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.viewpagerindicator; import android.content.Context; import android.content.res.Resources; import android.content.res.TypedArray; import android.graphics.Canvas; import android.graphics.Paint; import android.graphics.Paint.Style; import android.graphics.drawable.Drawable; import android.support.v4.view.ViewPager; import android.util.AttributeSet; import android.view.View; import static android.graphics.Paint.ANTI_ALIAS_FLAG; import static android.widget.LinearLayout.HORIZONTAL; import static android.widget.LinearLayout.VERTICAL; /** * Draws circles (one for each view). The current view position is filled and * others are only stroked. */ public class EgouCirclePageIndicator extends View implements PageIndicator { private float mRadius; 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; private float mPageOffset; private int mScrollState; private int mOrientation; private boolean mCentered; private boolean mSnap; private float mCirclePadding; private int mCount; public EgouCirclePageIndicator(Context context) { this(context, null); } public EgouCirclePageIndicator(Context context, AttributeSet attrs) { this(context, attrs, R.attr.vpiCirclePageIndicatorStyle); } public EgouCirclePageIndicator(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); if (isInEditMode()) return; // Load defaults from resources final Resources res = getResources(); final int defaultPageColor = res.getColor(R.color.default_circle_indicator_page_color); final int defaultFillColor = res.getColor(R.color.default_circle_indicator_fill_color); final int defaultOrientation = res.getInteger(R.integer.default_circle_indicator_orientation); final int defaultStrokeColor = res.getColor(R.color.default_circle_indicator_stroke_color); final float defaultStrokeWidth = res.getDimension(R.dimen.default_circle_indicator_stroke_width); final float defaultRadius = res.getDimension(R.dimen.default_circle_indicator_radius); final boolean defaultCentered = res.getBoolean(R.bool.default_circle_indicator_centered); final boolean defaultSnap = res.getBoolean(R.bool.default_circle_indicator_snap); final float defaultIndicatorPadding = res.getDimension(R.dimen.default_indicator_padding); // Retrieve styles attributes TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.CirclePageIndicator, defStyle, 0); mCentered = a.getBoolean(R.styleable.CirclePageIndicator_centered, defaultCentered); mOrientation = a.getInt(R.styleable.CirclePageIndicator_android_orientation, defaultOrientation); 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); mSnap = a.getBoolean(R.styleable.CirclePageIndicator_snap, defaultSnap); mCirclePadding = a.getDimension(R.styleable.CirclePageIndicator_circlePadding, defaultIndicatorPadding); Drawable background = a.getDrawable(R.styleable.CirclePageIndicator_android_background); if (background != null) { setBackgroundDrawable(background); } a.recycle(); } 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; 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; } public void setCirclePadding(float circlePadding) { mCirclePadding = circlePadding; invalidate(); } public float getCirclePadding() { return mCirclePadding; } public void setCount(int count) { mCount = count; invalidate(); } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); if (mViewPager == null || mCount == 0) { 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 * 4; final float shortOffset = shortPaddingBefore + mRadius; float longOffset = longPaddingBefore + mRadius / 2.0f; if (mCentered) { longOffset = ((longSize - longPaddingBefore - longPaddingAfter) / 2.0f) - (((mCount - 1) * mCirclePadding) / 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 < mCount; iLoop++) { float drawLong = longOffset + (iLoop * mCirclePadding); 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 = mCurrentPage * mCirclePadding; if (!mSnap) { cx += mPageOffset * mCirclePadding; } if (mOrientation == HORIZONTAL) { dX = longOffset + cx; dY = shortOffset; } else { dX = shortOffset; dY = longOffset + cx; } 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 % mCount; invalidate(); } public void setPageOffset(float pageOffset) { this.mPageOffset = pageOffset; } @Override public void notifyDataSetChanged() { invalidate(); } @Override public void onPageScrollStateChanged(int state) { mScrollState = state; if (mListener != null) { mListener.onPageScrollStateChanged(state); } } @Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { if (mCurrentPage - position % mCount < 0 && mCurrentPage == 0) { mCurrentPage = position % mCount; mPageOffset = 0; setSnap(true); } else if (position % mCount - mCurrentPage == 0 && mCurrentPage == mCount - 1) { mCurrentPage = position % mCount; mPageOffset = 0; setSnap(true); } else { mCurrentPage = position % mCount; mPageOffset = positionOffset; setSnap(false); } if (mListener != null) { mListener.onPageScrolled(position, positionOffset, positionOffsetPixels); } } @Override public void onPageSelected(int position) { if (mSnap || mScrollState == ViewPager.SCROLL_STATE_IDLE) { mCurrentPage = position % mCount; 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) { 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; 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 result = (int) (getPaddingLeft() + getPaddingRight() + (mCount * 2 * mRadius) + (mCount - 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; 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; } }