[Android] Change null returns for exceptions to avoid ambiguity (micr…

…osoft#2715)

* Fallback with exceptions v1

* Fix bugs in previous version and add more descriptive details to exception

* Update comment

source/android/adaptivecards/src/main/java/io/adaptivecards/renderer/ActionLayoutRenderer.java

@@ -50,7 +50,8 @@ public View renderActions(
  BaseActionElementVector baseActionElementList,
  ICardActionHandler cardActionHandler,
  HostConfig hostConfig,
- RenderArgs renderArgs) {
+ RenderArgs renderArgs) throws AdaptiveFallbackException
+ {
  long size;
  if (baseActionElementList == null || (size = baseActionElementList.size()) <= 0)
  {
@@ -126,56 +127,74 @@ else if (alignment == ActionAlignment.Center.swigValue())
  BaseActionElement actionElement = baseActionElementList.get(i);
 
  IBaseActionElementRenderer actionRenderer = CardRendererRegistration.getInstance().getActionRenderer(actionElement.GetElementTypeString());
- View returnedView = null;
- if (actionRenderer != null)
+
+ try
  {
- returnedView = actionRenderer.render(renderedCard, context, fragmentManager, actionButtonsLayout, actionElement, cardActionHandler, hostConfig, renderArgs);
- }
+ if (actionRenderer == null)
+ {
+ throw new AdaptiveFallbackException(actionElement);
+ }
 
- boolean elementHasFallback = (actionElement.GetFallbackType() != FallbackType.None);
- if (actionRenderer == null || returnedView == null)
+ actionRenderer.render(renderedCard, context, fragmentManager, actionButtonsLayout, actionElement, cardActionHandler, hostConfig, renderArgs);
+ }
+ catch (AdaptiveFallbackException e)
  {
+ boolean elementHasFallback = (actionElement.GetFallbackType() != FallbackType.None);
+
  if (elementHasFallback)
  {
- if(actionElement.GetFallbackType() == FallbackType.Content)
+ if (actionElement.GetFallbackType() == FallbackType.Content)
  {
  BaseElement fallbackElement = actionElement.GetFallbackContent();
 
  while (fallbackElement != null)
  {
- BaseActionElement fallbackActionElement = null;
- if (fallbackElement instanceof BaseActionElement)
- {
- fallbackActionElement = (BaseActionElement) fallbackElement;
- }
- else if ((fallbackActionElement = BaseActionElement.dynamic_cast(fallbackElement)) == null)
+ try
  {
- throw new InternalError("Unable to convert BaseElement to BaseActionElement object model.");
- }
-
- IBaseActionElementRenderer fallbackActionRenderer = CardRendererRegistration.getInstance().getActionRenderer(fallbackActionElement.GetElementTypeString());;
+ BaseActionElement fallbackActionElement = null;
+ if (fallbackElement instanceof BaseActionElement)
+ {
+ fallbackActionElement = (BaseActionElement) fallbackElement;
+ }
+ else if ((fallbackActionElement = BaseActionElement.dynamic_cast(fallbackElement)) == null)
+ {
+ throw new InternalError("Unable to convert BaseElement to BaseActionElement object model.");
+ }
+
+ IBaseActionElementRenderer fallbackActionRenderer = CardRendererRegistration.getInstance().getActionRenderer(fallbackActionElement.GetElementTypeString());
+
+ if (fallbackActionRenderer == null)
+ {
+ throw new AdaptiveFallbackException(fallbackElement);
+ }
 
- if (fallbackActionRenderer != null)
- {
  fallbackActionRenderer.render(renderedCard, context, fragmentManager, actionButtonsLayout, fallbackActionElement, cardActionHandler, hostConfig, renderArgs);
  break;
  }
-
- if (fallbackActionElement.GetFallbackType() == FallbackType.Content)
+ catch (AdaptiveFallbackException e2)
  {
- fallbackElement = fallbackActionElement.GetFallbackContent();
- }
- else
- {
- // Either fallback is "drop" or not defined, in that case, stop trying
- break;
+ // As the fallback element didn't exist, go back to trying
+ if (fallbackElement.GetFallbackType() == FallbackType.Content)
+ {
+ fallbackElement = fallbackElement.GetFallbackContent();
+ }
+ else
+ {
+ // The element has no fallback, just clear the element so the cycle ends
+ fallbackElement = null;
+ }
  }
  }
  }
  }
+ else if (renderArgs.getAncestorHasFallback())
+ {
+ // There's an ancestor with fallback so we throw to trigger it
+ throw e;
+ }
  else
  {
- renderedCard.addWarning(new AdaptiveWarning(AdaptiveWarning.UNKNOWN_ELEMENT_TYPE,"Unsupported card element type: " + actionElement.GetElementTypeString()));
+ renderedCard.addWarning(new AdaptiveWarning(AdaptiveWarning.UNKNOWN_ELEMENT_TYPE, "Unsupported card element type: " + actionElement.GetElementTypeString()));
  continue;
  }
  }

source/android/adaptivecards/src/main/java/io/adaptivecards/renderer/AdaptiveCardRenderer.java

@@ -149,7 +149,13 @@ public View internalRender(RenderedAdaptiveCard renderedCard,
 
  RenderArgs renderArgs = new RenderArgs();
  renderArgs.setContainerStyle(style);
- CardRendererRegistration.getInstance().render(renderedCard, context, fragmentManager, layout, adaptiveCard, baseCardElementList, cardActionHandler, hostConfig, renderArgs);
+ try
+ {
+ CardRendererRegistration.getInstance().render(renderedCard, context, fragmentManager, layout, adaptiveCard, baseCardElementList, cardActionHandler, hostConfig, renderArgs);
+ }
+ // Catches the exception as the method throws it for performing fallback with elements inside the card,
+ // no fallback should be performed here so we just catch the exception
+ catch (AdaptiveFallbackException e){}
 
  if (hostConfig.GetSupportsInteractivity())
  {
@@ -163,8 +169,15 @@ public View internalRender(RenderedAdaptiveCard renderedCard,
  rootLayout.addView(showCardsLayout);
 
  IActionLayoutRenderer actionLayoutRenderer = CardRendererRegistration.getInstance().getActionLayoutRenderer();
- if(actionLayoutRenderer != null) {
- actionLayoutRenderer.renderActions(renderedCard, context, fragmentManager, layout, baseActionElementList, cardActionHandler, hostConfig, renderArgs);
+ if(actionLayoutRenderer != null)
+ {
+ try
+ {
+ actionLayoutRenderer.renderActions(renderedCard, context, fragmentManager, layout, baseActionElementList, cardActionHandler, hostConfig, renderArgs);
+ }
+ // Catches the exception as the method throws it for performing fallback with elements inside the card,
+ // no fallback should be performed here so we just catch the exception
+ catch (AdaptiveFallbackException e) {}
  }
  }
  }

source/android/adaptivecards/src/main/java/io/adaptivecards/renderer/AdaptiveFallbackException.java

@@ -0,0 +1,20 @@
+package io.adaptivecards.renderer;
+
+import io.adaptivecards.objectmodel.BaseElement;
+
+/***
+ * Exception for signalizing that an element could not be rendered and fallback should be performed
+ */
+public class AdaptiveFallbackException extends Exception
+{
+ public AdaptiveFallbackException(BaseElement element)
+ {
+ super("No renderer exists for element type: " + element.GetElementTypeString());
+ m_element = element;
+ }
+
+ // I'm saving this object in case I ever need to debug this
+ // No getters or setters are provided as outside developers shouldn't have
+ // to find this Exception (unless overriding the action layout renderer)
+ private BaseElement m_element = null;
+}

source/android/adaptivecards/src/main/java/io/adaptivecards/renderer/IActionLayoutRenderer.java

@@ -17,5 +17,5 @@ public View renderActions(RenderedAdaptiveCard renderedCard,
  BaseActionElementVector baseActionElementList,
  ICardActionHandler cardActionHandler,
  HostConfig hostConfig,
- RenderArgs renderArgs);
+ RenderArgs renderArgs) throws AdaptiveFallbackException;
 }

source/android/adaptivecards/src/main/java/io/adaptivecards/renderer/IBaseActionElementRenderer.java

@@ -22,5 +22,5 @@ Button render(
  BaseActionElement baseActionElement,
  ICardActionHandler cardActionHandler,
  HostConfig hostConfig,
- RenderArgs renderArgs);
+ RenderArgs renderArgs) throws AdaptiveFallbackException;
 }

source/android/adaptivecards/src/main/java/io/adaptivecards/renderer/IBaseCardElementRenderer.java

@@ -23,5 +23,5 @@ View render(
  BaseCardElement baseCardElement,
  ICardActionHandler cardActionHandler,
  HostConfig hostConfig,
- RenderArgs renderArgs);
+ RenderArgs renderArgs) throws AdaptiveFallbackException;
 }

source/android/adaptivecards/src/main/java/io/adaptivecards/renderer/action/ActionSetRenderer.java

@@ -79,7 +79,11 @@ else if ((actionSet = ActionSet.dynamic_cast(baseCardElement)) == null)
 
  BaseActionElementVector baseActionElementList = actionSet.GetActions();
 
- ActionLayoutRenderer.getInstance().renderActions(renderedCard, context, fragmentManager, actionsLayout, baseActionElementList, cardActionHandler, hostConfig, renderArgs);
+ try
+ {
+ ActionLayoutRenderer.getInstance().renderActions(renderedCard, context, fragmentManager, actionsLayout, baseActionElementList, cardActionHandler, hostConfig, renderArgs);
+ }
+ catch (Exception e) {}
 
  viewGroup.addView(rootLayout);
  return rootLayout;

source/android/adaptivecards/src/main/java/io/adaptivecards/renderer/readonly/ColumnRenderer.java

@@ -12,6 +12,7 @@
 import io.adaptivecards.objectmodel.BackgroundImage;
 import io.adaptivecards.objectmodel.ContainerStyle;
 import io.adaptivecards.objectmodel.VerticalContentAlignment;
+import io.adaptivecards.renderer.AdaptiveFallbackException;
 import io.adaptivecards.renderer.BackgroundImageLoaderAsync;
 import io.adaptivecards.renderer.BaseActionElementRenderer;
 import io.adaptivecards.renderer.RenderArgs;
@@ -63,7 +64,7 @@ public View render(
  BaseCardElement baseCardElement,
  ICardActionHandler cardActionHandler,
  HostConfig hostConfig,
- RenderArgs renderArgs)
+ RenderArgs renderArgs) throws AdaptiveFallbackException
  {
  Column column;
  if (baseCardElement instanceof Column)
@@ -87,7 +88,7 @@ else if ((column = Column.dynamic_cast(baseCardElement)) == null)
  returnedView.setClipChildren(false);
  returnedView.setClipToPadding(false);
 
- if(!baseCardElement.GetIsVisible())
+ if (!baseCardElement.GetIsVisible())
  {
  returnedView.setVisibility(View.GONE);
  }
@@ -116,7 +117,7 @@ else if ((column = Column.dynamic_cast(baseCardElement)) == null)
  renderArgs1.setContainerStyle(styleForThis);
  if (!column.GetItems().isEmpty())
  {
- View v = CardRendererRegistration.getInstance().render(renderedCard,
+ CardRendererRegistration.getInstance().render(renderedCard,
  context,
  fragmentManager,
  verticalContentAlignmentLayout,
@@ -125,12 +126,6 @@ else if ((column = Column.dynamic_cast(baseCardElement)) == null)
  cardActionHandler,
  hostConfig,
  renderArgs1);
-
- // This failed to render, so return null
- if (v == null)
- {
- return null;
- }
  }
 
  if (styleForThis != renderArgs.getContainerStyle())

source/android/adaptivecards/src/main/java/io/adaptivecards/renderer/readonly/ColumnSetRenderer.java

@@ -2,22 +2,20 @@
 
 import android.content.Context;
 import android.graphics.Color;
-import android.nfc.Tag;
 import android.support.v4.app.FragmentManager;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.LinearLayout;
 
 import io.adaptivecards.objectmodel.ContainerStyle;
 import io.adaptivecards.objectmodel.HeightType;
+import io.adaptivecards.renderer.AdaptiveFallbackException;
 import io.adaptivecards.renderer.BaseActionElementRenderer;
 import io.adaptivecards.renderer.RenderArgs;
 import io.adaptivecards.renderer.RenderedAdaptiveCard;
 import io.adaptivecards.renderer.TagContent;
 import io.adaptivecards.renderer.Util;
-import io.adaptivecards.renderer.action.ActionElementRenderer;
 import io.adaptivecards.renderer.actionhandler.ICardActionHandler;
-import io.adaptivecards.renderer.inputhandler.IInputHandler;
 import io.adaptivecards.objectmodel.BaseCardElement;
 import io.adaptivecards.objectmodel.CardElementType;
 import io.adaptivecards.objectmodel.Column;
@@ -28,8 +26,6 @@
 import io.adaptivecards.renderer.registration.CardRendererRegistration;
 import io.adaptivecards.renderer.IBaseCardElementRenderer;
 
-import java.util.Vector;
-
 
 public class ColumnSetRenderer extends BaseCardElementRenderer
 {
@@ -56,7 +52,7 @@ public View render(
  BaseCardElement baseCardElement,
  ICardActionHandler cardActionHandler,
  HostConfig hostConfig,
- RenderArgs renderArgs)
+ RenderArgs renderArgs) throws AdaptiveFallbackException
  {
  ColumnSet columnSet = null;
  if (baseCardElement instanceof ColumnSet)
@@ -93,25 +89,23 @@ else if ((columnSet = ColumnSet.dynamic_cast(baseCardElement)) == null)
  }
 
  ContainerStyle containerStyle = renderArgs.getContainerStyle();
- for (int i = 0; i < columnVectorSize; i++) {
+ for (int i = 0; i < columnVectorSize; i++)
+ {
  Column column = columnVector.get(i);
 
  ColumnRenderer rendererAsColumnRenderer = null;
  if (columnRenderer instanceof ColumnRenderer)
  {
- rendererAsColumnRenderer = (ColumnRenderer)columnRenderer;
+ rendererAsColumnRenderer = (ColumnRenderer) columnRenderer;
  rendererAsColumnRenderer.setIsRenderingFirstColumn(i == 0);
  rendererAsColumnRenderer.setIsRenderingLastColumn(i == (columnVectorSize - 1));
  }
 
- View v = columnRenderer.render(renderedCard, context, fragmentManager, layout, column, cardActionHandler, hostConfig, renderArgs);
- if (v == null)
- {
- return null;
- }
+ columnRenderer.render(renderedCard, context, fragmentManager, layout, column, cardActionHandler, hostConfig, renderArgs);
  }
 
- if (columnSet.GetSelectAction() != null) {
+ if (columnSet.GetSelectAction() != null)
+ {
  layout.setClickable(true);
  layout.setOnClickListener(new BaseActionElementRenderer.SelectActionOnClickListener(renderedCard, columnSet.GetSelectAction(), cardActionHandler));
  }

source/android/adaptivecards/src/main/java/io/adaptivecards/renderer/readonly/ContainerRenderer.java

@@ -13,6 +13,7 @@
 import io.adaptivecards.objectmodel.ContainerStyle;
 import io.adaptivecards.objectmodel.HeightType;
 import io.adaptivecards.objectmodel.VerticalContentAlignment;
+import io.adaptivecards.renderer.AdaptiveFallbackException;
 import io.adaptivecards.renderer.BackgroundImageLoaderAsync;
 import io.adaptivecards.renderer.BaseActionElementRenderer;
 import io.adaptivecards.renderer.RenderArgs;
@@ -52,7 +53,7 @@ public View render(
  BaseCardElement baseCardElement,
  ICardActionHandler cardActionHandler,
  HostConfig hostConfig,
- RenderArgs renderArgs)
+ RenderArgs renderArgs) throws AdaptiveFallbackException
  {
  Container container = null;
  if (baseCardElement instanceof Container)
@@ -106,20 +107,15 @@ else if ((container = Container.dynamic_cast(baseCardElement)) == null)
 
  if (!container.GetItems().isEmpty())
  {
- View v = CardRendererRegistration.getInstance().render(renderedCard,
- context,
- fragmentManager,
- containerView,
- container,
- container.GetItems(),
- cardActionHandler,
- hostConfig,
- renderArgs);
-
- if (v == null)
- {
- return null;
- }
+ CardRendererRegistration.getInstance().render(renderedCard,
+ context,
+ fragmentManager,
+ containerView,
+ container,
+ container.GetItems(),
+ cardActionHandler,
+ hostConfig,
+ renderArgs);
  }
 
  if (styleForThis != containerStyle)

source/android/adaptivecards/src/main/java/io/adaptivecards/renderer/readonly/ImageSetRenderer.java

@@ -9,6 +9,7 @@
 
 import io.adaptivecards.objectmodel.ContainerStyle;
 import io.adaptivecards.objectmodel.HeightType;
+import io.adaptivecards.renderer.AdaptiveFallbackException;
 import io.adaptivecards.renderer.BaseCardElementRenderer;
 import io.adaptivecards.renderer.IBaseCardElementRenderer;
 import io.adaptivecards.renderer.RenderArgs;
@@ -90,8 +91,16 @@ else if ((imageSet = ImageSet.dynamic_cast(baseCardElement)) == null)
 
  // TODO: temporary - this will be handled in the object model
  image.SetImageSize(imageSize);
- View imageView = imageRenderer.render(renderedCard, context, fragmentManager, horizFlowLayout, image, cardActionHandler, hostConfig, renderArgs);
- ((ImageView) imageView).setMaxHeight(Util.dpToPixels(context, hostConfig.GetImageSet().getMaxImageHeight()));
+
+ try
+ {
+ View imageView = imageRenderer.render(renderedCard, context, fragmentManager, horizFlowLayout, image, cardActionHandler, hostConfig, renderArgs);
+ ((ImageView) imageView).setMaxHeight(Util.dpToPixels(context, hostConfig.GetImageSet().getMaxImageHeight()));
+ }
+ catch (AdaptiveFallbackException e)
+ {
+ continue;
+ }
  }
 
  if (imageSet.GetHeight() == HeightType.Stretch)