Allow ModelView usage without an xml layout

epoxy-annotations/src/main/java/com/airbnb/epoxy/ModelView.java

@@ -16,9 +16,34 @@
 @Target(ElementType.TYPE)
 @Retention(RetentionPolicy.CLASS)
 public @interface ModelView {
+
+  /**
+   * Use with {@link #autoLayout()} to declare what layout parameters should be used to size your
+   * view when it is added to a RecyclerView. This maps to the LayoutParams options {@code
+   * layout_width} and {@code layout_height}.
+   */
+  enum Size {
+    NONE,
+    WRAP_WIDTH_WRAP_HEIGHT,
+    WRAP_WIDTH_MATCH_HEIGHT,
+    MATCH_WIDTH_WRAP_HEIGHT,
+    MATCH_WIDTH_MATCH_HEIGHT
+  }
+
+  /**
+   * If set to an option besides {@link Size#NONE} Epoxy will create an instance of this view
+   * programmatically at runtime instead of inflating the view from xml. This is an alternative to
+   * using {@link #defaultLayout()}, and is a good option if you just need to specify layout
+   * parameters on your view with no other styling.
+   * <p>
+   * The size option you choose will define which layout parameters Epoxy uses at runtime when
+   * creating the view.
+   */
+  Size autoLayout() default Size.NONE;
+
   /**
    * The layout file to use in the generated model to inflate the view. This is required unless a
-   * default pattern is set via {@link PackageModelViewConfig}.
+   * default pattern is set via {@link PackageModelViewConfig} or {@link #autoLayout()} is used.
    * <p>
    * Overrides any default set in {@link PackageModelViewConfig}
    */

epoxy-processor/src/main/java/com/airbnb/epoxy/ClassNames.java

@@ -19,6 +19,8 @@ private ClassNames() {
   static final ClassName ANDROID_CONTEXT = get(PKG_ANDROID_CONTENT, "Context");
   static final ClassName ANDROID_VIEW = get(PKG_ANDROID_VIEW, "View");
   static final ClassName ANDROID_VIEW_GROUP = get(PKG_ANDROID_VIEW, "ViewGroup");
+  static final ClassName ANDROID_MARGIN_LAYOUT_PARAMS =
+      get(PKG_ANDROID_VIEW, "ViewGroup", "MarginLayoutParams");
   static final ClassName ANDROID_R = get(PKG_ANDROID, "R");
 
   static final ClassName LITHO_COMPONENT = get(PKG_LITHO, "Component");

epoxy-processor/src/main/java/com/airbnb/epoxy/GeneratedModelInfo.java

@@ -2,6 +2,7 @@
 
 import android.support.annotation.Nullable;
 
+import com.airbnb.epoxy.ModelView.Size;
 import com.squareup.javapoet.AnnotationSpec;
 import com.squareup.javapoet.ClassName;
 import com.squareup.javapoet.CodeBlock;
@@ -64,6 +65,12 @@ abstract class GeneratedModelInfo {
    */
   private ParisStyleAttributeInfo styleBuilderInfo;
 
+  /**
+   * An option set via {@link ModelView#autoLayout()} to have Epoxy create the view programmatically
+   * instead of via xml layout resource inflation.
+   */
+  Size layoutParams = Size.NONE;
+
   /**
    * Get information about methods returning class type of the original class so we can duplicate
    * them in the generated class for chaining purposes
@@ -204,12 +211,16 @@ boolean isStyleable() {
     return getStyleBuilderInfo() != null;
   }
 
-  public void setStyleable(
+  void setStyleable(
       @NotNull ParisStyleAttributeInfo parisStyleAttributeInfo) {
     styleBuilderInfo = parisStyleAttributeInfo;
     addAttribute(parisStyleAttributeInfo);
   }
 
+  boolean isProgrammaticView() {
+    return isStyleable() || layoutParams != Size.NONE;
+  }
+
   static class ConstructorInfo {
     final Set<Modifier> modifiers;
     final List<ParameterSpec> params;

epoxy-processor/src/main/java/com/airbnb/epoxy/GeneratedModelWriter.java

@@ -75,6 +75,11 @@ class GeneratedModelWriter {
   private static final String GET_DEFAULT_LAYOUT_METHOD_NAME = "getDefaultLayout";
   static final String ATTRIBUTES_BITSET_FIELD_NAME = "assignedAttributes" + GENERATED_FIELD_SUFFIX;
 
+  private static final CodeBlock LAYOUT_PARAMS_MATCH_PARENT =
+      CodeBlock.of("$T.MATCH_PARENT", ClassNames.ANDROID_MARGIN_LAYOUT_PARAMS);
+  private static final CodeBlock LAYOUT_PARAMS_WRAP_CONTENT =
+      CodeBlock.of("$T.WRAP_CONTENT", ClassNames.ANDROID_MARGIN_LAYOUT_PARAMS);
+
   private final Filer filer;
   private final Types typeUtils;
   private final ErrorLogger errorLogger;
@@ -151,6 +156,7 @@ void generateClassForModel(GeneratedModelInfo info, BuilderHooks builderHooks)
     generateDebugAddToMethodIfNeeded(builder, info);
 
     builder
+        .addMethods(generateProgrammaticViewMethods(info))
         .addMethods(generateBindMethods(info))
         .addMethods(generateStyleableViewMethods(info))
         .addMethods(generateSettersAndGetters(info))
@@ -175,7 +181,7 @@ void generateClassForModel(GeneratedModelInfo info, BuilderHooks builderHooks)
 
   private Iterable<MethodSpec> generateOtherLayoutOptions(GeneratedModelInfo info) {
     if (!info.includeOtherLayoutOptions
-        || info.isStyleable()) { // Layout resources can't be mixed with programmatic styles
+        || info.isProgrammaticView()) { // Layout resources can't be mixed with programmatic views
       return Collections.emptyList();
     }
 
@@ -410,6 +416,67 @@ private static int attributeIndex(GeneratedModelInfo modelInfo, AttributeInfo at
     return index;
   }
 
+  private Iterable<MethodSpec> generateProgrammaticViewMethods(GeneratedModelInfo modelInfo) {
+
+    if (!modelInfo.isProgrammaticView()) {
+      return Collections.emptyList();
+    }
+
+    List<MethodSpec> methods = new ArrayList<>();
+
+    // getViewType method so that view type is generated at runtime
+    methods.add(MethodSpec.methodBuilder("getViewType")
+        .addAnnotation(Override.class)
+        .addModifiers(PROTECTED)
+        .returns(TypeName.INT)
+        .addStatement("return 0", modelInfo.boundObjectTypeName)
+        .build());
+
+    // buildView method to return new view instance
+    Builder builder = MethodSpec.methodBuilder("buildView")
+        .addAnnotation(Override.class)
+        .addParameter(ClassNames.ANDROID_VIEW_GROUP, "parent")
+        .addModifiers(PROTECTED)
+        .returns(modelInfo.boundObjectTypeName)
+        .addStatement("$T v = new $T(parent.getContext())", modelInfo.boundObjectTypeName,
+            modelInfo.boundObjectTypeName);
+
+    CodeBlock layoutWidth;
+    CodeBlock layoutHeight;
+    switch (modelInfo.layoutParams) {
+      case WRAP_WIDTH_MATCH_HEIGHT:
+        layoutWidth = LAYOUT_PARAMS_WRAP_CONTENT;
+        layoutHeight = LAYOUT_PARAMS_MATCH_PARENT;
+        break;
+      case MATCH_WIDTH_MATCH_HEIGHT:
+        layoutWidth = LAYOUT_PARAMS_MATCH_PARENT;
+        layoutHeight = LAYOUT_PARAMS_MATCH_PARENT;
+        break;
+      case MATCH_WIDTH_WRAP_HEIGHT:
+        layoutWidth = LAYOUT_PARAMS_MATCH_PARENT;
+        layoutHeight = LAYOUT_PARAMS_WRAP_CONTENT;
+        break;
+      case WRAP_WIDTH_WRAP_HEIGHT:
+      default:
+        // This will be used for Styleable views as the default
+        layoutWidth = LAYOUT_PARAMS_WRAP_CONTENT;
+        layoutHeight = LAYOUT_PARAMS_WRAP_CONTENT;
+    }
+
+    builder
+        .addStatement("v.setLayoutParams(new $T($L, $L))",
+            ClassNames.ANDROID_MARGIN_LAYOUT_PARAMS, layoutWidth, layoutHeight);
+
+    ParisStyleAttributeInfo styleBuilderInfo = modelInfo.getStyleBuilderInfo();
+    if (styleBuilderInfo != null) {
+      addStyleApplierCode(builder, styleBuilderInfo, "v");
+    }
+
+    methods.add(builder.addStatement("return v").build());
+
+    return methods;
+  }
+
   private Iterable<MethodSpec> generateBindMethods(GeneratedModelInfo classInfo) {
     List<MethodSpec> methods = new ArrayList<>();
 
@@ -600,28 +667,6 @@ private Iterable<MethodSpec> generateStyleableViewMethods(GeneratedModelInfo mod
     TypeName styleType = styleBuilderInfo.getTypeName();
     ClassName styleBuilderClass = styleBuilderInfo.getStyleBuilderClass();
 
-    // buildView method to return new view instance
-    Builder buildViewMethodBuilder = MethodSpec.methodBuilder("buildView")
-        .addAnnotation(Override.class)
-        .addParameter(ClassNames.ANDROID_VIEW_GROUP, "parent")
-        .addModifiers(PROTECTED)
-        .returns(modelInfo.boundObjectTypeName)
-        .addStatement("$T v = new $T(parent.getContext())", modelInfo.boundObjectTypeName,
-            modelInfo.boundObjectTypeName)
-        .addStatement("v.setLayoutParams(parent.generateLayoutParams(null))");
-
-    addStyleApplierCode(buildViewMethodBuilder, styleBuilderInfo, "v");
-    buildViewMethodBuilder.addStatement("return v");
-    methods.add(buildViewMethodBuilder.build());
-
-    // getViewType method so that view type is generated at runtime
-    methods.add(MethodSpec.methodBuilder("getViewType")
-        .addAnnotation(Override.class)
-        .addModifiers(PROTECTED)
-        .returns(TypeName.INT)
-        .addStatement("return 0", modelInfo.boundObjectTypeName)
-        .build());
-
     // setter for style object
     Builder builder = MethodSpec.methodBuilder(PARIS_STYLE_ATTR_NAME)
         .addModifiers(PUBLIC)
@@ -684,13 +729,14 @@ private Iterable<MethodSpec> generateMethodsReturningClassType(GeneratedModelInf
           .varargs(methodInfo.varargs)
           .returns(info.getParameterizedGeneratedName());
 
-      if (info.isStyleable()
+      if (info.isProgrammaticView()
           && "layout".equals(methodInfo.name)
           && methodInfo.params.size() == 1
           && methodInfo.params.get(0).type == TypeName.INT) {
 
         builder
-            .addStatement("throw new $T(\"Layout resources are unsupported in @Styleable views.\")",
+            .addStatement(
+                "throw new $T(\"Layout resources are unsupported with programmatic views.\")",
                 UnsupportedOperationException.class);
       } else {
 
@@ -716,10 +762,12 @@ private Iterable<MethodSpec> generateMethodsReturningClassType(GeneratedModelInf
   private Iterable<MethodSpec> generateDefaultMethodImplementations(GeneratedModelInfo info) {
     List<MethodSpec> methods = new ArrayList<>();
 
-    if (info.isStyleable()) {
+    if (info.isProgrammaticView()) {
       methods.add(buildDefaultLayoutMethodBase()
           .toBuilder()
-          .addStatement("throw new $T(\"Layout resources are unsupported in @Styleable views\")",
+          .addStatement(
+              "throw new $T(\"Layout resources are unsupported for views created programmatically"
+                  + ".\")",
               UnsupportedOperationException.class)
           .build());
     } else {

epoxy-processor/src/main/java/com/airbnb/epoxy/ModelViewInfo.java

@@ -60,6 +60,7 @@ class ModelViewInfo extends GeneratedModelInfo {
     boundObjectTypeName = ClassName.get(viewElement.asType());
 
     saveViewState = viewAnnotation.saveViewState();
+    layoutParams = viewAnnotation.autoLayout();
     fullSpanSize = viewAnnotation.fullSpan();
     includeOtherLayoutOptions = configManager.includeAlternateLayoutsForViews(viewElement);
   }

epoxy-processortest/src/test/java/com/airbnb/epoxy/ViewProcessorTest.java

@@ -700,4 +700,14 @@ public void callbackPropMustBeNullable() {
   public void testModelBuilderInterface() {
     assertGeneration("TestManyTypesView.java", "TestManyTypesViewModelBuilder.java");
   }
+
+  @Test
+  public void testAutoLayout() {
+    assertGeneration("AutoLayoutModelView.java", "AutoLayoutModelViewModel_.java");
+  }
+
+  @Test
+  public void testAutoLayoutMatchParent() {
+    assertGeneration("AutoLayoutModelViewMatchParent.java", "AutoLayoutModelViewMatchParentModel_.java");
+  }
 }

epoxy-processortest/src/test/resources/AutoLayoutModelView.java

@@ -0,0 +1,17 @@
+package com.airbnb.epoxy;
+
+import android.content.Context;
+import android.view.View;
+
+@ModelView(autoLayout = ModelView.Size.WRAP_WIDTH_WRAP_HEIGHT)
+public class AutoLayoutModelView extends View {
+
+  public AutoLayoutModelView(Context context) {
+    super(context);
+  }
+
+  @ModelProp
+  void setValue(int value) {
+
+  }
+}

epoxy-processortest/src/test/resources/AutoLayoutModelViewMatchParent.java

@@ -0,0 +1,19 @@
+package com.airbnb.epoxy;
+
+import android.content.Context;
+import android.view.View;
+
+import com.airbnb.epoxy.ModelView.Size;
+
+@ModelView(autoLayout = Size.MATCH_WIDTH_MATCH_HEIGHT)
+public class AutoLayoutModelViewMatchParent extends View {
+
+  public AutoLayoutModelViewMatchParent(Context context) {
+    super(context);
+  }
+
+  @ModelProp
+  void setValue(int value) {
+
+  }
+}