c – 以编程方式调用Snap / Aero最大化

>如何接收和处理最大化事件？
>如何创建近似的航空按扣效果？

为了回答第一个问题,我们必须分析窗口最大化时触发的event handlers：

void resizeEvent(QResizeEvent* evt);   // Invoked first,void paintEvent(QPaintEvent* event);   // then second,void changeEvent(QEvent* evt);         // and at last.

首先通知Qt应用程序resizeEvent(),然后使用paintEvent()绘制窗口(或窗口小部件),并且只有在显示所有内容之后,才会调用changeEvent()以告知窗口小部件已最大化(也许接收这样的通知有点晚了,我不知道).

在所有这些中,我们唯一关心的是resizeEvent().此事件处理程序通知可用于与桌面大小进行比较的新窗口/窗口小部件大小,从而允许我们知道事件是否实际上是最大化请求.一旦我们确定了最大化请求,我们就可以确定应用程序是否应该最大化(并锚定)到屏幕的右侧,左侧或中心.

这将是创建aero snap小部件并将其作为用户视觉线索放置在屏幕上的时间.

要回答第二个问题,我认为无法调用本机Windows API并礼貌地请求它在您的窗口上执行此效果.唯一合乎逻辑的选择是编写一个自己近似于这种效果的代码.

可以通过绘制带阴影边框的透明窗口来复制视觉外观.在下面的源代码中演示的方法,创建并自定义QWidget,使其行为和看起来像一个航空快照窗口：

我知道,这不是世界上最美丽的事物.此演示为用户创建一个常规窗口进行交互,一旦最大化,它就会将自己置于屏幕左侧.对于正确尺寸的屏幕,它会显示类似于航空快照窗口的内容(如上所示).

aero snap小部件背后的想法非常简单：具有透明背景和自定义绘制过程的QWidget.换句话说,它是一个透明的窗口,它绘制一个带阴影的圆角矩形,就是这样.

为了使它更逼真,你应该添加一些动画来逐渐调整小部件的大小. for循环可能会起作用,但如果你需要一些花哨的东西,你最终会使用定时器.如果你拿look here,你可以看到最快的&使用Qt执行动画的最脏的方法,以及处理动画的更好方法.但是,对于像这样的简单任务,请坚持使用frame-based animation.

main.cpp中：

#include "window.h"
#include <QApplication>

int main(int argc,char* argv[])
{
    QApplication app(argc,argv);
    Window window;
    window.show();

    return app.exec();
}

在window.h：

#pragma once
#include "snapwindow.h"
#include <QMainWindow>
#include <QEvent>

class Window : public QMainWindow
{    
public:
    Window();

    void resizeEvent(QResizeEvent* evt);
    //void paintEvent(QPaintEvent* event);
    void changeEvent(QEvent* evt);

private:
    SnapWindow* _sw;
};

window.cpp：

#include "window.h"
#include "snapwindow.h"

#include <QDebug>
#include <QWindowStateChangeEvent>
#include <QApplication>
#include <QDesktopWidget>

Window::Window()
{
    setWindowTitle("AeroSnap");
    resize(300,300);    

    _sw = new SnapWindow(this);
    _sw->hide();
}

void Window::changeEvent(QEvent* evt)
{
    if (evt->type() == QEvent::WindowStateChange)
    {
        QWindowStateChangeEvent* event = static_cast<QWindowStateChangeEvent*>(evt);

        if (event->oldState() == Qt::WindowNoState &&
                windowState() == Qt::WindowMaximized)
        {
            qDebug() << "changeEvent: window is now maximized!";
        }
    }
}

// resizeEvent is triggered before window_maximized event
void Window::resizeEvent(QResizeEvent* evt)
{
    qDebug() << "resizeEvent: request to resize window to: " << evt->size();

    QSize desktop_sz = QApplication::desktop()->size();
    //qDebug() << "resizeEvent: desktop sz " << desktop_sz.width() << "x" << desktop_sz.height();

    // Apparently,the maximum size a window can have in my system (1920x1080)
    // is actually 1920x990. I suspect this happens because the taskbar has 90px of height:
    desktop_sz.setHeight(desktop_sz.height() - 90);

    // If this not a request to maximize the window,don't do anything crazy.
    if (desktop_sz.width() != evt->size().width() ||
        desktop_sz.height() != evt->size().height())
        return;

    // Alright,now we known it's a maximize request:
    qDebug() << "resizeEvent: maximize this window to the left";

    // so we update the window geometry (i.e. size and position)
    // to what we think it's appropriate: half width to the left
    int new_width = evt->size().width();
    int new_height = evt->size().height();
    int x_offset = 10;
    setGeometry(x_offset,45,new_width/2,new_height-45); // y 45 and height -45 are due to the 90px problem

    /* Draw aero snap widget */

    _sw->setGeometry(new_width/2-x_offset,new_height);
    _sw->show();

    // paintEvent() will be called automatically after this method ends,// and will draw this window with the appropriate geometry.
}

snapwindow.h：

#pragma once
#include <QWidget>

class SnapWindow : public QWidget
{
public:
    SnapWindow(QWidget* parent = 0);

    void paintEvent(QPaintEvent *event);
};

snapwindow.cpp：

#include "snapwindow.h"
#include <QPainter>
#include <QGraphicsDropShadowEffect>

SnapWindow::SnapWindow(QWidget* parent)
: QWidget(parent)
{      
    // Set this widget as top-level (i.e. owned by user)
    setParent(0);

    /* Behold: the magic of creating transparent windows */

    setWindowFlags(Qt::Widget | Qt::FramelessWindowHint);
    setStyleSheet("background:transparent;");
    setAttribute(Qt::WA_NoSystemBackground,true); // speed up drawing by removing unnecessary background initialization
    setAttribute(Qt::WA_TranslucentBackground);
    //setAutoFillBackground(true);

    /* Use Qt tricks to paint stuff with shadows */

    QGraphicsDropShadowEffect* effect = new QGraphicsDropShadowEffect();
    effect->setBlurRadius(12);
    effect->setOffset(0);
    effect->setColor(QColor(0,255));
    setGraphicsEffect(effect);
}

void SnapWindow::paintEvent(QPaintEvent *event)
{
    QWidget::paintEvent(event);

    /* Lazy way of painting a shadow */

    QPainter painter(this);
    QPen pen(QColor(180,180,200));
    pen.setWidth(3);
    painter.setPen(pen);

    // Offset 6 and 9 pixels so the shadow shows up properly
    painter.drawRoundedRect(QRect(6,6,(width()-1)-9,(height()-1)-9),18,18);
}

这只是一个快速演示,可以指出您正确的方向.它绝不是您正在寻找的效果的完整实现.