1/*
2 * Copyright (C) 2010 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.android.gallery3d.ui;
18
19import com.android.gallery3d.R;
20
21import android.content.Context;
22import android.graphics.Rect;
23import android.util.TypedValue;
24
25public class ScrollBarView extends GLView {
26    @SuppressWarnings("unused")
27    private static final String TAG = "ScrollBarView";
28
29    public interface Listener {
30        void onScrollBarPositionChanged(int position);
31    }
32
33    private int mBarHeight;
34
35    private int mGripHeight;
36    private int mGripPosition;  // left side of the grip
37    private int mGripWidth;     // zero if the grip is disabled
38    private int mGivenGripWidth;
39
40    private int mContentPosition;
41    private int mContentTotal;
42
43    private Listener mListener;
44    private NinePatchTexture mScrollBarTexture;
45
46    public ScrollBarView(Context context, int gripHeight, int gripWidth) {
47        TypedValue outValue = new TypedValue();
48        context.getTheme().resolveAttribute(
49                android.R.attr.scrollbarThumbHorizontal, outValue, true);
50        mScrollBarTexture = new NinePatchTexture(
51                context, outValue.resourceId);
52        mGripPosition = 0;
53        mGripWidth = 0;
54        mGivenGripWidth = gripWidth;
55        mGripHeight = gripHeight;
56    }
57
58    public void setListener(Listener listener) {
59        mListener = listener;
60    }
61
62    @Override
63    protected void onLayout(
64            boolean changed, int left, int top, int right, int bottom) {
65        if (!changed) return;
66        mBarHeight = bottom - top;
67    }
68
69    // The content position is between 0 to "total". The current position is
70    // in "position".
71    public void setContentPosition(int position, int total) {
72        if (position == mContentPosition && total == mContentTotal) {
73            return;
74        }
75
76        invalidate();
77
78        mContentPosition = position;
79        mContentTotal = total;
80
81        // If the grip cannot move, don't draw it.
82        if (mContentTotal <= 0) {
83            mGripPosition = 0;
84            mGripWidth = 0;
85            return;
86        }
87
88        // Map from the content range to scroll bar range.
89        //
90        // mContentTotal --> getWidth() - mGripWidth
91        // mContentPosition --> mGripPosition
92        mGripWidth = mGivenGripWidth;
93        float r = (getWidth() - mGripWidth) / (float) mContentTotal;
94        mGripPosition = Math.round(r * mContentPosition);
95    }
96
97    private void notifyContentPositionFromGrip() {
98        if (mContentTotal <= 0) return;
99        float r = (getWidth() - mGripWidth) / (float) mContentTotal;
100        int newContentPosition = Math.round(mGripPosition / r);
101        mListener.onScrollBarPositionChanged(newContentPosition);
102    }
103
104    @Override
105    protected void render(GLCanvas canvas) {
106        super.render(canvas);
107        if (mGripWidth == 0) return;
108        Rect b = bounds();
109        int y = (mBarHeight - mGripHeight) / 2;
110        mScrollBarTexture.draw(canvas, mGripPosition, y, mGripWidth, mGripHeight);
111    }
112
113    // The onTouch() handler is disabled because now we don't want the user
114    // to drag the bar (it's an indicator only).
115    /*
116    @Override
117    protected boolean onTouch(MotionEvent event) {
118        switch (event.getAction()) {
119            case MotionEvent.ACTION_DOWN: {
120                int x = (int) event.getX();
121                return (x >= mGripPosition && x < mGripPosition + mGripWidth);
122            }
123            case MotionEvent.ACTION_MOVE: {
124                // Adjust x by mGripWidth / 2 so the center of the grip
125                // matches the touch position.
126                int x = (int) event.getX() - mGripWidth / 2;
127                x = Utils.clamp(x, 0, getWidth() - mGripWidth);
128                if (mGripPosition != x) {
129                    mGripPosition = x;
130                    notifyContentPositionFromGrip();
131                    invalidate();
132                }
133                break;
134            }
135        }
136        return true;
137    }
138    */
139}
140