Java tutorial
/* * Copyright (C) 2017 The Android Open Source Project * * 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 android.support.wear.widget.drawer; import android.animation.Animator; 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.RadialGradient; import android.graphics.Shader; import android.graphics.Shader.TileMode; import android.os.Build; import android.support.annotation.RequiresApi; import android.support.annotation.RestrictTo; import android.support.annotation.RestrictTo.Scope; import android.support.v4.view.PagerAdapter; import android.support.v4.view.ViewPager; import android.support.v4.view.ViewPager.OnPageChangeListener; import android.support.wear.R; import android.support.wear.widget.SimpleAnimatorListener; import android.util.AttributeSet; import android.view.View; import java.util.concurrent.TimeUnit; /** * A page indicator for {@link ViewPager} based on {@link * android.support.wear.view.DotsPageIndicator} which identifies the current page in relation to * all available pages. Pages are represented as dots. The current page can be highlighted with a * different color or size dot. * * <p>The default behavior is to fade out the dots when the pager is idle (not settling or being * dragged). This can be changed with {@link #setDotFadeWhenIdle(boolean)}. * * <p>Use {@link #setPager(ViewPager)} to connect this view to a pager instance. * * @hide */ @RequiresApi(Build.VERSION_CODES.M) @RestrictTo(Scope.LIBRARY_GROUP) public class PageIndicatorView extends View implements OnPageChangeListener { private static final String TAG = "Dots"; private final Paint mDotPaint; private final Paint mDotPaintShadow; private final Paint mDotPaintSelected; private final Paint mDotPaintShadowSelected; private int mDotSpacing; private float mDotRadius; private float mDotRadiusSelected; private int mDotColor; private int mDotColorSelected; private boolean mDotFadeWhenIdle; private int mDotFadeOutDelay; private int mDotFadeOutDuration; private int mDotFadeInDuration; private float mDotShadowDx; private float mDotShadowDy; private float mDotShadowRadius; private int mDotShadowColor; private PagerAdapter mAdapter; private int mNumberOfPositions; private int mSelectedPosition; private int mCurrentViewPagerState; private boolean mVisible; public PageIndicatorView(Context context) { this(context, null); } public PageIndicatorView(Context context, AttributeSet attrs) { this(context, attrs, 0); } public PageIndicatorView(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); final TypedArray a = getContext().obtainStyledAttributes(attrs, R.styleable.PageIndicatorView, defStyleAttr, R.style.WsPageIndicatorViewStyle); mDotSpacing = a.getDimensionPixelOffset(R.styleable.PageIndicatorView_wsPageIndicatorDotSpacing, 0); mDotRadius = a.getDimension(R.styleable.PageIndicatorView_wsPageIndicatorDotRadius, 0); mDotRadiusSelected = a.getDimension(R.styleable.PageIndicatorView_wsPageIndicatorDotRadiusSelected, 0); mDotColor = a.getColor(R.styleable.PageIndicatorView_wsPageIndicatorDotColor, 0); mDotColorSelected = a.getColor(R.styleable.PageIndicatorView_wsPageIndicatorDotColorSelected, 0); mDotFadeOutDelay = a.getInt(R.styleable.PageIndicatorView_wsPageIndicatorDotFadeOutDelay, 0); mDotFadeOutDuration = a.getInt(R.styleable.PageIndicatorView_wsPageIndicatorDotFadeOutDuration, 0); mDotFadeInDuration = a.getInt(R.styleable.PageIndicatorView_wsPageIndicatorDotFadeInDuration, 0); mDotFadeWhenIdle = a.getBoolean(R.styleable.PageIndicatorView_wsPageIndicatorDotFadeWhenIdle, false); mDotShadowDx = a.getDimension(R.styleable.PageIndicatorView_wsPageIndicatorDotShadowDx, 0); mDotShadowDy = a.getDimension(R.styleable.PageIndicatorView_wsPageIndicatorDotShadowDy, 0); mDotShadowRadius = a.getDimension(R.styleable.PageIndicatorView_wsPageIndicatorDotShadowRadius, 0); mDotShadowColor = a.getColor(R.styleable.PageIndicatorView_wsPageIndicatorDotShadowColor, 0); a.recycle(); mDotPaint = new Paint(Paint.ANTI_ALIAS_FLAG); mDotPaint.setColor(mDotColor); mDotPaint.setStyle(Style.FILL); mDotPaintSelected = new Paint(Paint.ANTI_ALIAS_FLAG); mDotPaintSelected.setColor(mDotColorSelected); mDotPaintSelected.setStyle(Style.FILL); mDotPaintShadow = new Paint(Paint.ANTI_ALIAS_FLAG); mDotPaintShadowSelected = new Paint(Paint.ANTI_ALIAS_FLAG); mCurrentViewPagerState = ViewPager.SCROLL_STATE_IDLE; if (isInEditMode()) { // When displayed in layout preview: // Simulate 5 positions, currently on the 3rd position. mNumberOfPositions = 5; mSelectedPosition = 2; mDotFadeWhenIdle = false; } if (mDotFadeWhenIdle) { mVisible = false; animate().alpha(0f).setStartDelay(2000).setDuration(mDotFadeOutDuration).start(); } else { animate().cancel(); setAlpha(1.0f); } updateShadows(); } private void updateShadows() { updateDotPaint(mDotPaint, mDotPaintShadow, mDotRadius, mDotShadowRadius, mDotColor, mDotShadowColor); updateDotPaint(mDotPaintSelected, mDotPaintShadowSelected, mDotRadiusSelected, mDotShadowRadius, mDotColorSelected, mDotShadowColor); } private void updateDotPaint(Paint dotPaint, Paint shadowPaint, float baseRadius, float shadowRadius, int color, int shadowColor) { float radius = baseRadius + shadowRadius; float shadowStart = baseRadius / radius; Shader gradient = new RadialGradient(0, 0, radius, new int[] { shadowColor, shadowColor, Color.TRANSPARENT }, new float[] { 0f, shadowStart, 1f }, TileMode.CLAMP); shadowPaint.setShader(gradient); dotPaint.setColor(color); dotPaint.setStyle(Style.FILL); } /** * Supplies the ViewPager instance, and attaches this views {@link OnPageChangeListener} to the * pager. * * @param pager the pager for the page indicator */ public void setPager(ViewPager pager) { pager.addOnPageChangeListener(this); setPagerAdapter(pager.getAdapter()); mAdapter = pager.getAdapter(); if (mAdapter != null && mAdapter.getCount() > 0) { positionChanged(0); } } /** * Gets the center-to-center distance between page dots. * * @return the distance between page dots */ public float getDotSpacing() { return mDotSpacing; } /** * Sets the center-to-center distance between page dots. * * @param spacing the distance between page dots */ public void setDotSpacing(int spacing) { if (mDotSpacing != spacing) { mDotSpacing = spacing; requestLayout(); } } /** * Gets the radius of the page dots. * * @return the radius of the page dots */ public float getDotRadius() { return mDotRadius; } /** * Sets the radius of the page dots. * * @param radius the radius of the page dots */ public void setDotRadius(int radius) { if (mDotRadius != radius) { mDotRadius = radius; updateShadows(); invalidate(); } } /** * Gets the radius of the page dot for the selected page. * * @return the radius of the selected page dot */ public float getDotRadiusSelected() { return mDotRadiusSelected; } /** * Sets the radius of the page dot for the selected page. * * @param radius the radius of the selected page dot */ public void setDotRadiusSelected(int radius) { if (mDotRadiusSelected != radius) { mDotRadiusSelected = radius; updateShadows(); invalidate(); } } /** * Returns the color used for dots other than the selected page. * * @return color the color used for dots other than the selected page */ public int getDotColor() { return mDotColor; } /** * Sets the color used for dots other than the selected page. * * @param color the color used for dots other than the selected page */ public void setDotColor(int color) { if (mDotColor != color) { mDotColor = color; invalidate(); } } /** * Returns the color of the dot for the selected page. * * @return the color used for the selected page dot */ public int getDotColorSelected() { return mDotColorSelected; } /** * Sets the color of the dot for the selected page. * * @param color the color of the dot for the selected page */ public void setDotColorSelected(int color) { if (mDotColorSelected != color) { mDotColorSelected = color; invalidate(); } } /** * Indicates if the dots fade out when the pager is idle. * * @return whether the dots fade out when idle */ public boolean getDotFadeWhenIdle() { return mDotFadeWhenIdle; } /** * Sets whether the dots fade out when the pager is idle. * * @param fade whether the dots fade out when idle */ public void setDotFadeWhenIdle(boolean fade) { mDotFadeWhenIdle = fade; if (!fade) { fadeIn(); } } /** * Returns the duration of fade out animation, in milliseconds. * * @return the duration of the fade out animation, in milliseconds */ public int getDotFadeOutDuration() { return mDotFadeOutDuration; } /** * Sets the duration of the fade out animation. * * @param duration the duration of the fade out animation */ public void setDotFadeOutDuration(int duration, TimeUnit unit) { mDotFadeOutDuration = (int) TimeUnit.MILLISECONDS.convert(duration, unit); } /** * Returns the duration of the fade in duration, in milliseconds. * * @return the duration of the fade in duration, in milliseconds */ public int getDotFadeInDuration() { return mDotFadeInDuration; } /** * Sets the duration of the fade in animation. * * @param duration the duration of the fade in animation */ public void setDotFadeInDuration(int duration, TimeUnit unit) { mDotFadeInDuration = (int) TimeUnit.MILLISECONDS.convert(duration, unit); } /** * Sets the delay between the pager arriving at an idle state, and the fade out animation * beginning, in milliseconds. * * @return the delay before the fade out animation begins, in milliseconds */ public int getDotFadeOutDelay() { return mDotFadeOutDelay; } /** * Sets the delay between the pager arriving at an idle state, and the fade out animation * beginning, in milliseconds. * * @param delay the delay before the fade out animation begins, in milliseconds */ public void setDotFadeOutDelay(int delay) { mDotFadeOutDelay = delay; } /** * Sets the pixel radius of shadows drawn beneath the dots. * * @return the pixel radius of shadows rendered beneath the dots */ public float getDotShadowRadius() { return mDotShadowRadius; } /** * Sets the pixel radius of shadows drawn beneath the dots. * * @param radius the pixel radius of shadows rendered beneath the dots */ public void setDotShadowRadius(float radius) { if (mDotShadowRadius != radius) { mDotShadowRadius = radius; updateShadows(); invalidate(); } } /** * Returns the horizontal offset of shadows drawn beneath the dots. * * @return the horizontal offset of shadows drawn beneath the dots */ public float getDotShadowDx() { return mDotShadowDx; } /** * Sets the horizontal offset of shadows drawn beneath the dots. * * @param dx the horizontal offset of shadows drawn beneath the dots */ public void setDotShadowDx(float dx) { mDotShadowDx = dx; invalidate(); } /** * Returns the vertical offset of shadows drawn beneath the dots. * * @return the vertical offset of shadows drawn beneath the dots */ public float getDotShadowDy() { return mDotShadowDy; } /** * Sets the vertical offset of shadows drawn beneath the dots. * * @param dy the vertical offset of shadows drawn beneath the dots */ public void setDotShadowDy(float dy) { mDotShadowDy = dy; invalidate(); } /** * Returns the color of the shadows drawn beneath the dots. * * @return the color of the shadows drawn beneath the dots */ public int getDotShadowColor() { return mDotShadowColor; } /** * Sets the color of the shadows drawn beneath the dots. * * @param color the color of the shadows drawn beneath the dots */ public void setDotShadowColor(int color) { mDotShadowColor = color; updateShadows(); invalidate(); } private void positionChanged(int position) { mSelectedPosition = position; invalidate(); } private void updateNumberOfPositions() { int count = mAdapter.getCount(); if (count != mNumberOfPositions) { mNumberOfPositions = count; requestLayout(); } } private void fadeIn() { mVisible = true; animate().cancel(); animate().alpha(1f).setStartDelay(0).setDuration(mDotFadeInDuration).start(); } private void fadeOut(long delayMillis) { mVisible = false; animate().cancel(); animate().alpha(0f).setStartDelay(delayMillis).setDuration(mDotFadeOutDuration).start(); } private void fadeInOut() { mVisible = true; animate().cancel(); animate().alpha(1f).setStartDelay(0).setDuration(mDotFadeInDuration) .setListener(new SimpleAnimatorListener() { @Override public void onAnimationComplete(Animator animator) { mVisible = false; animate().alpha(0f).setListener(null).setStartDelay(mDotFadeOutDelay) .setDuration(mDotFadeOutDuration).start(); } }).start(); } @Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { if (mDotFadeWhenIdle) { if (mCurrentViewPagerState == ViewPager.SCROLL_STATE_DRAGGING) { if (positionOffset != 0) { if (!mVisible) { fadeIn(); } } else { if (mVisible) { fadeOut(0); } } } } } @Override public void onPageSelected(int position) { if (position != mSelectedPosition) { positionChanged(position); } } @Override public void onPageScrollStateChanged(int state) { if (mCurrentViewPagerState != state) { mCurrentViewPagerState = state; if (mDotFadeWhenIdle) { if (state == ViewPager.SCROLL_STATE_IDLE) { if (mVisible) { fadeOut(mDotFadeOutDelay); } else { fadeInOut(); } } } } } /** * Sets the {@link PagerAdapter}. */ public void setPagerAdapter(PagerAdapter adapter) { mAdapter = adapter; if (mAdapter != null) { updateNumberOfPositions(); if (mDotFadeWhenIdle) { fadeInOut(); } } } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { int totalWidth; if (MeasureSpec.getMode(widthMeasureSpec) == MeasureSpec.EXACTLY) { totalWidth = MeasureSpec.getSize(widthMeasureSpec); } else { int contentWidth = mNumberOfPositions * mDotSpacing; totalWidth = contentWidth + getPaddingLeft() + getPaddingRight(); } int totalHeight; if (MeasureSpec.getMode(heightMeasureSpec) == MeasureSpec.EXACTLY) { totalHeight = MeasureSpec.getSize(heightMeasureSpec); } else { float maxRadius = Math.max(mDotRadius + mDotShadowRadius, mDotRadiusSelected + mDotShadowRadius); int contentHeight = (int) Math.ceil(maxRadius * 2); contentHeight = (int) (contentHeight + mDotShadowDy); totalHeight = contentHeight + getPaddingTop() + getPaddingBottom(); } setMeasuredDimension(resolveSizeAndState(totalWidth, widthMeasureSpec, 0), resolveSizeAndState(totalHeight, heightMeasureSpec, 0)); } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); if (mNumberOfPositions > 1) { float dotCenterLeft = getPaddingLeft() + (mDotSpacing / 2f); float dotCenterTop = getHeight() / 2f; canvas.save(); canvas.translate(dotCenterLeft, dotCenterTop); for (int i = 0; i < mNumberOfPositions; i++) { if (i == mSelectedPosition) { float radius = mDotRadiusSelected + mDotShadowRadius; canvas.drawCircle(mDotShadowDx, mDotShadowDy, radius, mDotPaintShadowSelected); canvas.drawCircle(0, 0, mDotRadiusSelected, mDotPaintSelected); } else { float radius = mDotRadius + mDotShadowRadius; canvas.drawCircle(mDotShadowDx, mDotShadowDy, radius, mDotPaintShadow); canvas.drawCircle(0, 0, mDotRadius, mDotPaint); } canvas.translate(mDotSpacing, 0); } canvas.restore(); } } /** * Notifies the view that the data set has changed. */ public void notifyDataSetChanged() { if (mAdapter != null && mAdapter.getCount() > 0) { updateNumberOfPositions(); } } }