R.attr.colorForeground error from Google I / O SlidingTabStrip.java

Question

I am trying to embed tabs in my application and I added SlidingTabLayout.java and SlidingTabStrip.java from Google. I also took care to add the setDistributeEvenly method to the SlidingTabLayout class.

My problem comes from R.attr.colorForeground. I get the error "Cannot resolve sysmbol" colorForeground ".

Here are two classes for which they are created for tabs.

class SlidingTabStrip extends LinearLayout { private static final int DEFAULT_BOTTOM_BORDER_THICKNESS_DIPS = 0; private static final byte DEFAULT_BOTTOM_BORDER_COLOR_ALPHA = 0x26; private static final int SELECTED_INDICATOR_THICKNESS_DIPS = 3; private static final int DEFAULT_SELECTED_INDICATOR_COLOR = 0xFF33B5E5; private final int mBottomBorderThickness; private final Paint mBottomBorderPaint; private final int mSelectedIndicatorThickness; private final Paint mSelectedIndicatorPaint; private final int mDefaultBottomBorderColor; private final SimpleTabColorizer mDefaultTabColorizer; private int mSelectedPosition; private float mSelectionOffset; private SlidingTabLayout.TabColorizer mCustomTabColorizer; SlidingTabStrip(Context context) { this(context, null); } SlidingTabStrip(Context context, AttributeSet attrs) { super(context, attrs); setWillNotDraw(false); final float density = getResources().getDisplayMetrics().density; TypedValue outValue = new TypedValue(); context.getTheme().resolveAttribute(R.attr.colorForeground, outValue, true); final int themeForegroundColor = outValue.data; mDefaultBottomBorderColor = setColorAlpha(themeForegroundColor, DEFAULT_BOTTOM_BORDER_COLOR_ALPHA); mDefaultTabColorizer = new SimpleTabColorizer(); mDefaultTabColorizer.setIndicatorColors(DEFAULT_SELECTED_INDICATOR_COLOR); mBottomBorderThickness = (int) (DEFAULT_BOTTOM_BORDER_THICKNESS_DIPS * density); mBottomBorderPaint = new Paint(); mBottomBorderPaint.setColor(mDefaultBottomBorderColor); mSelectedIndicatorThickness = (int) (SELECTED_INDICATOR_THICKNESS_DIPS * density); mSelectedIndicatorPaint = new Paint(); } /** * Set the alpha value of the {@code color} to be the given {@code alpha} value. */ private static int setColorAlpha(int color, byte alpha) { return Color.argb(alpha, Color.red(color), Color.green(color), Color.blue(color)); } /** * Blend {@code color1} and {@code color2} using the given ratio. * * @param ratio of which to blend. 1.0 will return {@code color1}, 0.5 will give an even blend, * 0.0 will return {@code color2}. */ private static int blendColors(int color1, int color2, float ratio) { final float inverseRation = 1f - ratio; float r = (Color.red(color1) * ratio) + (Color.red(color2) * inverseRation); float g = (Color.green(color1) * ratio) + (Color.green(color2) * inverseRation); float b = (Color.blue(color1) * ratio) + (Color.blue(color2) * inverseRation); return Color.rgb((int) r, (int) g, (int) b); } void setCustomTabColorizer(SlidingTabLayout.TabColorizer customTabColorizer) { mCustomTabColorizer = customTabColorizer; invalidate(); } void setSelectedIndicatorColors(int... colors) { // Make sure that the custom colorizer is removed mCustomTabColorizer = null; mDefaultTabColorizer.setIndicatorColors(colors); invalidate(); } void onViewPagerPageChanged(int position, float positionOffset) { mSelectedPosition = position; mSelectionOffset = positionOffset; invalidate(); } @Override protected void onDraw(Canvas canvas) { final int height = getHeight(); final int childCount = getChildCount(); final SlidingTabLayout.TabColorizer tabColorizer = mCustomTabColorizer != null ? mCustomTabColorizer : mDefaultTabColorizer; // Thick colored underline below the current selection if (childCount > 0) { View selectedTitle = getChildAt(mSelectedPosition); int left = selectedTitle.getLeft(); int right = selectedTitle.getRight(); int color = tabColorizer.getIndicatorColor(mSelectedPosition); if (mSelectionOffset > 0f && mSelectedPosition < (getChildCount() - 1)) { int nextColor = tabColorizer.getIndicatorColor(mSelectedPosition + 1); if (color != nextColor) { color = blendColors(nextColor, color, mSelectionOffset); } // Draw the selection partway between the tabs View nextTitle = getChildAt(mSelectedPosition + 1); left = (int) (mSelectionOffset * nextTitle.getLeft() + (1.0f - mSelectionOffset) * left); right = (int) (mSelectionOffset * nextTitle.getRight() + (1.0f - mSelectionOffset) * right); } mSelectedIndicatorPaint.setColor(color); canvas.drawRect(left, height - mSelectedIndicatorThickness, right, height, mSelectedIndicatorPaint); } // Thin underline along the entire bottom edge canvas.drawRect(0, height - mBottomBorderThickness, getWidth(), height, mBottomBorderPaint); } private static class SimpleTabColorizer implements SlidingTabLayout.TabColorizer { private int[] mIndicatorColors; @Override public final int getIndicatorColor(int position) { return mIndicatorColors[position % mIndicatorColors.length]; } void setIndicatorColors(int... colors) { mIndicatorColors = colors; } } 

}

 public class SlidingTabLayout extends HorizontalScrollView { private static final int TITLE_OFFSET_DIPS = 24; private static final int TAB_VIEW_PADDING_DIPS = 16; private static final int TAB_VIEW_TEXT_SIZE_SP = 12; private final SlidingTabStrip mTabStrip; private int mTitleOffset; private int mTabViewLayoutId; private int mTabViewTextViewId; private boolean mDistributeEvenly; private ViewPager mViewPager; private SparseArray<String> mContentDescriptions = new SparseArray<String>(); private ViewPager.OnPageChangeListener mViewPagerPageChangeListener; public SlidingTabLayout(Context context) { this(context, null); } public SlidingTabLayout(Context context, AttributeSet attrs) { this(context, attrs, 0); } public SlidingTabLayout(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); // Disable the Scroll Bar setHorizontalScrollBarEnabled(false); // Make sure that the Tab Strips fills this View setFillViewport(true); mTitleOffset = (int) (TITLE_OFFSET_DIPS * getResources().getDisplayMetrics().density); mTabStrip = new SlidingTabStrip(context); addView(mTabStrip, LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT); } /** * Set the custom {@link TabColorizer} to be used. * <p/> * If you only require simple custmisation then you can use * {@link #setSelectedIndicatorColors(int...)} to achieve * similar effects. */ public void setCustomTabColorizer(TabColorizer tabColorizer) { mTabStrip.setCustomTabColorizer(tabColorizer); } public void setDistributeEvenly(boolean distributeEvenly) { mDistributeEvenly = distributeEvenly; } /** * Sets the colors to be used for indicating the selected tab. These colors are treated as a * circular array. Providing one color will mean that all tabs are indicated with the same color. */ public void setSelectedIndicatorColors(int... colors) { mTabStrip.setSelectedIndicatorColors(colors); } /** * Set the {@link ViewPager.OnPageChangeListener}. When using {@link SlidingTabLayout} you are * required to set any {@link ViewPager.OnPageChangeListener} through this method. This is so * that the layout can update it scroll position correctly. * * @see ViewPager#setOnPageChangeListener(ViewPager.OnPageChangeListener) */ public void setOnPageChangeListener(ViewPager.OnPageChangeListener listener) { mViewPagerPageChangeListener = listener; } /** * Set the custom layout to be inflated for the tab views. * * @param layoutResId Layout id to be inflated * @param textViewId id of the {@link TextView} in the inflated view */ public void setCustomTabView(int layoutResId, int textViewId) { mTabViewLayoutId = layoutResId; mTabViewTextViewId = textViewId; } /** * Sets the associated view pager. Note that the assumption here is that the pager content * (number of tabs and tab titles) does not change after this call has been made. */ public void setViewPager(ViewPager viewPager) { mTabStrip.removeAllViews(); mViewPager = viewPager; if (viewPager != null) { viewPager.setOnPageChangeListener(new InternalViewPagerListener()); populateTabStrip(); } } /** * Create a default view to be used for tabs. This is called if a custom tab view is not set via * {@link #setCustomTabView(int, int)}. */ protected TextView createDefaultTabView(Context context) { TextView textView = new TextView(context); textView.setGravity(Gravity.CENTER); textView.setTextSize(TypedValue.COMPLEX_UNIT_SP, TAB_VIEW_TEXT_SIZE_SP); textView.setTypeface(Typeface.DEFAULT_BOLD); textView.setLayoutParams(new LinearLayout.LayoutParams( ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT)); TypedValue outValue = new TypedValue(); getContext().getTheme().resolveAttribute(android.R.attr.selectableItemBackground, outValue, true); textView.setBackgroundResource(outValue.resourceId); textView.setAllCaps(true); int padding = (int) (TAB_VIEW_PADDING_DIPS * getResources().getDisplayMetrics().density); textView.setPadding(padding, padding, padding, padding); return textView; } private void populateTabStrip() { final PagerAdapter adapter = mViewPager.getAdapter(); final View.OnClickListener tabClickListener = new TabClickListener(); for (int i = 0; i < adapter.getCount(); i++) { View tabView = null; TextView tabTitleView = null; if (mTabViewLayoutId != 0) { // If there is a custom tab view layout id set, try and inflate it tabView = LayoutInflater.from(getContext()).inflate(mTabViewLayoutId, mTabStrip, false); tabTitleView = (TextView) tabView.findViewById(mTabViewTextViewId); } if (tabView == null) { tabView = createDefaultTabView(getContext()); } if (tabTitleView == null && TextView.class.isInstance(tabView)) { tabTitleView = (TextView) tabView; } if (mDistributeEvenly) { LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams) tabView.getLayoutParams(); lp.width = 0; lp.weight = 1; } tabTitleView.setText(adapter.getPageTitle(i)); tabView.setOnClickListener(tabClickListener); String desc = mContentDescriptions.get(i, null); if (desc != null) { tabView.setContentDescription(desc); } mTabStrip.addView(tabView); if (i == mViewPager.getCurrentItem()) { tabView.setSelected(true); } } } public void setContentDescription(int i, String desc) { mContentDescriptions.put(i, desc); } @Override protected void onAttachedToWindow() { super.onAttachedToWindow(); if (mViewPager != null) { scrollToTab(mViewPager.getCurrentItem(), 0); } } private void scrollToTab(int tabIndex, int positionOffset) { final int tabStripChildCount = mTabStrip.getChildCount(); if (tabStripChildCount == 0 || tabIndex < 0 || tabIndex >= tabStripChildCount) { return; } View selectedChild = mTabStrip.getChildAt(tabIndex); if (selectedChild != null) { int targetScrollX = selectedChild.getLeft() + positionOffset; if (tabIndex > 0 || positionOffset > 0) { // If we're not at the first child and are mid-scroll, make sure we obey the offset targetScrollX -= mTitleOffset; } scrollTo(targetScrollX, 0); } } /** * Allows complete control over the colors drawn in the tab layout. Set with * {@link #setCustomTabColorizer(TabColorizer)}. */ public interface TabColorizer { /** * @return return the color of the indicator used when {@code position} is selected. */ int getIndicatorColor(int position); } private class InternalViewPagerListener implements ViewPager.OnPageChangeListener { private int mScrollState; @Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { int tabStripChildCount = mTabStrip.getChildCount(); if ((tabStripChildCount == 0) || (position < 0) || (position >= tabStripChildCount)) { return; } mTabStrip.onViewPagerPageChanged(position, positionOffset); View selectedTitle = mTabStrip.getChildAt(position); int extraOffset = (selectedTitle != null) ? (int) (positionOffset * selectedTitle.getWidth()) : 0; scrollToTab(position, extraOffset); if (mViewPagerPageChangeListener != null) { mViewPagerPageChangeListener.onPageScrolled(position, positionOffset, positionOffsetPixels); } } @Override public void onPageScrollStateChanged(int state) { mScrollState = state; if (mViewPagerPageChangeListener != null) { mViewPagerPageChangeListener.onPageScrollStateChanged(state); } } @Override public void onPageSelected(int position) { if (mScrollState == ViewPager.SCROLL_STATE_IDLE) { mTabStrip.onViewPagerPageChanged(position, 0f); scrollToTab(position, 0); } for (int i = 0; i < mTabStrip.getChildCount(); i++) { mTabStrip.getChildAt(i).setSelected(position == i); } if (mViewPagerPageChangeListener != null) { mViewPagerPageChangeListener.onPageSelected(position); } } } private class TabClickListener implements View.OnClickListener { @Override public void onClick(View v) { for (int i = 0; i < mTabStrip.getChildCount(); i++) { if (v == mTabStrip.getChildAt(i)) { mViewPager.setCurrentItem(i); return; } } } } 

}

On both classes from google, they did not declare colorForeground, so I assume it is installed in Android? Any help would be greatly appreciated for fixing this issue with colorForeground.

Answer 1

This is due to the fact that Android cannot find R.attr.colorForeground , since you (as once) imported your R into SlidingTabStrip . It is better to import import android.R; (Android Studio warns you not to, tho) or use android.R.attr.colorForeground directly.

Answer 2

There is a difference between:

 android.R; is used for accessing public standard android SDK resources. 

and

 com.yourpackage.R; is used for accessing YOUR resources in your application. 

you can use but if you use the R link, you SHOULD explicitly allow either depending on where / what you need

Answer 3

Remove your own say ex: com.yourpackage.R . Put android.R.attr.colorForeground instead of R.attr.colorForeground