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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 com.android.setupwizardlib.view;
import android.content.Context;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.view.View;
import android.widget.FrameLayout;
import com.android.setupwizardlib.R;
/**
* A layout that will measure its children size based on the space it is given, by using its {@code
* android:minWidth}, {@code android:minHeight}, {@code android:maxWidth}, and {@code
* android:maxHeight} values.
*
* <p>Typically this is used to show an illustration image or video on the screen. For optimal UX,
* those assets typically want to occupy the remaining space available on screen within a certain
* range, and then stop scaling beyond the min/max size attributes. Therefore this view is typically
* used inside a ScrollView with {@code fillViewport} set to true, together with a linear layout
* weight or relative layout to fill the remaining space visible on screen.
*
* <p>When measuring, this view ignores its children and simply layout according to the minWidth /
* minHeight given. Therefore it is common for children of this layout to have width / height set to
* {@code match_parent}. The maxWidth / maxHeight values will then be applied to the children to
* make sure they are not too big.
*/
public class FillContentLayout extends FrameLayout {
private int maxWidth;
private int maxHeight;
public FillContentLayout(Context context) {
this(context, null);
}
public FillContentLayout(Context context, AttributeSet attrs) {
this(context, attrs, R.attr.suwFillContentLayoutStyle);
}
public FillContentLayout(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init(context, attrs, defStyleAttr);
}
private void init(Context context, AttributeSet attrs, int defStyleAttr) {
TypedArray a =
context.obtainStyledAttributes(attrs, R.styleable.SuwFillContentLayout, defStyleAttr, 0);
maxHeight = a.getDimensionPixelSize(R.styleable.SuwFillContentLayout_android_maxHeight, -1);
maxWidth = a.getDimensionPixelSize(R.styleable.SuwFillContentLayout_android_maxWidth, -1);
a.recycle();
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
// Measure this view with the minWidth and minHeight, without asking the children.
// (Children size is the drawable's intrinsic size, and we don't want that to influence
// the size of the illustration).
setMeasuredDimension(
getDefaultSize(getSuggestedMinimumWidth(), widthMeasureSpec),
getDefaultSize(getSuggestedMinimumHeight(), heightMeasureSpec));
int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
measureIllustrationChild(getChildAt(i), getMeasuredWidth(), getMeasuredHeight());
}
}
private void measureIllustrationChild(View child, int parentWidth, int parentHeight) {
// Modified from ViewGroup#measureChildWithMargins
final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
// Create measure specs that are no bigger than min(parentSize, maxSize)
int childWidthMeasureSpec =
getMaxSizeMeasureSpec(
Math.min(maxWidth, parentWidth),
getPaddingLeft() + getPaddingRight() + lp.leftMargin + lp.rightMargin,
lp.width);
int childHeightMeasureSpec =
getMaxSizeMeasureSpec(
Math.min(maxHeight, parentHeight),
getPaddingTop() + getPaddingBottom() + lp.topMargin + lp.bottomMargin,
lp.height);
child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
}
private static int getMaxSizeMeasureSpec(int maxSize, int padding, int childDimension) {
// Modified from ViewGroup#getChildMeasureSpec
int size = Math.max(0, maxSize - padding);
if (childDimension >= 0) {
// Child wants a specific size... so be it
return MeasureSpec.makeMeasureSpec(childDimension, MeasureSpec.EXACTLY);
} else if (childDimension == LayoutParams.MATCH_PARENT) {
// Child wants to be our size. So be it.
return MeasureSpec.makeMeasureSpec(size, MeasureSpec.EXACTLY);
} else if (childDimension == LayoutParams.WRAP_CONTENT) {
// Child wants to determine its own size. It can't be
// bigger than us.
return MeasureSpec.makeMeasureSpec(size, MeasureSpec.AT_MOST);
}
return 0;
}
}
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