Java tutorial
/* * Copyright (c) Facebook, Inc. and its affiliates. * * This source code is licensed under the MIT license found in the * LICENSE file in the root directory of this source tree. */ package com.facebook.react.views.scroll; import android.graphics.Color; import android.util.DisplayMetrics; import androidx.annotation.Nullable; import androidx.core.view.ViewCompat; import com.facebook.react.bridge.ReadableArray; import com.facebook.react.common.MapBuilder; import com.facebook.react.module.annotations.ReactModule; import com.facebook.react.uimanager.DisplayMetricsHolder; import com.facebook.react.uimanager.PixelUtil; import com.facebook.react.uimanager.ReactClippingViewGroupHelper; import com.facebook.react.uimanager.Spacing; import com.facebook.react.uimanager.ThemedReactContext; import com.facebook.react.uimanager.ViewGroupManager; import com.facebook.react.uimanager.ViewProps; import com.facebook.react.uimanager.annotations.ReactProp; import com.facebook.react.uimanager.annotations.ReactPropGroup; import com.facebook.yoga.YogaConstants; import java.util.ArrayList; import java.util.List; import java.util.Map; /** * View manager for {@link ReactScrollView} components. * * <p>Note that {@link ReactScrollView} and {@link ReactHorizontalScrollView} are exposed to JS as a * single ScrollView component, configured via the {@code horizontal} boolean property. */ @ReactModule(name = ReactScrollViewManager.REACT_CLASS) public class ReactScrollViewManager extends ViewGroupManager<ReactScrollView> implements ReactScrollViewCommandHelper.ScrollCommandHandler<ReactScrollView> { public static final String REACT_CLASS = "RCTScrollView"; private static final int[] SPACING_TYPES = { Spacing.ALL, Spacing.LEFT, Spacing.RIGHT, Spacing.TOP, Spacing.BOTTOM, }; private @Nullable FpsListener mFpsListener = null; public ReactScrollViewManager() { this(null); } public ReactScrollViewManager(@Nullable FpsListener fpsListener) { mFpsListener = fpsListener; } @Override public String getName() { return REACT_CLASS; } @Override public ReactScrollView createViewInstance(ThemedReactContext context) { return new ReactScrollView(context, mFpsListener); } @ReactProp(name = "scrollEnabled", defaultBoolean = true) public void setScrollEnabled(ReactScrollView view, boolean value) { view.setScrollEnabled(value); // Set focusable to match whether scroll is enabled. This improves keyboarding // experience by not making scrollview a tab stop when you cannot interact with it. view.setFocusable(value); } @ReactProp(name = "showsVerticalScrollIndicator") public void setShowsVerticalScrollIndicator(ReactScrollView view, boolean value) { view.setVerticalScrollBarEnabled(value); } @ReactProp(name = "decelerationRate") public void setDecelerationRate(ReactScrollView view, float decelerationRate) { view.setDecelerationRate(decelerationRate); } @ReactProp(name = "snapToInterval") public void setSnapToInterval(ReactScrollView view, float snapToInterval) { // snapToInterval needs to be exposed as a float because of the Javascript interface. DisplayMetrics screenDisplayMetrics = DisplayMetricsHolder.getScreenDisplayMetrics(); view.setSnapInterval((int) (snapToInterval * screenDisplayMetrics.density)); } @ReactProp(name = "snapToOffsets") public void setSnapToOffsets(ReactScrollView view, @Nullable ReadableArray snapToOffsets) { DisplayMetrics screenDisplayMetrics = DisplayMetricsHolder.getScreenDisplayMetrics(); List<Integer> offsets = new ArrayList<Integer>(); for (int i = 0; i < snapToOffsets.size(); i++) { offsets.add((int) (snapToOffsets.getDouble(i) * screenDisplayMetrics.density)); } view.setSnapOffsets(offsets); } @ReactProp(name = "snapToStart") public void setSnapToStart(ReactScrollView view, boolean snapToStart) { view.setSnapToStart(snapToStart); } @ReactProp(name = "snapToEnd") public void setSnapToEnd(ReactScrollView view, boolean snapToEnd) { view.setSnapToEnd(snapToEnd); } @ReactProp(name = ReactClippingViewGroupHelper.PROP_REMOVE_CLIPPED_SUBVIEWS) public void setRemoveClippedSubviews(ReactScrollView view, boolean removeClippedSubviews) { view.setRemoveClippedSubviews(removeClippedSubviews); } /** * Computing momentum events is potentially expensive since we post a runnable on the UI thread to * see when it is done. We only do that if {@param sendMomentumEvents} is set to true. This is * handled automatically in js by checking if there is a listener on the momentum events. * * @param view * @param sendMomentumEvents */ @ReactProp(name = "sendMomentumEvents") public void setSendMomentumEvents(ReactScrollView view, boolean sendMomentumEvents) { view.setSendMomentumEvents(sendMomentumEvents); } /** * Tag used for logging scroll performance on this scroll view. Will force momentum events to be * turned on (see setSendMomentumEvents). * * @param view * @param scrollPerfTag */ @ReactProp(name = "scrollPerfTag") public void setScrollPerfTag(ReactScrollView view, @Nullable String scrollPerfTag) { view.setScrollPerfTag(scrollPerfTag); } @ReactProp(name = "pagingEnabled") public void setPagingEnabled(ReactScrollView view, boolean pagingEnabled) { view.setPagingEnabled(pagingEnabled); } /** * When set, fills the rest of the scrollview with a color to avoid setting a background and * creating unnecessary overdraw. * * @param view * @param color */ @ReactProp(name = "endFillColor", defaultInt = Color.TRANSPARENT, customType = "Color") public void setBottomFillColor(ReactScrollView view, int color) { view.setEndFillColor(color); } /** Controls overScroll behaviour */ @ReactProp(name = "overScrollMode") public void setOverScrollMode(ReactScrollView view, String value) { view.setOverScrollMode(ReactScrollViewHelper.parseOverScrollMode(value)); } @ReactProp(name = "nestedScrollEnabled") public void setNestedScrollEnabled(ReactScrollView view, boolean value) { ViewCompat.setNestedScrollingEnabled(view, value); } @Override public @Nullable Map<String, Integer> getCommandsMap() { return ReactScrollViewCommandHelper.getCommandsMap(); } @Override public void receiveCommand(ReactScrollView scrollView, int commandId, @Nullable ReadableArray args) { ReactScrollViewCommandHelper.receiveCommand(this, scrollView, commandId, args); } @Override public void receiveCommand(ReactScrollView scrollView, String commandId, @Nullable ReadableArray args) { ReactScrollViewCommandHelper.receiveCommand(this, scrollView, commandId, args); } @Override public void flashScrollIndicators(ReactScrollView scrollView) { scrollView.flashScrollIndicators(); } @Override public void scrollTo(ReactScrollView scrollView, ReactScrollViewCommandHelper.ScrollToCommandData data) { if (data.mAnimated) { scrollView.smoothScrollTo(data.mDestX, data.mDestY); } else { scrollView.scrollTo(data.mDestX, data.mDestY); } } @ReactPropGroup(names = { ViewProps.BORDER_RADIUS, ViewProps.BORDER_TOP_LEFT_RADIUS, ViewProps.BORDER_TOP_RIGHT_RADIUS, ViewProps.BORDER_BOTTOM_RIGHT_RADIUS, ViewProps.BORDER_BOTTOM_LEFT_RADIUS }, defaultFloat = YogaConstants.UNDEFINED) public void setBorderRadius(ReactScrollView view, int index, float borderRadius) { if (!YogaConstants.isUndefined(borderRadius)) { borderRadius = PixelUtil.toPixelFromDIP(borderRadius); } if (index == 0) { view.setBorderRadius(borderRadius); } else { view.setBorderRadius(borderRadius, index - 1); } } @ReactProp(name = "borderStyle") public void setBorderStyle(ReactScrollView view, @Nullable String borderStyle) { view.setBorderStyle(borderStyle); } @ReactPropGroup(names = { ViewProps.BORDER_WIDTH, ViewProps.BORDER_LEFT_WIDTH, ViewProps.BORDER_RIGHT_WIDTH, ViewProps.BORDER_TOP_WIDTH, ViewProps.BORDER_BOTTOM_WIDTH, }, defaultFloat = YogaConstants.UNDEFINED) public void setBorderWidth(ReactScrollView view, int index, float width) { if (!YogaConstants.isUndefined(width)) { width = PixelUtil.toPixelFromDIP(width); } view.setBorderWidth(SPACING_TYPES[index], width); } @ReactPropGroup(names = { "borderColor", "borderLeftColor", "borderRightColor", "borderTopColor", "borderBottomColor" }, customType = "Color") public void setBorderColor(ReactScrollView view, int index, Integer color) { float rgbComponent = color == null ? YogaConstants.UNDEFINED : (float) (color & 0x00FFFFFF); float alphaComponent = color == null ? YogaConstants.UNDEFINED : (float) (color >>> 24); view.setBorderColor(SPACING_TYPES[index], rgbComponent, alphaComponent); } @ReactProp(name = "overflow") public void setOverflow(ReactScrollView view, @Nullable String overflow) { view.setOverflow(overflow); } @Override public void scrollToEnd(ReactScrollView scrollView, ReactScrollViewCommandHelper.ScrollToEndCommandData data) { // ScrollView always has one child - the scrollable area int bottom = scrollView.getChildAt(0).getHeight() + scrollView.getPaddingBottom(); if (data.mAnimated) { scrollView.smoothScrollTo(scrollView.getScrollX(), bottom); } else { scrollView.scrollTo(scrollView.getScrollX(), bottom); } } @ReactProp(name = "persistentScrollbar") public void setPersistentScrollbar(ReactScrollView view, boolean value) { view.setScrollbarFadingEnabled(!value); } @ReactProp(name = "fadingEdgeLength") public void setFadingEdgeLength(ReactScrollView view, int value) { if (value > 0) { view.setVerticalFadingEdgeEnabled(true); view.setFadingEdgeLength(value); } else { view.setVerticalFadingEdgeEnabled(false); view.setFadingEdgeLength(0); } } @Override public @Nullable Map<String, Object> getExportedCustomDirectEventTypeConstants() { return createExportedCustomDirectEventTypeConstants(); } public static Map<String, Object> createExportedCustomDirectEventTypeConstants() { return MapBuilder.<String, Object>builder() .put(ScrollEventType.getJSEventName(ScrollEventType.SCROLL), MapBuilder.of("registrationName", "onScroll")) .put(ScrollEventType.getJSEventName(ScrollEventType.BEGIN_DRAG), MapBuilder.of("registrationName", "onScrollBeginDrag")) .put(ScrollEventType.getJSEventName(ScrollEventType.END_DRAG), MapBuilder.of("registrationName", "onScrollEndDrag")) .put(ScrollEventType.getJSEventName(ScrollEventType.MOMENTUM_BEGIN), MapBuilder.of("registrationName", "onMomentumScrollBegin")) .put(ScrollEventType.getJSEventName(ScrollEventType.MOMENTUM_END), MapBuilder.of("registrationName", "onMomentumScrollEnd")) .build(); } }