Android動畫機制源碼分析(待完善)

分類：編程 時間:2017-02-15

android動畫機制源碼分析(待完善)

本文著重講解Android3.0後推出的屬性動畫框架Property Animation——Animator的相關源碼分析

概述

3.0之前已有的動畫框架——Animation存在一些局限性， Animation框架定義了透明度，旋轉，縮放和位移幾種常見的動畫，而且控制的是整個View，實現原理是每次繪制視圖時View所在的ViewGroup中的drawChild函數獲取該View的Animation的Transformation值，然後調用canvas.concat(transformToApply.getMatrix())，通過矩陣運算完成動畫幀，如果動畫沒有完成，繼續調用invalidate()函數，啟動下次繪制來驅動動畫，動畫過程中的幀之間間隙時間是繪制函數所消耗的時間，可能會導致動畫消耗比較多的CPU資源，最重要的是，動畫改變的只是顯示，並不能改變相應事件作用的位置。3.0之前的動畫我們一般稱為View動畫.
而在Animator框架中使用最多的是AnimatorSet和ObjectAnimator配合，使用ObjectAnimator進行更精細化控制，只控制一個對象的一個屬性值，多個ObjectAnimator組合到AnimatorSet形成一個動畫。而且ObjectAnimator能夠自動驅動，可以調用setFrameDelay(longframeDelay)設置動畫幀之間的間隙時間，調整幀率，減少動畫過程中頻繁繪制界面，而在不影響動畫效果的前提下減少CPU資源消耗。因此，Anroid推出的強大的屬性動畫框架，基本可以實現所有的動畫效果。

簡單實例

在分析源碼之前先列出幾個常用的實例.後面的源碼分析也會用到其中的實例.

實例1:監聽動畫的過程

  1. public void changMultiplePropertyByValueAnimator(final View v) { 
  2. 	RelativeLayout.LayoutParams params = (RelativeLayout.LayoutParams) v
  3. 			.getLayoutParams();
  5. 	PropertyValuesHolder pvh_left = PropertyValuesHolder.ofFloat(
  6. 			"margin_left", params.leftMargin, 500);
  7. 	PropertyValuesHolder pvh_top = PropertyValuesHolder.ofFloat(
  8. 			"margin_top", params.topMargin, 500);
  10. 	ValueAnimator ani = ValueAnimator.ofPropertyValuesHolder(pvh_left,
  11. 			pvh_top).setDuration(1000);
  13. 	ani.addupdateListener(new ValueAnimator.AnimatorUpdateListener() {
  14. 		@Override
  15. 		public void onAnimationUpdate(ValueAnimator valueAnimator) {
  16. 			float margin_left = (Float) valueAnimator
  17. 					.getAnimatedValue("margin_left");
  18. 			float margin_top = (Float) valueAnimator
  19. 					.getAnimatedValue("margin_top");
  21. 			RelativeLayout.LayoutParams p = (LayoutParams) v.getLayoutParams();
  23. 			p.leftMargin = (int) margin_left;
  24. 			p.topMargin = (int) margin_top;
  25. 			v.setLayoutParams(p);
  26. 		}
  27. 	});
  28. 	ani.start();
  29. }

實例2:使用ObjectAnimator動畫改變背景色

  1. /**
  2.  * 使用ObjectAnimator直接設置屬性和值
  3.  */
  4. public void changOneProperty(View v) {
  5. 	ValueAnimator colorAnimator = ObjectAnimator.ofInt(v,
  6. 			"backgroundColor", 0xffff8080 /*red*/ , 0xff8080ff /*Blue*/ );
  7. 	colorAnimator.setDuration(1000);
  8. 	colorAnimator.setEvaluator(new ArgbEvaluator());
  9. 	colorAnimator.setRepeatCount(ValueAnimator.INFINITE);
  10. 	colorAnimator.setRepeatMode(ValueAnimator.REVERSE);// ValueAnimator.RESTART
  11. 	colorAnimator.start();
  12. }

實例3:使用AnimatorSet改變多個屬性.

  1. public void changMultiplePropertyByValueAnimator2(View v) {
  3. 	/**
  4. 	 * 支持屬性: translationX and translationY: These properties control where
  5. 	 * the View is located as a delta from its left and top coordinates
  6. 	 * which are set by its layout container.
  7. 	 * 
  8. 	 * rotation, rotationX, and rotationY: These properties control the
  9. 	 * rotation in 2D (rotation property) and 3D around the pivot point.
  10. 	 * 
  11. 	 * scaleX and scaleY: These properties control the 2D scaling of a View
  12. 	 * around its pivot point.
  13. 	 * 
  14. 	 * pivotX and pivotY: These properties control the location of the pivot
  15. 	 * point, around which the rotation and scaling transforms occur. By
  16. 	 * default, the pivot point is located at the center of the object.
  17. 	 * 
  18. 	 * x and y: These are simple utility properties to describe the final
  19. 	 * location of the View in its container, as a sum of the left and top
  20. 	 * values and translationX and translationY values.
  21. 	 * 
  22. 	 * alpha: Represents the alpha transparency on the View. This value is 1
  23. 	 * (opaque) by default, with a value of 0 representing full transparency
  24. 	 * (not visible).
  25. 	 */
  26. 	AnimatorSet set = new AnimatorSet();
  27. 	set.playTogether(
  28. 			ObjectAnimator.ofFloat(v, "rotation", 0, -90f),
  29. 			ObjectAnimator.ofFloat(v, "rotationX", 0, 360f),
  30. 			ObjectAnimator.ofFloat(v, "rotationY", 0, 360f),
  31. 			ObjectAnimator.ofFloat(v, "translationX", 0, 200f),
  32. 			ObjectAnimator.ofFloat(v, "translationY", 0, 200f),
  33. 			ObjectAnimator.ofFloat(v, "scalY", 1, 1.5f),
  34. 			ObjectAnimator.ofFloat(v, "scalX", 1, 2.0f),
  35. 			ObjectAnimator.ofFloat(v, "alpan", 1, 0.25f, 1),
  36. 			ObjectAnimator.ofFloat(v, "translationY", 0, 200f));
  37. 	//set.playSequentially(animator1,animator2,animator3);
  38. 	//set.play(ObjectAnimator.ofFloat(v, "rotation", 0, -90f)).with(anim)
  39. 	set.setDuration(1000);
  40. 	set.start();
  42. }

實例4:使用PropertyValuesHolder和ObjectAnimator改變多個屬性.

  1. /**
  2.  * 使用PropertyValuesHolder: scal alpha
  3.  * @param view
  4.  */
  5. public void propertyValuesHolder(View view) {
  6. 	PropertyValuesHolder pvhX = PropertyValuesHolder.ofFloat("alpha", 1f,0f, 1f
                

                    

                    

                    

                    
                     
    
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