1
我跟着guideline I found in the Android Developer Blog調整大小的ImageView與捏
但問題是，這只是移動和圖像視圖邊界內變焦。我想要的是用兩個手指手勢調整圖像視圖的大小。它應該變得更大或更小根據捏。我已經一直在調整整天的谷歌搜索，並無法弄清楚。所有的教程只指出我在ImageView中縮放而不是調整大小。 以下是我的自定義圖像視圖代碼產生的博客。
public class InteractableImageView extends ImageView implements View.OnTouchListener {
private static final int INVALID_POINTER_ID = -1;
private ScaleGestureDetector mScaleDetector;
private float mScaleFactor = 1.f;
private int mActivePointerId = INVALID_POINTER_ID;
private float mPosX;
private float mPosY;
private float mLastTouchX;
private float mLastTouchY;
public InteractableImageView(Context context) {
this(context, null, 0);
mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
}
public InteractableImageView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
}
public InteractableImageView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
}
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);
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;
}
@Override public void onDraw(Canvas canvas) {
canvas.save();
canvas.translate(mPosX, mPosY);
canvas.scale(mScaleFactor, mScaleFactor);
super.onDraw(canvas);
canvas.restore();
}
@Override public boolean onTouch(View v, MotionEvent event) {
return false;
}
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, 5.0f));
invalidate();
return true;
}
}
}