【发布时间】：2017-06-08 12:16:12
【问题描述】：
我正在开发一个捏拉缩放 RecyclerView，并且捏拉缩放功能可以正常工作，但是一旦放大，onItemClickListeners 就位于错误的位置。下面是修改后的 RecyclerView 的代码。我还做了一个simple demo that is hosted on GitHub。在尝试演示时，当你点击一个项目时，你应该会得到一个 Toast，上面写着你点击的图标的编号。尝试不放大，然后放大并再次尝试查看问题。我相信我需要通知 RecyclerView onItemClickListener 位置需要更新，但找不到正确的方法来覆盖。感谢您的帮助！
public class PinchRecyclerView extends RecyclerView {
private static final int INVALID_POINTER_ID = -1;
private int mActivePointerId = INVALID_POINTER_ID;
private ScaleGestureDetector mScaleDetector;
private float mScaleFactor = 1.f;
private float maxWidth = 0.0f;
private float maxHeight = 0.0f;
private float mLastTouchX;
private float mLastTouchY;
private float mPosX;
private float mPosY;
private float width;
private float height;
public PinchRecyclerView(Context context) {
super(context);
if (!isInEditMode())
mScaleDetector = new ScaleGestureDetector(getContext(), new ScaleListener());
}
public PinchRecyclerView(Context context, AttributeSet attrs) {
super(context, attrs);
if (!isInEditMode())
mScaleDetector = new ScaleGestureDetector(getContext(), new ScaleListener());
}
public PinchRecyclerView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
if (!isInEditMode())
mScaleDetector = new ScaleGestureDetector(getContext(), new ScaleListener());
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
width = View.MeasureSpec.getSize(widthMeasureSpec);
height = View.MeasureSpec.getSize(heightMeasureSpec);
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
try {
return super.onInterceptTouchEvent(ev);
} catch (IllegalArgumentException ex) {
ex.printStackTrace();
}
return false;
}
@Override
public boolean onTouchEvent(@NonNull MotionEvent ev) {
super.onTouchEvent(ev);
final int action = ev.getAction();
mScaleDetector.onTouchEvent(ev);
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);
break;
}
case MotionEvent.ACTION_MOVE: {
final int pointerIndex = (action & MotionEvent.ACTION_POINTER_INDEX_MASK)
>> MotionEvent.ACTION_POINTER_INDEX_SHIFT;
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;
if (mPosX > 0.0f)
mPosX = 0.0f;
else if (mPosX < maxWidth)
mPosX = maxWidth;
if (mPosY > 0.0f)
mPosY = 0.0f;
else if (mPosY < maxHeight)
mPosY = maxHeight;
mLastTouchX = x;
mLastTouchY = y;
invalidate();
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 = (action & MotionEvent.ACTION_POINTER_INDEX_MASK) >> MotionEvent.ACTION_POINTER_INDEX_SHIFT;
final int pointerId = ev.getPointerId(pointerIndex);
if (pointerId == mActivePointerId) {
final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
mLastTouchX = ev.getX(newPointerIndex);
mLastTouchY = ev.getY(newPointerIndex);
mActivePointerId = ev.getPointerId(newPointerIndex);
}
break;
}
}
return true;
}
@Override
public void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.save(Canvas.MATRIX_SAVE_FLAG);
canvas.translate(mPosX, mPosY);
canvas.scale(mScaleFactor, mScaleFactor);
canvas.restore();
}
@Override
protected void dispatchDraw(@NonNull Canvas canvas) {
canvas.save(Canvas.MATRIX_SAVE_FLAG);
if (mScaleFactor == 1.0f) {
mPosX = 0.0f;
mPosY = 0.0f;
}
canvas.translate(mPosX, mPosY);
canvas.scale(mScaleFactor, mScaleFactor);
super.dispatchDraw(canvas);
canvas.restore();
invalidate();
}
private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {
@Override
public boolean onScale(ScaleGestureDetector detector) {
mScaleFactor *= detector.getScaleFactor();
mScaleFactor = Math.max(1.0f, Math.min(mScaleFactor, 3.0f));
maxWidth = width - (width * mScaleFactor);
maxHeight = height - (height * mScaleFactor);
invalidate();
return true;
}
}
}
【问题讨论】：
-
您正在使用
Canvas进行操作。相反，您必须使用实际的布局管理器，从而管理布局过程。目前你只是通过对画布进行更改来伪装，但它下面的布局完全没有被触及。 Imo，你必须继承GridLayoutManager并在那里执行繁重的工作。 -
你使用 recyclerView.setHasFixedSize(true) 吗？如果是，则删除该行并尝试
-
查看我的更新答案以获得更简洁的实现。
标签： android android-recyclerview