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/*
* Copyright (C) 2017 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.support.constraint;
import android.content.Context;
import android.content.res.Configuration;
import android.content.res.TypedArray;
import android.os.Build;
import android.util.AttributeSet;
import android.view.View;
/**
* <b>Added in 1.1</b>
* <p>
* A Barrier references multiple widgets as input, and creates a virtual guideline based on the most
* extreme widget on the specified side. For example, a left barrier will align to the left of all the referenced views.
* </p>
* <p>
* <h2>Example</h2>
* <p><div align="center" >
* <img width="325px" src="resources/images/barrier-buttons.png">
* </div>
* Let's have two buttons, @id/button1 and @id/button2. The constraint_referenced_ids field will reference
* them by simply having them as comma-separated list:
* <pre>
* {@code
* <android.support.constraint.Barrier
* android:id="@+id/barrier"
* android:layout_width="wrap_content"
* android:layout_height="wrap_content"
* app:barrierDirection="start"
* app:constraint_referenced_ids="button1,button2" />
* }
* </pre>
* <p>
* With the barrier direction set to start, we will have the following result:
* <p><div align="center" >
* <img width="325px" src="resources/images/barrier-start.png">
* </div>
* <p>
* Reversely, with the direction set to end, we will have:
* <p><div align="center" >
* <img width="325px" src="resources/images/barrier-end.png">
* </div>
* <p>
* If the widgets dimensions change, the barrier will automatically move according to its direction to get
* the most extreme widget:
* <p><div align="center" >
* <img width="325px" src="resources/images/barrier-adapt.png">
* </div>
*
* <p>
* Other widgets can then be constrained to the barrier itself, instead of the individual widget. This allows a layout
* to automatically adapt on widget dimension changes (e.g. different languages will end up with different length for similar worlds).
* </p>
* <h2>GONE widgets handling</h2>
* <p>If the barrier references GONE widgets, the default behavior is to create a barrier on the resolved position of the GONE widget.
* If you do not want to have the barrier take GONE widgets into account, you can change this by setting the attribute <i>barrierAllowsGoneWidgets</i>
* to false (default being true).</p>
* </p>
* </p>
*
*/
public class Barrier extends ConstraintHelper {
/**
* Left direction constant
*/
public static final int LEFT = android.support.constraint.solver.widgets.Barrier.LEFT;
/**
* Top direction constant
*/
public static final int TOP = android.support.constraint.solver.widgets.Barrier.TOP;
/**
* Right direction constant
*/
public static final int RIGHT = android.support.constraint.solver.widgets.Barrier.RIGHT;
/**
* Bottom direction constant
*/
public static final int BOTTOM = android.support.constraint.solver.widgets.Barrier.BOTTOM;
/**
* Start direction constant
*/
public static final int START = BOTTOM + 2;
/**
* End Barrier constant
*/
public static final int END = START + 1;
private int mIndicatedType = LEFT;
private int mResolvedType = LEFT;
private android.support.constraint.solver.widgets.Barrier mBarrier;
public Barrier(Context context) {
super(context);
super.setVisibility(View.GONE);
}
public Barrier(Context context, AttributeSet attrs) {
super(context, attrs);
super.setVisibility(View.GONE);
}
public Barrier(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
super.setVisibility(View.GONE);
}
/**
* Get the barrier type ({@code Barrier.LEFT}, {@code Barrier.TOP},
* {@code Barrier.RIGHT}, {@code Barrier.BOTTOM}, {@code Barrier.END},
* {@code Barrier.START})
*/
public int getType() {
return mIndicatedType;
}
/**
* Set the barrier type ({@code Barrier.LEFT}, {@code Barrier.TOP},
* {@code Barrier.RIGHT}, {@code Barrier.BOTTOM}, {@code Barrier.END},
* {@code Barrier.START})
*/
public void setType(int type) {
mIndicatedType = type;
mResolvedType = type;
if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN_MR1) {
// Pre JB MR1, left/right should take precedence, unless they are
// not defined and somehow a corresponding start/end constraint exists
if (mIndicatedType == START) {
mResolvedType = LEFT;
} else if (mIndicatedType == END) {
mResolvedType = RIGHT;
}
} else {
// Post JB MR1, if start/end are defined, they take precedence over left/right
Configuration config = getResources().getConfiguration();
boolean isRtl = (View.LAYOUT_DIRECTION_RTL == config.getLayoutDirection());
if (isRtl) {
if (mIndicatedType == START) {
mResolvedType = RIGHT;
} else if (mIndicatedType == END) {
mResolvedType = LEFT;
}
} else {
if (mIndicatedType == START) {
mResolvedType = LEFT;
} else if (mIndicatedType == END) {
mResolvedType = RIGHT;
}
}
}
mBarrier.setBarrierType(mResolvedType);
}
/**
* @hide
* @param attrs
*/
@Override
protected void init(AttributeSet attrs) {
super.init(attrs);
mBarrier = new android.support.constraint.solver.widgets.Barrier();
if (attrs != null) {
TypedArray a = getContext().obtainStyledAttributes(attrs, R.styleable.ConstraintLayout_Layout);
final int N = a.getIndexCount();
for (int i = 0; i < N; i++) {
int attr = a.getIndex(i);
if (attr == R.styleable.ConstraintLayout_Layout_barrierDirection) {
setType(a.getInt(attr, LEFT));
} else if (attr == R.styleable.ConstraintLayout_Layout_barrierAllowsGoneWidgets) {
mBarrier.setAllowsGoneWidget(a.getBoolean(attr, true));
}
}
}
mHelperWidget = mBarrier;
validateParams();
}
}
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