Java tutorial
/* * Copyright (C) 2011 Patrik Akerfeldt * Copyright (C) 2011 Jake Wharton * * 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 yahier.exst.widget; import android.content.Context; import android.content.res.TypedArray; import android.graphics.Canvas; import android.graphics.Paint; import android.graphics.Paint.Style; import android.os.Parcel; import android.os.Parcelable; import android.support.v4.view.ViewPager; import android.util.AttributeSet; import android.view.View; import com.stbl.stbl.R; import com.stbl.stbl.util.DimenUtils; import static android.graphics.Paint.ANTI_ALIAS_FLAG; /** * Draws circles (one for each view). The current view position is filled and * others are only stroked. */ public class CirclePageIndicator extends View implements PageIndicator { private float mRadius; private float mGap; private final Paint mPaintPageFill = new Paint(ANTI_ALIAS_FLAG); private final Paint mPaintStroke = new Paint(ANTI_ALIAS_FLAG); private final Paint mPaintFill = new Paint(ANTI_ALIAS_FLAG); private ViewPager mViewPager; private ViewPager.OnPageChangeListener mListener; private int mCurrentPage; public CirclePageIndicator(Context context) { this(context, null); } public CirclePageIndicator(Context context, AttributeSet attrs) { this(context, attrs, 0); } public CirclePageIndicator(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); final int defaultPageColor = 0x7FFFFFFF; final int defaultFillColor = 0xFFFFFFFF; final int defaultStrokeColor = 0xffdddddd; final float defaultStrokeWidth = 0; final float defaultRadius = DimenUtils.dp2px(3); final float defaultGap = DimenUtils.dp2px(8); //Retrieve styles attributes TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.CirclePageIndicator, defStyle, 0); mPaintPageFill.setStyle(Style.FILL); mPaintPageFill.setColor(a.getColor(R.styleable.CirclePageIndicator_pageColor, defaultPageColor)); mPaintStroke.setStyle(Style.STROKE); mPaintStroke.setColor(a.getColor(R.styleable.CirclePageIndicator_strokeColor, defaultStrokeColor)); mPaintStroke .setStrokeWidth(a.getDimension(R.styleable.CirclePageIndicator_strokeWidth, defaultStrokeWidth)); mPaintFill.setStyle(Style.FILL); mPaintFill.setColor(a.getColor(R.styleable.CirclePageIndicator_fillColor, defaultFillColor)); mRadius = a.getDimension(R.styleable.CirclePageIndicator_radius, defaultRadius); mGap = a.getDimension(R.styleable.CirclePageIndicator_gap, defaultGap); a.recycle(); } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); if (mViewPager == null) { return; } final int count = mViewPager.getAdapter().getCount(); if (count == 0) { return; } int paddingLeft = getPaddingLeft(); int paddingTop = getPaddingTop(); float dX; float dY = paddingTop + mRadius; float pageFillRadius = mRadius; if (mPaintStroke.getStrokeWidth() > 0) { pageFillRadius = mRadius - mPaintStroke.getStrokeWidth(); } //Draw stroked circles for (int i = 0; i < count; i++) { dX = paddingLeft + mRadius + i * (mRadius * 2 + mGap); // Only paint fill if not completely transparent if (mPaintPageFill.getAlpha() > 0) { canvas.drawCircle(dX, dY, pageFillRadius, mPaintPageFill); } // Only paint stroke if a stroke width was non-zero if (pageFillRadius != mRadius) { canvas.drawCircle(dX, dY, mRadius, mPaintStroke); } } dX = paddingLeft + mRadius + mCurrentPage * (mRadius * 2 + mGap); canvas.drawCircle(dX, dY, mRadius, mPaintFill); } @Override public void setViewPager(ViewPager view) { if (mViewPager == view) { return; } if (mViewPager != null) { mViewPager.setOnPageChangeListener(null); } if (view.getAdapter() == null) { throw new IllegalStateException("ViewPager does not have adapter instance."); } mViewPager = view; mViewPager.setOnPageChangeListener(this); invalidate(); } @Override public void setViewPager(ViewPager view, int initialPosition) { setViewPager(view); setCurrentItem(initialPosition); } @Override public void setCurrentItem(int item) { if (mViewPager == null) { throw new IllegalStateException("ViewPager has not been bound."); } mViewPager.setCurrentItem(item); mCurrentPage = item; invalidate(); } @Override public void notifyDataSetChanged() { invalidate(); } @Override public void onPageScrollStateChanged(int state) { if (mListener != null) { mListener.onPageScrollStateChanged(state); } } @Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { if (mListener != null) { mListener.onPageScrolled(position, positionOffset, positionOffsetPixels); } } @Override public void onPageSelected(int position) { mCurrentPage = position; invalidate(); if (mListener != null) { mListener.onPageSelected(position); } } @Override public void setOnPageChangeListener(ViewPager.OnPageChangeListener listener) { mListener = listener; } /* * (non-Javadoc) * * @see android.view.View#onMeasure(int, int) */ @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { setMeasuredDimension(measureWidth(widthMeasureSpec), measureHeight(heightMeasureSpec)); } /** * Determines the width of this view * * @param measureSpec A measureSpec packed into an int * @return The width of the view, honoring constraints from measureSpec */ private int measureWidth(int measureSpec) { int result; int specMode = MeasureSpec.getMode(measureSpec); int specSize = MeasureSpec.getSize(measureSpec); if ((specMode == MeasureSpec.EXACTLY) || (mViewPager == null)) { //We were told how big to be result = specSize; } else { //Calculate the width according the views count final int count = mViewPager.getAdapter().getCount(); result = (int) (getPaddingLeft() + getPaddingRight() + count * 2 * mRadius + (count - 1) * mGap + 1); //Respect AT_MOST value if that was what is called for by measureSpec if (specMode == MeasureSpec.AT_MOST) { result = Math.min(result, specSize); } } return result; } /** * Determines the height of this view * * @param measureSpec A measureSpec packed into an int * @return The height of the view, honoring constraints from measureSpec */ private int measureHeight(int measureSpec) { int result; int specMode = MeasureSpec.getMode(measureSpec); int specSize = MeasureSpec.getSize(measureSpec); if (specMode == MeasureSpec.EXACTLY) { //We were told how big to be result = specSize; } else { //Measure the height result = (int) (2 * mRadius + getPaddingTop() + getPaddingBottom() + 1); //Respect AT_MOST value if that was what is called for by measureSpec if (specMode == MeasureSpec.AT_MOST) { result = Math.min(result, specSize); } } return result; } @Override public void onRestoreInstanceState(Parcelable state) { SavedState savedState = (SavedState) state; super.onRestoreInstanceState(savedState.getSuperState()); mCurrentPage = savedState.currentPage; requestLayout(); } @Override public Parcelable onSaveInstanceState() { Parcelable superState = super.onSaveInstanceState(); SavedState savedState = new SavedState(superState); savedState.currentPage = mCurrentPage; return savedState; } static class SavedState extends BaseSavedState { int currentPage; public SavedState(Parcelable superState) { super(superState); } private SavedState(Parcel in) { super(in); currentPage = in.readInt(); } @Override public void writeToParcel(Parcel dest, int flags) { super.writeToParcel(dest, flags); dest.writeInt(currentPage); } @SuppressWarnings("UnusedDeclaration") 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]; } }; } }