/*
* Copyright 2011 SWM Services GmbH.
*
* 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.
*/
package de.swm.commons.mobile.client.widgets.scroll;
import com.google.gwt.dom.client.Element;
import com.google.gwt.dom.client.Node;
import com.google.gwt.dom.client.NodeList;
import com.google.gwt.dom.client.Style;
import com.google.gwt.dom.client.Style.Unit;
import com.google.gwt.user.client.ui.HasWidgets;
import com.google.gwt.user.client.ui.Widget;
import de.swm.commons.mobile.client.SWMMobile;
import de.swm.commons.mobile.client.base.PanelBase;
import de.swm.commons.mobile.client.event.*;
import de.swm.commons.mobile.client.utils.Utils;
/**
* Scroll panel - has the ability to keep the {@link de.swm.commons.mobile.client.widgets.itf.IHeaderPanel} implementations always on the top.
*/
public class ScrollPanel extends PanelBase implements HasWidgets, DragEventsHandler, SwipeEventsHandler, IScrollPanel {
private static final int TIME_FACTOR = 3000;
private static final double DISTANCE_FACTOR = 0.25;
private static final int DEFAULT_TRANSITION_DURATION = 500;
private static final int OFFSET = 2;
private boolean myHasTextBox = false;
private IScrollMonitor scrollMonitor;
private ScrollPanelEventsHandler scrollPanelEventsHandler;
private int offsetHeight = -1;
/**
* Defines how many pixels a button overscrolling should be possible (e.g 50px).
*/
private int overscrollButtonTolerance = 0;
/**
* Default constructor.
*/
public ScrollPanel() {
setStyleName(SWMMobile.getTheme().getMGWTCssBundle().getScrollPanelCss().scrollPanel());
}
/**
* A scroll monitor provides callback when the scrolling is done.
*
* @param scrollMonitor
*/
@Override
public void setScrollMonitor(IScrollMonitor scrollMonitor) {
this.scrollMonitor = scrollMonitor;
}
public void setHasTextBox(boolean hasTextBox) {
myHasTextBox = hasTextBox && SWMMobile.getOsDetection().isAndroid();
}
public boolean getHasTextBox() {
return myHasTextBox;
}
@Override
public void onLoad() {
DragController.get().addDragEventsHandler(this);
DragController.get().addSwipeEventsHandler(this);
}
@Override
public void onUnload() {
DragController.get().removeDragEventsHandler(this);
DragController.get().removeSwipeEventHandler(this);
}
@Override
public Widget getWidget() {
return myFlowPanel.getWidget(0);
}
public ScrollPanelEventsHandler getScrollPanelEventsHandler() {
return scrollPanelEventsHandler;
}
/**
* Neuen Handler fuer Scroll Panel Events registrieren.
*
* @param scrollPanelEventsHandler eventhandler
*/
public void addScrollPanelEventsHandler(ScrollPanelEventsHandler scrollPanelEventsHandler) {
this.scrollPanelEventsHandler = scrollPanelEventsHandler;
}
/**
* Sets the button overscroll tolerance in px
* @param overscrollButtonTolerance
*/
public void setOverscrollButtonTolerance(int overscrollButtonTolerance) {
this.overscrollButtonTolerance = overscrollButtonTolerance;
}
/**
* Scrolls to the default position.
*/
public void reset() {
Utils.setTransitionDuration(getWidget().getElement(), 0);
Utils.setTranslateY(getWidget().getElement(), 0);
}
/**
* Scrolls to the top.
*/
@Override
public void setPostionToTop() {
Utils.setTransitionDuration(getWidget().getElement(), 0);
Utils.setTranslateY(getWidget().getElement(), 0);
}
/**
* Scrolls to the button.
*/
@Override
public void setPositionToBottom() {
Utils.setTransitionDuration(getWidget().getElement(), 0);
Utils.setTranslateY(getWidget().getElement(), this.getElement().getClientHeight()
- this.getElement().getScrollHeight());
}
/**
* Sets the croll position
*
* @param pos the x axis pos
*/
@Override
public void setScrollPosition(int pos) {
if (myHasTextBox) {
setStyleTop(pos);
} else {
Element element = getWidget().getElement();
Utils.setTranslateY(element, pos);
}
}
/**
* Returns the current scroll position.
*
* @return the position
*/
@Override
public int getScrollPosition() {
if (myHasTextBox) {
return getStyleTop();
} else {
Element element = getWidget().getElement();
return Utils.getTranslateY(element);
}
}
/**
* Returns the next scroll position
*
* @return then next scroll position
*/
@Override
public int getScrollToPosition() {
if (myHasTextBox) {
return getStyleTop();
} else {
Element element = getWidget().getElement();
return Utils.getMatrixY(element);
}
}
@Override
public void onDragStart(DragEvent e) {
if (scrollMonitor != null) {
scrollMonitor.onScrollStart();
}
int matrix = getScrollToPosition();
int current = getScrollPosition();
Utils.setTransitionDuration(getWidget().getElement(), 0);
if (current != matrix) { // scroll on going
int diff = current - matrix;
int offset = diff > OFFSET ? OFFSET : diff > -OFFSET ? diff : -OFFSET;
setScrollPosition(matrix + offset);
DragController.get().suppressNextClick();
}
}
@Override
public void onDragMove(DragEvent e) {
Element widgetEle = getWidget().getElement();
int panelHeight = Utils.getHeight(this.getElement());
int widgetHeight = calcOffsetHeight(widgetEle);
int current = getScrollPosition();
if (current > 0) {
// exceed top boundary
if (e.getOffsetY() > 0) { // resist scroll down.
current += (int) (e.getOffsetY() / OFFSET); // need the cast for production mode.
} else {
current += e.getOffsetY() * OFFSET;
}
} else if (-current + panelHeight > widgetHeight) {
//correct only scroll position if overscroll is prohibited
if (overscrollButtonTolerance == 0) {
// exceed bottom boundary
if (e.getOffsetY() < 0) { // resist scroll up.
current += (int) (e.getOffsetY() / OFFSET);
} else {
current += e.getOffsetY() * OFFSET;
}
} else {
//if button overscrolling is allowed
current += e.getOffsetY();
}
} else {
current += e.getOffsetY();
}
setScrollPosition(current);
}
private int calcOffsetHeight(Element widgetEle) {
return ((this.offsetHeight > 0) ? this.offsetHeight : widgetEle.getOffsetHeight());
}
/**
* A value greater zero will set the offset height of the panel manually.
* Otherwise it will be calculated automatically.
*
* @param offsetHeight the offset height.
*/
@Override
public void setOffsetHeight(int offsetHeight) {
this.offsetHeight = offsetHeight;
}
@Override
public void onDragEnd(DragEvent e) {
Element widgetEle = getWidget().getElement();
if (scrollMonitor != null) {
scrollMonitor.onScrollEnd();
}
int current = getScrollPosition();
if (current == 0) {
return;
}
int panelHeight = Utils.getHeight(this.getElement());
int widgetHeight = getHeightOfElementOrChildElements(widgetEle);
if (current > 0 // exceed top boundary
|| panelHeight > widgetHeight) {
// fire eventshandler for top boundary
if (getScrollPanelEventsHandler() != null) {
getScrollPanelEventsHandler().onTop(e);
}
Utils.setTransitionDuration(widgetEle, DEFAULT_TRANSITION_DURATION);
setScrollPosition(0);
} else if (-current + panelHeight > widgetHeight) { // exceed bottom boundary
// fire eventshandler for bottom boundary
if (getScrollPanelEventsHandler() != null) {
getScrollPanelEventsHandler().onBottom(e);
}
Utils.setTransitionDuration(widgetEle, DEFAULT_TRANSITION_DURATION);
setScrollPosition((panelHeight - overscrollButtonTolerance) - widgetHeight);
}
}
@Override
public void onSwipeVertical(SwipeEvent e) {
Element widgetEle = getWidget().getElement();
int panelHeight = Utils.getHeight(this.getElement());
int widgetHeight = widgetEle.getOffsetHeight();
long current = getScrollPosition();
if ((current >= 0) // exceed top boundary
|| (-current + panelHeight >= widgetHeight)) { // exceed bottom boundary
return;
}
double speed = e.getSpeed();
double timeFactor = TIME_FACTOR;
long time = (long) Math.abs(speed * timeFactor);
double dicstanceFactor = DISTANCE_FACTOR;
long distance = (long) (speed * time * dicstanceFactor);
// Utils.Console("speed " + speed + " time " + time + " distance " + distance + " current " + current);
current += distance;
// exceed top boundary?
if (current > 0) {
double timeAdj = 1 - (double) current / distance;
time = (long) (time * timeAdj);
current = 0;
} else if (-current + panelHeight > widgetHeight) { // exceed bottom boundary
long bottom = panelHeight - widgetHeight;
double timeAdj = 1 - (double) (current - bottom) / distance;
time = (long) (time * timeAdj);
current = bottom;
}
Utils.setTransitionDuration(widgetEle, time);
setScrollPosition((int) current);
}
@Override
public void onSwipeHorizontal(SwipeEvent e) {
}
@Override
public void add(Widget w) {
super.add(w);
if (SWMMobile.getOsDetection().isIOs()) {
Utils.setTranslateY(w.getElement(), 0); // anti-flickering on iOS.
}
}
/**
* Returns the height of the given element. If the element has a height of 0 it searches
* recursively for the height of the next visible child (e.g. the next visible slide of a
* SliderPanel).
*
* @param element parent element
* @return height of the element of a visible child
*/
private int getHeightOfElementOrChildElements(Element element) {
if (this.offsetHeight > 0) {
return this.offsetHeight;
}
// current element has height? Return this height.
if (element.getOffsetHeight() != 0) {
return element.getOffsetHeight();
}
// current element is hidden? no height for this element.
if (element.getStyle().getVisibility().equals("hidden")
|| element.getStyle().getDisplay().equals("none")) {
return 0;
}
// search children for height
NodeList<Node> children = element.getChildNodes();
if (children.getLength() == 0) {
return 0;
}
int height = 0;
for (int i = 0; i < children.getLength(); i++) {
Node currentNode = children.getItem(i);
if (currentNode instanceof Element) {
height = getHeightOfElementOrChildElements((Element) currentNode);
}
if (height != 0) {
return height;
}
}
return 0;
}
/**
* Returns the top style
*
* @return the top style in px
*/
private int getStyleTop() {
Style style = getWidget().getElement().getStyle();
String top = style.getTop();
if (top.isEmpty()) {
return 0;
} else {
return Integer.parseInt(top.replace("px", ""));
}
}
/**
* Sets the top stype in pixel
*
* @param top the top syle
*/
private void setStyleTop(int top) {
Style style = getWidget().getElement().getStyle();
style.setTop(top, Unit.PX);
}
}