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      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 
     17 package com.android.gallery3d.ui;
     18 
     19 import android.content.Context;
     20 import android.graphics.Rect;
     21 import android.util.TypedValue;
     22 
     23 public class ScrollBarView extends GLView {
     24     @SuppressWarnings("unused")
     25     private static final String TAG = "ScrollBarView";
     26 
     27     private int mBarHeight;
     28 
     29     private int mGripHeight;
     30     private int mGripPosition;  // left side of the grip
     31     private int mGripWidth;     // zero if the grip is disabled
     32     private int mGivenGripWidth;
     33 
     34     private int mContentPosition;
     35     private int mContentTotal;
     36 
     37     private NinePatchTexture mScrollBarTexture;
     38 
     39     public ScrollBarView(Context context, int gripHeight, int gripWidth) {
     40         TypedValue outValue = new TypedValue();
     41         context.getTheme().resolveAttribute(
     42                 android.R.attr.scrollbarThumbHorizontal, outValue, true);
     43         mScrollBarTexture = new NinePatchTexture(
     44                 context, outValue.resourceId);
     45         mGripPosition = 0;
     46         mGripWidth = 0;
     47         mGivenGripWidth = gripWidth;
     48         mGripHeight = gripHeight;
     49     }
     50 
     51     @Override
     52     protected void onLayout(
     53             boolean changed, int left, int top, int right, int bottom) {
     54         if (!changed) return;
     55         mBarHeight = bottom - top;
     56     }
     57 
     58     // The content position is between 0 to "total". The current position is
     59     // in "position".
     60     public void setContentPosition(int position, int total) {
     61         if (position == mContentPosition && total == mContentTotal) {
     62             return;
     63         }
     64 
     65         invalidate();
     66 
     67         mContentPosition = position;
     68         mContentTotal = total;
     69 
     70         // If the grip cannot move, don't draw it.
     71         if (mContentTotal <= 0) {
     72             mGripPosition = 0;
     73             mGripWidth = 0;
     74             return;
     75         }
     76 
     77         // Map from the content range to scroll bar range.
     78         //
     79         // mContentTotal --> getWidth() - mGripWidth
     80         // mContentPosition --> mGripPosition
     81         mGripWidth = mGivenGripWidth;
     82         float r = (getWidth() - mGripWidth) / (float) mContentTotal;
     83         mGripPosition = Math.round(r * mContentPosition);
     84     }
     85 
     86     @Override
     87     protected void render(GLCanvas canvas) {
     88         super.render(canvas);
     89         if (mGripWidth == 0) return;
     90         Rect b = bounds();
     91         int y = (mBarHeight - mGripHeight) / 2;
     92         mScrollBarTexture.draw(canvas, mGripPosition, y, mGripWidth, mGripHeight);
     93     }
     94 }
     95