setY(getY()-yOffset);
                requestLayout();
                setAdjustViewBounds(true);

                oldDist=newDist; 

Answer 3

我尝试使用矩阵在视图上实现多点触摸而不是位图，现在我成功了。现在我认为它对你有助于多个图像的个人手势。尝试一下，它最适合我。

public class MultiTouchImageView extends ImageView implements OnTouchListener{

float[] lastEvent = null;
float d = 0f;
float newRot = 0f;
public static String fileNAME;
public static int framePos = 0;
//private ImageView view;
private boolean isZoomAndRotate;
private boolean isOutSide;
// We can be in one of these 3 states
private static final int NONE = 0;
private static final int DRAG = 1;
private static final int ZOOM = 2;
private int mode = NONE;

private PointF start = new PointF();
private PointF mid = new PointF();
float oldDist = 1f;
public MultiTouchImageView(Context context) {
    super(context);
}


public MultiTouchImageView(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
}


public MultiTouchImageView(Context context, AttributeSet attrs) {
    super(context, attrs);
}


@SuppressWarnings("deprecation")
@Override
public boolean onTouch(View v, MotionEvent event) {
    //view = (ImageView) v;
    bringToFront();
    // Handle touch events here...
    switch (event.getAction() & MotionEvent.ACTION_MASK) {
    case MotionEvent.ACTION_DOWN:
        //savedMatrix.set(matrix);
        start.set(event.getX(), event.getY());
        mode = DRAG;
        lastEvent = null;
        break;
    case MotionEvent.ACTION_POINTER_DOWN:
        oldDist = spacing(event);
        if (oldDist > 10f) {
            midPoint(mid, event);
            mode = ZOOM;
        }

        lastEvent = new float[4];
        lastEvent[0] = event.getX(0);
        lastEvent[1] = event.getX(1);
        lastEvent[2] = event.getY(0);
        lastEvent[3] = event.getY(1);
        d =  rotation(event);
        break;
    case MotionEvent.ACTION_UP:
        isZoomAndRotate = false;
    case MotionEvent.ACTION_OUTSIDE:
        isOutSide = true;
        mode = NONE;
        lastEvent = null;
    case MotionEvent.ACTION_POINTER_UP:
        mode = NONE;
        lastEvent = null;
        break;
    case MotionEvent.ACTION_MOVE:
        if(!isOutSide){
            if (mode == DRAG && !isZoomAndRotate) {
                isZoomAndRotate = false;
                setTranslationX((event.getX() - start.x) + getTranslationX());
                setTranslationY((event.getY() - start.y) + getTranslationY());
            } else if (mode == ZOOM && event.getPointerCount() == 2) {
                isZoomAndRotate = true;
                boolean isZoom = false;
                if(!isRotate(event)){
                    float newDist = spacing(event);
                    if (newDist > 10f) {
                        float scale = newDist / oldDist * getScaleX();
                        setScaleX(scale);
                        setScaleY(scale);
                        isZoom = true;
                    }
                }
                else if(!isZoom){
                    newRot = rotation(event);
                    setRotation((float)(getRotation() + (newRot - d)));
                }
            }
        }

        break;
    }
    new GestureDetector(new MyGestureDectore());
    Constants.currentSticker = this;
    return true;
}
private class MyGestureDectore extends GestureDetector.SimpleOnGestureListener{

    @Override
    public boolean onDoubleTap(MotionEvent e) {
        bringToFront();
        return false;
    }

    @Override
    public boolean onDoubleTapEvent(MotionEvent e) {
        return false;
    }

}
private float rotation(MotionEvent event) {
    double delta_x = (event.getX(0) - event.getX(1));
    double delta_y = (event.getY(0) - event.getY(1));
    double radians = Math.atan2(delta_y, delta_x);
    return (float) Math.toDegrees(radians);
}
private float spacing(MotionEvent event) {
    float x = event.getX(0) - event.getX(1);
    float y = event.getY(0) - event.getY(1);
    return FloatMath.sqrt(x * x + y * y);
}

private void midPoint(PointF point, MotionEvent event) {
    float x = event.getX(0) + event.getX(1);
    float y = event.getY(0) + event.getY(1);
    point.set(x / 2, y / 2);
}

private boolean isRotate(MotionEvent event){
    int dx1 = (int) (event.getX(0) - lastEvent[0]);
    int dy1 = (int) (event.getY(0) - lastEvent[2]);
    int dx2 = (int) (event.getX(1) - lastEvent[1]);
    int dy2 = (int) (event.getY(1) - lastEvent[3]);
    Log.d("dx1 ", ""+ dx1);
    Log.d("dx2 ", "" + dx2);
    Log.d("dy1 ", "" + dy1);
    Log.d("dy2 ", "" + dy2);
    //pointer 1
    if(Math.abs(dx1) > Math.abs(dy1) && Math.abs(dx2) > Math.abs(dy2)) {
        if(dx1 >= 2.0 && dx2 <=  -2.0){
            Log.d("first pointer ", "right");
            return true;
        }
        else if(dx1 <= -2.0 && dx2 >= 2.0){
            Log.d("first pointer ", "left");
            return true;
        }
    }
    else {
         if(dy1 >= 2.0 && dy2 <=  -2.0){
                Log.d("seccond pointer ", "top");
                return true;
            }
            else if(dy1 <= -2.0 && dy2 >= 2.0){
                Log.d("second pointer ", "bottom");
                return true; 
            }

    }

    return false;
}
}

Answer 4

由于 scaleType 设置为矩阵，所有这些示例都支持故障手势。当我尝试缩放时，我无法将图像保持在中心并控制缩放量。所以我做了一些研究并为此编写了一个小而简单但非常令人愉悦的代码：https://stackoverflow.com/a/65697376/13339685