Java tutorial
/* Copyright (C) 2014 Yuki Anzai anzai.y.aa@gmail.com * * 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 net.yanzm.mth; import android.content.Context; import android.content.res.Resources; import android.content.res.TypedArray; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.PorterDuff; import android.graphics.drawable.ColorDrawable; import android.graphics.drawable.Drawable; import android.graphics.drawable.ShapeDrawable; import android.graphics.drawable.StateListDrawable; import android.os.Build; import android.support.v4.view.ViewCompat; import android.support.v4.view.ViewPager; import android.util.AttributeSet; import android.util.TypedValue; import android.view.Gravity; import android.view.LayoutInflater; import android.view.View; import android.widget.FrameLayout; import android.widget.LinearLayout; import android.widget.TabHost; import android.widget.TabWidget; import android.widget.TextView; /** * MaterialTabHost make easy to create Material Design Fixed Tabs * http://www.google.com/design/spec/components/tabs.html */ public class MaterialTabHost extends TabHost implements ViewPager.OnPageChangeListener { // http://www.google.com/design/spec/what-is-material/objects-in-3d-space.html#objects-in-3d-space-elevation private static final int APP_TAB_ELEVATION = 4; // 4dp public static enum Type { FullScreenWidth, Centered, LeftOffset; } public interface OnTabChangeListener { public void onTabSelected(int position); } private final LayoutInflater inflater; private final TabWidget tabWidget; private final ShapeDrawable indicator; private final int indicatorHeight; private final int leftOffset; private final int colorControlActivated; private Type type = Type.FullScreenWidth; private OnTabChangeListener listener; private int maxTabWidth = Integer.MIN_VALUE; private int scrollingState = ViewPager.SCROLL_STATE_IDLE; private int position = 0; private float positionOffset = 0; public MaterialTabHost(Context context) { this(context, null); } public MaterialTabHost(Context context, AttributeSet attrs) { super(context, attrs); inflater = LayoutInflater.from(context); TypedArray a = context.getTheme().obtainStyledAttributes(attrs, R.styleable.MaterialTabHost, 0, 0); int indicatorColor = a.getColor(R.styleable.MaterialTabHost_colorTabIndicator, Color.YELLOW); colorControlActivated = a.getColor(R.styleable.MaterialTabHost_colorBackground, Color.WHITE); setBackgroundColor(colorControlActivated); a.recycle(); // ColorDrawable on 2.x does not use getBounds() so use ShapeDrawable indicator = new ShapeDrawable(); indicator.setColorFilter(indicatorColor, PorterDuff.Mode.SRC_ATOP); Resources res = context.getResources(); indicatorHeight = res.getDimensionPixelSize(R.dimen.mth_tab_indicator_height); leftOffset = res.getDimensionPixelSize(R.dimen.mth_tab_left_offset); int tabHeight = res.getDimensionPixelSize(R.dimen.mth_tab_height); tabWidget = new TabWidget(context); tabWidget.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, tabHeight)); tabWidget.setId(android.R.id.tabs); tabWidget.setStripEnabled(false); if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) { tabWidget.setShowDividers(LinearLayout.SHOW_DIVIDER_NONE); } addView(tabWidget); FrameLayout fl = new FrameLayout(context); fl.setLayoutParams(new LayoutParams(0, 0)); fl.setId(android.R.id.tabcontent); addView(fl); setup(); setOnTabChangedListener(new TabHost.OnTabChangeListener() { @Override public void onTabChanged(String tabId) { if (listener != null) { listener.onTabSelected(Integer.valueOf(tabId)); } } }); float density = getResources().getDisplayMetrics().density; // set elevation for App bar // http://www.google.com/design/spec/what-is-material/objects-in-3d-space.html#objects-in-3d-space-elevation ViewCompat.setElevation(this, APP_TAB_ELEVATION * density); } protected int getLayoutId(Type type) { switch (type) { case FullScreenWidth: return R.layout.mth_tab_widget_full; case Centered: return R.layout.mth_tab_widget; case LeftOffset: return R.layout.mth_tab_widget; default: return R.layout.mth_tab_widget_full; } } /** * add new tab with title text * * @param title title text */ public void addTab(CharSequence title) { int layoutId = getLayoutId(type); TextView tv = (TextView) inflater.inflate(layoutId, tabWidget, false); tv.setText(title); if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) { tv.setBackgroundResource(R.drawable.mth_tab_widget_background_ripple); } else { // create background using colorControlActivated StateListDrawable d = new StateListDrawable(); d.addState(new int[] { android.R.attr.state_pressed }, new ColorDrawable(colorControlActivated)); d.setAlpha(180); if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) { tv.setBackground(d); } else { tv.setBackgroundDrawable(d); } } int tabId = tabWidget.getTabCount(); addTab(newTabSpec(String.valueOf(tabId)).setIndicator(tv).setContent(android.R.id.tabcontent)); } /** * add new tab with specified view * * @param view tab view */ public void addTab(View view) { if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) { view.setBackgroundResource(R.drawable.mth_tab_widget_background_ripple); } else { // create background using colorControlActivated StateListDrawable d = new StateListDrawable(); d.addState(new int[] { android.R.attr.state_pressed }, new ColorDrawable(colorControlActivated)); d.setAlpha(180); if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) { view.setBackground(d); } else { view.setBackgroundDrawable(d); } } int tabId = tabWidget.getTabCount(); addTab(newTabSpec(String.valueOf(tabId)).setIndicator(view).setContent(android.R.id.tabcontent)); } @Override protected void onLayout(boolean changed, int left, int top, int right, int bottom) { if (type == Type.Centered) { if (maxTabWidth == Integer.MIN_VALUE) { for (int i = 0; i < tabWidget.getTabCount(); i++) { View tabView = tabWidget.getChildTabViewAt(i); if (tabView.getMeasuredWidth() > maxTabWidth) { maxTabWidth = tabView.getMeasuredWidth(); } } if (maxTabWidth > 0) { for (int i = 0; i < tabWidget.getTabCount(); i++) { View tabView = tabWidget.getChildTabViewAt(i); LinearLayout.LayoutParams params = (LinearLayout.LayoutParams) tabView.getLayoutParams(); params.width = maxTabWidth; tabView.setLayoutParams(params); } } } } super.onLayout(changed, left, top, right, bottom); } @Override protected void dispatchDraw(Canvas canvas) { super.dispatchDraw(canvas); if (getChildCount() == 0) { return; } final Drawable d = indicator; View tabView = tabWidget.getChildTabViewAt(position); if (tabView == null) { return; } View nextTabView = position + 1 < tabWidget.getTabCount() ? tabWidget.getChildTabViewAt(position + 1) : null; int tabWidth = tabView.getWidth(); int nextTabWidth = nextTabView == null ? tabWidth : nextTabView.getWidth(); int indicatorWidth = (int) (nextTabWidth * positionOffset + tabWidth * (1 - positionOffset)); int indicatorLeft = (int) (getPaddingLeft() + tabView.getLeft() + positionOffset * tabWidth); int height = getHeight(); d.setBounds(indicatorLeft, height - indicatorHeight, indicatorLeft + indicatorWidth, height); d.draw(canvas); } public void setOnTabChangeListener(OnTabChangeListener l) { listener = l; } public void setType(Type type) { this.type = type; switch (type) { case FullScreenWidth: tabWidget.setGravity(Gravity.LEFT); setPadding(0, 0, 0, 0); break; case Centered: tabWidget.setGravity(Gravity.CENTER_HORIZONTAL); setPadding(0, 0, 0, 0); break; case LeftOffset: tabWidget.setGravity(Gravity.LEFT); setPadding(leftOffset, 0, 0, 0); break; default: tabWidget.setGravity(Gravity.LEFT); setPadding(0, 0, 0, 0); } } @Override public void onPageSelected(int position) { if (scrollingState == ViewPager.SCROLL_STATE_IDLE) { updateIndicatorPosition(position, 0); } setCurrentTab(position); } @Override public void onPageScrollStateChanged(int state) { scrollingState = state; } @Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { updateIndicatorPosition(position, positionOffset); } private void updateIndicatorPosition(int position, float positionOffset) { this.position = position; this.positionOffset = positionOffset; invalidate(); } }