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am 04c0f415: Merge "Update alpha documentation" into mnc-dev

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* commit '04c0f415b566932a98a65076a403a2e3b589a86c':
  Update alpha documentation
This commit is contained in:
Chris Craik
2015-05-01 20:47:15 +00:00
committed by Android Git Automerger
parent 3f5f1cb664 04c0f415b5
commit 3059dbb65a
1 changed files with 20 additions and 11 deletions
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31
core/java/android/view/View.java
View File

@@ -11091,25 +11091,34 @@ public class View implements Drawable.Callback, KeyEvent.Callback,
}
/**
* <p>Sets the opacity of the view. This is a value from 0 to 1, where 0 means the view is
* completely transparent and 1 means the view is completely opaque.</p>
* Sets the opacity of the view to a value from 0 to 1, where 0 means the view is
* completely transparent and 1 means the view is completely opaque.
*
* <p> Note that setting alpha to a translucent value (0 < alpha < 1) can have significant
* performance implications, especially for large views. It is best to use the alpha property
* sparingly and transiently, as in the case of fading animations.</p>
* <p class="note"><strong>Note:</strong> setting alpha to a translucent value (0 < alpha < 1)
* can have significant performance implications, especially for large views. It is best to use
* the alpha property sparingly and transiently, as in the case of fading animations.</p>
*
* <p>For a view with a frequently changing alpha, such as during a fading animation, it is
* strongly recommended for performance reasons to either override
* {@link #hasOverlappingRendering()} to return false if appropriate, or setting a
* {@link #setLayerType(int, android.graphics.Paint) layer type} on the view.</p>
* {@link #hasOverlappingRendering()} to return <code>false</code> if appropriate, or setting a
* {@link #setLayerType(int, android.graphics.Paint) layer type} on the view for the duration
* of the animation. On versions {@link android.os.Build.VERSION_CODES#MNC} and below,
* the default path for rendering an unlayered View with alpha could add multiple milliseconds
* of rendering cost, even for simple or small views. Starting with
* {@link android.os.Build.VERSION_CODES#MNC}, {@link #LAYER_TYPE_HARDWARE} is automatically
* applied to the view at the rendering level.</p>
*
* <p>If this view overrides {@link #onSetAlpha(int)} to return true, then this view is
* responsible for applying the opacity itself.</p>
*
* <p>Note that if the view is backed by a
* {@link #setLayerType(int, android.graphics.Paint) layer} and is associated with a
* {@link #setLayerPaint(android.graphics.Paint) layer paint}, setting an alpha value less than
* 1.0 will supersede the alpha of the layer paint.</p>
* <p>On versions {@link android.os.Build.VERSION_CODES#LOLLIPOP_MR1} and below, note that if
* the view is backed by a {@link #setLayerType(int, android.graphics.Paint) layer} and is
* associated with a {@link #setLayerPaint(android.graphics.Paint) layer paint}, setting an
* alpha value less than 1.0 will supersede the alpha of the layer paint.</p>
*
* <p>Starting with {@link android.os.Build.VERSION_CODES#MNC}, setting a translucent alpha
* value will clip a View to its bounds, unless the View returns <code>false</code> from
* {@link #hasOverlappingRendering}.</p>
*
* @param alpha The opacity of the view.
*