/*
* Copyright (C) 2013 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 com.example.android.apis.view;
// Need the following import to get access to the app resources, since this
// class is in a sub-package.
import android.graphics.Rect;
import com.example.android.apis.R;
import android.content.Context;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.view.Gravity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.RemoteViews;
/**
* Example of writing a custom layout manager. This is a fairly full-featured
* layout manager that is relatively general, handling all layout cases. You
* can simplify it for more specific cases.
*/
@RemoteViews.RemoteView
public class CustomLayout extends ViewGroup {
/** The amount of space used by children in the left gutter. */
private int mLeftWidth;
/** The amount of space used by children in the right gutter. */
private int mRightWidth;
/** These are used for computing child frames based on their gravity. */
private final Rect mTmpContainerRect = new Rect();
private final Rect mTmpChildRect = new Rect();
public CustomLayout(Context context) {
super(context);
}
public CustomLayout(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public CustomLayout(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
/**
* Any layout manager that doesn't scroll will want this.
*/
@Override
public boolean shouldDelayChildPressedState() {
return false;
}
/**
* Ask all children to measure themselves and compute the measurement of this
* layout based on the children.
*/
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int count = getChildCount();
// These keep track of the space we are using on the left and right for
// views positioned there; we need member variables so we can also use
// these for layout later.
mLeftWidth = 0;
mRightWidth = 0;
// Measurement will ultimately be computing these values.
int maxHeight = 0;
int maxWidth = 0;
int childState = 0;
// Iterate through all children, measuring them and computing our dimensions
// from their size.
for (int i = 0; i < count; i++) {
final View child = getChildAt(i);
if (child.getVisibility() != GONE) {
// Measure the child.
measureChildWithMargins(child, widthMeasureSpec, 0, heightMeasureSpec, 0);
// Update our size information based on the layout params. Children
// that asked to be positioned on the left or right go in those gutters.
final LayoutParams lp = (LayoutParams) child.getLayoutParams();
if (lp.position == LayoutParams.POSITION_LEFT) {
mLeftWidth += Math.max(maxWidth,
child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin);
} else if (lp.position == LayoutParams.POSITION_RIGHT) {
mRightWidth += Math.max(maxWidth,
child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin);
} else {
maxWidth = Math.max(maxWidth,
child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin);
}
maxHeight = Math.max(maxHeight,
child.getMeasuredHeight() + lp.topMargin + lp.bottomMargin);
childState = combineMeasuredStates(childState, child.getMeasuredState());
}
}
// Total width is the maximum width of all inner children plus the gutters.
maxWidth += mLeftWidth + mRightWidth;
// Check against our minimum height and width
maxHeight = Math.max(maxHeight, getSuggestedMinimumHeight());
maxWidth = Math.max(maxWidth, getSuggestedMinimumWidth());
// Report our final dimensions.
setMeasuredDimension(resolveSizeAndState(maxWidth, widthMeasureSpec, childState),
resolveSizeAndState(maxHeight, heightMeasureSpec,
childState << MEASURED_HEIGHT_STATE_SHIFT));
}
/**
* Position all children within this layout.
*/
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
final int count = getChildCount();
// These are the far left and right edges in which we are performing layout.
int leftPos = getPaddingLeft();
int rightPos = right - left - getPaddingRight();
// This is the middle region inside of the gutter.
final int middleLeft = leftPos + mLeftWidth;
final int middleRight = rightPos - mRightWidth;
// These are the top and bottom edges in which we are performing layout.
final int parentTop = getPaddingTop();
final int parentBottom = bottom - top - getPaddingBottom();
for (int i = 0; i < count; i++) {
final View child = getChildAt(i);
if (child.getVisibility() != GONE) {
final LayoutParams lp = (LayoutParams) child.getLayoutParams();
final int width = child.getMeasuredWidth();
final int height = child.getMeasuredHeight();
// Compute the frame in which we are placing this child.
if (lp.position == LayoutParams.POSITION_LEFT) {
mTmpContainerRect.left = leftPos + lp.leftMargin;
mTmpContainerRect.right = leftPos + width + lp.rightMargin;
leftPos = mTmpContainerRect.right;
} else if (lp.position == LayoutParams.POSITION_RIGHT) {
mTmpContainerRect.right = rightPos - lp.rightMargin;
mTmpContainerRect.left = rightPos - width - lp.leftMargin;
rightPos = mTmpContainerRect.left;
} else {
mTmpContainerRect.left = middleLeft + lp.leftMargin;
mTmpContainerRect.right = middleRight - lp.rightMargin;
}
mTmpContainerRect.top = parentTop + lp.topMargin;
mTmpContainerRect.bottom = parentBottom - lp.bottomMargin;
// Use the child's gravity and size to determine its final
// frame within its container.
Gravity.apply(lp.gravity, width, height, mTmpContainerRect, mTmpChildRect);
// Place the child.
child.layout(mTmpChildRect.left, mTmpChildRect.top,
mTmpChildRect.right, mTmpChildRect.bottom);
}
}
}
// ----------------------------------------------------------------------
// The rest of the implementation is for custom per-child layout parameters.
// If you do not need these (for example you are writing a layout manager
// that does fixed positioning of its children), you can drop all of this.
@Override
public LayoutParams generateLayoutParams(AttributeSet attrs) {
return new CustomLayout.LayoutParams(getContext(), attrs);
}
@Override
protected LayoutParams generateDefaultLayoutParams() {
return new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
}
@Override
protected ViewGroup.LayoutParams generateLayoutParams(ViewGroup.LayoutParams p) {
return new LayoutParams(p);
}
@Override
protected boolean checkLayoutParams(ViewGroup.LayoutParams p) {
return p instanceof LayoutParams;
}
/**
* Custom per-child layout information.
*/
public static class LayoutParams extends MarginLayoutParams {
/**
* The gravity to apply with the View to which these layout parameters
* are associated.
*/
public int gravity = Gravity.TOP | Gravity.START;
public static int POSITION_MIDDLE = 0;
public static int POSITION_LEFT = 1;
public static int POSITION_RIGHT = 2;
public int position = POSITION_MIDDLE;
public LayoutParams(Context c, AttributeSet attrs) {
super(c, attrs);
// Pull the layout param values from the layout XML during
// inflation. This is not needed if you don't care about
// changing the layout behavior in XML.
TypedArray a = c.obtainStyledAttributes(attrs, R.styleable.CustomLayoutLP);
gravity = a.getInt(R.styleable.CustomLayoutLP_android_layout_gravity, gravity);
position = a.getInt(R.styleable.CustomLayoutLP_layout_position, position);
a.recycle();
}
public LayoutParams(int width, int height) {
super(width, height);
}
public LayoutParams(ViewGroup.LayoutParams source) {
super(source);
}
}
}