Java tutorial
/* * Copyright (C) 2013 Andreas Stuetz <andreas.stuetz@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 com.azhansy.linky.view; import android.annotation.SuppressLint; import android.content.Context; import android.content.res.TypedArray; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.graphics.Paint.Style; import android.graphics.RectF; import android.os.Build; import android.os.Parcel; import android.os.Parcelable; import android.support.v4.view.ViewPager; import android.support.v4.view.ViewPager.OnPageChangeListener; import android.util.AttributeSet; import android.util.DisplayMetrics; import android.util.TypedValue; import android.view.View; import android.view.ViewTreeObserver.OnGlobalLayoutListener; import android.widget.HorizontalScrollView; import android.widget.LinearLayout; import com.azhansy.linky.R; public class PagerSlidingIndicator extends HorizontalScrollView { public interface IColorTransition { void transitionColor(float fraction); } public interface OnIndicatorItemClickListener { boolean onIndicatorItemClick(int position); } private LinearLayout.LayoutParams defaultTabLayoutParams; private LinearLayout.LayoutParams expandedTabLayoutParams; private final PageListener pageListener = new PageListener(); private LinearLayout tabsContainer; private ViewPager pager; private int tabCount; private int currentPosition = 0; private float currentPositionOffset = 0f; private Paint backgroundPaint; private Paint checkedBackgroundPaint; private int backgroundStrokeColor = Color.TRANSPARENT; private int backgroundStrokeWidth = 1; // 1dp private int backgroundColor = Color.WHITE; private int checkedBackgroundColor = Color.TRANSPARENT; private boolean shouldExpand = false; private int scrollOffset = 52; private int lastScrollX = 0; // ???? private RectF mTempRectF = new RectF(); private int mNoPagerPosition; private OnIndicatorItemClickListener mOnIndicatorItemClickListener; public PagerSlidingIndicator(Context context) { this(context, null); } public PagerSlidingIndicator(Context context, AttributeSet attrs) { this(context, attrs, 0); } public PagerSlidingIndicator(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); setFillViewport(true); setWillNotDraw(false); DisplayMetrics dm = getResources().getDisplayMetrics(); scrollOffset = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, scrollOffset, dm); backgroundStrokeWidth = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, backgroundStrokeWidth, dm); TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.PagerSlidingIndicator); shouldExpand = a.getBoolean(R.styleable.PagerSlidingIndicator_shouldExpand, shouldExpand); scrollOffset = a.getDimensionPixelSize(R.styleable.PagerSlidingIndicator_scrollOffset, scrollOffset); backgroundStrokeColor = a.getColor(R.styleable.PagerSlidingIndicator_background_stroke_color, backgroundStrokeColor); backgroundStrokeWidth = a.getDimensionPixelSize(R.styleable.PagerSlidingIndicator_background_stroke_width, backgroundStrokeWidth); backgroundColor = a.getColor(R.styleable.PagerSlidingIndicator_background_color, backgroundColor); checkedBackgroundColor = a.getColor(R.styleable.PagerSlidingIndicator_checked_background_color, checkedBackgroundColor); a.recycle(); // backgroundPaint = new Paint(Paint.ANTI_ALIAS_FLAG | Paint.DITHER_FLAG); backgroundPaint.setColor(backgroundColor); backgroundPaint.setStyle(Style.FILL); // checkedBackgroundPaint = new Paint(Paint.ANTI_ALIAS_FLAG | Paint.DITHER_FLAG); checkedBackgroundPaint.setColor(checkedBackgroundColor); checkedBackgroundPaint.setStyle(Style.FILL); defaultTabLayoutParams = new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.MATCH_PARENT); expandedTabLayoutParams = new LinearLayout.LayoutParams(0, LayoutParams.MATCH_PARENT, 1.0f); } @Override public void onFinishInflate() { super.onFinishInflate(); tabsContainer = (LinearLayout) getChildAt(0); for (int i = 0; i < tabsContainer.getChildCount(); i++) { final int position = i; View v = tabsContainer.getChildAt(i); v.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { if (mOnIndicatorItemClickListener == null || !mOnIndicatorItemClickListener.onIndicatorItemClick(position)) { if (pager != null) { pager.setCurrentItem(position); } else { setSelection(position); } } } }); } setSelection(0); } public void setViewPager(ViewPager pager) { this.pager = pager; if (pager.getAdapter() == null) { throw new IllegalStateException("ViewPager does not have adapter instance."); } pager.addOnPageChangeListener(pageListener); notifyDataSetChanged(); } public void notifyDataSetChanged() { tabCount = pager.getAdapter().getCount(); getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener() { @SuppressWarnings("deprecation") @SuppressLint("NewApi") @Override public void onGlobalLayout() { if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN) { getViewTreeObserver().removeGlobalOnLayoutListener(this); } else { getViewTreeObserver().removeOnGlobalLayoutListener(this); } currentPosition = pager.getCurrentItem(); scrollToChild(currentPosition, 0); } }); } private void scrollToChild(int position, int offset) { if (tabCount == 0) { return; } int newScrollX = tabsContainer.getChildAt(position).getLeft() + offset; if (position > 0 || offset > 0) { newScrollX -= scrollOffset; } if (newScrollX != lastScrollX) { lastScrollX = newScrollX; scrollTo(newScrollX, 0); } } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); if (isInEditMode()) { return; } final int height = getHeight(); float radius = height / 2.0f; drawBackground(canvas); if (pager != null) { // default: line below current tab View currentTab = tabsContainer.getChildAt(currentPosition); float lineLeft = currentTab.getLeft(); float lineRight = currentTab.getRight(); // if there is an offset, start interpolating left and right coordinates between current and next tab if (currentPositionOffset > 0f && currentPosition < tabCount - 1) { View nextTab = tabsContainer.getChildAt(currentPosition + 1); final float nextTabLeft = nextTab.getLeft(); final float nextTabRight = nextTab.getRight(); lineLeft = (currentPositionOffset * nextTabLeft + (1f - currentPositionOffset) * lineLeft); lineRight = (currentPositionOffset * nextTabRight + (1f - currentPositionOffset) * lineRight); } mTempRectF.set(lineLeft, 0, lineRight, height); checkedBackgroundPaint.setColor(checkedBackgroundColor); canvas.drawRoundRect(mTempRectF, radius, radius, checkedBackgroundPaint); updateTextColor(); } else { View tab = tabsContainer.getChildAt(mNoPagerPosition); float lineLeft = tab.getLeft(); float lineRight = tab.getRight(); mTempRectF.set(lineLeft, 0, lineRight, height); checkedBackgroundPaint.setColor(checkedBackgroundColor); canvas.drawRoundRect(mTempRectF, radius, radius, checkedBackgroundPaint); } } private void updateTextColor() { View currentTab = tabsContainer.getChildAt(currentPosition); if (currentTab instanceof IColorTransition) { ((IColorTransition) currentTab).transitionColor(currentPositionOffset); } if (currentPosition < tabCount - 1) { View nextTab = tabsContainer.getChildAt(currentPosition + 1); if (nextTab instanceof IColorTransition) { ((IColorTransition) nextTab).transitionColor(1.0f - currentPositionOffset); } } for (int i = 0; i < tabsContainer.getChildCount(); i++) { if (i != currentPosition && i != currentPosition + 1) { View tab = tabsContainer.getChildAt(i); if (tab instanceof IColorTransition) { ((IColorTransition) tab).transitionColor(1.0f); } } } } /** * ?? */ private void drawBackground(Canvas canvas) { float left = backgroundStrokeWidth; float top = backgroundStrokeWidth; float right = getWidth() - backgroundStrokeWidth; float bottom = getHeight() - backgroundStrokeWidth; mTempRectF.set(left, top, right, bottom); float radius = getHeight() / 2.0f; // backgroundPaint.setStyle(Style.FILL); backgroundPaint.setColor(backgroundColor); canvas.drawRoundRect(mTempRectF, radius, radius, backgroundPaint); // ?? backgroundPaint.setStyle(Style.STROKE); backgroundPaint.setColor(backgroundStrokeColor); canvas.drawRoundRect(mTempRectF, radius, radius, backgroundPaint); } private class PageListener implements OnPageChangeListener { @Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { currentPosition = position; currentPositionOffset = positionOffset; scrollToChild(position, (int) (positionOffset * tabsContainer.getChildAt(position).getWidth())); invalidate(); } @Override public void onPageScrollStateChanged(int state) { // if (state == ViewPager.SCROLL_STATE_IDLE) { // scrollToChild(pager.getCurrentItem(), 0); // } } @Override public void onPageSelected(int position) { scrollToChild(position, 0); } } public void setOnIndicatorItemClickListener(OnIndicatorItemClickListener listener) { mOnIndicatorItemClickListener = listener; } public void setSelection(int position) { mNoPagerPosition = position; for (int i = 0; i < tabsContainer.getChildCount(); i++) { View tab = tabsContainer.getChildAt(i); if (tab instanceof IColorTransition) { ((IColorTransition) tab).transitionColor(i == position ? 0f : 1.0f); } } invalidate(); } public int getPagerPosition() { return mNoPagerPosition; } public void setScrollOffset(int scrollOffsetPx) { this.scrollOffset = scrollOffsetPx; invalidate(); } public int getScrollOffset() { return scrollOffset; } public void setShouldExpand(boolean shouldExpand) { this.shouldExpand = shouldExpand; requestLayout(); } public void setIndicatorBackgroundColor(int backgroundColor) { this.backgroundColor = backgroundColor; invalidate(); } public void setCheckedBackgroundColor(int color) { this.checkedBackgroundColor = color; invalidate(); } @Override public void onRestoreInstanceState(Parcelable state) { SavedState savedState = (SavedState) state; super.onRestoreInstanceState(savedState.getSuperState()); currentPosition = savedState.currentPosition; requestLayout(); } @Override public Parcelable onSaveInstanceState() { Parcelable superState = super.onSaveInstanceState(); SavedState savedState = new SavedState(superState); savedState.currentPosition = currentPosition; return savedState; } static class SavedState extends BaseSavedState { int currentPosition; public SavedState(Parcelable superState) { super(superState); } private SavedState(Parcel in) { super(in); currentPosition = in.readInt(); } @Override public void writeToParcel(Parcel dest, int flags) { super.writeToParcel(dest, flags); dest.writeInt(currentPosition); } public static final Creator<SavedState> CREATOR = new Creator<SavedState>() { @Override public SavedState createFromParcel(Parcel in) { return new SavedState(in); } @Override public SavedState[] newArray(int size) { return new SavedState[size]; } }; } }