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      1 /*
      2  * Copyright (C) 2011 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 android.widget;
     18 
     19 import android.content.Context;
     20 import android.graphics.Canvas;
     21 import android.util.AttributeSet;
     22 import android.view.View;
     23 
     24 /**
     25  * Space is a lightweight View subclass that may be used to create gaps between components
     26  * in general purpose layouts.
     27  */
     28 public final class Space extends View {
     29     /**
     30      * {@inheritDoc}
     31      */
     32     public Space(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
     33         super(context, attrs, defStyleAttr, defStyleRes);
     34         if (getVisibility() == VISIBLE) {
     35             setVisibility(INVISIBLE);
     36         }
     37     }
     38 
     39     /**
     40      * {@inheritDoc}
     41      */
     42     public Space(Context context, AttributeSet attrs, int defStyleAttr) {
     43         this(context, attrs, defStyleAttr, 0);
     44     }
     45 
     46     /**
     47      * {@inheritDoc}
     48      */
     49     public Space(Context context, AttributeSet attrs) {
     50         this(context, attrs, 0);
     51     }
     52 
     53     /**
     54      * {@inheritDoc}
     55      */
     56     public Space(Context context) {
     57         //noinspection NullableProblems
     58         this(context, null);
     59     }
     60 
     61     /**
     62      * Draw nothing.
     63      *
     64      * @param canvas an unused parameter.
     65      */
     66     @Override
     67     public void draw(Canvas canvas) {
     68     }
     69 
     70     /**
     71      * Compare to: {@link View#getDefaultSize(int, int)}
     72      * If mode is AT_MOST, return the child size instead of the parent size
     73      * (unless it is too big).
     74      */
     75     private static int getDefaultSize2(int size, int measureSpec) {
     76         int result = size;
     77         int specMode = MeasureSpec.getMode(measureSpec);
     78         int specSize = MeasureSpec.getSize(measureSpec);
     79 
     80         switch (specMode) {
     81             case MeasureSpec.UNSPECIFIED:
     82                 result = size;
     83                 break;
     84             case MeasureSpec.AT_MOST:
     85                 result = Math.min(size, specSize);
     86                 break;
     87             case MeasureSpec.EXACTLY:
     88                 result = specSize;
     89                 break;
     90         }
     91         return result;
     92     }
     93 
     94     @Override
     95     protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
     96         setMeasuredDimension(
     97                 getDefaultSize2(getSuggestedMinimumWidth(), widthMeasureSpec),
     98                 getDefaultSize2(getSuggestedMinimumHeight(), heightMeasureSpec));
     99     }
    100 }
    101