/*
* Copyright (C) 2006 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.widget;
import com.android.internal.R;
import android.annotation.DrawableRes;
import android.annotation.Nullable;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.os.Build;
import android.util.AttributeSet;
import android.view.View;
import android.view.View.OnFocusChangeListener;
import android.view.ViewGroup;
import android.view.accessibility.AccessibilityEvent;
/**
*
* Displays a list of tab labels representing each page in the parent's tab
* collection.
* <p>
* The container object for this widget is {@link android.widget.TabHost TabHost}.
* When the user selects a tab, this object sends a message to the parent
* container, TabHost, to tell it to switch the displayed page. You typically
* won't use many methods directly on this object. The container TabHost is
* used to add labels, add the callback handler, and manage callbacks. You
* might call this object to iterate the list of tabs, or to tweak the layout
* of the tab list, but most methods should be called on the containing TabHost
* object.
*
* @attr ref android.R.styleable#TabWidget_divider
* @attr ref android.R.styleable#TabWidget_tabStripEnabled
* @attr ref android.R.styleable#TabWidget_tabStripLeft
* @attr ref android.R.styleable#TabWidget_tabStripRight
*/
public class TabWidget extends LinearLayout implements OnFocusChangeListener {
private final Rect mBounds = new Rect();
private OnTabSelectionChanged mSelectionChangedListener;
// This value will be set to 0 as soon as the first tab is added to TabHost.
private int mSelectedTab = -1;
private Drawable mLeftStrip;
private Drawable mRightStrip;
private boolean mDrawBottomStrips = true;
private boolean mStripMoved;
// When positive, the widths and heights of tabs will be imposed so that
// they fit in parent.
private int mImposedTabsHeight = -1;
private int[] mImposedTabWidths;
public TabWidget(Context context) {
this(context, null);
}
public TabWidget(Context context, AttributeSet attrs) {
this(context, attrs, com.android.internal.R.attr.tabWidgetStyle);
}
public TabWidget(Context context, AttributeSet attrs, int defStyleAttr) {
this(context, attrs, defStyleAttr, 0);
}
public TabWidget(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
super(context, attrs, defStyleAttr, defStyleRes);
final TypedArray a = context.obtainStyledAttributes(
attrs, R.styleable.TabWidget, defStyleAttr, defStyleRes);
mDrawBottomStrips = a.getBoolean(R.styleable.TabWidget_tabStripEnabled, mDrawBottomStrips);
// Tests the target SDK version, as set in the Manifest. Could not be
// set using styles.xml in a values-v? directory which targets the
// current platform SDK version instead.
final boolean isTargetSdkDonutOrLower =
context.getApplicationInfo().targetSdkVersion <= Build.VERSION_CODES.DONUT;
final boolean hasExplicitLeft = a.hasValueOrEmpty(R.styleable.TabWidget_tabStripLeft);
if (hasExplicitLeft) {
mLeftStrip = a.getDrawable(R.styleable.TabWidget_tabStripLeft);
} else if (isTargetSdkDonutOrLower) {
mLeftStrip = context.getDrawable(R.drawable.tab_bottom_left_v4);
} else {
mLeftStrip = context.getDrawable(R.drawable.tab_bottom_left);
}
final boolean hasExplicitRight = a.hasValueOrEmpty(R.styleable.TabWidget_tabStripRight);
if (hasExplicitRight) {
mRightStrip = a.getDrawable(R.styleable.TabWidget_tabStripRight);
} else if (isTargetSdkDonutOrLower) {
mRightStrip = context.getDrawable(R.drawable.tab_bottom_right_v4);
} else {
mRightStrip = context.getDrawable(R.drawable.tab_bottom_right);
}
a.recycle();
setChildrenDrawingOrderEnabled(true);
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
mStripMoved = true;
super.onSizeChanged(w, h, oldw, oldh);
}
@Override
protected int getChildDrawingOrder(int childCount, int i) {
if (mSelectedTab == -1) {
return i;
} else {
// Always draw the selected tab last, so that drop shadows are drawn
// in the correct z-order.
if (i == childCount - 1) {
return mSelectedTab;
} else if (i >= mSelectedTab) {
return i + 1;
} else {
return i;
}
}
}
@Override
void measureChildBeforeLayout(View child, int childIndex, int widthMeasureSpec, int totalWidth,
int heightMeasureSpec, int totalHeight) {
if (!isMeasureWithLargestChildEnabled() && mImposedTabsHeight >= 0) {
widthMeasureSpec = MeasureSpec.makeMeasureSpec(
totalWidth + mImposedTabWidths[childIndex], MeasureSpec.EXACTLY);
heightMeasureSpec = MeasureSpec.makeMeasureSpec(mImposedTabsHeight,
MeasureSpec.EXACTLY);
}
super.measureChildBeforeLayout(child, childIndex,
widthMeasureSpec, totalWidth, heightMeasureSpec, totalHeight);
}
@Override
void measureHorizontal(int widthMeasureSpec, int heightMeasureSpec) {
if (MeasureSpec.getMode(widthMeasureSpec) == MeasureSpec.UNSPECIFIED) {
super.measureHorizontal(widthMeasureSpec, heightMeasureSpec);
return;
}
// First, measure with no constraint
final int width = MeasureSpec.getSize(widthMeasureSpec);
final int unspecifiedWidth = MeasureSpec.makeSafeMeasureSpec(width,
MeasureSpec.UNSPECIFIED);
mImposedTabsHeight = -1;
super.measureHorizontal(unspecifiedWidth, heightMeasureSpec);
int extraWidth = getMeasuredWidth() - width;
if (extraWidth > 0) {
final int count = getChildCount();
int childCount = 0;
for (int i = 0; i < count; i++) {
final View child = getChildAt(i);
if (child.getVisibility() == GONE) continue;
childCount++;
}
if (childCount > 0) {
if (mImposedTabWidths == null || mImposedTabWidths.length != count) {
mImposedTabWidths = new int[count];
}
for (int i = 0; i < count; i++) {
final View child = getChildAt(i);
if (child.getVisibility() == GONE) continue;
final int childWidth = child.getMeasuredWidth();
final int delta = extraWidth / childCount;
final int newWidth = Math.max(0, childWidth - delta);
mImposedTabWidths[i] = newWidth;
// Make sure the extra width is evenly distributed, no int division remainder
extraWidth -= childWidth - newWidth; // delta may have been clamped
childCount--;
mImposedTabsHeight = Math.max(mImposedTabsHeight, child.getMeasuredHeight());
}
}
}
// Measure again, this time with imposed tab widths and respecting
// initial spec request.
super.measureHorizontal(widthMeasureSpec, heightMeasureSpec);
}
/**
* Returns the tab indicator view at the given index.
*
* @param index the zero-based index of the tab indicator view to return
* @return the tab indicator view at the given index
*/
public View getChildTabViewAt(int index) {
return getChildAt(index);
}
/**
* Returns the number of tab indicator views.
*
* @return the number of tab indicator views
*/
public int getTabCount() {
return getChildCount();
}
/**
* Sets the drawable to use as a divider between the tab indicators.
*
* @param drawable the divider drawable
* @attr ref android.R.styleable#TabWidget_divider
*/
@Override
public void setDividerDrawable(@Nullable Drawable drawable) {
super.setDividerDrawable(drawable);
}
/**
* Sets the drawable to use as a divider between the tab indicators.
*
* @param resId the resource identifier of the drawable to use as a divider
* @attr ref android.R.styleable#TabWidget_divider
*/
public void setDividerDrawable(@DrawableRes int resId) {
setDividerDrawable(mContext.getDrawable(resId));
}
/**
* Sets the drawable to use as the left part of the strip below the tab
* indicators.
*
* @param drawable the left strip drawable
* @see #getLeftStripDrawable()
* @attr ref android.R.styleable#TabWidget_tabStripLeft
*/
public void setLeftStripDrawable(@Nullable Drawable drawable) {
mLeftStrip = drawable;
requestLayout();
invalidate();
}
/**
* Sets the drawable to use as the left part of the strip below the tab
* indicators.
*
* @param resId the resource identifier of the drawable to use as the left
* strip drawable
* @see #getLeftStripDrawable()
* @attr ref android.R.styleable#TabWidget_tabStripLeft
*/
public void setLeftStripDrawable(@DrawableRes int resId) {
setLeftStripDrawable(mContext.getDrawable(resId));
}
/**
* @return the drawable used as the left part of the strip below the tab
* indicators, may be {@code null}
* @see #setLeftStripDrawable(int)
* @see #setLeftStripDrawable(Drawable)
* @attr ref android.R.styleable#TabWidget_tabStripLeft
*/
@Nullable
public Drawable getLeftStripDrawable() {
return mLeftStrip;
}
/**
* Sets the drawable to use as the right part of the strip below the tab
* indicators.
*
* @param drawable the right strip drawable
* @see #getRightStripDrawable()
* @attr ref android.R.styleable#TabWidget_tabStripRight
*/
public void setRightStripDrawable(@Nullable Drawable drawable) {
mRightStrip = drawable;
requestLayout();
invalidate();
}
/**
* Sets the drawable to use as the right part of the strip below the tab
* indicators.
*
* @param resId the resource identifier of the drawable to use as the right
* strip drawable
* @see #getRightStripDrawable()
* @attr ref android.R.styleable#TabWidget_tabStripRight
*/
public void setRightStripDrawable(@DrawableRes int resId) {
setRightStripDrawable(mContext.getDrawable(resId));
}
/**
* @return the drawable used as the right part of the strip below the tab
* indicators, may be {@code null}
* @see #setRightStripDrawable(int)
* @see #setRightStripDrawable(Drawable)
* @attr ref android.R.styleable#TabWidget_tabStripRight
*/
@Nullable
public Drawable getRightStripDrawable() {
return mRightStrip;
}
/**
* Controls whether the bottom strips on the tab indicators are drawn or
* not. The default is to draw them. If the user specifies a custom
* view for the tab indicators, then the TabHost class calls this method
* to disable drawing of the bottom strips.
* @param stripEnabled true if the bottom strips should be drawn.
*/
public void setStripEnabled(boolean stripEnabled) {
mDrawBottomStrips = stripEnabled;
invalidate();
}
/**
* Indicates whether the bottom strips on the tab indicators are drawn
* or not.
*/
public boolean isStripEnabled() {
return mDrawBottomStrips;
}
@Override
public void childDrawableStateChanged(View child) {
if (getTabCount() > 0 && child == getChildTabViewAt(mSelectedTab)) {
// To make sure that the bottom strip is redrawn
invalidate();
}
super.childDrawableStateChanged(child);
}
@Override
public void dispatchDraw(Canvas canvas) {
super.dispatchDraw(canvas);
// Do nothing if there are no tabs.
if (getTabCount() == 0) return;
// If the user specified a custom view for the tab indicators, then
// do not draw the bottom strips.
if (!mDrawBottomStrips) {
// Skip drawing the bottom strips.
return;
}
final View selectedChild = getChildTabViewAt(mSelectedTab);
final Drawable leftStrip = mLeftStrip;
final Drawable rightStrip = mRightStrip;
leftStrip.setState(selectedChild.getDrawableState());
rightStrip.setState(selectedChild.getDrawableState());
if (mStripMoved) {
final Rect bounds = mBounds;
bounds.left = selectedChild.getLeft();
bounds.right = selectedChild.getRight();
final int myHeight = getHeight();
leftStrip.setBounds(Math.min(0, bounds.left - leftStrip.getIntrinsicWidth()),
myHeight - leftStrip.getIntrinsicHeight(), bounds.left, myHeight);
rightStrip.setBounds(bounds.right, myHeight - rightStrip.getIntrinsicHeight(),
Math.max(getWidth(), bounds.right + rightStrip.getIntrinsicWidth()), myHeight);
mStripMoved = false;
}
leftStrip.draw(canvas);
rightStrip.draw(canvas);
}
/**
* Sets the current tab.
* <p>
* This method is used to bring a tab to the front of the Widget,
* and is used to post to the rest of the UI that a different tab
* has been brought to the foreground.
* <p>
* Note, this is separate from the traditional "focus" that is
* employed from the view logic.
* <p>
* For instance, if we have a list in a tabbed view, a user may be
* navigating up and down the list, moving the UI focus (orange
* highlighting) through the list items. The cursor movement does
* not effect the "selected" tab though, because what is being
* scrolled through is all on the same tab. The selected tab only
* changes when we navigate between tabs (moving from the list view
* to the next tabbed view, in this example).
* <p>
* To move both the focus AND the selected tab at once, please use
* {@link #setCurrentTab}. Normally, the view logic takes care of
* adjusting the focus, so unless you're circumventing the UI,
* you'll probably just focus your interest here.
*
* @param index the index of the tab that you want to indicate as the
* selected tab (tab brought to the front of the widget)
* @see #focusCurrentTab
*/
public void setCurrentTab(int index) {
if (index < 0 || index >= getTabCount() || index == mSelectedTab) {
return;
}
if (mSelectedTab != -1) {
getChildTabViewAt(mSelectedTab).setSelected(false);
}
mSelectedTab = index;
getChildTabViewAt(mSelectedTab).setSelected(true);
mStripMoved = true;
}
@Override
public CharSequence getAccessibilityClassName() {
return TabWidget.class.getName();
}
/** @hide */
@Override
public void onInitializeAccessibilityEventInternal(AccessibilityEvent event) {
super.onInitializeAccessibilityEventInternal(event);
event.setItemCount(getTabCount());
event.setCurrentItemIndex(mSelectedTab);
}
/**
* Sets the current tab and focuses the UI on it.
* This method makes sure that the focused tab matches the selected
* tab, normally at {@link #setCurrentTab}. Normally this would not
* be an issue if we go through the UI, since the UI is responsible
* for calling TabWidget.onFocusChanged(), but in the case where we
* are selecting the tab programmatically, we'll need to make sure
* focus keeps up.
*
* @param index The tab that you want focused (highlighted in orange)
* and selected (tab brought to the front of the widget)
*
* @see #setCurrentTab
*/
public void focusCurrentTab(int index) {
final int oldTab = mSelectedTab;
// set the tab
setCurrentTab(index);
// change the focus if applicable.
if (oldTab != index) {
getChildTabViewAt(index).requestFocus();
}
}
@Override
public void setEnabled(boolean enabled) {
super.setEnabled(enabled);
final int count = getTabCount();
for (int i = 0; i < count; i++) {
final View child = getChildTabViewAt(i);
child.setEnabled(enabled);
}
}
@Override
public void addView(View child) {
if (child.getLayoutParams() == null) {
final LinearLayout.LayoutParams lp = new LayoutParams(
0, ViewGroup.LayoutParams.MATCH_PARENT, 1.0f);
lp.setMargins(0, 0, 0, 0);
child.setLayoutParams(lp);
}
// Ensure you can navigate to the tab with the keyboard, and you can touch it
child.setFocusable(true);
child.setClickable(true);
super.addView(child);
// TODO: detect this via geometry with a tabwidget listener rather
// than potentially interfere with the view's listener
child.setOnClickListener(new TabClickListener(getTabCount() - 1));
}
@Override
public void removeAllViews() {
super.removeAllViews();
mSelectedTab = -1;
}
/**
* Provides a way for {@link TabHost} to be notified that the user clicked
* on a tab indicator.
*/
void setTabSelectionListener(OnTabSelectionChanged listener) {
mSelectionChangedListener = listener;
}
@Override
public void onFocusChange(View v, boolean hasFocus) {
// No-op. Tab selection is separate from keyboard focus.
}
// registered with each tab indicator so we can notify tab host
private class TabClickListener implements OnClickListener {
private final int mTabIndex;
private TabClickListener(int tabIndex) {
mTabIndex = tabIndex;
}
public void onClick(View v) {
mSelectionChangedListener.onTabSelectionChanged(mTabIndex, true);
}
}
/**
* Lets {@link TabHost} know that the user clicked on a tab indicator.
*/
interface OnTabSelectionChanged {
/**
* Informs the TabHost which tab was selected. It also indicates
* if the tab was clicked/pressed or just focused into.
*
* @param tabIndex index of the tab that was selected
* @param clicked whether the selection changed due to a touch/click or
* due to focus entering the tab through navigation.
* {@code true} if it was due to a press/click and
* {@code false} otherwise.
*/
void onTabSelectionChanged(int tabIndex, boolean clicked);
}
}