Android開發提高篇之“多方向”抽屜

這個Panel控件可以輕易實現不同方向的抽屜效果，比SlidingDrawer有更強的擴展性！

在多次使用Panel的過程中，發現Panel有個bug，會間斷性出現“閃爍”，也就是在onTouchListener裡面的觸發ACTION_DOWN後，抽屜瞬間彈出然後瞬間回收(版本日期為Feb 3, 2009)。把原Panel的OnTouchListener，即以下代碼：

1. OnTouchListener touchListener = new OnTouchListener() {
2. int initX;
3. int initY;
4. boolean setInitialPosition;
5. public boolean onTouch(View v, MotionEvent event) {
6. if (mState == State.ANIMATING) {
7. // we are animating
8. return false;
9. }
10. / Log.d(TAG, "state: " + mState + " x: " + event.getX() + " y: " + event.getY());
11. int action = event.getAction();
12. if (action == MotionEvent.ACTION_DOWN) {
13. if (mBringToFront) {
14. bringToFront();
15. }
16. initX = 0;
17. initY = 0;
18. if (mContent.getVisibility() == GONE) {
19. // since we may not know content dimensions we use factors here
20. if (mOrientation == VERTICAL) {
21. initY = mPosition == TOP? -1 : 1;
22. } else {
23. initX = mPosition == LEFT? -1 : 1;
24. }
25. }
26. setInitialPosition = true;
27. } else {
28. if (setInitialPosition) {
29. // now we know content dimensions, so we multiply factors...
30. initX *= mContentWidth;
31. initY *= mContentHeight;
32. // ... and set initial panel's position
33. mGestureListener.setScroll(initX, initY);
34. setInitialPosition = false;
35. // for offsetLocation we have to invert values
36. initX = -initX;
37. initY = -initY;
38. }
39. // offset every ACTION_MOVE & ACTION_UP event
40. event.offsetLocation(initX, initY);
41. }
42. if (!mGestureDetector.onTouchEvent(event)) {
43. if (action == MotionEvent.ACTION_UP) {
44. // tup up after scrolling
45. post(startAnimation);
46. }
47. }
48. return false;
49. }
50. };

替換為：

1. OnTouchListener touchListener = new OnTouchListener() {
2. float touchX, touchY;
4. public boolean onTouch(View v, MotionEvent event) {
5. if (mState == State.ANIMATING) {
6. // we are animating
7. return false;
8. }
10. int action = event.getAction();
11. if (action == MotionEvent.ACTION_DOWN) {
12. if (mBringToFront) {
13. bringToFront();
14. }
15. touchX = event.getX();
16. touchY = event.getY();
17. }
19. if (!mGestureDetector.onTouchEvent(event)) {
20. if (action == MotionEvent.ACTION_UP) {
21. // tup up after scrolling
22. int size = (int) (Math.abs(touchX - event.getX()) + Math
23. .abs(touchY - event.getY()));
25. if (size == mContentWidth || size == mContentHeight) {
26. mState = State.ABOUT_TO_ANIMATE;
27. //Log.e("size", String.valueOf(size));
28. //Log.e(String.valueOf(mContentWidth),String.valueOf(mContentHeight));
29. }
31. post(startAnimation);
32. }
33. }
34. return false;
35. }
36. };

即可修復這個bug，並且也同樣實現了OnClickListener的功能，可以把原Panel的OnClickListener給刪掉了！