英文:
Unable to receive precise pen input in a QQuickWindow
问题
我找不到在QML中处理触笔输入的方法，所以我子类化了QQuickWindow，并将其设置为我的QML应用程序的根窗口：
#ifndef TABLETWINDOW_H
#define TABLETWINDOW_H
#include <QObject>
#include <QQuickWindow>
class TabletWindow : public QQuickWindow
{
Q_OBJECT
public:
TabletWindow();
void tabletEvent(QTabletEvent* event) override{
qDebug() << event->posF();
}
#endif // TABLETWINDOW_H
调试输出显示触笔事件的位置没有双精度（例如，QPoint(200, 300)）。然后，我使用QMainWindow和Qt小部件进行了相同的测试：
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
MainWindow(){}
void tabletEvent(QTabletEvent* event){
qDebug() << event->posF();
}
};
使用小部件方法时，事件具有双精度（因此更精确）。我对此感到有些困惑，因为我以为QQuickWindow和QMainWindow都是子类化QWindow，因此它们的虚拟函数签名之间不应该有太大的区别。我在Windows 10上使用Qt 5.12进行了测试。
英文:
I found no way to handle stylus input in QML so I subclass a QQuickWindow and set it as my root window in my QML app:
#ifndef TABLETWINDOW_H
#define TABLETWINDOW_H
#include <QObject>
#include <QQuickWindow>
class TabletWindow : public QQuickWindow
{
Q_OBJECT
public:
TabletWindow();
void tabletEvent(QTabletEvent* event) override{
qDebug() << event->posF();
}
#endif // TABLETWINDOW_H
The debug output shows that the positions of the tablet events have no double precision (e.g QPoint(200,300). Then I tested the same thing using QMainWindow and Qt widgets:
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
MainWindow(){}
void tabletEvent(QTabletEvent* event){
qDebug() << event->posF();
}
};
With the widgets approach the event do have double precision (and hence are much more precise). I am a bit confused by this since I thought QQuickWindow and QMainWindow both subclass QWindow and hence there shouldn't be much difference between their virtual function signatures.
I have tested this on Windows 10 with Qt 5.12
答案1
得分: 1
在调查后，我注意到使用 QTabletEvent::highResGlobalX 和 QTabletEvent::highResGlobalY 可以获得双精度的坐标。这非常奇怪和让人讨厌，因为我不得不使用 QWindow::mapFromGlobal，而该函数只对 QPoint 进行操作，所以我必须获取坐标的整数部分（使用 std::modf），然后构建一个 QPoint 并创建一个新的 QPointF，将坐标的小数部分相加。
英文:
After investigating this, I notice that using QTabletEvent::highResGlobalX and QTabletEvent::highResGlobalY I get the coordinates with double precision. This is very strange and annoying since I had to use QWindow::mapFromGlobal, which only operates on QPoint, so I had to get the integer parts of the coordinates (using std::modf) and then construct pass a QPoint and create a new QPointF with the addition of the fractional parts of the coordinates.
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