[Lists] Added initial MaterialListItem implementation

lib/build.gradle

@@ -54,6 +54,7 @@ def srcDirs = [
   'com/google/android/material/floatingactionbutton',
   'com/google/android/material/imageview',
   'com/google/android/material/internal',
+  'com/google/android/material/lists',
   'com/google/android/material/math',
   'com/google/android/material/menu',
   'com/google/android/material/navigation',

lib/java/com/google/android/material/lists/item/MaterialListItem.java

@@ -0,0 +1,101 @@
+/*
+ * Copyright 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.material.lists.item;
+
+import android.content.Context;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.FrameLayout;
+import android.widget.TextView;
+
+import androidx.annotation.NonNull;
+import androidx.recyclerview.widget.RecyclerView;
+
+import com.google.android.material.R;
+
+public class MaterialListItem extends RecyclerView.ViewHolder {
+
+  private Visual visual;
+  private TextCollection textCollection;
+  private SecondaryContent secondaryContent;
+
+  @NonNull
+  public Visual getVisual() {
+    return visual;
+  }
+
+  @NonNull
+  public TextView getOverlineText() {
+    return textCollection.getOverlineText();
+  }
+
+  @NonNull
+  public TextView getPrimaryText() {
+    return textCollection.getPrimaryText();
+  }
+
+  @NonNull
+  public TextView getSecondaryText() {
+    return textCollection.getSecondaryText();
+  }
+
+  @NonNull
+  public TextView getMetadata() {
+    return secondaryContent.getMetadata();
+  }
+
+  @NonNull
+  public SecondaryContent getSecondaryContent() {
+    return secondaryContent;
+  }
+
+  @NonNull
+  public FrameLayout getAction() {
+    return secondaryContent.getAction();
+  }
+
+  public MaterialListItem(@NonNull ViewGroup parent) {
+
+    super(inflateListItemLayout(parent));
+
+    visual = itemView.findViewById(R.id.material_list_item_visual);
+    textCollection = itemView.findViewById(R.id.material_list_item_text_collection);
+    secondaryContent = itemView.findViewById(R.id.material_list_item_secondary_content);
+
+    textCollection.setTotalLinesListener(new TotalLinesListener() {
+      @Override
+      public void onTotalLinesChange(int totalLines) {
+        updateTotalLines(totalLines);
+      }
+    });
+
+    updateTotalLines(0);
+  }
+
+  private static View inflateListItemLayout(@NonNull ViewGroup parent) {
+    Context context = parent.getContext();
+    LayoutInflater layoutInflater = LayoutInflater.from(context);
+    View itemView = layoutInflater.inflate(R.layout.material_list_item, parent, false);
+    return itemView;
+  }
+
+  private void updateTotalLines(int totalLines) {
+    visual.onTotalLinesChange(totalLines);
+    textCollection.onTotalLinesChange(totalLines);
+    secondaryContent.onTotalLinesChange(totalLines);
+  }
+}

lib/java/com/google/android/material/lists/item/SecondaryContent.java

@@ -0,0 +1,114 @@
+/*
+ * Copyright 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.material.lists.item;
+
+import android.content.Context;
+import android.util.AttributeSet;
+import android.view.Gravity;
+import android.view.LayoutInflater;
+import android.widget.FrameLayout;
+import android.widget.LinearLayout;
+import android.widget.TextView;
+
+import androidx.annotation.DimenRes;
+import androidx.annotation.Dimension;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import com.google.android.material.R;
+
+public class SecondaryContent extends FrameLayout implements TotalLinesListener {
+
+  private TextView metadata;
+  private FrameLayout action;
+
+  @NonNull
+  public TextView getMetadata() {
+    return metadata;
+  }
+
+  @NonNull
+  public FrameLayout getAction() {
+    return action;
+  }
+
+  public SecondaryContent(@NonNull Context context) {
+    this(context, null);
+  }
+
+  public SecondaryContent(@NonNull Context context, @Nullable AttributeSet attrs) {
+    this(context, attrs, 0);
+  }
+
+  public SecondaryContent(@NonNull Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
+    super(context, attrs, defStyleAttr);
+
+    LayoutInflater layoutInflater = LayoutInflater.from(getContext());
+    metadata = (TextView) layoutInflater.inflate(R.layout.material_list_item_metadata, this, false);
+    action = (FrameLayout) layoutInflater.inflate(R.layout.material_list_item_action, this, false);
+    addView(metadata);
+    addView(action);
+  }
+
+  @Override
+  public void onTotalLinesChange(int totalLines) {
+
+    int[] layoutMargins = calculateLayoutMargins(totalLines);
+    int gravity = calculateGravity(totalLines);
+
+    LinearLayout.LayoutParams layoutParams = (LinearLayout.LayoutParams) getLayoutParams();
+    layoutParams.setMargins(layoutMargins[0], layoutMargins[1], layoutMargins[2], layoutMargins[3]);
+    layoutParams.gravity = gravity;
+  }
+
+  private int[] calculateLayoutMargins(int totalLines) {
+    int layoutMarginSmall = getDimensionInt(R.dimen.mtrl_list_item_secondary_content_layout_margin_small);
+    int layoutMarginNormal = getDimensionInt(R.dimen.mtrl_list_item_secondary_content_layout_margin_normal);
+    int layoutMarginLarge = getDimensionInt(R.dimen.mtrl_list_item_secondary_content_layout_margin_large);
+
+    int[] layoutMargins = {
+        layoutMarginNormal,
+        layoutMarginNormal,
+        layoutMarginNormal,
+        layoutMarginNormal};
+
+    int verticalMargin = layoutMarginNormal;
+
+    if (totalLines <= 1) {
+      verticalMargin = layoutMarginSmall;
+    } else if (totalLines == 2) {
+      verticalMargin = layoutMarginLarge;
+    }
+
+    layoutMargins[1] = verticalMargin;
+    layoutMargins[3] = verticalMargin;
+
+    return layoutMargins;
+  }
+
+  private int calculateGravity(int totalLines) {
+    int gravity = Gravity.CENTER_VERTICAL;
+    if (totalLines >= 2) {
+      gravity = Gravity.TOP;
+    }
+    return gravity;
+  }
+
+  @Dimension
+  private int getDimensionInt(@DimenRes int resource) {
+    return (int) getContext().getResources().getDimension(resource);
+  }
+}