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FastScroller.java
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/
FastScroller.java
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/*
* Copyright 2019 Google LLC
*
* 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
*
* https://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 me.zhanghai.android.fastscroll;
import android.content.Context;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.text.TextUtils;
import android.view.Gravity;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.view.ViewGroupOverlay;
import android.widget.FrameLayout;
import android.widget.TextView;
import java.util.Objects;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.widget.AppCompatTextView;
import androidx.core.math.MathUtils;
import androidx.core.util.Consumer;
public class FastScroller {
private final int mMinTouchTargetSize;
private final int mTouchSlop;
@NonNull
private final ViewGroup mView;
@NonNull
private final ViewHelper mViewHelper;
@Nullable
private Rect mUserPadding;
@NonNull
private final AnimationHelper mAnimationHelper;
private final int mTrackWidth;
private final int mThumbWidth;
private final int mThumbHeight;
@NonNull
private final View mTrackView;
@NonNull
private final View mThumbView;
@NonNull
private final TextView mPopupView;
private boolean mScrollbarEnabled;
private int mThumbOffset;
private float mDownX;
private float mDownY;
private float mLastY;
private float mDragStartY;
private int mDragStartThumbOffset;
private boolean mDragging;
@NonNull
private final Runnable mAutoHideScrollbarRunnable = this::autoHideScrollbar;
@NonNull
private final Rect mTempRect = new Rect();
public FastScroller(@NonNull ViewGroup view, @NonNull ViewHelper viewHelper,
@Nullable Rect padding, @NonNull Drawable trackDrawable,
@NonNull Drawable thumbDrawable, @NonNull Consumer<TextView> popupStyle,
@NonNull AnimationHelper animationHelper) {
mMinTouchTargetSize = view.getResources().getDimensionPixelSize(
R.dimen.afs_min_touch_target_size);
Context context = view.getContext();
mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();
mView = view;
mViewHelper = viewHelper;
mUserPadding = padding;
mAnimationHelper = animationHelper;
mTrackWidth = requireNonNegative(trackDrawable.getIntrinsicWidth(),
"trackDrawable.getIntrinsicWidth() < 0");
mThumbWidth = requireNonNegative(thumbDrawable.getIntrinsicWidth(),
"thumbDrawable.getIntrinsicWidth() < 0");
mThumbHeight = requireNonNegative(thumbDrawable.getIntrinsicHeight(),
"thumbDrawable.getIntrinsicHeight() < 0");
mTrackView = new View(context);
mTrackView.setBackground(trackDrawable);
mThumbView = new View(context);
mThumbView.setBackground(thumbDrawable);
mPopupView = new AppCompatTextView(context);
mPopupView.setLayoutParams(new FrameLayout.LayoutParams(
ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT));
popupStyle.accept(mPopupView);
ViewGroupOverlay overlay = mView.getOverlay();
overlay.add(mTrackView);
overlay.add(mThumbView);
overlay.add(mPopupView);
postAutoHideScrollbar();
mPopupView.setAlpha(0);
mViewHelper.addOnPreDrawListener(this::onPreDraw);
mViewHelper.addOnScrollChangedListener(this::onScrollChanged);
mViewHelper.addOnTouchEventListener(this::onTouchEvent);
}
private static int requireNonNegative(int value, @NonNull String message) {
if (value < 0) {
throw new IllegalArgumentException(message);
}
return value;
}
public void setPadding(int left, int top, int right, int bottom) {
if (mUserPadding != null && mUserPadding.left == left && mUserPadding.top == top
&& mUserPadding.right == right && mUserPadding.bottom == bottom) {
return;
}
if (mUserPadding == null) {
mUserPadding = new Rect();
}
mUserPadding.set(left, top, right, bottom);
mView.invalidate();
}
public void setPadding(@Nullable Rect padding) {
if (Objects.equals(mUserPadding, padding)) {
return;
}
if (padding != null) {
if (mUserPadding == null) {
mUserPadding = new Rect();
}
mUserPadding.set(padding);
} else {
mUserPadding = null;
}
mView.invalidate();
}
@NonNull
private Rect getPadding() {
if (mUserPadding != null) {
mTempRect.set(mUserPadding);
} else {
mTempRect.set(mView.getPaddingLeft(), mView.getPaddingTop(), mView.getPaddingRight(),
mView.getPaddingBottom());
}
return mTempRect;
}
private void onPreDraw() {
updateScrollbarState();
mTrackView.setVisibility(mScrollbarEnabled ? View.VISIBLE : View.INVISIBLE);
mThumbView.setVisibility(mScrollbarEnabled ? View.VISIBLE : View.INVISIBLE);
if (!mScrollbarEnabled) {
mPopupView.setVisibility(View.INVISIBLE);
return;
}
int layoutDirection = mView.getLayoutDirection();
mTrackView.setLayoutDirection(layoutDirection);
mThumbView.setLayoutDirection(layoutDirection);
mPopupView.setLayoutDirection(layoutDirection);
boolean isLayoutRtl = layoutDirection == View.LAYOUT_DIRECTION_RTL;
int viewWidth = mView.getWidth();
int viewHeight = mView.getHeight();
Rect padding = getPadding();
int trackLeft = isLayoutRtl ? padding.left : viewWidth - padding.right - mTrackWidth;
layoutView(mTrackView, trackLeft, padding.top, trackLeft + mTrackWidth,
Math.max(viewHeight - padding.bottom, padding.top));
int thumbLeft = isLayoutRtl ? padding.left : viewWidth - padding.right - mThumbWidth;
int thumbTop = padding.top + mThumbOffset;
layoutView(mThumbView, thumbLeft, thumbTop, thumbLeft + mThumbWidth,
thumbTop + mThumbHeight);
String popupText = mViewHelper.getPopupText();
boolean hasPopup = !TextUtils.isEmpty(popupText);
mPopupView.setVisibility(hasPopup ? View.VISIBLE : View.INVISIBLE);
if (hasPopup) {
FrameLayout.LayoutParams popupLayoutParams = (FrameLayout.LayoutParams)
mPopupView.getLayoutParams();
if (!Objects.equals(mPopupView.getText(), popupText)) {
mPopupView.setText(popupText);
int widthMeasureSpec = ViewGroup.getChildMeasureSpec(
View.MeasureSpec.makeMeasureSpec(viewWidth, View.MeasureSpec.EXACTLY),
padding.left + padding.right + mThumbWidth + popupLayoutParams.leftMargin
+ popupLayoutParams.rightMargin, popupLayoutParams.width);
int heightMeasureSpec = ViewGroup.getChildMeasureSpec(
View.MeasureSpec.makeMeasureSpec(viewHeight, View.MeasureSpec.EXACTLY),
padding.top + padding.bottom + popupLayoutParams.topMargin
+ popupLayoutParams.bottomMargin, popupLayoutParams.height);
mPopupView.measure(widthMeasureSpec, heightMeasureSpec);
}
int popupWidth = mPopupView.getMeasuredWidth();
int popupHeight = mPopupView.getMeasuredHeight();
int popupLeft = isLayoutRtl ? padding.left + mThumbWidth + popupLayoutParams.leftMargin
: viewWidth - padding.right - mThumbWidth - popupLayoutParams.rightMargin
- popupWidth;
int popupAnchorY;
switch (popupLayoutParams.gravity & Gravity.HORIZONTAL_GRAVITY_MASK) {
case Gravity.LEFT:
default:
popupAnchorY = 0;
break;
case Gravity.CENTER_HORIZONTAL:
popupAnchorY = popupHeight / 2;
break;
case Gravity.RIGHT:
popupAnchorY = popupHeight;
break;
}
int thumbAnchorY;
switch (popupLayoutParams.gravity & Gravity.VERTICAL_GRAVITY_MASK) {
case Gravity.TOP:
default:
thumbAnchorY = mThumbView.getPaddingTop();
break;
case Gravity.CENTER_VERTICAL: {
int thumbPaddingTop = mThumbView.getPaddingTop();
thumbAnchorY = thumbPaddingTop + (mThumbHeight - thumbPaddingTop
- mThumbView.getPaddingBottom()) / 2;
break;
}
case Gravity.BOTTOM:
thumbAnchorY = mThumbHeight - mThumbView.getPaddingBottom();
break;
}
int popupTop = MathUtils.clamp(thumbTop + thumbAnchorY - popupAnchorY,
padding.top + popupLayoutParams.topMargin,
viewHeight - padding.bottom - popupLayoutParams.bottomMargin - popupHeight);
layoutView(mPopupView, popupLeft, popupTop, popupLeft + popupWidth,
popupTop + popupHeight);
}
}
private void updateScrollbarState() {
int scrollOffsetRange = getScrollOffsetRange();
mScrollbarEnabled = scrollOffsetRange > 0;
mThumbOffset = mScrollbarEnabled ? (int) ((long) getThumbOffsetRange()
* mViewHelper.getScrollOffset() / scrollOffsetRange) : 0;
}
private void layoutView(@NonNull View view, int left, int top, int right, int bottom) {
int scrollX = mView.getScrollX();
int scrollY = mView.getScrollY();
view.layout(scrollX + left, scrollY + top, scrollX + right, scrollY + bottom);
}
private void onScrollChanged() {
updateScrollbarState();
if (!mScrollbarEnabled) {
return;
}
mAnimationHelper.showScrollbar(mTrackView, mThumbView);
postAutoHideScrollbar();
}
private boolean onTouchEvent(@NonNull MotionEvent event) {
if (!mScrollbarEnabled) {
return false;
}
float eventX = event.getX();
float eventY = event.getY();
Rect padding = getPadding();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
mDownX = eventX;
mDownY = eventY;
if (mThumbView.getAlpha() > 0 && isInViewTouchTarget(mThumbView, eventX, eventY)) {
mDragStartY = eventY;
mDragStartThumbOffset = mThumbOffset;
setDragging(true);
}
break;
case MotionEvent.ACTION_MOVE:
if (!mDragging && isInViewTouchTarget(mTrackView, mDownX, mDownY)
&& Math.abs(eventY - mDownY) > mTouchSlop) {
if (isInViewTouchTarget(mThumbView, mDownX, mDownY)) {
mDragStartY = mLastY;
mDragStartThumbOffset = mThumbOffset;
} else {
mDragStartY = eventY;
mDragStartThumbOffset = (int) (eventY - padding.top - mThumbHeight / 2f);
scrollToThumbOffset(mDragStartThumbOffset);
}
setDragging(true);
}
if (mDragging) {
int thumbOffset = mDragStartThumbOffset + (int) (eventY - mDragStartY);
scrollToThumbOffset(thumbOffset);
}
break;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_CANCEL:
setDragging(false);
break;
}
mLastY = eventY;
return mDragging;
}
private boolean isInView(@NonNull View view, float x, float y) {
int scrollX = mView.getScrollX();
int scrollY = mView.getScrollY();
return x >= view.getLeft() - scrollX && x < view.getRight() - scrollX
&& y >= view.getTop() - scrollY && y < view.getBottom() - scrollY;
}
private boolean isInViewTouchTarget(@NonNull View view, float x, float y) {
int scrollX = mView.getScrollX();
int scrollY = mView.getScrollY();
return isInTouchTarget(x, view.getLeft() - scrollX, view.getRight() - scrollX, 0,
mView.getWidth())
&& isInTouchTarget(y, view.getTop() - scrollY, view.getBottom() - scrollY, 0,
mView.getHeight());
}
private boolean isInTouchTarget(float position, int viewStart, int viewEnd, int parentStart,
int parentEnd) {
int viewSize = viewEnd - viewStart;
if (viewSize >= mMinTouchTargetSize) {
return position >= viewStart && position < viewEnd;
}
int touchTargetStart = viewStart - (mMinTouchTargetSize - viewSize) / 2;
if (touchTargetStart < parentStart) {
touchTargetStart = parentStart;
}
int touchTargetEnd = touchTargetStart + mMinTouchTargetSize;
if (touchTargetEnd > parentEnd) {
touchTargetEnd = parentEnd;
touchTargetStart = touchTargetEnd - mMinTouchTargetSize;
if (touchTargetStart < parentStart) {
touchTargetStart = parentStart;
}
}
return position >= touchTargetStart && position < touchTargetEnd;
}
private void scrollToThumbOffset(int thumbOffset) {
int thumbOffsetRange = getThumbOffsetRange();
thumbOffset = MathUtils.clamp(thumbOffset, 0, thumbOffsetRange);
int scrollOffset = (int) ((long) getScrollOffsetRange() * thumbOffset / thumbOffsetRange);
mViewHelper.scrollTo(scrollOffset);
}
private int getScrollOffsetRange() {
return mViewHelper.getScrollRange() - mView.getHeight();
}
private int getThumbOffsetRange() {
Rect padding = getPadding();
return mView.getHeight() - padding.top - padding.bottom - mThumbHeight;
}
private void setDragging(boolean dragging) {
if (mDragging == dragging) {
return;
}
mDragging = dragging;
if (mDragging) {
mView.getParent().requestDisallowInterceptTouchEvent(true);
}
mTrackView.setPressed(mDragging);
mThumbView.setPressed(mDragging);
if (mDragging) {
cancelAutoHideScrollbar();
mAnimationHelper.showScrollbar(mTrackView, mThumbView);
mAnimationHelper.showPopup(mPopupView);
} else {
postAutoHideScrollbar();
mAnimationHelper.hidePopup(mPopupView);
}
}
private void postAutoHideScrollbar() {
cancelAutoHideScrollbar();
if (mAnimationHelper.isScrollbarAutoHideEnabled()) {
mView.postDelayed(mAutoHideScrollbarRunnable,
mAnimationHelper.getScrollbarAutoHideDelayMillis());
}
}
private void autoHideScrollbar() {
if (mDragging) {
return;
}
mAnimationHelper.hideScrollbar(mTrackView, mThumbView);
}
private void cancelAutoHideScrollbar() {
mView.removeCallbacks(mAutoHideScrollbarRunnable);
}
public interface ViewHelper {
void addOnPreDrawListener(@NonNull Runnable onPreDraw);
void addOnScrollChangedListener(@NonNull Runnable onScrollChanged);
void addOnTouchEventListener(@NonNull Predicate<MotionEvent> onTouchEvent);
int getScrollRange();
int getScrollOffset();
void scrollTo(int offset);
@Nullable
default String getPopupText() {
return null;
}
}
public interface AnimationHelper {
void showScrollbar(@NonNull View trackView, @NonNull View thumbView);
void hideScrollbar(@NonNull View trackView, @NonNull View thumbView);
boolean isScrollbarAutoHideEnabled();
int getScrollbarAutoHideDelayMillis();
void showPopup(@NonNull View popupView);
void hidePopup(@NonNull View popupView);
}
}