第11章 GUI Page421~422 步骤六 支持文字

运行效果：

关键代码：

新增头文件：

//item_text.hpp
#ifndef ITEM_TEXT_HPP_INCLUDED
#define ITEM_TEXT_HPP_INCLUDED
#include "item_i.hpp"

class TextItem : public IItem
{
public:
    TextItem()
        : _startPosition(0, 0), _endPosition(0, 0)
    {
        _text = wxT("hello d2schol");
    }

    void Draw(wxDC& dc) const;

    void OnDrawStart(wxPoint const& point) override
    {
        _startPosition = point;
    }

    void OnDrawEnd(wxPoint const& point) override
    {
        _endPosition = point;
    }

private:
    wxPoint _startPosition, _endPosition;
    wxString _text;
};


#endif // ITEM_TEXT_HPP_INCLUDED

新增源文件

//item_text.cpp
#include "item_text.hpp"
#include <cmath>
#include <wx/font.h>

void TextItem::Draw(wxDC& dc) const
{
    if(_text.IsEmpty()) //空串，直接返回
    {
        return; //直接返回，动作干脆利落还可以防止后面发生除零错
    }

    int w = std::abs(_endPosition.x - _startPosition.x) / _text.Length();
    int h = std::abs(_endPosition.y - _startPosition.y);

    if(w == 0 || h == 0)
    {
        return;
    }

    wxFont old_font = dc.GetFont();
    wxFont font(wxSize(w, h)
                , wxFONTFAMILY_DEFAULT
                , wxFONTSTYLE_NORMAL
                , wxFONTWEIGHT_NORMAL);

    int x = std::min(_startPosition.x, _endPosition.x);
    int y = std::min(_startPosition.y, _endPosition.y);

    dc.SetFont(font);
    dc.DrawText(_text, x, y);
    dc.SetFont(old_font);
}

新增加宏：