Cannot resize linear layout children in android react native module

问题

Full code here

Video of correct behavior in java and incorrect in react native here

I have modified a linear layout to respond to touch by resizing the left child while the right child takes up the rest of the space, simulating a horizontal scroll that can be 'opened' or 'closed' using the following code

    LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams) leftView.getLayoutParams();
    //Log.d("ll","width " + newWidth);
    lp.width=newWidth;
    leftView.setLayoutParams(lp);

In react native, touch is still calling this method and logging the expected values, but the size of the children is not updated. The only time it updates is when I switch the visibility to gone then visible again. Calling invalidate/requestLayout on the view from java or forceUpdate from js does not have any effect.

Is there some other code I need to call to invalidate and redraw the view? Is there a hint I need to give to react that this component scrolls or responds to touch?

回答1:

I had the same problem and I found the answer on this old reported issue on react native's repo.

Add the following code in your custom layout and after that there is no need to even call requestLayout() or invalidate(). The changes are propagated as soon as you update your layout's LayoutParams. This solution is the same as the ones used in ReactPicker.java and ReactToolbar.java.

@Override
public void requestLayout() {
    super.requestLayout();

    // The spinner relies on a measure + layout pass happening after it calls requestLayout().
    // Without this, the widget never actually changes the selection and doesn't call the
    // appropriate listeners. Since we override onLayout in our ViewGroups, a layout pass never
    // happens after a call to requestLayout, so we simulate one here.
    post(measureAndLayout);
}

private final Runnable measureAndLayout = new Runnable() {
    @Override
    public void run() {
        measure(
                MeasureSpec.makeMeasureSpec(getWidth(), MeasureSpec.EXACTLY),
                MeasureSpec.makeMeasureSpec(getHeight(), MeasureSpec.EXACTLY));
        layout(getLeft(), getTop(), getRight(), getBottom());
    }
};

回答2:

RN android is indeed not updating children layout or visibility or adapter changes under most conditions. By inserting hooks into the custom view when an update is needed that will invalidate/requestLayout then call this code normal behavior is restored, mostly. There are still some cases where measurement does not happen like it does normally and I have to postDelayed Runnables that then cause this invalidation. Dealing with a node's parents may not be strictly necessary in all cases, but it is for some.

In View Manager

Method markNewLayout, getShadowNode;

public ViewManager(){
    super();
    if (markNewLayout == null) {
        try {
            markNewLayout = CSSNode.class.getDeclaredMethod("markHasNewLayout");
            markNewLayout.setAccessible(true);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    try{
    if (getShadowNode==null){
        getShadowNode = UIImplementation.class.getDeclaredMethod("resolveShadowNode",int.class);
        getShadowNode.setAccessible(true);
    }
    } catch (Exception e) {
    e.printStackTrace();
}
public class MyShadowNode extends LayoutShadowNode {
@Override
public void markUpdated(){
    super.markUpdated();
    if (hasNewLayout()) markLayoutSeen();
    dirty();
}
@Override
public boolean isDirty(){
    return true;
}




 @Override
    protected CustomView createViewInstance(final ThemedReactContext reactContext) {

 view.setRnUpdateListener(new CustomView.RNUpdateListener() {
            MyShadowNode node;
            @Override
            public void needsUpdate() {
                view.requestLayout();


                Runnable r = new Runnable() {
                    @Override
                    public void run() {

                        if (node ==null){
                            try {
                                node = (MyShadowNode) getShadowNode.invoke(uiImplementation, view.getId());
                            }
                            catch (Exception e){
                                e.printStackTrace();
                            }
                        }
                            if (node != null) {
                                if (node.hasNewLayout()) node.markLayoutSeen();
                                ReactShadowNode parent = node.getParent();
                                while (parent != null) {
                                    if (parent.hasNewLayout()) {
                                        try {
                                            markNewLayout.invoke(parent,view.getId());
                                        } catch (Exception e) {
                                            e.printStackTrace();
                                        }
                                        parent.markLayoutSeen();
                                    }
                                    parent = parent.getParent();
                                }
                                node.markUpdated();
                            }
                            Log.d(getName(), "markUpdated");
                    }

                };
                reactContext.runOnNativeModulesQueueThread(r);
            }
        });


    }

回答3:

Try removing content of the layout one by one. May be one among those children has wrap content. You can use hierarchyViewer and uiautomatorviewer for it Also think about weights also. If possible post the hierarchyViewer data.

回答4:

LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams) leftView.getLayoutParams();
lp.width=newWidth;
leftView.setLayoutParams(lp);
leftView.requestLayout(); 

Above code will solve you problem.

来源：https://stackoverflow.com/questions/38934776/cannot-resize-linear-layout-children-in-android-react-native-module