123 lines
4.9 KiB
Java
123 lines
4.9 KiB
Java
/*
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* Copyright (C) 2017 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.android.setupwizardlib.view;
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import android.content.Context;
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import android.content.res.TypedArray;
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import android.util.AttributeSet;
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import android.view.View;
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import android.widget.FrameLayout;
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import com.android.setupwizardlib.R;
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/**
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* A layout that will measure its children size based on the space it is given, by using its {@code
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* android:minWidth}, {@code android:minHeight}, {@code android:maxWidth}, and {@code
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* android:maxHeight} values.
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*
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* <p>Typically this is used to show an illustration image or video on the screen. For optimal UX,
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* those assets typically want to occupy the remaining space available on screen within a certain
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* range, and then stop scaling beyond the min/max size attributes. Therefore this view is typically
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* used inside a ScrollView with {@code fillViewport} set to true, together with a linear layout
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* weight or relative layout to fill the remaining space visible on screen.
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*
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* <p>When measuring, this view ignores its children and simply layout according to the minWidth /
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* minHeight given. Therefore it is common for children of this layout to have width / height set to
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* {@code match_parent}. The maxWidth / maxHeight values will then be applied to the children to
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* make sure they are not too big.
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*/
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public class FillContentLayout extends FrameLayout {
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private int maxWidth;
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private int maxHeight;
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public FillContentLayout(Context context) {
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this(context, null);
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}
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public FillContentLayout(Context context, AttributeSet attrs) {
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this(context, attrs, R.attr.suwFillContentLayoutStyle);
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}
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public FillContentLayout(Context context, AttributeSet attrs, int defStyleAttr) {
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super(context, attrs, defStyleAttr);
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init(context, attrs, defStyleAttr);
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}
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private void init(Context context, AttributeSet attrs, int defStyleAttr) {
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TypedArray a =
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context.obtainStyledAttributes(attrs, R.styleable.SuwFillContentLayout, defStyleAttr, 0);
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maxHeight = a.getDimensionPixelSize(R.styleable.SuwFillContentLayout_android_maxHeight, -1);
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maxWidth = a.getDimensionPixelSize(R.styleable.SuwFillContentLayout_android_maxWidth, -1);
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a.recycle();
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}
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@Override
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protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
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// Measure this view with the minWidth and minHeight, without asking the children.
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// (Children size is the drawable's intrinsic size, and we don't want that to influence
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// the size of the illustration).
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setMeasuredDimension(
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getDefaultSize(getSuggestedMinimumWidth(), widthMeasureSpec),
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getDefaultSize(getSuggestedMinimumHeight(), heightMeasureSpec));
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int childCount = getChildCount();
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for (int i = 0; i < childCount; i++) {
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measureIllustrationChild(getChildAt(i), getMeasuredWidth(), getMeasuredHeight());
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}
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}
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private void measureIllustrationChild(View child, int parentWidth, int parentHeight) {
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// Modified from ViewGroup#measureChildWithMargins
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final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
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// Create measure specs that are no bigger than min(parentSize, maxSize)
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int childWidthMeasureSpec =
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getMaxSizeMeasureSpec(
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Math.min(maxWidth, parentWidth),
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getPaddingLeft() + getPaddingRight() + lp.leftMargin + lp.rightMargin,
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lp.width);
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int childHeightMeasureSpec =
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getMaxSizeMeasureSpec(
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Math.min(maxHeight, parentHeight),
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getPaddingTop() + getPaddingBottom() + lp.topMargin + lp.bottomMargin,
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lp.height);
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child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
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}
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private static int getMaxSizeMeasureSpec(int maxSize, int padding, int childDimension) {
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// Modified from ViewGroup#getChildMeasureSpec
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int size = Math.max(0, maxSize - padding);
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if (childDimension >= 0) {
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// Child wants a specific size... so be it
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return MeasureSpec.makeMeasureSpec(childDimension, MeasureSpec.EXACTLY);
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} else if (childDimension == LayoutParams.MATCH_PARENT) {
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// Child wants to be our size. So be it.
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return MeasureSpec.makeMeasureSpec(size, MeasureSpec.EXACTLY);
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} else if (childDimension == LayoutParams.WRAP_CONTENT) {
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// Child wants to determine its own size. It can't be
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// bigger than us.
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return MeasureSpec.makeMeasureSpec(size, MeasureSpec.AT_MOST);
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}
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return 0;
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}
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}
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