LayoutWrapContentUpdater.java

package your.name.here.util;

import android.util.Log;
import android.view.View;
import android.view.View.MeasureSpec;
import android.view.ViewGroup;
import android.view.ViewGroup.LayoutParams;

/**
 * README: Must be called on UI-Thread (main thread), so post to a handler if needed
 * 
 * NOTES: 
 * 		- To enable easier debugging, tag your nodes with android:tag="Name-of-my-node"
 * 		- Avoid using wrap_content on ScrollView!
 * 		- If you have center or right/bottom gravity, you should re-layout all nodes, not only the wrap_content: just call the method with the boolean set to true
 * 
 * @author Eric, April 2014
 */
public class LayoutWrapContentUpdater
{
	public static final String TAG = LayoutWrapContentUpdater.class.getName();


	/**
	 * Does what a proper requestLayout() should do about layout_width or layout_height = "wrap_content"
	 * 
	 * Warning: if the subTreeRoot itself has a "wrap_content" layout param, the size will be computed without boundaries maximum size.
	 * 			If you do have limits, consider either passing the parent, or calling the method with the size parameters (View.MeasureSpec)
	 * 
	 * @param subTreeRoot  root of the sub tree you want to recompute
	 */
	public static final void wrapContentAgain( ViewGroup subTreeRoot )
	{
		wrapContentAgain( subTreeRoot, false, MeasureSpec.UNSPECIFIED, MeasureSpec.UNSPECIFIED );
	}
	/** Same but allows re-layout of all views, not only those with "wrap_content". Necessary for "center", "right", "bottom",... */
	public static final void wrapContentAgain( ViewGroup subTreeRoot, boolean relayoutAllNodes )
	{
		wrapContentAgain( subTreeRoot, relayoutAllNodes, MeasureSpec.UNSPECIFIED, MeasureSpec.UNSPECIFIED );
	}
	/**
	 * Same as previous, but with given size in case subTreeRoot itself has layout_width or layout_height = "wrap_content"
	 */
	public static void wrapContentAgain( ViewGroup subTreeRoot, boolean relayoutAllNodes,
			int subTreeRootWidthMeasureSpec, int subTreeRootHeightMeasureSpec  )
	{
		Log.d(TAG, "+++ LayoutWrapContentUpdater wrapContentAgain on subTreeRoot=["+ subTreeRoot +"], with w="
				+ subTreeRootWidthMeasureSpec +" and h="+ subTreeRootHeightMeasureSpec );
		assert( "main".equals( Thread.currentThread().getName() ) );
		
		if (subTreeRoot == null)
			return;
		LayoutParams layoutParams = subTreeRoot.getLayoutParams();

		// --- First, we force measure on the subTree
		int widthMeasureSpec 	= subTreeRootWidthMeasureSpec;
		// When LayoutParams.MATCH_PARENT and Width > 0, we apply measured width to avoid getting dimensions too big
		if ( layoutParams.width  != LayoutParams.WRAP_CONTENT && subTreeRoot.getWidth() > 0 )
			widthMeasureSpec 	=  MeasureSpec.makeMeasureSpec( subTreeRoot.getWidth(), MeasureSpec.EXACTLY );
		int heightMeasureSpec 	= subTreeRootHeightMeasureSpec;
		// When LayoutParams.MATCH_PARENT and Height > 0, we apply measured height to avoid getting dimensions too big
		if ( layoutParams.height != LayoutParams.WRAP_CONTENT && subTreeRoot.getHeight() > 0 )
			heightMeasureSpec 	=  MeasureSpec.makeMeasureSpec( subTreeRoot.getHeight(), MeasureSpec.EXACTLY );
		// This measure recursively the whole sub-tree
		subTreeRoot.measure( widthMeasureSpec, heightMeasureSpec ); 

		// --- Then recurse on all children to correct the sizes 
		recurseWrapContent( subTreeRoot, relayoutAllNodes );

		// --- RequestLayout to finish properly
		subTreeRoot.requestLayout();		
		return;
	}


	/**
	 * Internal method to recurse on view tree. Tag you View nodes in XML layouts to read the logs more easily
	 */
	private static void recurseWrapContent( View nodeView, boolean relayoutAllNodes )
	{
		// Does not recurse when visibility GONE
		if ( nodeView.getVisibility() == View.GONE ) {
			// nodeView.layout( nodeView.getLeft(), nodeView.getTop(), 0, 0 );		// No need
			return;
		}
		
		LayoutParams layoutParams = nodeView.getLayoutParams();
		boolean isWrapWidth  = ( layoutParams.width  == LayoutParams.WRAP_CONTENT ) || relayoutAllNodes;
		boolean isWrapHeight = ( layoutParams.height == LayoutParams.WRAP_CONTENT ) || relayoutAllNodes;

		if ( isWrapWidth || isWrapHeight ) {
			
			boolean changed = false;
			int right  = nodeView.getRight();
			int bottom = nodeView.getBottom();
			
			if ( isWrapWidth  && nodeView.getMeasuredWidth() > 0 ) {
				right = nodeView.getLeft() + nodeView.getMeasuredWidth();
				changed = true;
				Log.v(TAG, "+++ LayoutWrapContentUpdater recurseWrapContent set Width to "+ nodeView.getMeasuredWidth() +" of node Tag="+ nodeView.getTag() +" ["+ nodeView +"]");
			}
			if ( isWrapHeight && nodeView.getMeasuredHeight() > 0 ) {
				bottom = nodeView.getTop() + nodeView.getMeasuredHeight();
				changed = true;
				Log.v(TAG, "+++ LayoutWrapContentUpdater recurseWrapContent set Height to "+ nodeView.getMeasuredHeight() +" of node Tag="+ nodeView.getTag() +" ["+ nodeView +"]");
			}
			
			if (changed) {
				nodeView.layout( nodeView.getLeft(), nodeView.getTop(), right, bottom );
				// FIXME: Adjust left & top position when gravity = "center" / "bottom" / "right"
			}
		}

		// --- Recurse
		if ( nodeView instanceof ViewGroup ) {
			ViewGroup nodeGroup = (ViewGroup)nodeView;
			for (int i = 0; i < nodeGroup.getChildCount(); i++) {
				recurseWrapContent( nodeGroup.getChildAt(i), relayoutAllNodes );
			}
		}
		return;
	}

	// End of class
}