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 com.valohyd.nextseries.models; import android.content.Context; import android.content.res.Resources; 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.MotionEventCompat; import android.support.v4.view.ViewConfigurationCompat; import android.support.v4.view.ViewPager; import android.util.AttributeSet; import android.view.MotionEvent; import android.view.View; import android.view.ViewConfiguration; import com.valohyd.nextseries.R; /** * Draws circles (one for each view). The current view position is filled and * others are only stroked. */ public class CirclePageIndicator extends View implements PageIndicator { public static final int HORIZONTAL = 0; public static final int VERTICAL = 1; private float mRadius; private final Paint mPaintPageFill; private final Paint mPaintStroke; private final Paint mPaintFill; private ViewPager mViewPager; private ViewPager.OnPageChangeListener mListener; private int mCurrentPage; private int mSnapPage; private int mCurrentOffset; private int mScrollState; private int mPageSize; private int mOrientation; private boolean mCentered; private boolean mSnap; private static final int INVALID_POINTER = -1; private int mTouchSlop; private float mLastMotionX = -1; private int mActivePointerId = INVALID_POINTER; private boolean mIsDragging; 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); //Load defaults from resources final Resources res = getResources(); final int defaultPageColor = res.getColor(R.color.blue_lightDark); final int defaultFillColor = res.getColor(android.R.color.white); final int defaultOrientation = 0; final int defaultStrokeColor = res.getColor(R.color.bg_dk_grey); final float defaultStrokeWidth = 2; final float defaultRadius = 7; final boolean defaultCentered = true; final boolean defaultSnap = true; mCentered = defaultCentered; mOrientation = defaultOrientation; mPaintPageFill = new Paint(Paint.ANTI_ALIAS_FLAG); mPaintPageFill.setStyle(Style.FILL); mPaintPageFill.setColor(defaultPageColor); mPaintStroke = new Paint(Paint.ANTI_ALIAS_FLAG); mPaintStroke.setStyle(Style.STROKE); mPaintStroke.setColor(defaultStrokeColor); mPaintStroke.setStrokeWidth(defaultStrokeWidth); mPaintFill = new Paint(Paint.ANTI_ALIAS_FLAG); mPaintFill.setStyle(Style.FILL); mPaintFill.setColor(defaultFillColor); mRadius = defaultRadius; mSnap = defaultSnap; final ViewConfiguration configuration = ViewConfiguration.get(context); mTouchSlop = ViewConfigurationCompat.getScaledPagingTouchSlop(configuration); } public void setCentered(boolean centered) { mCentered = centered; invalidate(); } public boolean isCentered() { return mCentered; } public void setPageColor(int pageColor) { mPaintPageFill.setColor(pageColor); invalidate(); } public int getPageColor() { return mPaintPageFill.getColor(); } public void setFillColor(int fillColor) { mPaintFill.setColor(fillColor); invalidate(); } public int getFillColor() { return mPaintFill.getColor(); } public void setOrientation(int orientation) { switch (orientation) { case HORIZONTAL: case VERTICAL: mOrientation = orientation; updatePageSize(); requestLayout(); break; default: throw new IllegalArgumentException("Orientation must be either HORIZONTAL or VERTICAL."); } } public int getOrientation() { return mOrientation; } public void setStrokeColor(int strokeColor) { mPaintStroke.setColor(strokeColor); invalidate(); } public int getStrokeColor() { return mPaintStroke.getColor(); } public void setStrokeWidth(float strokeWidth) { mPaintStroke.setStrokeWidth(strokeWidth); invalidate(); } public float getStrokeWidth() { return mPaintStroke.getStrokeWidth(); } public void setRadius(float radius) { mRadius = radius; invalidate(); } public float getRadius() { return mRadius; } public void setSnap(boolean snap) { mSnap = snap; invalidate(); } public boolean isSnap() { return mSnap; } /* * (non-Javadoc) * * @see android.view.View#onDraw(android.graphics.Canvas) */ @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); if (mViewPager == null) { return; } final int count = mViewPager.getAdapter().getCount(); if (count == 0) { return; } if (mCurrentPage >= count) { setCurrentItem(count - 1); return; } int longSize; int longPaddingBefore; int longPaddingAfter; int shortPaddingBefore; if (mOrientation == HORIZONTAL) { longSize = getWidth(); longPaddingBefore = getPaddingLeft(); longPaddingAfter = getPaddingRight(); shortPaddingBefore = getPaddingTop(); } else { longSize = getHeight(); longPaddingBefore = getPaddingTop(); longPaddingAfter = getPaddingBottom(); shortPaddingBefore = getPaddingLeft(); } final float threeRadius = mRadius * 3; final float shortOffset = shortPaddingBefore + mRadius; float longOffset = longPaddingBefore + mRadius; if (mCentered) { longOffset += ((longSize - longPaddingBefore - longPaddingAfter) / 2.0f) - ((count * threeRadius) / 2.0f); } float dX; float dY; float pageFillRadius = mRadius; if (mPaintStroke.getStrokeWidth() > 0) { pageFillRadius -= mPaintStroke.getStrokeWidth() / 2.0f; } //Draw stroked circles for (int iLoop = 0; iLoop < count; iLoop++) { float drawLong = longOffset + (iLoop * threeRadius); if (mOrientation == HORIZONTAL) { dX = drawLong; dY = shortOffset; } else { dX = shortOffset; dY = drawLong; } // 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); } } //Draw the filled circle according to the current scroll float cx = (mSnap ? mSnapPage : mCurrentPage) * threeRadius; if (!mSnap && (mPageSize != 0)) { cx += (mCurrentOffset * 1.0f / mPageSize) * threeRadius; } if (mOrientation == HORIZONTAL) { dX = longOffset + cx; dY = shortOffset; } else { dX = shortOffset; dY = longOffset + cx; } canvas.drawCircle(dX, dY, mRadius, mPaintFill); } public boolean onTouchEvent(android.view.MotionEvent ev) { if (super.onTouchEvent(ev)) { return true; } if ((mViewPager == null) || (mViewPager.getAdapter().getCount() == 0)) { return false; } final int action = ev.getAction(); switch (action & MotionEventCompat.ACTION_MASK) { case MotionEvent.ACTION_DOWN: mActivePointerId = MotionEventCompat.getPointerId(ev, 0); mLastMotionX = ev.getX(); break; case MotionEvent.ACTION_MOVE: { final int activePointerIndex = MotionEventCompat.findPointerIndex(ev, mActivePointerId); final float x = MotionEventCompat.getX(ev, activePointerIndex); final float deltaX = x - mLastMotionX; if (!mIsDragging) { if (Math.abs(deltaX) > mTouchSlop) { mIsDragging = true; } } if (mIsDragging) { if (!mViewPager.isFakeDragging()) { mViewPager.beginFakeDrag(); } mLastMotionX = x; mViewPager.fakeDragBy(deltaX); } break; } case MotionEvent.ACTION_CANCEL: case MotionEvent.ACTION_UP: if (!mIsDragging) { final int count = mViewPager.getAdapter().getCount(); final int width = getWidth(); final float halfWidth = width / 2f; final float sixthWidth = width / 6f; if ((mCurrentPage > 0) && (ev.getX() < halfWidth - sixthWidth)) { mViewPager.setCurrentItem(mCurrentPage - 1); return true; } else if ((mCurrentPage < count - 1) && (ev.getX() > halfWidth + sixthWidth)) { mViewPager.setCurrentItem(mCurrentPage + 1); return true; } } mIsDragging = false; mActivePointerId = INVALID_POINTER; if (mViewPager.isFakeDragging()) mViewPager.endFakeDrag(); break; case MotionEventCompat.ACTION_POINTER_DOWN: { final int index = MotionEventCompat.getActionIndex(ev); final float x = MotionEventCompat.getX(ev, index); mLastMotionX = x; mActivePointerId = MotionEventCompat.getPointerId(ev, index); break; } case MotionEventCompat.ACTION_POINTER_UP: final int pointerIndex = MotionEventCompat.getActionIndex(ev); final int pointerId = MotionEventCompat.getPointerId(ev, pointerIndex); if (pointerId == mActivePointerId) { final int newPointerIndex = pointerIndex == 0 ? 1 : 0; mActivePointerId = MotionEventCompat.getPointerId(ev, newPointerIndex); } mLastMotionX = MotionEventCompat.getX(ev, MotionEventCompat.findPointerIndex(ev, mActivePointerId)); break; } return true; }; public void setViewPager(ViewPager view) { if (view.getAdapter() == null) { throw new IllegalStateException("ViewPager does not have adapter instance."); } mViewPager = view; mViewPager.setOnPageChangeListener(this); updatePageSize(); invalidate(); } private void updatePageSize() { if (mViewPager != null) { mPageSize = (mOrientation == HORIZONTAL) ? mViewPager.getWidth() : mViewPager.getHeight(); } } public void setViewPager(ViewPager view, int initialPosition) { setViewPager(view); setCurrentItem(initialPosition); } public void setCurrentItem(int item) { if (mViewPager == null) { throw new IllegalStateException("ViewPager has not been bound."); } mViewPager.setCurrentItem(item); mCurrentPage = item; invalidate(); } public void notifyDataSetChanged() { invalidate(); } public void onPageScrollStateChanged(int state) { mScrollState = state; if (mListener != null) { mListener.onPageScrollStateChanged(state); } } public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { mCurrentPage = position; mCurrentOffset = positionOffsetPixels; updatePageSize(); invalidate(); if (mListener != null) { mListener.onPageScrolled(position, positionOffset, positionOffsetPixels); } } public void onPageSelected(int position) { if (mSnap || mScrollState == ViewPager.SCROLL_STATE_IDLE) { mCurrentPage = position; mSnapPage = position; invalidate(); } if (mListener != null) { mListener.onPageSelected(position); } } 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) { if (mOrientation == HORIZONTAL) { setMeasuredDimension(measureLong(widthMeasureSpec), measureShort(heightMeasureSpec)); } else { setMeasuredDimension(measureShort(widthMeasureSpec), measureLong(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 measureLong(int measureSpec) { int result = 0; 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) * mRadius + 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 measureShort(int measureSpec) { int result = 0; 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; mSnapPage = 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); } public static final Parcelable.Creator<SavedState> CREATOR = new Parcelable.Creator<SavedState>() { public SavedState createFromParcel(Parcel in) { return new SavedState(in); } public SavedState[] newArray(int size) { return new SavedState[size]; } }; } }