Qt's Custom layout manager (Qcardlayout)

Briefly

Manual layout The other way is to write your own layout manager by inheriting the Qlayout class.

Let's give an example-qcardlayout in detail below. It is inspired by the Java layout manager with the same name. Also known as the card layout, each item is offset by qlayout::spacing ().

• Briefly
• Defined
• Realize
  • Effect
  • Source

Defined

To write your own layout, you must define the following:

• A data structure that stores layout-processing items, each of which is a qlayoutitem, and this example uses Qlist.

• AddItem () How to add a project layout.

• Setgeometry () How to control the layout.

• The preferred size of the sizehint () layout.

• Itemat () How to traverse the layout.

• Takeat () How to delete items in a layout.

In most cases, the minimumsize () will also be implemented.

Achieve results

Source

QCardLayoud.h

#ifndef Qcardlayout_h#define QCARDLAYOUT_H#include <QWidget>#include <QLayout>#include <QLayoutItem> class qcardlayout :  public qlayout{ Public: Qcardlayout (Qwidget *parent =0); ~qcardlayout ();voidAddItem (Qlayoutitem *item); Qsize Sizehint ()Const; Qsize MinimumSize ()Const;intCount ()Const; Qlayoutitem *itemat (int)Const; Qlayoutitem *takeat (int);voidSetgeometry (ConstQrect &rect);Private: Qlist<qlayoutitem*> list;};#endif//qcardlayout_h

QCardLayoud.cpp

#include "QCardLayout.h"Qcardlayout::qcardlayout (Qwidget *parent): qlayout (parent) {}//Because Qlayoutitem does not inherit from Qobject, it must be deleted manually. In the destructor, use Takeat () to delete each item in the list and then delete it. Qcardlayout::~qcardlayout () {Qlayoutitem *item; while(item = Takeat (0)))DeleteItem;}//Gets the number of items in the listintQcardlayout::count ()Const{return List. Size ();}//Get index of the item corresponding to IDXQlayoutitem *qcardlayout::itemat (intIdxConst{return List. value (idx);}//Remove the item corresponding to the index IDX and returnQlayoutitem *qcardlayout::takeat (intIDX) {returnIDX >=0&& IDX <List. Size ()?List. Takeat (IDX):0;}//Add ItemvoidQcardlayout::additem (Qlayoutitem *item) {List. append (item);}//The layout is actually controlled, and the rectangle provided as a parameter does not include margin (). Related, use spacing () as the distance between items. voidQcardlayout::setgeometry (ConstQrect &r) {qlayout::setgeometry (R);if(List. Size () = =0)return;intW = r.width ()-(List. Count ()-1) * spacing ();inth = r.height ()-(List. Count ()-1) * spacing ();inti =0; while(I <List. Size ()) {Qlayoutitem *o =List. at (i);        Qrect Geom (r.x () + i * spacing (), r.y () + i * spacing (), W, h);        O->setgeometry (GEOM);    ++i; }}//Sizehint () and minimumsize () are usually very similar. The dimensions returned by these two functions should include spacing (), but not margin (). Qsize Qcardlayout::sizehint ()Const{qsize S (0,0);intn =List. Count ();if(N >0) s = qsize ( -, -);inti =0; while(I < N) {Qlayoutitem *o =List. at (i);        s = s.expandedto (O->sizehint ());    ++i; }returnS + n*qsize (spacing (), spacing ());} Qsize qcardlayout::minimumsize ()Const{qsize S (0,0);intn =List. Count ();inti =0; while(I < N) {Qlayoutitem *o =List. at (i);        s = s.expandedto (O->minimumsize ());    ++i; }returnS + n*qsize (spacing (), spacing ());}

Qt's Custom layout manager (Qcardlayout)