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Xamarin Android Custom MasterDetailPage not calling OnLayout when page pushed to detail page which is NavigaionPage

I took the source I found here:
https://github.com/xamarin/Xamarin.Forms/blob/master/Xamarin.Forms.Platform.Android/Renderers/MasterDetailRenderer.cs
And created a custom renderer in a Xamarin Forms Android project. I got the project to build and the menu to open / close as expected as well as display the starting detail page.
The detail page is a "NavigaionPage" in Xamarin.Forms which is actually just a ViewGroup with a bunch of code to make it work with Push / Pop functions.
When I push a new Page, one that has a custom renderer and native RelativeLayout as a subview, the Page appears blank white until I rotate orientation.
After some research in the code, I realized both OnMeasure and OnLayout was not being called in the Page which was being pushed to the NavigationPage / detail page (with the pushed page's size stuck at 0x0 until orientation change).
I created another custom renderer but this time for the NavigationPage which looks like this:
public class MasterDetailContentNavigationPageRenderer : NavigationPageRenderer
{
protected override void OnElementChanged(ElementChangedEventArgs<NavigationPage> e)
{
base.OnElementChanged(e);
if(e.OldElement != null)
{
e.OldElement.Pushed -= handleOnPushed;
}
if(e.NewElement != null)
{
e.NewElement.Pushed += handleOnPushed;
}
}
private void handleOnPushed(object sender, EventArgs e)
{
var w = MeasureSpec.MakeMeasureSpec(MeasuredWidth, MeasureSpecMode.Exactly);
var h = MeasureSpec.MakeMeasureSpec(MeasuredHeight, MeasureSpecMode.Exactly);
Measure(w, h);
Layout(Left, Top, Right, Bottom);
}
}
This custom renderer for the detail page / NavigaionPage worked for 2 out of 3 of my pushed Pages.
The main / most important page did not fully add all of the UI elements.
The Page that was pushed and missing UI has SOME of the UI. The following is a list of how the page is displayed:
--- SongViewerLayout : RelativeLayout
------ RelativeLayout
--------- ViewerTopBar (draws all buttons except one)
--------- DocumentView (blank white spot between top bar and pagination)
--------- ViewerPagination (draws background color but not page buttons)
If I change orientations the missing button appears in the top bar, the page numbers show up and the document view sort of draws but it's off.
If I go back to using Xamarin.Forms provided MasterDetailPage the UI just loads as expected.
I have studied the code in the Xamarin.Forms repo but none of it really applies to the inner workings of the elements that are added. In other words, the detail page (which in my case is a NavigationPage) gets added on SetElement(...) and some handlers are assigned ... but nothing I could tell that looks for Pages being pushed and then responding. I would assume / expect the NavigationPage just to work as expected now that it's a subview of the MasterDetailPage / DrawerLayout.
Note: the views that seems to have the most issues are added programmatically and given "LayoutParamaters". The views found in the AXML seem to just show up.
Is there something I am missing to "initialize" a layout in Android? I have made native apps in Android and not had to do anything special.
Why would the UI above the NavigationPage cause the NavigationPage not to do standard initialization?
What am I missing???
Edit:
I created a working example of this issue on my GitHub account which you can clone here:
https://github.com/XamarinMonkey/CustomMasterDetail
Build and run CustomMasterDetail.Droid (Notice the UI is a MasterDetailPage)
Tap any item
The bottom blue bar has no page numbers.
Rotate orientation the page numbers display.
Stop the build
Comment out the entire class "MainMasterDetailPageRenderer.cs"
Rebuild / run the app
Tap any item
Page numbers are shown right away as expected just because it is now using the default MasterDetailPage!
Give suggestions please!
Edit #2:
Thanks to some feedback, it does not seem to be an issue in 6.0 devices. My testing device is a "Samsung Galaxy Tab Pro" with v5.1.1. And unfortunately I need this app to go back to 4!
Edit #3:
The issue has to be adding a view programmatically in Android 5.1.1 to a native RelativeLayout (which is pushed to a NavigationPage detail page ) after it is inflated in Xamarin.Forms. Calling Measure / Layout manually seems to solve the issue. But I need a more automated solution.

I came up with a solution that works. It might be expensive but it seems to layout fast on devices I have tested.
Basicly, I read up on Android and found a way to listen for layout changes using the ViewTreeObserver.GlobalLayout event combined with calling Measure / Layout on the detail and master ViewGroups.
public void MeasureAndLayoutNative()
{
if(_childView != null)
{
IVisualElementRenderer renderer = Platform.GetRenderer(_childView);
if(renderer.ViewGroup != null)
{
var nativeView = renderer.ViewGroup;
var w = MeasureSpec.MakeMeasureSpec(nativeView.MeasuredWidth, MeasureSpecMode.Exactly);
var h = MeasureSpec.MakeMeasureSpec(nativeView.MeasuredHeight, MeasureSpecMode.Exactly);
nativeView.Measure(w, h);
nativeView.Layout(nativeView.Left, nativeView.Top, nativeView.Right, nativeView.Bottom);
}
}
}
I updated my code example above with the working changes!

Custom Tabbed Page Renderer Xamarin Android

So know how to set up a custom renderer (only partially apparently) with an OnElementChanged method. I followed this (http://forums.xamarin.com/discussion/17654/tabbedpage-icons-not-visible-android)
protected override void OnElementChanged(ElementChangedEventArgs<TabbedPage> e)
{
base.OnElementChanged(e);
_activity = this.Context as Activity;
}
This gets hit, but it never displays the page afterwards.
Anyone have any ideas?

It is showing up now. I had to use the base class of TabbedRender rather than TabbedPageRenderer. I also had to add this.SetWillNotDraw(false) in the CustomRenderer constructor.

Here you can find a full TabbedPageRenderer ready to be modified. It comes directly from Xamarin.Forms Android.
Still I'm trying to set a different Font Size...

Moving between "pages" ( CCLayer ) in cocos2dx

I have 2 MyGameScreen objects that extends cocos2d::CCLayer. I am capturing the ccTouchesMove of the first screen so that I can create the moving effect exactly like sliding between pages of iOS application screen.
My class is like so:
class MyGameScreen: public cocos2d::CCLayer {
cocos2d::CCLayer* m_pNextScreen;
}
bool MyGameScreen::init() {
m_pNextScreen = MyOtherScreen::create();
}
void MyGameScreen::ccTouchesMoved(CCSet *touches, CCEvent *event){
// it crashes here... on the setPosition... m_pNextScreen is valid pointer though I am not sure that MyOtherScreen::create() is all I need to do...
m_pNextScreen->setPosition( CCPointMake( (fMoveTo - (2*fScreenHalfWidth)), 0.0f ) );
}
EDIT: adding clear question
It crashed when I try to setPosition on m_pNextScreen...
I have no idea why it crashed as m_pNextScreen is a valid pointer and is properly initialized. Could anybody explain why?
EDIT: adding progress report
I remodelled the whole system and make a class CContainerLayer : public cocos2d::CCLayer that contains both MyGameScreen and MyOtherScreen side by side. However, this looked like not an efficient approach, as when it grows I may need to have more than 2 pages scrollable side by side, I'd prefer to load the next page only when it is needed rather than the entire CContainerLayer that contains all the upcoming pages whether the user will scroll there or not... Do you have any better idea or github open source sample that does this?
Thank you very much for your input!

Use paging enable scrollview.download files from following link and place in your cocos2d/extenision/gui/ after that you have to set property of scrollview to enablepaging true with paging view size.
https://github.com/shauket/paging-scrollview

For Scene Transitions you can do this:
void MyGameScreen::ccTouchesMoved(CCSet *touches, CCEvent *event)
{
CCScene* MyOtherScene = CCTransitionFadeUp::create(0.2f, MyOtherScreen::scene());
CCDirector::sharedDirector()->replaceScene(MyOtherScene);
}

WebView appears as plain white box after the second time it's been initialised

EDIT: tl;dr: WebView appears as white box, even though I appear to be setting it up correctly, and indeed it does work the first two times, but fails subsequently)
EDIT: Video showing the problem in action...
I have the following bit of code which inflates a view (Which contains a WebView) from the xml which defines it:
private void createCard(ViewGroup cvFrame, Card card) {
//... setup vairables...
cvFrame.clearDisappearingChildren();
cvFrame.clearAnimation();
try {
View cv = LayoutInflater.from(getBaseContext()).inflate(R.layout.card_back_view,
cvFrame, true);
cv.setBackgroundDrawable(Drawable.createFromStream(mngr.open(deckName + "_Card_back.png"), deckName));
TextView suit = (TextView)cv.findViewWithTag("card_back_suit");
//...setup text view for suit, this code works fine every time...
WebView title = (WebView)cv.findViewWithTag("card_back_title");
//This WebView doesn't appear to be the one which actually appears on screen (I can change settings till I'm blue in the face, with no effect)
if (title != null) {
title.setBackgroundColor(0x00000000);
title.loadData(titleText, "text/html", "UTF-8");
} else {
Log.e("CardView", "Error can't find title WebView");
}
} catch (IOException e) {
Log.e("CardView", "Error making cards: ", e);
}
}
When this method is called as part of the onCreate method in my Activity, the WebView contains the correct code, and is suitably transparent.
I have a gesture listener which replaces the contents of the ViewGroup with different content (It animates the top card off to the left, replaces the contents of the top card with card 2, puts the top card back, then replaces card 2 with card 3)
//Gesture listener event
ViewGroup cvFrame = (ViewGroup)findViewById(R.id.firstCard);
cardLoc++
cvFrame.startAnimation(slideLeft);
(onAnimationEnd code)
public void onAnimationEnd(Animation animation) {
if (animation == slideLeft) {
ViewGroup cvFrameOldFront = (ViewGroup)findViewById(R.id.firstCard);
ViewGroup cvFrameNewFront = (ViewGroup)findViewById(R.id.secondCard);
createCard(cvFrameOldFront, cards.get((cardLoc)%cards.size()));
createCard(cvFrameNewFront, cards.get((cardLoc+1)%cards.size()));
TranslateAnimation slideBack = new TranslateAnimation(0,0,0,0);
slideBack.setDuration(1);
slideBack.setFillAfter(true);
cvFrameOldFront.startAnimation(slideBack);
}
}
When the animation has happened and I replace the contents of the cards, the TextView suit is replaced fine and the code definitely passes through the code to replace the WebView contents, but for some reason I end up with a white rectangle the size and shape of the WebView, no content, no transparency.
If I change the WebView to a TextView, it's contents is replaced fine, so it's an issue that occurs only with the WebView control :S
Can anyone tell me why / suggest a fix?

It turns out the WebView doesn't get cleared down when using the LayoutInflater to replace the contents of a ViewGroup. The other controls all seem to get removed (or at least the findViewWithTag() returns the right reference for every other control). I've just added in the line cvFrame.removeAllViews() immediately before the LayoutInflater does it's stuff and that fixed the issue.
If anyone has any better explanation for this I'll throw the points their way otherwise they will just go into the ether...

By calling findViewById, you are getting a reference on the previously loaded webview do you ?
so the loadData call that fails is the second one you make on a single webview instance.
you may want to check this :
Android WebView - 1st LoadData() works fine, subsequent calls do not update display
It appears that loadData() won't load data twice... you may want to try WebView.loadDataWithBaseUri()
Hope that helps.

I had a similar problem loading several WebViews content.
It was because of a misusing of the pauseTimers function
The situation was : the first webView weren't needed anymore, conscientiously I wanted to pause it before to release it. Calling onPause() and pauseTimers()
pauseTimers being common to any web views, it broke every use of webviews occuring after that, there were displaying only white rectangles.
Maybe its not your problem here, but it's worth checking your not calling WebView.pauseTimers() somewhere.

To confirm your answer, the source code for LayoutInflater.inflate(int resource, ViewGroup root, boolean attachToRoot) does in fact internally calls root.addView() which attaches the newly inflated view at the end of the root's children instead of replacing them.
So the mystery now is why did your call to findViewWithTag() is returning the expected objects for your other widgets (which would be the top, most recently created instances), but for your WebView it was returning something else.
Is it possible that there is another object in your layout XML which shares the same "card_back_title" tag?
I was also wondering why you didn't use the more common findViewById() instead, but I am not sure whether it would make a difference.

Transparent InputMethod for Android

Trying to make an Android InputMethod that is transparent - i.e. the underlying content shows through to the keyboard that I am developing.
I've been able to make the View that I pass to the system transparent - I think - but there seems to be something underneath my view that is solid white - and obfuscating the underlying content.
It is definitely possible, these guys do it:
https://play.google.com/store/apps/details?id=com.aitype.android.tablet.p&feature=search_result#?t=W251bGwsMSwxLDEsImNvbS5haXR5cGUuYW5kcm9pZC50YWJsZXQucCJd

I figured it out! Not sure if this is how the guys in your play store link did it, but this is what worked for me. Also, I realize this post is over a year old, but I'm still answering it just in case someone else out there discovers this when trying to create a transparent keyboard.
The "something" under your view is actually nothing - it's empty space. Your keyboard pushed the entire view up and out of the way to make room for its height, leaving empty white space behind. Your transparent keyboard let this white space show through.
Here's the solution: instead of returning your view in onCreateInputView, return it in onCreateCandidatesView. That's the view that normally lives above the keyboard and lists the autocorrect suggestions. But you're going to use this to house your actual keyboard.
The reason you want to have your keyboard be a candidates view is because the input view most often pushes the underlying view up. Individual apps can decide how they want to behave when a keyboard is shown via android:windowSoftInputMode and the input view respects their preference, but the candidates view always uses adjustPan.
From the docs: "Note that because the candidate view tends to be shown and hidden a lot, it does not impact the application UI in the same way as the soft input view: it will never cause application windows to resize, only cause them to be panned if needed for the user to see the current focus." http://developer.android.com/reference/android/inputmethodservice/InputMethodService.html
So, return your transparent view from onCreateCandidatesView, return null from onCreateInputView and make sure to call setCandidatesViewShown(true) so your candidates view shows up (I call it in onWindowShown).

Normally InputMethodServices uses background color which is same with current binding application's background color. If you want to make this transparent, I think you should make it as popup-window structure, not an inputmethod window I think.

It may such easy to make the full screen keyboard layout extra area transparent via java reflection only if you're quite familiar with InputMethodService.
the extra area has an id name fullscreenArea, you can fetch the area's id, then findViewById() then set its background.
the keyboard look as this before I done my practice :
a giant blank cover the below page.
so after is :
you can see the below page which contained an EditText and others displayed.
here is my code :
public static void makeKeyboardTransparent(InputMethodService service) {
try {
View decorView = service.getWindow().getWindow().getDecorView();
final int viewId = fetchInternalRId("fullscreenArea");
View fullscreenArea = decorView.findViewById(viewId);
if (fullscreenArea != null) {
modifyView(fullscreenArea);
return;
}
} catch (Exception e) {
}
try {
Class<?> superClass = service.getClass().getSuperclass();
Field fullscreenAreaField = superClass.getDeclaredField("mFullscreenArea");
fullscreenAreaField.setAccessible(true);
View fullscreenArea = (View) fullscreenAreaField.get(service);
if (fullscreenArea != null) {
modifyView(fullscreenArea);
}
} catch (Exception e) {
}
}
private static void modifyView(View fullscreenArea) {
fullscreenArea.setBackgroundColor(Color.TRANSPARENT);
}
private static int fetchInternalRId(String name) throws Exception {
Class<?> rIdClass = Class.forName("com.android.internal.R$id");
return rIdClass.getDeclaredField(name).getInt(rIdClass);
}
I provided two approach to make the blank area transparent, both of them worked fine in my test, all you need is pass your InputMethodService into makeKeyboardTransparent() and see what it can do.