/
ReactHorizontalScrollView.java
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/
ReactHorizontalScrollView.java
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/**
* Copyright (c) 2015-present, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*/
package com.facebook.react.views.scroll;
import android.annotation.TargetApi;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Rect;
import android.graphics.drawable.ColorDrawable;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.LayerDrawable;
import android.view.MotionEvent;
import android.view.View;
import android.widget.HorizontalScrollView;
import com.facebook.infer.annotation.Assertions;
import com.facebook.react.uimanager.MeasureSpecAssertions;
import com.facebook.react.uimanager.ReactClippingViewGroup;
import com.facebook.react.uimanager.ReactClippingViewGroupHelper;
import com.facebook.react.uimanager.events.NativeGestureUtil;
import com.facebook.react.views.view.ReactViewBackgroundDrawable;
import javax.annotation.Nullable;
/**
* Similar to {@link ReactScrollView} but only supports horizontal scrolling.
*/
public class ReactHorizontalScrollView extends HorizontalScrollView implements
ReactClippingViewGroup {
private final OnScrollDispatchHelper mOnScrollDispatchHelper = new OnScrollDispatchHelper();
private final VelocityHelper mVelocityHelper = new VelocityHelper();
private boolean mActivelyScrolling;
private @Nullable Rect mClippingRect;
private boolean mDragging;
private boolean mPagingEnabled = false;
private @Nullable Runnable mPostTouchRunnable;
private boolean mRemoveClippedSubviews;
private boolean mScrollEnabled = true;
private boolean mSendMomentumEvents;
private @Nullable FpsListener mFpsListener = null;
private @Nullable String mScrollPerfTag;
private @Nullable Drawable mEndBackground;
private int mEndFillColor = Color.TRANSPARENT;
private @Nullable ReactViewBackgroundDrawable mReactBackgroundDrawable;
public ReactHorizontalScrollView(Context context) {
this(context, null);
}
public ReactHorizontalScrollView(Context context, @Nullable FpsListener fpsListener) {
super(context);
mFpsListener = fpsListener;
}
public void setScrollPerfTag(@Nullable String scrollPerfTag) {
mScrollPerfTag = scrollPerfTag;
}
@Override
public void setRemoveClippedSubviews(boolean removeClippedSubviews) {
if (removeClippedSubviews && mClippingRect == null) {
mClippingRect = new Rect();
}
mRemoveClippedSubviews = removeClippedSubviews;
updateClippingRect();
}
@Override
public boolean getRemoveClippedSubviews() {
return mRemoveClippedSubviews;
}
public void setSendMomentumEvents(boolean sendMomentumEvents) {
mSendMomentumEvents = sendMomentumEvents;
}
public void setScrollEnabled(boolean scrollEnabled) {
mScrollEnabled = scrollEnabled;
}
public void setPagingEnabled(boolean pagingEnabled) {
mPagingEnabled = pagingEnabled;
}
public void flashScrollIndicators() {
awakenScrollBars();
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
MeasureSpecAssertions.assertExplicitMeasureSpec(widthMeasureSpec, heightMeasureSpec);
setMeasuredDimension(
MeasureSpec.getSize(widthMeasureSpec),
MeasureSpec.getSize(heightMeasureSpec));
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
// Call with the present values in order to re-layout if necessary
scrollTo(getScrollX(), getScrollY());
}
@Override
protected void onScrollChanged(int x, int y, int oldX, int oldY) {
super.onScrollChanged(x, y, oldX, oldY);
if (mOnScrollDispatchHelper.onScrollChanged(x, y)) {
if (mRemoveClippedSubviews) {
updateClippingRect();
}
mActivelyScrolling = true;
ReactScrollViewHelper.emitScrollEvent(
this,
mOnScrollDispatchHelper.getXFlingVelocity(),
mOnScrollDispatchHelper.getYFlingVelocity());
}
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
if (!mScrollEnabled) {
return false;
}
if (super.onInterceptTouchEvent(ev)) {
NativeGestureUtil.notifyNativeGestureStarted(this, ev);
ReactScrollViewHelper.emitScrollBeginDragEvent(this);
mDragging = true;
enableFpsListener();
return true;
}
return false;
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
if (!mScrollEnabled) {
return false;
}
mVelocityHelper.calculateVelocity(ev);
int action = ev.getAction() & MotionEvent.ACTION_MASK;
if (action == MotionEvent.ACTION_UP && mDragging) {
ReactScrollViewHelper.emitScrollEndDragEvent(
this,
mVelocityHelper.getXVelocity(),
mVelocityHelper.getYVelocity());
mDragging = false;
// After the touch finishes, we may need to do some scrolling afterwards either as a result
// of a fling or because we need to page align the content
handlePostTouchScrolling();
}
return super.onTouchEvent(ev);
}
@Override
public void fling(int velocityX) {
if (mPagingEnabled) {
smoothScrollToPage(velocityX);
} else {
super.fling(velocityX);
}
handlePostTouchScrolling();
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
if (mRemoveClippedSubviews) {
updateClippingRect();
}
}
@Override
protected void onAttachedToWindow() {
super.onAttachedToWindow();
if (mRemoveClippedSubviews) {
updateClippingRect();
}
}
@Override
public void updateClippingRect() {
if (!mRemoveClippedSubviews) {
return;
}
Assertions.assertNotNull(mClippingRect);
ReactClippingViewGroupHelper.calculateClippingRect(this, mClippingRect);
View contentView = getChildAt(0);
if (contentView instanceof ReactClippingViewGroup) {
((ReactClippingViewGroup) contentView).updateClippingRect();
}
}
@Override
public void getClippingRect(Rect outClippingRect) {
outClippingRect.set(Assertions.assertNotNull(mClippingRect));
}
public void setEndFillColor(int color) {
if (color != mEndFillColor) {
mEndFillColor = color;
mEndBackground = new ColorDrawable(mEndFillColor);
}
}
private void enableFpsListener() {
if (isScrollPerfLoggingEnabled()) {
Assertions.assertNotNull(mFpsListener);
Assertions.assertNotNull(mScrollPerfTag);
mFpsListener.enable(mScrollPerfTag);
}
}
private void disableFpsListener() {
if (isScrollPerfLoggingEnabled()) {
Assertions.assertNotNull(mFpsListener);
Assertions.assertNotNull(mScrollPerfTag);
mFpsListener.disable(mScrollPerfTag);
}
}
private boolean isScrollPerfLoggingEnabled() {
return mFpsListener != null && mScrollPerfTag != null && !mScrollPerfTag.isEmpty();
}
@Override
public void draw(Canvas canvas) {
if (mEndFillColor != Color.TRANSPARENT) {
final View content = getChildAt(0);
if (mEndBackground != null && content != null && content.getRight() < getWidth()) {
mEndBackground.setBounds(content.getRight(), 0, getWidth(), getHeight());
mEndBackground.draw(canvas);
}
}
super.draw(canvas);
}
/**
* This handles any sort of scrolling that may occur after a touch is finished. This may be
* momentum scrolling (fling) or because you have pagingEnabled on the scroll view. Because we
* don't get any events from Android about this lifecycle, we do all our detection by creating a
* runnable that checks if we scrolled in the last frame and if so assumes we are still scrolling.
*/
@TargetApi(16)
private void handlePostTouchScrolling() {
// If we aren't going to do anything (send events or snap to page), we can early out.
if (!mSendMomentumEvents && !mPagingEnabled && !isScrollPerfLoggingEnabled()) {
return;
}
// Check if we are already handling this which may occur if this is called by both the touch up
// and a fling call
if (mPostTouchRunnable != null) {
return;
}
if (mSendMomentumEvents) {
ReactScrollViewHelper.emitScrollMomentumBeginEvent(this);
}
mActivelyScrolling = false;
mPostTouchRunnable = new Runnable() {
private boolean mSnappingToPage = false;
@Override
public void run() {
if (mActivelyScrolling) {
// We are still scrolling so we just post to check again a frame later
mActivelyScrolling = false;
ReactHorizontalScrollView.this.postOnAnimationDelayed(this, ReactScrollViewHelper.MOMENTUM_DELAY);
} else {
if (mPagingEnabled && !mSnappingToPage) {
// Only if we have pagingEnabled and we have not snapped to the page do we
// need to continue checking for the scroll. And we cause that scroll by asking for it
mSnappingToPage = true;
smoothScrollToPage(0);
ReactHorizontalScrollView.this.postOnAnimationDelayed(this, ReactScrollViewHelper.MOMENTUM_DELAY);
} else {
if (mSendMomentumEvents) {
ReactScrollViewHelper.emitScrollMomentumEndEvent(ReactHorizontalScrollView.this);
}
ReactHorizontalScrollView.this.mPostTouchRunnable = null;
disableFpsListener();
}
}
}
};
postOnAnimationDelayed(mPostTouchRunnable, ReactScrollViewHelper.MOMENTUM_DELAY);
}
/**
* This will smooth scroll us to the nearest page boundary
* It currently just looks at where the content is relative to the page and slides to the nearest
* page. It is intended to be run after we are done scrolling, and handling any momentum
* scrolling.
*/
private void smoothScrollToPage(int velocity) {
int width = getWidth();
int currentX = getScrollX();
// TODO (t11123799) - Should we do anything beyond linear accounting of the velocity
int predictedX = currentX + velocity;
int page = currentX / width;
if (predictedX > page * width + width / 2) {
page = page + 1;
}
smoothScrollTo(page * width, getScrollY());
}
@Override
public void setBackgroundColor(int color) {
if (color == Color.TRANSPARENT && mReactBackgroundDrawable == null) {
// don't do anything, no need to allocate ReactBackgroundDrawable for transparent background
} else {
getOrCreateReactViewBackground().setColor(color);
}
}
public void setBorderWidth(int position, float width) {
getOrCreateReactViewBackground().setBorderWidth(position, width);
}
public void setBorderColor(int position, float color, float alpha) {
getOrCreateReactViewBackground().setBorderColor(position, color, alpha);
}
public void setBorderRadius(float borderRadius) {
getOrCreateReactViewBackground().setRadius(borderRadius);
}
public void setBorderRadius(float borderRadius, int position) {
getOrCreateReactViewBackground().setRadius(borderRadius, position);
}
public void setBorderStyle(@Nullable String style) {
getOrCreateReactViewBackground().setBorderStyle(style);
}
private ReactViewBackgroundDrawable getOrCreateReactViewBackground() {
if (mReactBackgroundDrawable == null) {
mReactBackgroundDrawable = new ReactViewBackgroundDrawable();
Drawable backgroundDrawable = getBackground();
super.setBackground(null); // required so that drawable callback is cleared before we add the
// drawable back as a part of LayerDrawable
if (backgroundDrawable == null) {
super.setBackground(mReactBackgroundDrawable);
} else {
LayerDrawable layerDrawable =
new LayerDrawable(new Drawable[]{mReactBackgroundDrawable, backgroundDrawable});
super.setBackground(layerDrawable);
}
}
return mReactBackgroundDrawable;
}
}