如何确定QTableWidget的正确大小？ [英] How to determine the correct size of a QTableWidget?

问题描述

有没有任何方式设置QTableWidget的正确大小？ （我是新手）这个测试代码只有25行，在两个文件中，有文件Test.h：

  #include< QtGui> 
 class Test：public QMainWindow {
 Q_OBJECT 
 public：
 Test（）; 
}; 
  

和文件Test.cpp：

  #includeTest.h
 Test :: Test（）：QMainWindow（）{
 QVBoxLayout * vbox = new QVBoxLayout; 
 QPushButton * btn = new QPushButton（Hello World etc etc etc etc etc）; 
 QTableWidget * tbl = new QTableWidget（2，2）; 
 vbox-> addWidget（btn）; 
 vBox-> addWidget（tbl）; 
 QWidget * w = new QWidget; 
 setCentralWidget（w）; 
 w-> setLayout（vbox）; 
 resize（1,1）; 
} 
 
 int main（int argc，char * argv []）{
 QApplication app（argc，argv）; 
测试测试; 
 test.show（）; 
 app.exec（）; 
} 
  

然后执行命令：

  qmake-project&&& qmake&&制作&& ./Test 
  

提供窗口：

但我们想要的是更像：

使用 tbl-> width（）似乎没有用，因为它默认为 test.show（）之前的<640 ，以及 195 后的不需要的值。我看过Qt大小提示和政策，直到我的头旋转，我试过 setResizeMode（QHeaderView :: Fixed）和 setStretchLastSection false）。也许我缺少一些明显的东西？这是在CentOS 5上Qt 4.7.4，如果这很重要。

：为了回应DK，如果 resize（1,1）; 不存在，有等于和相反问题：窗口太大。

并且响应Donotalo，添加：

  tbl- ; setMaximumWidth（222）; 
 tbl-> setMinimumWidth（222）; 
 tbl-> setMaximumHeight（88）; 
 tbl-> setMinimumHeight（88）; 
  

会提供所需的窗口大小（至少在我的机器上），但 em>以所需的方式。我们应该如何计算常数 222 和 88？

以及Ton对之前的布局中的窗口小部件的大小。

：

这是我的最终版本 - 但我不是很高兴。

adjustSize（）和 layout（） - > invalidate（）和 Qt :: WA_DontShowOnScreen p>

博客将Qt小部件缩小到最小所需大小很有趣，但使用 setSizeConstraint（）

setSizeConstraint（）和 move（）

在我的测试中有一个奇怪的事情，在CentOS 5上使用Qt 4.6.3和4.7 .4。对于 hide（）; show（）; 序列，保存/恢复窗口位置。但是大约25％的时间（图案化是不规则的），恢复的位置将在屏幕上高出24像素，可能是窗口标题的高度。大约10％的时间， pos（）返回的值将是 null 。 Qt网站表示，对于X11，它需要<$ c

> $ c> nfty启发式和聪明的代码

Is there any way to set the "correct" size of a QTableWidget? (I'm a newbie) This test code is only 25 lines long, in two files, with the file Test.h:

#include <QtGui>
class Test : public QMainWindow {
   Q_OBJECT
public:
   Test();
};

and the file Test.cpp:

#include "Test.h"
Test::Test() : QMainWindow() {
   QVBoxLayout *vbox = new QVBoxLayout;
   QPushButton  *btn = new QPushButton("Hello World etc etc etc etc etc");
   QTableWidget *tbl = new QTableWidget(2, 2);
   vbox->addWidget(btn);
   vbox->addWidget(tbl);
   QWidget *w = new QWidget;
   setCentralWidget(w);
   w->setLayout(vbox);
   resize(1, 1);
}

int main(int argc, char *argv[]) {
   QApplication app(argc, argv);
   Test test;
   test.show();
   app.exec();
}

Then the command:

   qmake -project && qmake && make && ./Test

gives the window:

But what we want of course is something more like:

Using tbl->width() seems to be useless, as it gives a default of 640 before test.show(), and the unwanted value of 195 after. I've looked at the Qt Size Hints and Policies until my head spun, and I've tried setResizeMode(QHeaderView::Fixed) and setStretchLastSection(false). Maybe I'm missing something obvious? This is with Qt 4.7.4 on CentOS 5, if this matters. Thank you for any help.

Edit: In response to DK, if the line resize(1, 1); is not present, there is the equal and opposite problem: the window is too large.

And in response to Donotalo, adding:

tbl->setMaximumWidth(222);
tbl->setMinimumWidth(222);
tbl->setMaximumHeight(88);
tbl->setMinimumHeight(88); 

will give the desired window size (at least on my machine), but not in the desired way. How should we calculate the 'constants' 222 and 88?

And Ton's answer to Qt: How to force a hidden widget to calculate its layout? doesn't seem to work here: the addition of tbl->setAttribute(Qt::WA_DontShowOnScreen); tbl->show(); left the value of tbl->width() unchanged at 640.

解决方案

The thread How to set a precise size of QTableWidget to prevent from having scroll bars? (Qt-interest Archive, June 2007) between Lingfa Yang and Susan Macchia seems to resolve my question. I will post more details shortly, if my testing works.

Update #1: My test now generates the nice-looking window:

The complete test code for this, with Test.h unchanged, is:

#include "Test.h"

static QSize myGetQTableWidgetSize(QTableWidget *t) {
   int w = t->verticalHeader()->width() + 4; // +4 seems to be needed
   for (int i = 0; i < t->columnCount(); i++)
      w += t->columnWidth(i); // seems to include gridline (on my machine)
   int h = t->horizontalHeader()->height() + 4;
   for (int i = 0; i < t->rowCount(); i++)
      h += t->rowHeight(i);
   return QSize(w, h);
}

static void myRedoGeometry(QWidget *w) {
   const bool vis = w->isVisible();
   const QPoint pos = w->pos();
   w->hide();
   w->show();
   w->setVisible(vis);
   if (vis && !pos.isNull())
      w->move(pos);
}

Test::Test() : QMainWindow() {
   QVBoxLayout *vbox = new QVBoxLayout;
   QPushButton *btn  = new QPushButton("Hello World etc etc etc etc etc");
   QTableWidget *tbl = new QTableWidget(2, 2);
   vbox->addWidget(btn);
   vbox->addWidget(tbl);
   setCentralWidget(new QWidget);
   centralWidget()->setLayout(vbox);
   layout()->setSizeConstraint(QLayout::SetMinimumSize); // or SetFixedSize

   tbl->setVerticalHeaderItem(1, new QTableWidgetItem("two")); // change size
   myRedoGeometry(this);
   tbl->setMaximumSize(myGetQTableWidgetSize(tbl));
   tbl->setMinimumSize(tbl->maximumSize()); // optional
}

int main(int argc, char *argv[]) {
   QApplication app(argc, argv);
   Test test;
   test.show();
   app.exec();
}

Some notes:

• The above thread's inclusion of verticalScrollBar()->width() seems to be wrong. And, in my testing, this was always either a default value of 100, or the value 15, if the scrollbar had been displayed.

• Applying the show(); hide(); sequence just to the QTableWidget was not sufficient to force Qt to recalculate the geometry, in this test. I needed to apply it to the whole window.

• Any suggestions for improvements would be welome. (I'll wait a bit before accepting my own answer, in case there are better solutions.)

Update #2:

• The Qt-interest thread may be wrong (or, at least, it disagrees with my version of Qt running my machine) regarding details on how to calculate the size: the +1 for each gridline is unnecessary, but an overall +4 is needed.

• I'm still working through layout()->invalidate() vs. e.g. QT: How to preview sizes of widgets in layout BEFORE a show().

Update #3:

• This is my final version--but I'm not very happy with it. Any improvements would be very welcome.

• Things like adjustSize() and layout()->invalidate() and Qt::WA_DontShowOnScreen don't seem to help.

• The blog Shrinking Qt widgets to minimum needed size is interesting, but using setSizeConstraint() is just as good.

• The setSizeConstraint() and move() methods are needed for subsequent changes to the table, not shown here.

• There was an odd thing in my testing, done on CentOS 5 with Qt 4.6.3 and 4.7.4. For the hide(); show(); sequence, the window position is saved/restored. But about 25% of the time (the patterning was irregular) the restored position would be 24 pixels higher on the screen, presumably the height of the window title. And about 10% of the time the value returned by pos() would be null. The Qt site says for X11 it needs nifty heuristics and clever code for this, but something seems to be broken somewhere.

这篇关于如何确定QTableWidget的正确大小？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！