package com.yaoyumeng.v2ex.ui.swipeback;
import android.app.Activity;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.support.v4.view.ViewCompat;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.widget.FrameLayout;
import com.yaoyumeng.v2ex.R;
import java.util.ArrayList;
import java.util.List;
public class SwipeBackLayout extends FrameLayout {
/**
* Minimum velocity that will be detected as a fling
*/
private static final int MIN_FLING_VELOCITY = 400; // dips per second
private static final int DEFAULT_SCRIM_COLOR = 0x99000000;
private static final int FULL_ALPHA = 255;
/**
* Edge flag indicating that the left edge should be affected.
*/
public static final int EDGE_LEFT = ViewDragHelper.EDGE_LEFT;
/**
* A view is not currently being dragged or animating as a result of a
* fling/snap.
*/
public static final int STATE_IDLE = ViewDragHelper.STATE_IDLE;
/**
* A view is currently being dragged. The position is currently changing as
* a result of user input or simulated user input.
*/
public static final int STATE_DRAGGING = ViewDragHelper.STATE_DRAGGING;
/**
* A view is currently settling into place as a result of a fling or
* predefined non-interactive motion.
*/
public static final int STATE_SETTLING = ViewDragHelper.STATE_SETTLING;
/**
* Default threshold of scroll
*/
private static final float DEFAULT_SCROLL_THRESHOLD = 0.3f;
private static final int OVERSCROLL_DISTANCE = 10;
private int mEdgeFlag;
/**
* Threshold of scroll, we will close the activity, when scrollPercent over
* this value;
*/
private float mScrollThreshold = DEFAULT_SCROLL_THRESHOLD;
private Activity mActivity;
private boolean mEnable = true;
private View mContentView;
private ViewDragHelper mDragHelper;
private float mScrollPercent;
private int mContentLeft;
private int mContentTop;
/**
* The set of listeners to be sent events through.
*/
private List<SwipeListener> mListeners;
private Drawable mShadowLeft;
private float mScrimOpacity;
private int mScrimColor = DEFAULT_SCRIM_COLOR;
private boolean mInLayout;
private Rect mTmpRect = new Rect();
/**
* Edge being dragged
*/
private int mTrackingEdge;
public SwipeBackLayout(Context context) {
super(context);
init();
}
public SwipeBackLayout(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public SwipeBackLayout(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init();
}
private void init(){
mDragHelper = ViewDragHelper.create(this, new ViewDragCallback());
setShadow(R.drawable.shadow_left);
final float density = getResources().getDisplayMetrics().density;
final float minVel = MIN_FLING_VELOCITY * density;
mDragHelper.setMinVelocity(minVel);
setEdgeTrackingEnabled(EDGE_LEFT);
}
/**
* Sets the sensitivity of the NavigationLayout.
*
* @param context The application context.
* @param sensitivity value between 0 and 1, the final value for touchSlop =
* ViewConfiguration.getScaledTouchSlop * (1 / s);
*/
public void setSensitivity(Context context, float sensitivity) {
mDragHelper.setSensitivity(context, sensitivity);
}
/**
* Set up contentView which will be moved by user gesture
*
* @param view
*/
private void setContentView(View view) {
mContentView = view;
}
public void setEnableGesture(boolean enable) {
mEnable = enable;
}
/**
* Enable edge tracking for the selected edges of the parent view. The
* callback's
* methods will only be invoked for edges for which edge tracking has been
* enabled.
*
* @param edgeFlags Combination of edge flags describing the edges to watch
* @see #EDGE_LEFT
*/
public void setEdgeTrackingEnabled(int edgeFlags) {
mEdgeFlag = edgeFlags;
mDragHelper.setEdgeTrackingEnabled(mEdgeFlag);
}
/**
* Set a color to use for the scrim that obscures primary content while a
* drawer is open.
*
* @param color Color to use in 0xAARRGGBB format.
*/
public void setScrimColor(int color) {
mScrimColor = color;
invalidate();
}
/**
* Set the size of an edge. This is the range in pixels along the edges of
* this view that will actively detect edge touches or drags if edge
* tracking is enabled.
*
* @param size The size of an edge in pixels
*/
public void setEdgeSize(int size) {
mDragHelper.setEdgeSize(size);
}
/**
* Register a callback to be invoked when a swipe event is sent to this
* view.
*
* @param listener the swipe listener to attach to this view
* @deprecated use {@link #addSwipeListener} instead
*/
@Deprecated
public void setSwipeListener(SwipeListener listener) {
addSwipeListener(listener);
}
/**
* Add a callback to be invoked when a swipe event is sent to this view.
*
* @param listener the swipe listener to attach to this view
*/
public void addSwipeListener(SwipeListener listener) {
if (mListeners == null) {
mListeners = new ArrayList<SwipeListener>();
}
mListeners.add(listener);
}
/**
* Removes a listener from the set of listeners
*
* @param listener
*/
public void removeSwipeListener(SwipeListener listener) {
if (mListeners == null) {
return;
}
mListeners.remove(listener);
}
public static interface SwipeListener {
/**
* Invoke when state change
*
* @param state flag to describe scroll state
* @see #STATE_IDLE
* @see #STATE_DRAGGING
* @see #STATE_SETTLING
* @param scrollPercent scroll percent of this view
*/
public void onScrollStateChange(int state, float scrollPercent);
/**
* Invoke when edge touched
*
* @param edgeFlag edge flag describing the edge being touched
* @see #EDGE_LEFT
*/
public void onEdgeTouch(int edgeFlag);
/**
* Invoke when scroll percent over the threshold for the first time
*/
public void onScrollOverThreshold();
}
/**
* Set scroll threshold, we will close the activity, when scrollPercent over
* this value
*
* @param threshold
*/
public void setScrollThresHold(float threshold) {
if (threshold >= 1.0f || threshold <= 0) {
throw new IllegalArgumentException("Threshold value should be between 0 and 1.0");
}
mScrollThreshold = threshold;
}
/**
* Set a drawable used for edge shadow.
*
* @param shadow Drawable to use
* @see #EDGE_LEFT
*/
public void setShadow(Drawable shadow) {
mShadowLeft = shadow;
invalidate();
}
/**
* Set a drawable used for edge shadow.
*
* @param resId Resource of drawable to use
* @see #EDGE_LEFT
*/
public void setShadow(int resId) {
setShadow(getResources().getDrawable(resId));
}
/**
* Scroll out contentView and finish the activity
*/
public void scrollToFinishActivity() {
final int childWidth = mContentView.getWidth();
int top = 0;
int left = childWidth + mShadowLeft.getIntrinsicWidth() + OVERSCROLL_DISTANCE;
mTrackingEdge = EDGE_LEFT;
mDragHelper.smoothSlideViewTo(mContentView, left, top);
invalidate();
}
@Override
public boolean onInterceptTouchEvent(MotionEvent event) {
if (!mEnable) {
return false;
}
try {
return mDragHelper.shouldInterceptTouchEvent(event);
} catch (ArrayIndexOutOfBoundsException e) {
// FIXME: handle exception
// issues #9
return false;
}
}
@Override
public boolean onTouchEvent(MotionEvent event) {
if (!mEnable) {
return false;
}
mDragHelper.processTouchEvent(event);
return true;
}
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
mInLayout = true;
if (mContentView != null)
mContentView.layout(mContentLeft, mContentTop,
mContentLeft + mContentView.getMeasuredWidth(),
mContentTop + mContentView.getMeasuredHeight());
mInLayout = false;
}
@Override
public void requestLayout() {
if (!mInLayout) {
super.requestLayout();
}
}
@Override
protected boolean drawChild(Canvas canvas, View child, long drawingTime) {
final boolean drawContent = child == mContentView;
boolean ret = super.drawChild(canvas, child, drawingTime);
if (mScrimOpacity > 0 && drawContent
&& mDragHelper.getViewDragState() != ViewDragHelper.STATE_IDLE) {
drawShadow(canvas, child);
drawScrim(canvas, child);
}
return ret;
}
private void drawScrim(Canvas canvas, View child) {
final int baseAlpha = (mScrimColor & 0xff000000) >>> 24;
final int alpha = (int) (baseAlpha * mScrimOpacity);
final int color = alpha << 24 | (mScrimColor & 0xffffff);
canvas.clipRect(0, 0, child.getLeft(), getHeight());
canvas.drawColor(color);
}
private void drawShadow(Canvas canvas, View child) {
final Rect childRect = mTmpRect;
child.getHitRect(childRect);
if ((mEdgeFlag & EDGE_LEFT) != 0) {
mShadowLeft.setBounds(childRect.left - mShadowLeft.getIntrinsicWidth(), childRect.top,
childRect.left, childRect.bottom);
mShadowLeft.setAlpha((int) (mScrimOpacity * FULL_ALPHA));
mShadowLeft.draw(canvas);
}
}
public void attachToActivity(Activity activity) {
mActivity = activity;
TypedArray a = activity.getTheme().obtainStyledAttributes(new int[] {
android.R.attr.windowBackground
});
int background = a.getResourceId(0, 0);
a.recycle();
ViewGroup decor = (ViewGroup) activity.getWindow().getDecorView();
ViewGroup decorChild = (ViewGroup) decor.getChildAt(0);
decorChild.setBackgroundResource(background);
decor.removeView(decorChild);
addView(decorChild);
setContentView(decorChild);
decor.addView(this);
}
@Override
public void computeScroll() {
mScrimOpacity = 1 - mScrollPercent;
if (mDragHelper.continueSettling(true)) {
ViewCompat.postInvalidateOnAnimation(this);
}
}
private class ViewDragCallback extends ViewDragHelper.Callback {
private boolean mIsScrollOverValid;
@Override
public boolean tryCaptureView(View view, int i) {
boolean ret = mDragHelper.isEdgeTouched(mEdgeFlag, i);
if (ret) {
if (mDragHelper.isEdgeTouched(EDGE_LEFT, i)) {
mTrackingEdge = EDGE_LEFT;
}
if (mListeners != null && !mListeners.isEmpty()) {
for (SwipeListener listener : mListeners) {
listener.onEdgeTouch(mTrackingEdge);
}
}
mIsScrollOverValid = true;
}
return ret;
}
@Override
public int getViewHorizontalDragRange(View child) {
return mEdgeFlag & EDGE_LEFT;
}
@Override
public int getViewVerticalDragRange(View child) {
return mEdgeFlag;
}
@Override
public void onViewPositionChanged(View changedView, int left, int top, int dx, int dy) {
super.onViewPositionChanged(changedView, left, top, dx, dy);
if ((mTrackingEdge & EDGE_LEFT) != 0) {
mScrollPercent = Math.abs((float) left
/ (mContentView.getWidth() + mShadowLeft.getIntrinsicWidth()));
}
mContentLeft = left;
mContentTop = top;
invalidate();
if (mScrollPercent < mScrollThreshold && !mIsScrollOverValid) {
mIsScrollOverValid = true;
}
if (mListeners != null && !mListeners.isEmpty()
&& mDragHelper.getViewDragState() == STATE_DRAGGING
&& mScrollPercent >= mScrollThreshold && mIsScrollOverValid) {
mIsScrollOverValid = false;
for (SwipeListener listener : mListeners) {
listener.onScrollOverThreshold();
}
}
if (mScrollPercent >= 1) {
if (!mActivity.isFinishing())
mActivity.finish();
}
}
@Override
public void onViewReleased(View releasedChild, float xvel, float yvel) {
final int childWidth = releasedChild.getWidth();
int top = 0;
int left = xvel > 0 || xvel == 0 && mScrollPercent > mScrollThreshold ? childWidth
+ mShadowLeft.getIntrinsicWidth() + OVERSCROLL_DISTANCE : 0;
mDragHelper.settleCapturedViewAt(left, top);
invalidate();
}
@Override
public int clampViewPositionHorizontal(View child, int left, int dx) {
return Math.min(child.getWidth(), Math.max(left, 0));
}
@Override
public int clampViewPositionVertical(View child, int top, int dy) {
return 0;
}
@Override
public void onViewDragStateChanged(int state) {
super.onViewDragStateChanged(state);
if (mListeners != null && !mListeners.isEmpty()) {
for (SwipeListener listener : mListeners) {
listener.onScrollStateChange(state, mScrollPercent);
}
}
}
}
}