1/*
2 * Copyright (C) 2014 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
5 * in compliance with the License. You may obtain a copy of the License at
6 *
7 * http://www.apache.org/licenses/LICENSE-2.0
8 *
9 * Unless required by applicable law or agreed to in writing, software distributed under the License
10 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
11 * or implied. See the License for the specific language governing permissions and limitations under
12 * the License.
13 */
14package android.support.v17.leanback.widget;
15
16import android.graphics.Paint;
17import android.support.v17.leanback.R;
18import android.view.LayoutInflater;
19import android.view.View;
20import android.view.ViewGroup;
21import android.widget.TextView;
22
23/**
24 * RowHeaderPresenter provides a default presentation for {@link HeaderItem} using a
25 * {@link RowHeaderView}. If a subclass creates its own view, the subclass must also override
26 * {@link #onSelectLevelChanged(ViewHolder)}.
27 */
28public class RowHeaderPresenter extends Presenter {
29
30    private final int mLayoutResourceId;
31    private final Paint mFontMeasurePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
32    private boolean mNullItemVisibilityGone;
33    private final boolean mAnimateSelect;
34
35    public RowHeaderPresenter() {
36        this(R.layout.lb_row_header);
37    }
38
39    /**
40     * @hide
41     */
42    public RowHeaderPresenter(int layoutResourceId) {
43        this(layoutResourceId, true);
44    }
45
46    /**
47     * @hide
48     */
49    public RowHeaderPresenter(int layoutResourceId, boolean animateSelect) {
50        mLayoutResourceId = layoutResourceId;
51        mAnimateSelect = animateSelect;
52    }
53
54    /**
55     * Optionally sets the view visibility to {@link View#GONE} when bound to null.
56     */
57    public void setNullItemVisibilityGone(boolean nullItemVisibilityGone) {
58        mNullItemVisibilityGone = nullItemVisibilityGone;
59    }
60
61    /**
62     * Returns true if the view visibility is set to {@link View#GONE} when bound to null.
63     */
64    public boolean isNullItemVisibilityGone() {
65        return mNullItemVisibilityGone;
66    }
67
68    /**
69     * A ViewHolder for the RowHeaderPresenter.
70     */
71    public static class ViewHolder extends Presenter.ViewHolder {
72        float mSelectLevel;
73        int mOriginalTextColor;
74        float mUnselectAlpha;
75
76        public ViewHolder(View view) {
77            super(view);
78        }
79        public final float getSelectLevel() {
80            return mSelectLevel;
81        }
82    }
83
84    @Override
85    public Presenter.ViewHolder onCreateViewHolder(ViewGroup parent) {
86        RowHeaderView headerView = (RowHeaderView) LayoutInflater.from(parent.getContext())
87                .inflate(mLayoutResourceId, parent, false);
88
89        ViewHolder viewHolder = new ViewHolder(headerView);
90        viewHolder.mOriginalTextColor = headerView.getCurrentTextColor();
91        viewHolder.mUnselectAlpha = parent.getResources().getFraction(
92                R.fraction.lb_browse_header_unselect_alpha, 1, 1);
93        if (mAnimateSelect) {
94            setSelectLevel(viewHolder, 0);
95        }
96        return viewHolder;
97    }
98
99    @Override
100    public void onBindViewHolder(Presenter.ViewHolder viewHolder, Object item) {
101        HeaderItem headerItem = item == null ? null : ((Row) item).getHeaderItem();
102        if (headerItem == null) {
103            ((RowHeaderView) viewHolder.view).setText(null);
104            viewHolder.view.setContentDescription(null);
105            if (mNullItemVisibilityGone) {
106                viewHolder.view.setVisibility(View.GONE);
107            }
108        } else {
109            viewHolder.view.setVisibility(View.VISIBLE);
110            ((RowHeaderView) viewHolder.view).setText(headerItem.getName());
111            viewHolder.view.setContentDescription(headerItem.getContentDescription());
112        }
113    }
114
115    @Override
116    public void onUnbindViewHolder(Presenter.ViewHolder viewHolder) {
117        ((RowHeaderView) viewHolder.view).setText(null);
118        if (mAnimateSelect) {
119            setSelectLevel((ViewHolder) viewHolder, 0);
120        }
121    }
122
123    /**
124     * Sets the select level.
125     */
126    public final void setSelectLevel(ViewHolder holder, float selectLevel) {
127        holder.mSelectLevel = selectLevel;
128        onSelectLevelChanged(holder);
129    }
130
131    /**
132     * Called when the select level changes.  The default implementation sets the alpha on the view.
133     */
134    protected void onSelectLevelChanged(ViewHolder holder) {
135        if (mAnimateSelect) {
136            holder.view.setAlpha(holder.mUnselectAlpha + holder.mSelectLevel *
137                    (1f - holder.mUnselectAlpha));
138        }
139    }
140
141    /**
142     * Returns the space (distance in pixels) below the baseline of the
143     * text view, if one exists; otherwise, returns 0.
144     */
145    public int getSpaceUnderBaseline(ViewHolder holder) {
146        int space = holder.view.getPaddingBottom();
147        if (holder.view instanceof TextView) {
148            space += (int) getFontDescent((TextView) holder.view, mFontMeasurePaint);
149        }
150        return space;
151    }
152
153    protected static float getFontDescent(TextView textView, Paint fontMeasurePaint) {
154        if (fontMeasurePaint.getTextSize() != textView.getTextSize()) {
155            fontMeasurePaint.setTextSize(textView.getTextSize());
156        }
157        if (fontMeasurePaint.getTypeface() != textView.getTypeface()) {
158            fontMeasurePaint.setTypeface(textView.getTypeface());
159        }
160        return fontMeasurePaint.descent();
161    }
162}
163