两种方法：

一，利用ScaleGestureDetector。代码在customview中。

    

    

设为View的成员变量；

    

    

构造方法中传入OnScaleGestureListener，覆写缩放的三个方法；

    

    

覆写customView的onTouchEven(MotionEvent event)方法，将event传给

ScaleGestureDetector.

 onTouchEven(

MotionEvent event

)处理。

1. OnScaleGestureListener listener = new OnScaleGestureListener() {
3. @Override
4. public void onScaleEnd(ScaleGestureDetector detector) {
5. Log.i("OnScaleGestureListener", "onScaleEnd");
6. }
8. @Override
9. public boolean onScaleBegin(ScaleGestureDetector detector) {
10. Log.i("OnScaleGestureListener", "onScaleBegin");
11. return true;
12. }
14. @Override
15. public boolean onScale(ScaleGestureDetector detector) {
16. Log.i("OnScaleGestureListener", "onScale");
18. float dXStart = detector.getPreviousSpanX();
19. float dXEnd = detector.getCurrentSpanX();
20. float dScale = (dXEnd - dXStart) / getWidth();
21. scale += dScale;
22. if(scale > 3f) {
23. scale = 3f;
24. }
25. if(scale < 1) {
26. scale = 1f;
27. }
29. // Log.i("xFirstStart,xSecondStart,xFirstEnd", xFirstStart + "," + xSecondStart + "," + xFirstEnd + "," + xSecondEnd);
30. // Log.i("dXStart,dXEnd,scale,kcvKchart.getWidth()", dXStart + "," + dXEnd + "," + scale + "," + kcvKchart.getWidth());
31. setScaleX(scale);
33. return false;
34. }
35. };

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二，直接设置customView的onTouchEventListener，覆写onTouch()方法。代码在activity中。

    

    这里注意，可以使用

MotionEvent.ACTION_POINTER_DOWN事件，比较方便；

    

    如果不使用pointerdown事件，则在down事件中不能获取第二个pointer信息，只能在move事件中获取，第一获取后不做处理，第二次获取后做缩放。

1. // 没有使用MotionEvent.ACTION_POINTER_DOWN事件
2. kcvKchart.setOnTouchListener(new OnTouchListener() {
3. private float xFirstStart;
4. private float xSecondStart;
5. private float xFirstEnd;
6. private float xSecondEnd;
7. private int dXFirst;
8. private int oldPointerCount;
9. private int newPointerCount;
10. private float scale = 1f;
12. @Override
13. public boolean onTouch(View v, MotionEvent event) {
    // can be written in KChartView‘s onTouchEven(--)
14. switch (event.getAction()) {
15. case MotionEvent.ACTION_DOWN:
16. xFirstStart = event.getX();// to WindowScreen
17. oldPointerCount = event.getPointerCount();
19. break;
20. case MotionEvent.ACTION_MOVE:
21. newPointerCount = event.getPointerCount();
22. if(newPointerCount == 1) {
    // one finger translate
23. xFirstEnd = event.getX();
24. dXFirst = Math.round(xFirstStart - xFirstEnd);// the closest integer to the argument,including positive & negative .
25. // TODO condition:if left x axis < 0 || right x axis > view.getWidth, then left x=0 || right x=view.getWidth return
26. kcvKchart.scrollBy(dXFirst, 0); // can called repeatedly
27. // Log.i("startX - endX, distanceX", xFirstStart - xFirstEnd + "," + dXFirst);
28. xFirstStart = xFirstEnd;
29. } else {
    // two or more finger scale
30. xFirstEnd = event.getX();
31. xSecondEnd = event.getX(1);
32. if(oldPointerCount == 1) {
    // initialize second pointer axis
33. // 由于第二个pointer的初始坐标不能再down事件中获取，只能在第一次move时获取，故第一次move不能进行缩放，需要过滤
34. oldPointerCount = newPointerCount;
35. } else {
36. float dXStart = Math.abs(xFirstStart - xSecondStart);
37. float dXEnd = Math.abs(xFirstEnd - xSecondEnd);
38. float dScale = (dXEnd - dXStart) / kcvKchart.getWidth();
39. scale += dScale;
40. if(scale > 3f) {
41. scale = 3f;
42. }
43. if(scale < 1) {
44. scale = 1f;
45. }
47. // Log.i("xFirstStart,xSecondStart,xFirstEnd", xFirstStart + "," + xSecondStart + "," + xFirstEnd + "," + xSecondEnd);
48. // Log.i("dXStart,dXEnd,scale,kcvKchart.getWidth()", dXStart + "," + dXEnd + "," + scale + "," + kcvKchart.getWidth());
49. kcvKchart.setScaleX(scale);
50. }
51. xFirstStart = xFirstEnd;
52. xSecondStart = xSecondEnd;
53. }
54. break;
55. case MotionEvent.ACTION_POINTER_DOWN:
57. break;
59. default:
60. break;
61. }
62. return true;
63. }
64. } );