/*
* Copyright (C) 2016 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.internal.widget;
import android.content.Context;
import android.graphics.drawable.Drawable;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.Gravity;
import android.view.View;
import android.view.ViewTreeObserver;
import android.widget.ListView;
import android.widget.FrameLayout;
import java.util.ArrayList;
/**
* Layout for the decor for ListViews on watch-type devices with small screens.
* <p>
* Supports one panel with the gravity set to top, and one panel with gravity set to bottom.
* <p>
* Use with one ListView child. The top and bottom panels will track the ListView's scrolling.
* If there is no ListView child, it will act like a normal FrameLayout.
*/
public class WatchListDecorLayout extends FrameLayout
implements ViewTreeObserver.OnScrollChangedListener {
private int mForegroundPaddingLeft = 0;
private int mForegroundPaddingTop = 0;
private int mForegroundPaddingRight = 0;
private int mForegroundPaddingBottom = 0;
private final ArrayList<View> mMatchParentChildren = new ArrayList<>(1);
/** Track the amount the ListView has to scroll up to account for padding change difference. */
private int mPendingScroll;
private View mBottomPanel;
private View mTopPanel;
private ListView mListView;
private ViewTreeObserver mObserver;
public WatchListDecorLayout(Context context, AttributeSet attrs) {
super(context, attrs);
}
public WatchListDecorLayout(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
public WatchListDecorLayout(
Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
super(context, attrs, defStyleAttr, defStyleRes);
}
@Override
protected void onAttachedToWindow() {
super.onAttachedToWindow();
mPendingScroll = 0;
for (int i = 0; i < getChildCount(); ++i) {
View child = getChildAt(i);
if (child instanceof ListView) {
if (mListView != null) {
throw new IllegalArgumentException("only one ListView child allowed");
}
mListView = (ListView) child;
mListView.setNestedScrollingEnabled(true);
mObserver = mListView.getViewTreeObserver();
mObserver.addOnScrollChangedListener(this);
} else {
int gravity = (((LayoutParams) child.getLayoutParams()).gravity
& Gravity.VERTICAL_GRAVITY_MASK);
if (gravity == Gravity.TOP && mTopPanel == null) {
mTopPanel = child;
} else if (gravity == Gravity.BOTTOM && mBottomPanel == null) {
mBottomPanel = child;
}
}
}
}
@Override
public void onDetachedFromWindow() {
mListView = null;
mBottomPanel = null;
mTopPanel = null;
if (mObserver != null) {
if (mObserver.isAlive()) {
mObserver.removeOnScrollChangedListener(this);
}
mObserver = null;
}
}
private void applyMeasureToChild(View child, int widthMeasureSpec, int heightMeasureSpec) {
final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
final int childWidthMeasureSpec;
if (lp.width == LayoutParams.MATCH_PARENT) {
final int width = Math.max(0, getMeasuredWidth()
- getPaddingLeftWithForeground() - getPaddingRightWithForeground()
- lp.leftMargin - lp.rightMargin);
childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(
width, MeasureSpec.EXACTLY);
} else {
childWidthMeasureSpec = getChildMeasureSpec(widthMeasureSpec,
getPaddingLeftWithForeground() + getPaddingRightWithForeground() +
lp.leftMargin + lp.rightMargin,
lp.width);
}
final int childHeightMeasureSpec;
if (lp.height == LayoutParams.MATCH_PARENT) {
final int height = Math.max(0, getMeasuredHeight()
- getPaddingTopWithForeground() - getPaddingBottomWithForeground()
- lp.topMargin - lp.bottomMargin);
childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(
height, MeasureSpec.EXACTLY);
} else {
childHeightMeasureSpec = getChildMeasureSpec(heightMeasureSpec,
getPaddingTopWithForeground() + getPaddingBottomWithForeground() +
lp.topMargin + lp.bottomMargin,
lp.height);
}
child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
}
private int measureAndGetHeight(View child, int widthMeasureSpec, int heightMeasureSpec) {
if (child != null) {
if (child.getVisibility() != GONE) {
applyMeasureToChild(mBottomPanel, widthMeasureSpec, heightMeasureSpec);
return child.getMeasuredHeight();
} else if (getMeasureAllChildren()) {
applyMeasureToChild(mBottomPanel, widthMeasureSpec, heightMeasureSpec);
}
}
return 0;
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int count = getChildCount();
final boolean measureMatchParentChildren =
MeasureSpec.getMode(widthMeasureSpec) != MeasureSpec.EXACTLY ||
MeasureSpec.getMode(heightMeasureSpec) != MeasureSpec.EXACTLY;
mMatchParentChildren.clear();
int maxHeight = 0;
int maxWidth = 0;
int childState = 0;
for (int i = 0; i < count; i++) {
final View child = getChildAt(i);
if (getMeasureAllChildren() || child.getVisibility() != GONE) {
measureChildWithMargins(child, widthMeasureSpec, 0, heightMeasureSpec, 0);
final LayoutParams lp = (LayoutParams) child.getLayoutParams();
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());
if (measureMatchParentChildren) {
if (lp.width == LayoutParams.MATCH_PARENT ||
lp.height == LayoutParams.MATCH_PARENT) {
mMatchParentChildren.add(child);
}
}
}
}
// Account for padding too
maxWidth += getPaddingLeftWithForeground() + getPaddingRightWithForeground();
maxHeight += getPaddingTopWithForeground() + getPaddingBottomWithForeground();
// Check against our minimum height and width
maxHeight = Math.max(maxHeight, getSuggestedMinimumHeight());
maxWidth = Math.max(maxWidth, getSuggestedMinimumWidth());
// Check against our foreground's minimum height and width
final Drawable drawable = getForeground();
if (drawable != null) {
maxHeight = Math.max(maxHeight, drawable.getMinimumHeight());
maxWidth = Math.max(maxWidth, drawable.getMinimumWidth());
}
setMeasuredDimension(resolveSizeAndState(maxWidth, widthMeasureSpec, childState),
resolveSizeAndState(maxHeight, heightMeasureSpec,
childState << MEASURED_HEIGHT_STATE_SHIFT));
if (mListView != null) {
if (mPendingScroll != 0) {
mListView.scrollListBy(mPendingScroll);
mPendingScroll = 0;
}
int paddingTop = Math.max(mListView.getPaddingTop(),
measureAndGetHeight(mTopPanel, widthMeasureSpec, heightMeasureSpec));
int paddingBottom = Math.max(mListView.getPaddingBottom(),
measureAndGetHeight(mBottomPanel, widthMeasureSpec, heightMeasureSpec));
if (paddingTop != mListView.getPaddingTop()
|| paddingBottom != mListView.getPaddingBottom()) {
mPendingScroll += mListView.getPaddingTop() - paddingTop;
mListView.setPadding(
mListView.getPaddingLeft(), paddingTop,
mListView.getPaddingRight(), paddingBottom);
}
}
count = mMatchParentChildren.size();
if (count > 1) {
for (int i = 0; i < count; i++) {
final View child = mMatchParentChildren.get(i);
if (mListView == null || (child != mTopPanel && child != mBottomPanel)) {
applyMeasureToChild(child, widthMeasureSpec, heightMeasureSpec);
}
}
}
}
@Override
public void setForegroundGravity(int foregroundGravity) {
if (getForegroundGravity() != foregroundGravity) {
super.setForegroundGravity(foregroundGravity);
// calling get* again here because the set above may apply default constraints
final Drawable foreground = getForeground();
if (getForegroundGravity() == Gravity.FILL && foreground != null) {
Rect padding = new Rect();
if (foreground.getPadding(padding)) {
mForegroundPaddingLeft = padding.left;
mForegroundPaddingTop = padding.top;
mForegroundPaddingRight = padding.right;
mForegroundPaddingBottom = padding.bottom;
}
} else {
mForegroundPaddingLeft = 0;
mForegroundPaddingTop = 0;
mForegroundPaddingRight = 0;
mForegroundPaddingBottom = 0;
}
}
}
private int getPaddingLeftWithForeground() {
return isForegroundInsidePadding() ? Math.max(mPaddingLeft, mForegroundPaddingLeft) :
mPaddingLeft + mForegroundPaddingLeft;
}
private int getPaddingRightWithForeground() {
return isForegroundInsidePadding() ? Math.max(mPaddingRight, mForegroundPaddingRight) :
mPaddingRight + mForegroundPaddingRight;
}
private int getPaddingTopWithForeground() {
return isForegroundInsidePadding() ? Math.max(mPaddingTop, mForegroundPaddingTop) :
mPaddingTop + mForegroundPaddingTop;
}
private int getPaddingBottomWithForeground() {
return isForegroundInsidePadding() ? Math.max(mPaddingBottom, mForegroundPaddingBottom) :
mPaddingBottom + mForegroundPaddingBottom;
}
@Override
public void onScrollChanged() {
if (mListView == null) {
return;
}
if (mTopPanel != null) {
if (mListView.getChildCount() > 0) {
if (mListView.getFirstVisiblePosition() == 0) {
View firstChild = mListView.getChildAt(0);
setScrolling(mTopPanel,
firstChild.getY() - mTopPanel.getHeight() - mTopPanel.getTop());
} else {
// shift to hide the frame, last child is not the last position
setScrolling(mTopPanel, -mTopPanel.getHeight());
}
} else {
setScrolling(mTopPanel, 0); // no visible child, fallback to default behaviour
}
}
if (mBottomPanel != null) {
if (mListView.getChildCount() > 0) {
if (mListView.getLastVisiblePosition() >= mListView.getCount() - 1) {
View lastChild = mListView.getChildAt(mListView.getChildCount() - 1);
setScrolling(mBottomPanel,
lastChild.getY() + lastChild.getHeight() - mBottomPanel.getTop());
} else {
// shift to hide the frame, last child is not the last position
setScrolling(mBottomPanel, mBottomPanel.getHeight());
}
} else {
setScrolling(mBottomPanel, 0); // no visible child, fallback to default behaviour
}
}
}
/** Only set scrolling for the panel if there is a change in its translationY. */
private void setScrolling(View panel, float translationY) {
if (panel.getTranslationY() != translationY) {
panel.setTranslationY(translationY);
}
}
}