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 ScrollBarView(Context context, int gripHeight, int gripWidth)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 onLayout( boolean changed, int left, int top, int right, int bottom)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". setContentPosition(int position, int total)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 render(GLCanvas canvas)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