package pl.djvuhtml5.client.ui;
import static pl.djvuhtml5.client.TileRenderer.MAX_SUBSAMPLE;
import static pl.djvuhtml5.client.TileRenderer.toSubsample;
import static pl.djvuhtml5.client.TileRenderer.toZoom;
import java.util.ArrayList;
import com.google.gwt.canvas.client.Canvas;
import com.google.gwt.canvas.dom.client.Context2d;
import com.google.gwt.dom.client.CanvasElement;
import com.google.gwt.dom.client.Element;
import com.google.gwt.event.dom.client.DomEvent;
import com.google.gwt.event.dom.client.KeyCodes;
import com.google.gwt.event.dom.client.KeyDownEvent;
import com.google.gwt.event.dom.client.KeyDownHandler;
import com.google.gwt.event.dom.client.MouseDownEvent;
import com.google.gwt.event.dom.client.MouseWheelEvent;
import com.google.gwt.event.dom.client.MouseWheelHandler;
import com.google.gwt.event.dom.client.TouchStartEvent;
import com.google.gwt.http.client.UrlBuilder;
import com.google.gwt.user.client.Timer;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.ui.Widget;
import com.lizardtech.djvu.DjVuInfo;
import com.lizardtech.djvu.GRect;
import pl.djvuhtml5.client.DataStore;
import pl.djvuhtml5.client.DjvuContext;
import pl.djvuhtml5.client.Djvu_html5;
import pl.djvuhtml5.client.ui.Scrollbar.ScrollPanListener;
public class SinglePageLayout {
interface ChangeListener {
void pageChanged(int currentPage);
void zoomChanged(int currentZoom);
}
private final Djvu_html5 app;
private double zoom = 0;
private double zoom100;
private int page;
private final DataStore dataStore;
private DjVuInfo pageInfo;
/**
* Location of the center of the screen in the coordinates of the scaled
* page (one point is one pixel on the screen).
*/
private int centerX, centerY;
private final Canvas canvas;
private ChangeListener changeListener;
private String background;
private final int pageMargin;
private CanvasElement[][] imagesArray;
private GRect range = new GRect();
private final boolean locationUpdateEnabled;
private Timer locationUpdater;
private boolean enableScrollPageJump = true;
public SinglePageLayout(Djvu_html5 app) {
this.app = app;
this.dataStore = app.getDataStore();
this.canvas = app.getCanvas();
this.background = DjvuContext.getBackground();
this.pageMargin = DjvuContext.getPageMargin();
new PanController(app.getTextLayer());
boolean pageParam = false;
try {
page = Integer.parseInt(Window.Location.getParameter("p")) - 1;
pageParam = true;
} catch (Exception e) {
page = 0;
}
locationUpdateEnabled = pageParam || DjvuContext.getLocationUpdateEnabled();
DjvuContext.setPage(page);
dataStore.addPageCountListener(pageCount -> {
app.getToolbar().setPageCount(pageCount);
int newPage = Math.max(0, Math.min(pageCount - 1, page));
setPage(newPage);
});
dataStore.addInfoListener(pageNum -> {
if (pageNum == page)
setPage(pageNum);
});
dataStore.addTileListener(pageNum -> {
if (pageNum == page)
redraw();
});
}
public void setPage(int pageNum) {
page = pageNum;
DjVuInfo newInfo = app.getDataStore().getPageInfo(pageNum);
if (newInfo != null) {
pageInfo = newInfo;
app.getToolbar().setZoomOptions(findZoomOptions());
} else {
pageInfo = null;
}
viewChanged();
DjvuContext.setPage(pageNum);
if (changeListener != null)
changeListener.pageChanged(pageNum);
scheduleURLUpdate();
}
private void scheduleURLUpdate() {
if (!locationUpdateEnabled)
return;
if (locationUpdater == null) {
locationUpdater = new Timer() {
@Override
public void run() {
UrlBuilder url = Window.Location.createUrlBuilder();
if (page > 0) {
url.setParameter("p", Integer.toString(page + 1));
} else {
url.removeParameter("p");
}
updateURLWithoutReloading(url.buildString());
}
private native void updateURLWithoutReloading(String newUrl) /*-{
$wnd.history.replaceState(newUrl, "", newUrl);
}-*/;
};
}
locationUpdater.cancel();
locationUpdater.schedule(500);
}
public int getPage() {
return page;
}
public void canvasResized() {
viewChanged();
}
public void zoomToFitPage() {
if (pageInfo == null)
return;
doSetZoom(Math.min((1.0f * canvas.getCoordinateSpaceWidth() - pageMargin * 2) / pageInfo.width,
(1.0f * canvas.getCoordinateSpaceHeight() - pageMargin * 2) / pageInfo.height));
}
public void zoomToFitWidth() {
if (pageInfo == null)
return;
doSetZoom((1.0f * canvas.getCoordinateSpaceWidth() - pageMargin * 2) / pageInfo.width);
}
public void setZoom(int percent) {
if (pageInfo == null)
return;
doSetZoom(percent * zoom100 / 100);
}
public int getZoom() {
return (int) (zoom / zoom100 * 100 + 0.5);
}
public double getPreciseZoom() {
return zoom;
}
private void doSetZoom(double zoom) {
if (this.zoom == zoom)
return;
centerX *= zoom / this.zoom;
centerY *= zoom / this.zoom;
this.zoom = zoom;
viewChanged();
if (changeListener != null)
changeListener.zoomChanged(getZoom());
}
private ArrayList<Integer> findZoomOptions() {
ArrayList<Integer> result = new ArrayList<>();
result.add(100);
final int screenDPI = DjvuContext.getScreenDPI();
zoom100 = 1.0 * screenDPI / pageInfo.dpi;
int subsample = toSubsample(zoom100);
if (toZoom(subsample) / zoom100 > zoom100 / toZoom(subsample + 1))
subsample++;
zoom100 = toZoom(subsample);
if (zoom == 0)
zoom = zoom100;
double z = zoom100;
for (int i = subsample + 1; i <= MAX_SUBSAMPLE; i++) {
double z2 = toZoom(i);
if (z / z2 > 1.2) {
z = z2;
result.add((int) (z / zoom100 * 100 + 0.5));
}
}
z = zoom100;
for (int i = subsample - 1; i >= 1; i--) {
double z2 = toZoom(i);
if (z2 / z > 1.2) {
z = z2;
result.add(0, (int) (z / zoom100 * 100 + 0.5));
}
}
return result;
}
private void viewChanged() {
if (pageInfo == null) {
redraw();
return;
}
int w = canvas.getCoordinateSpaceWidth(), h = canvas.getCoordinateSpaceHeight();
int pw = (int) (pageInfo.width * zoom), ph = (int) (pageInfo.height * zoom);
if (pw < w) {
centerX = pw / 2;
} else {
centerX = Math.max(centerX, w / 2 - pageMargin);
centerX = Math.min(centerX, pw - w / 2 + pageMargin);
}
if (ph < h) {
centerY = ph / 2;
} else {
centerY = Math.max(centerY, h / 2 - pageMargin);
centerY = Math.min(centerY, ph - h / 2 + pageMargin);
}
double pw2 = pw + 2 * pageMargin, ph2 = ph + 2 * pageMargin;
app.getHorizontalScrollbar().setThumb((centerX + pageMargin) / pw2, w / pw2);
app.getVerticalScrollbar().setThumb((centerY + pageMargin) / ph2, h / ph2);
if (app.getTextLayer() != null)
app.getTextLayer().setViewPosition(page, w / 2 - centerX, h / 2 - centerY, zoom);
redraw();
}
private void changePage(int targetPage, int horizontalPosition, int verticalPosition) {
if (targetPage >= 0 && targetPage < dataStore.getPageCount()) {
if (horizontalPosition < 0)
centerX = 0;
else if (horizontalPosition > 0)
centerX = Integer.MAX_VALUE;
if (verticalPosition < 0)
centerY = 0;
else if (verticalPosition > 0)
centerY = Integer.MAX_VALUE;
setPage(targetPage);
}
}
/**
* @param left position of page's left edge on the canvas
* @param top position of page's top edge on the canvas
*/
public void externalScroll(int page, int left, int top) {
int w = canvas.getCoordinateSpaceWidth(), h = canvas.getCoordinateSpaceHeight();
if (page == this.page && centerX == w / 2 - left && centerY == h / 2 - top)
return;
int oldX = centerX, oldY = centerY;
int newX = w / 2 - left;
int newY = h / 2 - top;
centerX = newX;
centerY = newY;
if (page != this.page) {
setPage(page);
} else {
viewChanged();
if (oldX == centerX && oldY == centerY && enableScrollPageJump) {
if (newY < oldY) {
changePage(page - 1, 0, 1);
} else if (newY > oldY) {
changePage(page + 1, 0, -1);
} else if (newX < oldX) {
changePage(page - 1, 1, 0);
} else if (newX > oldX) {
changePage(page + 1, -1, 0);
}
}
}
}
public void setChangeListener(ChangeListener changeListener) {
this.changeListener = changeListener;
}
public void redraw() {
Context2d graphics2d = canvas.getContext2d();
int w = canvas.getCoordinateSpaceWidth(), h = canvas.getCoordinateSpaceHeight();
graphics2d.setFillStyle(background);
graphics2d.fillRect(0, 0, w, h);
if (pageInfo == null)
return;
int subsample = toSubsample(zoom);
double scale = zoom / toZoom(subsample);
graphics2d.save();
int startX = w / 2 - centerX, startY = h / 2 - centerY;
graphics2d.translate(startX, startY);
graphics2d.scale(scale, scale);
graphics2d.translate(-startX, -startY);
graphics2d.scale(1, -1); // DjVu images have y-axis inverted
int tileSize = DjvuContext.getTileSize();
int pw = (int) (pageInfo.width * zoom), ph = (int) (pageInfo.height * zoom);
range.xmin = (int) (Math.max(0, centerX - w * 0.5) / tileSize / scale);
range.xmax = (int) Math.ceil(Math.min(pw, centerX + w * 0.5) / tileSize / scale);
range.ymin = (int) (Math.max(0, centerY - h * 0.5) / tileSize / scale);
range.ymax = (int) Math.ceil(Math.min(ph, centerY + h * 0.5) / tileSize / scale);
imagesArray = dataStore.getTileImages(page, subsample, range , imagesArray);
for (int y = range.ymin; y <= range.ymax; y++) {
for (int x = range.xmin; x <= range.xmax; x++) {
CanvasElement canvasElement = imagesArray[y - range.ymin][x - range.xmin];
for (int repeats = scale == 1 ? 1 : 3; repeats > 0; repeats--) {
graphics2d.drawImage(canvasElement, startX + x * tileSize,
-startY - y * tileSize - canvasElement.getHeight());
}
}
}
graphics2d.restore();
// missing tile graphics may exceed the page boundary
graphics2d.fillRect(startX + pw, 0, w, h);
graphics2d.fillRect(0, startY + ph, w, h);
DjvuContext.setTileRange(range, subsample);
}
private class PanController extends PanListener implements MouseWheelHandler, KeyDownHandler, ScrollPanListener {
private static final int KEY_PLUS = 187;
private static final int KEY_MINUS = 189;
public PanController(Widget widget) {
super(widget);
widget.addDomHandler(this, MouseWheelEvent.getType());
widget.addDomHandler(this, KeyDownEvent.getType());
app.getHorizontalScrollbar().addScrollPanListener(this);
app.getVerticalScrollbar().addScrollPanListener(this);
}
@Override
public void onMouseDown(MouseDownEvent event) {
widget.getElement().focus();
if (!isOnText(event))
super.onMouseDown(event);
}
@Override
public void onTouchStart(TouchStartEvent event) {
if (isOnText(event)) {
enableScrollPageJump = false;
} else {
widget.getElement().focus();
super.onTouchStart(event);
}
}
@Override
public void onKeyDown(KeyDownEvent event) {
int key = event.getNativeKeyCode();
if (event.isControlKeyDown()) {
if (key == KEY_PLUS || key == KEY_MINUS) {
app.getToolbar().zoomChangeClicked(key == KEY_PLUS ? 1 : -1);
event.preventDefault();
}
} else if (!event.isShiftKeyDown()) {
boolean handled = true;
switch (key) {
case KeyCodes.KEY_HOME:
changePage(0, -1, -1);
break;
case KeyCodes.KEY_END:
changePage(dataStore.getPageCount() - 1, 1, 1);
break;
default:
handled = false;
}
if (handled)
event.preventDefault();
}
}
@Override
public void onMouseWheel(MouseWheelEvent event) {
if (event.isControlKeyDown()) {
int delta = event.getDeltaY();
app.getToolbar().zoomChangeClicked(Integer.signum(-delta));
event.preventDefault();
}
}
@Override
public void thumbDragged(double newCenter, boolean isHorizontal) {
if (pageInfo == null)
return;
if (isHorizontal) {
double pw2 = pageInfo.width * zoom + 2 * pageMargin;
tryPan((int) (newCenter * pw2 - pageMargin + 0.5) - centerX, 0);
} else {
double ph2 = pageInfo.height * zoom + 2 * pageMargin;
tryPan(0, (int) (newCenter * ph2 - pageMargin + 0.5) - centerY);
}
}
@Override
protected void pan(int dx, int dy) {
tryPan(-dx, -dy);
}
private boolean isOnText(DomEvent<?> event) {
return "SPAN".equals(Element.as(event.getNativeEvent().getEventTarget()).getNodeName());
}
private boolean tryPan(int dx, int dy) {
int oldX = centerX;
int oldY = centerY;
centerX += dx;
centerY += dy;
viewChanged(); // applies constraints to x,y
if (centerX != oldX || centerY != oldY) {
redraw();
return true;
}
return false;
}
}
}
