multi-touch - Multitouch GTK3示例

Question

据我所知，GTK +从3.4版开始就添加了多点触摸支持。我还不清楚这是否仅适用于电话/平板电脑等触摸屏，还是适用于Apple风格的触摸板(Ubuntu/Unity和OS X在触摸板上使用多点触摸手势的方式)。

我也很难找到有关如何实现手势以及如何跟踪多点触摸事件的示例。

有没有很好的例子说明如何使用GTK(或类似Clutter的东西)实现多点触摸？

Answer 1

我也找不到示例，因此这是我的知识:

鼠标事件(简介):

使用鼠标时，Gdk传播事件GDK_BUTTON_PRESS，GDK_BUTTON_RELEASE(和一些other)。可以将其转换为GtkWidget信号(如button-press-event)，然后转换为更高级别的信号(如GtkButton的clicked)(如果适用)。将回调连接到button-press-event信号可以访问GdkEventButton structure。但是，使用clicked可以使您摆脱跟踪(单击和释放)还是仅释放(例如在动态滚动过程中)的跟踪。

触摸事件:

触摸效果略有不同。有4 touch events:

GDK_TOUCH_BEGIN
A new touch event sequence has just started. This event type was added in 3.4.

GDK_TOUCH_UPDATE
A touch event sequence has been updated. This event type was added in 3.4.

GDK_TOUCH_END
A touch event sequence has finished. This event type was added in 3.4.

GDK_TOUCH_CANCEL
A touch event sequence has been canceled. This event type was added in 3.4.

GdkEventTouch structure使用GdkEventSequence区分手指。在我看来，它只是一个值(无法在源代码中找到定义)，但在这里我可能会误会。 GtkWidget具有类似于button-press-event等的touch-event信号，该信号也被转换为诸如clicked的事件。

示例代码(使用gtkmm，但核心方面相同):

#include <gtkmm.h>
#include <iostream>

int main()
{
    auto app = Gtk::Application::create();
    Gtk::Window window;
    window.set_default_size(1024, 768);
    app->signal_startup().connect([&]
    {
        app->add_window(window);
    });

    window.show();

    //code works for me without adding events mask but let's be thorough
    window.add_events(Gdk::TOUCH_MASK);
    window.signal_touch_event().connect([&](GdkEventTouch* event)->bool
    {
        std::cout<<"TOUCH EVENT: ";
        switch(event->type)
        {
        case GDK_TOUCH_BEGIN:
            std::cout<<"begin ";
            break;
        case GDK_TOUCH_UPDATE:
            std::cout<<"update ";
            break;
        case GDK_TOUCH_END:
            std::cout<<"end ";
            break;
        case GDK_TOUCH_CANCEL:
            std::cout<<"cancel ";
            break;
        default:
            std::cout<<"something else ";
        }
        std::cout<<event->sequence<<" "
                 <<gdk_event_get_event_sequence((GdkEvent*)event)<<" "
                 <<std::endl;
        return GDK_EVENT_PROPAGATE;
    });
    window.signal_event().connect([&](GdkEvent* event)->bool
    {
        std::cout<<"EVENT: "<<event->type<<std::endl;
        return GDK_EVENT_PROPAGATE;
    });

    app->run();
    return 0;
}

触摸板事件:

也有touchpad & pad events和structures，但似乎在Gtk级别上没有显式处理。必须在event信号的回调中通过检查GdkEventType并将其转换为适当的结构来完成。