Java tutorial
package wnayes.campuszoneapp; /* * Copyright (C) 2014 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. */ import android.content.Context; import android.content.res.Resources; import android.content.res.TypedArray; import android.graphics.Canvas; import android.support.v4.view.ViewCompat; import android.util.AttributeSet; import android.util.DisplayMetrics; import android.view.MotionEvent; import android.view.View; import android.view.ViewConfiguration; import android.view.ViewGroup; import android.view.animation.AccelerateInterpolator; import android.view.animation.Animation; import android.view.animation.Animation.AnimationListener; import android.view.animation.DecelerateInterpolator; import android.view.animation.Transformation; import android.widget.AbsListView; import android.graphics.Paint; import android.graphics.Rect; import android.graphics.RectF; import android.view.animation.AnimationUtils; import android.view.animation.Interpolator; import android.support.v4.view.MotionEventCompat; import android.util.Log; /** * The SwipeRefreshLayout should be used whenever the user can refresh the * contents of a view via a vertical swipe gesture. The activity that * instantiates this view should add an OnRefreshListener to be notified * whenever the swipe to refresh gesture is completed. The SwipeRefreshLayout * will notify the listener each and every time the gesture is completed again; * the listener is responsible for correctly determining when to actually * initiate a refresh of its content. If the listener determines there should * not be a refresh, it must call setRefreshing(false) to cancel any visual * indication of a refresh. If an activity wishes to show just the progress * animation, it should call setRefreshing(true). To disable the gesture and progress * animation, call setEnabled(false) on the view. * * <p> This layout should be made the parent of the view that will be refreshed as a * result of the gesture and can only support one direct child. This view will * also be made the target of the gesture and will be forced to match both the * width and the height supplied in this layout. The SwipeRefreshLayout does not * provide accessibility events; instead, a menu item must be provided to allow * refresh of the content wherever this gesture is used.</p> * * <p>This is a standalone version of the pre-material design SwipeRefreshLayout.</p> */ public class SwipeRefreshLayoutLegacy extends ViewGroup { private static final String LOG_TAG = SwipeRefreshLayoutLegacy.class.getSimpleName(); private static final long RETURN_TO_ORIGINAL_POSITION_TIMEOUT = 300; private static final float ACCELERATE_INTERPOLATION_FACTOR = 1.5f; private static final float DECELERATE_INTERPOLATION_FACTOR = 2f; private static final float PROGRESS_BAR_HEIGHT = 3; private static final float MAX_SWIPE_DISTANCE_FACTOR = .6f; private static final int REFRESH_TRIGGER_DISTANCE = 56; private static final int INVALID_POINTER = -1; private SwipeProgressBar mProgressBar; private View mTarget; private int mOriginalOffsetTop; private OnRefreshListener mListener; private int mFrom; private boolean mRefreshing = false; private int mTouchSlop; private float mDistanceToTriggerSync = -1; private int mMediumAnimationDuration; private float mFromPercentage = 0; private float mCurrPercentage = 0; private int mProgressBarHeight; private int mCurrentTargetOffsetTop; private int mProgressBarTop; private float mInitialMotionY; private float mLastMotionY; private boolean mIsBeingDragged; private int mActivePointerId = INVALID_POINTER; // Target is returning to its start offset because it was cancelled or a refresh was triggered. private boolean mReturningToStart; private final DecelerateInterpolator mDecelerateInterpolator; private final AccelerateInterpolator mAccelerateInterpolator; private static final int[] LAYOUT_ATTRS = new int[] { android.R.attr.enabled }; private final Animation mAnimateToStartPosition = new Animation() { @Override public void applyTransformation(float interpolatedTime, Transformation t) { int targetTop = 0; if (mFrom != mOriginalOffsetTop) { targetTop = (mFrom + (int) ((mOriginalOffsetTop - mFrom) * interpolatedTime)); } int offset = targetTop - mTarget.getTop(); final int currentTop = mTarget.getTop(); if (offset + currentTop < 0) { offset = 0 - currentTop; } setTargetOffsetTopAndBottom(offset); } }; private Animation mShrinkTrigger = new Animation() { @Override public void applyTransformation(float interpolatedTime, Transformation t) { float percent = mFromPercentage + ((0 - mFromPercentage) * interpolatedTime); mProgressBar.setTriggerPercentage(percent); } }; private final AnimationListener mReturnToStartPositionListener = new BaseAnimationListener() { @Override public void onAnimationEnd(Animation animation) { // Once the target content has returned to its start position, reset // the target offset to 0. mCurrentTargetOffsetTop = 0; } }; private final AnimationListener mShrinkAnimationListener = new BaseAnimationListener() { @Override public void onAnimationEnd(Animation animation) { mCurrPercentage = 0; } }; private final Runnable mReturnToStartPosition = new Runnable() { @Override public void run() { mReturningToStart = true; animateOffsetToStartPosition(mCurrentTargetOffsetTop + getPaddingTop(), mReturnToStartPositionListener); } }; // Cancel the refresh gesture and animate everything back to its original state. private final Runnable mCancel = new Runnable() { @Override public void run() { mReturningToStart = true; // Timeout fired since the user last moved their finger; animate the // trigger to 0 and put the target back at its original position if (mProgressBar != null) { mFromPercentage = mCurrPercentage; mShrinkTrigger.setDuration(mMediumAnimationDuration); mShrinkTrigger.setAnimationListener(mShrinkAnimationListener); mShrinkTrigger.reset(); mShrinkTrigger.setInterpolator(mDecelerateInterpolator); startAnimation(mShrinkTrigger); } animateOffsetToStartPosition(mCurrentTargetOffsetTop + getPaddingTop(), mReturnToStartPositionListener); } }; /** Simple constructor to use when creating a SwipeRefreshLayout from code. */ public SwipeRefreshLayoutLegacy(Context context) { this(context, null); } /** Constructor that is called when inflating SwipeRefreshLayout from XML. */ public SwipeRefreshLayoutLegacy(Context context, AttributeSet attrs) { super(context, attrs); mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop(); mMediumAnimationDuration = getResources().getInteger(android.R.integer.config_mediumAnimTime); setWillNotDraw(false); mProgressBar = new SwipeProgressBar(this); final DisplayMetrics metrics = getResources().getDisplayMetrics(); mProgressBarHeight = (int) (metrics.density * PROGRESS_BAR_HEIGHT); mDecelerateInterpolator = new DecelerateInterpolator(DECELERATE_INTERPOLATION_FACTOR); mAccelerateInterpolator = new AccelerateInterpolator(ACCELERATE_INTERPOLATION_FACTOR); final TypedArray a = context.obtainStyledAttributes(attrs, LAYOUT_ATTRS); setEnabled(a.getBoolean(0, true)); a.recycle(); } @Override public void onAttachedToWindow() { super.onAttachedToWindow(); removeCallbacks(mCancel); removeCallbacks(mReturnToStartPosition); } @Override public void onDetachedFromWindow() { super.onDetachedFromWindow(); removeCallbacks(mReturnToStartPosition); removeCallbacks(mCancel); } private void animateOffsetToStartPosition(int from, AnimationListener listener) { mFrom = from; mAnimateToStartPosition.reset(); mAnimateToStartPosition.setDuration(mMediumAnimationDuration); mAnimateToStartPosition.setAnimationListener(listener); mAnimateToStartPosition.setInterpolator(mDecelerateInterpolator); mTarget.startAnimation(mAnimateToStartPosition); } /** Set the listener to be notified when a refresh is triggered via the swipe gesture. */ public void setOnRefreshListener(OnRefreshListener listener) { mListener = listener; } private void setTriggerPercentage(float percent) { if (percent == 0f) { // No-op. A null trigger means it's uninitialized, and setting it to zero-percent // means we're trying to reset state, so there's nothing to reset in this case. mCurrPercentage = 0; return; } mCurrPercentage = percent; mProgressBar.setTriggerPercentage(percent); } /** * Notify the widget that refresh state has changed. Do not call this when * refresh is triggered by a swipe gesture. * * @param refreshing Whether or not the view should show refresh progress. */ public void setRefreshing(boolean refreshing) { if (mRefreshing == refreshing) return; ensureTarget(); mCurrPercentage = 0; mRefreshing = refreshing; if (mRefreshing) mProgressBar.start(); else mProgressBar.stop(); } /** * Set the four colors used in the progress animation from color resources. * The first color will also be the color of the bar that grows in response * to a user swipe gesture. */ public void setColorSchemeResources(int colorRes1, int colorRes2, int colorRes3, int colorRes4) { final Resources res = getResources(); setColorSchemeColors(res.getColor(colorRes1), res.getColor(colorRes2), res.getColor(colorRes3), res.getColor(colorRes4)); } /** * Set the four colors used in the progress animation. The first color will * also be the color of the bar that grows in response to a user swipe * gesture. */ public void setColorSchemeColors(int color1, int color2, int color3, int color4) { ensureTarget(); mProgressBar.setColorScheme(color1, color2, color3, color4); } /** * @return Whether the SwipeRefreshWidget is actively showing refresh progress. */ public boolean isRefreshing() { return mRefreshing; } private void ensureTarget() { // Don't bother getting the parent height if the parent hasn't been laid out yet. if (mTarget == null) { if (getChildCount() > 1 && !isInEditMode()) { throw new IllegalStateException("SwipeRefreshLayout can host only one direct child"); } mTarget = getChildAt(0); mOriginalOffsetTop = mTarget.getTop() + getPaddingTop(); } if (mDistanceToTriggerSync == -1) { if (getParent() != null && ((View) getParent()).getHeight() > 0) { final DisplayMetrics metrics = getResources().getDisplayMetrics(); mDistanceToTriggerSync = (int) Math.min( ((View) getParent()).getHeight() * MAX_SWIPE_DISTANCE_FACTOR, REFRESH_TRIGGER_DISTANCE * metrics.density); } } } @Override public void draw(Canvas canvas) { super.draw(canvas); mProgressBar.draw(canvas); } public void setProgressBarTop(int top) { mProgressBarTop = top; mProgressBar.setBounds(0, mProgressBarTop, getWidth(), mProgressBarTop + mProgressBarHeight); } @Override protected void onLayout(boolean changed, int left, int top, int right, int bottom) { final int width = getMeasuredWidth(); final int height = getMeasuredHeight(); mProgressBar.setBounds(0, mProgressBarTop, getWidth(), mProgressBarTop + mProgressBarHeight); if (getChildCount() == 0) return; final View child = getChildAt(0); final int childLeft = getPaddingLeft(); final int childTop = mCurrentTargetOffsetTop + getPaddingTop(); final int childWidth = width - getPaddingLeft() - getPaddingRight(); final int childHeight = height - getPaddingTop() - getPaddingBottom(); child.layout(childLeft, childTop, childLeft + childWidth, childTop + childHeight); } @Override public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); if (getChildCount() > 1 && !isInEditMode()) { throw new IllegalStateException("SwipeRefreshLayout can host only one direct child"); } if (getChildCount() > 0) { getChildAt(0).measure( MeasureSpec.makeMeasureSpec(getMeasuredWidth() - getPaddingLeft() - getPaddingRight(), MeasureSpec.EXACTLY), MeasureSpec.makeMeasureSpec(getMeasuredHeight() - getPaddingTop() - getPaddingBottom(), MeasureSpec.EXACTLY)); } } /** * @return Whether it is possible for the child view of this layout to * scroll up. Override this if the child view is a custom view. */ public boolean canChildScrollUp() { if (android.os.Build.VERSION.SDK_INT < 14) { if (mTarget instanceof AbsListView) { final AbsListView absListView = (AbsListView) mTarget; return absListView.getChildCount() > 0 && (absListView.getFirstVisiblePosition() > 0 || absListView.getChildAt(0).getTop() < absListView.getPaddingTop()); } else return mTarget.getScrollY() > 0; } else return ViewCompat.canScrollVertically(mTarget, -1); } @Override public boolean onInterceptTouchEvent(MotionEvent ev) { ensureTarget(); final int action = MotionEventCompat.getActionMasked(ev); if (mReturningToStart && action == MotionEvent.ACTION_DOWN) mReturningToStart = false; if (!isEnabled() || mReturningToStart || canChildScrollUp()) { // Fail fast if we're not in a state where a swipe is possible return false; } switch (action) { case MotionEvent.ACTION_DOWN: mLastMotionY = mInitialMotionY = ev.getY(); mActivePointerId = MotionEventCompat.getPointerId(ev, 0); mIsBeingDragged = false; mCurrPercentage = 0; break; case MotionEvent.ACTION_MOVE: if (mActivePointerId == INVALID_POINTER) { Log.e(LOG_TAG, "Got ACTION_MOVE event but don't have an active pointer id."); return false; } final int pointerIndex = MotionEventCompat.findPointerIndex(ev, mActivePointerId); if (pointerIndex < 0) { Log.e(LOG_TAG, "Got ACTION_MOVE event but have an invalid active pointer id."); return false; } final float y = MotionEventCompat.getY(ev, pointerIndex); final float yDiff = y - mInitialMotionY; if (yDiff > mTouchSlop) { mLastMotionY = y; mIsBeingDragged = true; } break; case MotionEventCompat.ACTION_POINTER_UP: onSecondaryPointerUp(ev); break; case MotionEvent.ACTION_UP: case MotionEvent.ACTION_CANCEL: mIsBeingDragged = false; mCurrPercentage = 0; mActivePointerId = INVALID_POINTER; break; } return mIsBeingDragged; } @Override public void requestDisallowInterceptTouchEvent(boolean b) { // Nope. } @Override public boolean onTouchEvent(MotionEvent ev) { final int action = MotionEventCompat.getActionMasked(ev); if (mReturningToStart && action == MotionEvent.ACTION_DOWN) { mReturningToStart = false; } if (!isEnabled() || mReturningToStart || canChildScrollUp()) { // Fail fast if we're not in a state where a swipe is possible return false; } switch (action) { case MotionEvent.ACTION_DOWN: mLastMotionY = mInitialMotionY = ev.getY(); mActivePointerId = MotionEventCompat.getPointerId(ev, 0); mIsBeingDragged = false; mCurrPercentage = 0; break; case MotionEvent.ACTION_MOVE: final int pointerIndex = MotionEventCompat.findPointerIndex(ev, mActivePointerId); if (pointerIndex < 0) { Log.e(LOG_TAG, "Got ACTION_MOVE event but have an invalid active pointer id."); return false; } final float y = MotionEventCompat.getY(ev, pointerIndex); final float yDiff = y - mInitialMotionY; if (!mIsBeingDragged && yDiff > mTouchSlop) { mIsBeingDragged = true; } if (mIsBeingDragged) { // User velocity passed min velocity; trigger a refresh if (yDiff > mDistanceToTriggerSync) { // User movement passed distance; trigger a refresh startRefresh(); } else { // Just track the user's movement setTriggerPercentage(mAccelerateInterpolator.getInterpolation(yDiff / mDistanceToTriggerSync)); updateContentOffsetTop((int) (yDiff)); if (mLastMotionY > y && mTarget.getTop() == getPaddingTop()) { // If the user puts the view back at the top, we // don't need to. This shouldn't be considered // cancelling the gesture as the user can restart from the top. removeCallbacks(mCancel); } else { updatePositionTimeout(); } } mLastMotionY = y; } break; case MotionEventCompat.ACTION_POINTER_DOWN: { final int index = MotionEventCompat.getActionIndex(ev); mLastMotionY = MotionEventCompat.getY(ev, index); mActivePointerId = MotionEventCompat.getPointerId(ev, index); break; } case MotionEventCompat.ACTION_POINTER_UP: onSecondaryPointerUp(ev); break; case MotionEvent.ACTION_UP: case MotionEvent.ACTION_CANCEL: mIsBeingDragged = false; mCurrPercentage = 0; mActivePointerId = INVALID_POINTER; return false; } return true; } private void startRefresh() { removeCallbacks(mCancel); mReturnToStartPosition.run(); setRefreshing(true); mListener.onRefresh(); } private void updateContentOffsetTop(int targetTop) { final int currentTop = mTarget.getTop(); if (targetTop > mDistanceToTriggerSync) { targetTop = (int) mDistanceToTriggerSync; } else if (targetTop < 0) { targetTop = 0; } setTargetOffsetTopAndBottom(targetTop - currentTop); } private void setTargetOffsetTopAndBottom(int offset) { mTarget.offsetTopAndBottom(offset); mCurrentTargetOffsetTop = mTarget.getTop(); } private void updatePositionTimeout() { removeCallbacks(mCancel); postDelayed(mCancel, RETURN_TO_ORIGINAL_POSITION_TIMEOUT); } private void onSecondaryPointerUp(MotionEvent ev) { final int pointerIndex = MotionEventCompat.getActionIndex(ev); final int pointerId = MotionEventCompat.getPointerId(ev, pointerIndex); if (pointerId == mActivePointerId) { // This was our active pointer going up. Choose a new // active pointer and adjust accordingly. final int newPointerIndex = pointerIndex == 0 ? 1 : 0; mLastMotionY = MotionEventCompat.getY(ev, newPointerIndex); mActivePointerId = MotionEventCompat.getPointerId(ev, newPointerIndex); } } /** * Classes that wish to be notified when the swipe gesture correctly * triggers a refresh should implement this interface. */ public interface OnRefreshListener { public void onRefresh(); } /** * Simple AnimationListener to avoid having to implement unneeded methods in * AnimationListeners. */ private class BaseAnimationListener implements AnimationListener { @Override public void onAnimationStart(Animation animation) { } @Override public void onAnimationEnd(Animation animation) { } @Override public void onAnimationRepeat(Animation animation) { } } /** * Custom progress bar that shows a cycle of colors as widening circles that * overdraw each other. When finished, the bar is cleared from the inside out as * the main cycle continues. Before running, this can also indicate how close * the user is to triggering something (e.g. how far they need to pull down to * trigger a refresh). */ final class SwipeProgressBar { // Default progress animation colors are grays. private final static int COLOR1 = 0xB3000000; private final static int COLOR2 = 0x80000000; private final static int COLOR3 = 0x4d000000; private final static int COLOR4 = 0x1a000000; // The duration of the animation cycle. private static final int ANIMATION_DURATION_MS = 2000; // The duration of the animation to clear the bar. private static final int FINISH_ANIMATION_DURATION_MS = 1000; // Interpolator for varying the speed of the animation. private final Interpolator INTERPOLATOR = new BakedBezierInterpolator(); private final Paint mPaint = new Paint(); private final RectF mClipRect = new RectF(); private float mTriggerPercentage; private long mStartTime; private long mFinishTime; private boolean mRunning; // Colors used when rendering the animation, private int mColor1; private int mColor2; private int mColor3; private int mColor4; private View mParent; private Rect mBounds = new Rect(); public SwipeProgressBar(View parent) { mParent = parent; mColor1 = COLOR1; mColor2 = COLOR2; mColor3 = COLOR3; mColor4 = COLOR4; } /** * Set the four colors used in the progress animation. The first color will * also be the color of the bar that grows in response to a user swipe * gesture. * * @param color1 Integer representation of a color. * @param color2 Integer representation of a color. * @param color3 Integer representation of a color. * @param color4 Integer representation of a color. */ void setColorScheme(int color1, int color2, int color3, int color4) { mColor1 = color1; mColor2 = color2; mColor3 = color3; mColor4 = color4; } /** * Update the progress the user has made toward triggering the swipe * gesture. and use this value to update the percentage of the trigger that * is shown. */ void setTriggerPercentage(float triggerPercentage) { mTriggerPercentage = triggerPercentage; mStartTime = 0; ViewCompat.postInvalidateOnAnimation(mParent); } /** * Start showing the progress animation. */ void start() { if (!mRunning) { mTriggerPercentage = 0; mStartTime = AnimationUtils.currentAnimationTimeMillis(); mRunning = true; mParent.postInvalidate(); } } /** * Stop showing the progress animation. */ void stop() { if (mRunning) { mTriggerPercentage = 0; mFinishTime = AnimationUtils.currentAnimationTimeMillis(); mRunning = false; mParent.postInvalidate(); } } /** * @return Return whether the progress animation is currently running. */ boolean isRunning() { return mRunning || mFinishTime > 0; } void draw(Canvas canvas) { final int width = mBounds.width(); final int cx = width / 2; final int cy = mBounds.top + mBounds.height() / 2; boolean drawTriggerWhileFinishing = false; int restoreCount = canvas.save(); canvas.clipRect(mBounds); if (mRunning || (mFinishTime > 0)) { long now = AnimationUtils.currentAnimationTimeMillis(); long elapsed = (now - mStartTime) % ANIMATION_DURATION_MS; long iterations = (now - mStartTime) / ANIMATION_DURATION_MS; float rawProgress = (elapsed / (ANIMATION_DURATION_MS / 100f)); // If we're not running anymore, that means we're running through // the finish animation. if (!mRunning) { // If the finish animation is done, don't draw anything, and // don't repost. if ((now - mFinishTime) >= FINISH_ANIMATION_DURATION_MS) { mFinishTime = 0; return; } // Otherwise, use a 0 opacity alpha layer to clear the animation // from the inside out. This layer will prevent the circles from // drawing within its bounds. long finishElapsed = (now - mFinishTime) % FINISH_ANIMATION_DURATION_MS; float finishProgress = (finishElapsed / (FINISH_ANIMATION_DURATION_MS / 100f)); float pct = (finishProgress / 100f); // Radius of the circle is half of the screen. float clearRadius = width / 2 * INTERPOLATOR.getInterpolation(pct); mClipRect.set(cx - clearRadius, mBounds.top, cx + clearRadius, mBounds.bottom); canvas.saveLayerAlpha(mClipRect, 0, 0); // Only draw the trigger if there is a space in the center of // this refreshing view that needs to be filled in by the // trigger. If the progress view is just still animating, let it // continue animating. drawTriggerWhileFinishing = true; } // First fill in with the last color that would have finished drawing. if (iterations == 0) { canvas.drawColor(mColor1); } else { if (rawProgress >= 0 && rawProgress < 25) { canvas.drawColor(mColor4); } else if (rawProgress >= 25 && rawProgress < 50) { canvas.drawColor(mColor1); } else if (rawProgress >= 50 && rawProgress < 75) { canvas.drawColor(mColor2); } else { canvas.drawColor(mColor3); } } // Then draw up to 4 overlapping concentric circles of varying radii, based on how far // along we are in the cycle. // progress 0-50 draw mColor2 // progress 25-75 draw mColor3 // progress 50-100 draw mColor4 // progress 75 (wrap to 25) draw mColor1 if ((rawProgress >= 0 && rawProgress <= 25)) { float pct = (((rawProgress + 25) * 2) / 100f); drawCircle(canvas, cx, cy, mColor1, pct); } if (rawProgress >= 0 && rawProgress <= 50) { float pct = ((rawProgress * 2) / 100f); drawCircle(canvas, cx, cy, mColor2, pct); } if (rawProgress >= 25 && rawProgress <= 75) { float pct = (((rawProgress - 25) * 2) / 100f); drawCircle(canvas, cx, cy, mColor3, pct); } if (rawProgress >= 50 && rawProgress <= 100) { float pct = (((rawProgress - 50) * 2) / 100f); drawCircle(canvas, cx, cy, mColor4, pct); } if ((rawProgress >= 75 && rawProgress <= 100)) { float pct = (((rawProgress - 75) * 2) / 100f); drawCircle(canvas, cx, cy, mColor1, pct); } if (mTriggerPercentage > 0 && drawTriggerWhileFinishing) { // There is some portion of trigger to draw. Restore the canvas, // then draw the trigger. Otherwise, the trigger does not appear // until after the bar has finished animating and appears to // just jump in at a larger width than expected. canvas.restoreToCount(restoreCount); restoreCount = canvas.save(); canvas.clipRect(mBounds); drawTrigger(canvas, cx, cy); } // Keep running until we finish out the last cycle. ViewCompat.postInvalidateOnAnimation(mParent); } else { // Otherwise if we're in the middle of a trigger, draw that. if (mTriggerPercentage > 0 && mTriggerPercentage <= 1.0) { drawTrigger(canvas, cx, cy); } } canvas.restoreToCount(restoreCount); } private void drawTrigger(Canvas canvas, int cx, int cy) { mPaint.setColor(mColor1); canvas.drawCircle(cx, cy, cx * mTriggerPercentage, mPaint); } /** * Draws a circle centered in the view. * * @param canvas the canvas to draw on * @param cx the center x coordinate * @param cy the center y coordinate * @param color the color to draw * @param pct the percentage of the view that the circle should cover */ private void drawCircle(Canvas canvas, float cx, float cy, int color, float pct) { mPaint.setColor(color); canvas.save(); canvas.translate(cx, cy); float radiusScale = INTERPOLATOR.getInterpolation(pct); canvas.scale(radiusScale, radiusScale); canvas.drawCircle(0, 0, cx, mPaint); canvas.restore(); } /** * Set the drawing bounds of this SwipeProgressBar. */ void setBounds(int left, int top, int right, int bottom) { mBounds.left = left; mBounds.top = top; mBounds.right = right; mBounds.bottom = bottom; } } /** * A pre-baked bezier-curved interpolator for indeterminate progress animations. */ final class BakedBezierInterpolator implements Interpolator { private BakedBezierInterpolator() { super(); } /** * Lookup table values. * Generated using a Bezier curve from (0,0) to (1,1) with control points: * P0 (0,0) * P1 (0.4, 0) * P2 (0.2, 1.0) * P3 (1.0, 1.0) * * Values sampled with x at regular intervals between 0 and 1. */ private final float[] VALUES = new float[] { 0.0f, 0.0002f, 0.0009f, 0.0019f, 0.0036f, 0.0059f, 0.0086f, 0.0119f, 0.0157f, 0.0209f, 0.0257f, 0.0321f, 0.0392f, 0.0469f, 0.0566f, 0.0656f, 0.0768f, 0.0887f, 0.1033f, 0.1186f, 0.1349f, 0.1519f, 0.1696f, 0.1928f, 0.2121f, 0.237f, 0.2627f, 0.2892f, 0.3109f, 0.3386f, 0.3667f, 0.3952f, 0.4241f, 0.4474f, 0.4766f, 0.5f, 0.5234f, 0.5468f, 0.5701f, 0.5933f, 0.6134f, 0.6333f, 0.6531f, 0.6698f, 0.6891f, 0.7054f, 0.7214f, 0.7346f, 0.7502f, 0.763f, 0.7756f, 0.7879f, 0.8f, 0.8107f, 0.8212f, 0.8326f, 0.8415f, 0.8503f, 0.8588f, 0.8672f, 0.8754f, 0.8833f, 0.8911f, 0.8977f, 0.9041f, 0.9113f, 0.9165f, 0.9232f, 0.9281f, 0.9328f, 0.9382f, 0.9434f, 0.9476f, 0.9518f, 0.9557f, 0.9596f, 0.9632f, 0.9662f, 0.9695f, 0.9722f, 0.9753f, 0.9777f, 0.9805f, 0.9826f, 0.9847f, 0.9866f, 0.9884f, 0.9901f, 0.9917f, 0.9931f, 0.9944f, 0.9955f, 0.9964f, 0.9973f, 0.9981f, 0.9986f, 0.9992f, 0.9995f, 0.9998f, 1.0f, 1.0f }; private final float STEP_SIZE = 1.0f / (VALUES.length - 1); @Override public float getInterpolation(float input) { if (input >= 1.0f) { return 1.0f; } if (input <= 0f) { return 0f; } int position = Math.min((int) (input * (VALUES.length - 1)), VALUES.length - 2); float quantized = position * STEP_SIZE; float difference = input - quantized; float weight = difference / STEP_SIZE; return VALUES[position] + weight * (VALUES[position + 1] - VALUES[position]); } } }