Wt

Hello,

I am developing an Windows application with WT, using the WPaintedWidget and server-initiated updates. It works fine with Windows + Linux Browsers. But with an iPad i have the problem, that the application responds on a mouse click not directly. If I click on the iPad (touch it with my finger), i get no response. If I click again, I get the response of the first click. The third click, sends the response of the second click ... and so on.

The WT-application is part of a 3-tier application (server-application - WT-application - browser) and works in the following way:

1) Create the WPaintedWidget and bind an handler for mouse click.

2) Create an socket connection to the server-applikation.

3) If the mouse handler gets an click, send it via the socket to the server-application

4) Create an thread, which reads input from the server-application via the socket.

5) If the server-application sends data, read it in the thread and paint it in the WPaintedWidget with server-initiated updates.

The application is a bit complex. So I have reduced it to a small example, that reproduces the problem. The sending of data to the other application is simulated with a Windows-Event object. The thread waits for the events and the mouse handler signals the event. The data is the position of the click and the response is the drawing of a rectangle on this position. On Firefox/Chrome under Windows/Linux the rectangle will be painted on the position where I clicked (this is OK). With Safari on the iPad the rectangle will be painted on the position where I clicked before this click (this is the problem).

Here is the code of the example:

#include "stdafx.h"

#include <Wt/WApplication>
#include <Wt/WEnvironment>
#include <Wt/WText>
#include <Wt/WPainter>
#include <Wt/WPaintedWidget>
#include <Wt/WContainerWidget>
using namespace Wt;

#include <process.h>

class HtmlCanvas : public WPaintedWidget
{
private:
    int cnt;
    int x, y;

public:
    HtmlCanvas(WContainerWidget *parent = 0);
    void changeContent(int nx, int ny);

protected:
    virtual void paintEvent(WPaintDevice *paintDevice);
};

HtmlCanvas::HtmlCanvas(WContainerWidget *parent)
  : WPaintedWidget(parent)
{
    cnt = 0; x = 10; y = 10;
    resize(300, 400);
}

void HtmlCanvas::changeContent(int px, int py) {
    x = px;
    y = py;
}

void HtmlCanvas::paintEvent(WPaintDevice *paintDevice) {
    wchar_t buff[20];

    _swprintf(buff, _T("%d"), cnt);
    cnt++;
    WPainter painter(paintDevice);
    painter.drawRect(0.0, 0.0, 300, 400);
    painter.setBrush(WBrush(WColor(200, 200, 200)));
    painter.drawRect(x, y, 100, 30);
    painter.drawText(x+5, y+5, 100-10, 30-10, AlignCenter, WString(buff));  
}

class SimpleApplication : public WApplication {

public:
    HANDLE m_signalData;
    HtmlCanvas* m_htmlCanvas;

    SimpleApplication (const WEnvironment& env);
    void HtmlCanvasMouseUp(const Wt::WMouseEvent& e);
};

SimpleApplication::SimpleApplication (const WEnvironment& env)
  : WApplication(env) {

    enableUpdates(true);

    setTitle("SimpleWt");

    root()->addWidget(new WText("<h1>SimpleWt</h1>"));

    m_htmlCanvas = new HtmlCanvas(root());
    m_htmlCanvas->setPreferredMethod(WPaintedWidget::HtmlCanvas);
    m_htmlCanvas->setOffsets(WLength(0), WFlags<Side>(Top));
    m_htmlCanvas->setOffsets(WLength(0), WFlags<Side>(Left));

    m_htmlCanvas->mouseWentUp().connect(this, &SimpleApplication::HtmlCanvasMouseUp);
    m_signalData = CreateEvent(NULL, FALSE, FALSE, NULL);
}

void SimpleApplication::HtmlCanvasMouseUp(const Wt::WMouseEvent& e) {
    m_htmlCanvas->changeContent(e.widget().x, e.widget().y);
    SetEvent(m_signalData);
} 

static void StartThread(void* p) {
    SimpleApplication* simpleApplication = (SimpleApplication*)p;
    for(;;) {
        WaitForSingleObject(simpleApplication->m_signalData , INFINITE);

        WApplication* wAp = simpleApplication;
        Wt::WApplication::UpdateLock lock(wAp);
        if (lock) {
            WFlags<PaintFlag> fl(PaintUpdate);

            simpleApplication->m_htmlCanvas->update(fl);
            wAp->triggerUpdate();
        }
    }
}

WApplication* createWTApp(const WEnvironment& env) {
    SimpleApplication* simpleApplication = new SimpleApplication (env);
    _beginthread(StartThread, 0, (LPVOID)simpleApplication);
    return simpleApplication;
}


int APIENTRY _tWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPTSTR lpCmdLine, int nCmdShow) {
    char *argv[] = { "SimpleWt.exe", "--http-address=0.0.0.0", "--http-port=8080", "--deploy-path=/simpleWt", "--docroot=."};

    WRun(5, argv, &createWTApp);
}

I used the following environment:

• Visual Studio 2008
• WT 3.2.1
• boost-1.46.1
• Windows XP Service Pack 3
• iPad2 Version 5.1(9B176)

The problem only occurs with the http-connector. With the ISAPI-connector the response will be send directly on the iPad too. I have not tried the fastCGI connector, because it is not available on windows.

I have added the Visual Studio Project of the example as attachment.

Thank you for solving the problem.

Herbert Zenz

Nonne & Schneider Informationssysteme GmbH

hrz@nsi.de