Add additional method for setPageTransformer.
Add new method that allows to specify if setting PageTransformer should
also enable hardware type layers for the ViewPager pages.
Additionally, clarify the impact of the default behavior of setting
PageTransformer.
Bug: 29358872
Change-Id: I9e2b1ab6d1c319259c670b9e0a22b966849abd14
diff --git a/api/current.txt b/api/current.txt
index d2d255b..ae131ad 100644
--- a/api/current.txt
+++ b/api/current.txt
@@ -6495,6 +6495,7 @@
method public void setPageMarginDrawable(android.graphics.drawable.Drawable);
method public void setPageMarginDrawable(int);
method public void setPageTransformer(boolean, android.support.v4.view.ViewPager.PageTransformer);
+ method public void setPageTransformer(boolean, android.support.v4.view.ViewPager.PageTransformer, int);
field public static final int SCROLL_STATE_DRAGGING = 1; // 0x1
field public static final int SCROLL_STATE_IDLE = 0; // 0x0
field public static final int SCROLL_STATE_SETTLING = 2; // 0x2
diff --git a/core-ui/java/android/support/v4/view/ViewPager.java b/core-ui/java/android/support/v4/view/ViewPager.java
index ba4a6a6..1a2e5c0 100644
--- a/core-ui/java/android/support/v4/view/ViewPager.java
+++ b/core-ui/java/android/support/v4/view/ViewPager.java
@@ -243,6 +243,7 @@
private OnPageChangeListener mInternalPageChangeListener;
private List<OnAdapterChangeListener> mAdapterChangeListeners;
private PageTransformer mPageTransformer;
+ private int mPageTransformerLayerType;
private Method mSetChildrenDrawingOrderEnabled;
private static final int DRAW_ORDER_DEFAULT = 0;
@@ -749,18 +750,47 @@
}
/**
- * Set a {@link PageTransformer} that will be called for each attached page whenever
+ * Sets a {@link PageTransformer} that will be called for each attached page whenever
* the scroll position is changed. This allows the application to apply custom property
- * transformations to each page, overriding the default sliding look and feel.
+ * transformations to each page, overriding the default sliding behavior.
*
* <p><em>Note:</em> Prior to Android 3.0 the property animation APIs did not exist.
- * As a result, setting a PageTransformer prior to Android 3.0 (API 11) will have no effect.</p>
+ * As a result, setting a PageTransformer prior to Android 3.0 (API 11) will have no effect.
+ * By default, calling this method will cause contained pages to use
+ * {@link ViewCompat#LAYER_TYPE_HARDWARE}. This layer type allows custom alpha transformations,
+ * but it will cause issues if any of your pages contain a {@link android.view.SurfaceView}
+ * and you have not called {@link android.view.SurfaceView#setZOrderOnTop(boolean)} to put that
+ * {@link android.view.SurfaceView} above your app content. To disable this behavior, call
+ * {@link #setPageTransformer(boolean,PageTransformer,int)} and pass
+ * {@link ViewCompat#LAYER_TYPE_NONE} for {@code pageLayerType}.</p>
*
* @param reverseDrawingOrder true if the supplied PageTransformer requires page views
* to be drawn from last to first instead of first to last.
* @param transformer PageTransformer that will modify each page's animation properties
*/
public void setPageTransformer(boolean reverseDrawingOrder, PageTransformer transformer) {
+ setPageTransformer(reverseDrawingOrder, transformer, ViewCompat.LAYER_TYPE_HARDWARE);
+ }
+
+ /**
+ * Sets a {@link PageTransformer} that will be called for each attached page whenever
+ * the scroll position is changed. This allows the application to apply custom property
+ * transformations to each page, overriding the default sliding behavior.
+ *
+ * <p><em>Note:</em> Prior to Android 3.0 ({@link Build.VERSION_CODES#HONEYCOMB API 11}),
+ * the property animation APIs did not exist. As a result, setting a PageTransformer prior
+ * to API 11 will have no effect.</p>
+ *
+ * @param reverseDrawingOrder true if the supplied PageTransformer requires page views
+ * to be drawn from last to first instead of first to last.
+ * @param transformer PageTransformer that will modify each page's animation properties
+ * @param pageLayerType View layer type that should be used for ViewPager pages. It should be
+ * either {@link ViewCompat#LAYER_TYPE_HARDWARE},
+ * {@link ViewCompat#LAYER_TYPE_SOFTWARE}, or
+ * {@link ViewCompat#LAYER_TYPE_NONE}.
+ */
+ public void setPageTransformer(boolean reverseDrawingOrder, PageTransformer transformer,
+ int pageLayerType) {
if (Build.VERSION.SDK_INT >= 11) {
final boolean hasTransformer = transformer != null;
final boolean needsPopulate = hasTransformer != (mPageTransformer != null);
@@ -768,6 +798,7 @@
setChildrenDrawingOrderEnabledCompat(hasTransformer);
if (hasTransformer) {
mDrawingOrder = reverseDrawingOrder ? DRAW_ORDER_REVERSE : DRAW_ORDER_FORWARD;
+ mPageTransformerLayerType = pageLayerType;
} else {
mDrawingOrder = DRAW_ORDER_DEFAULT;
}
@@ -2007,7 +2038,7 @@
final int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
final int layerType = enable
- ? ViewCompat.LAYER_TYPE_HARDWARE : ViewCompat.LAYER_TYPE_NONE;
+ ? mPageTransformerLayerType : ViewCompat.LAYER_TYPE_NONE;
ViewCompat.setLayerType(getChildAt(i), layerType, null);
}
}
