The Nana Programmer's Guide

Nana C++ Library
open-source C++ framework project
The Programmer's Guide
                nana::gui::label

                Description

                A label widget can dispaly a text string and images.

                Model
                of

                Widget Window 

                Public base classes

                class widget_object<widget_tag>: public
                    widget

                Typedefs

                C++ 03

                            struct command

                            {

    enum t{enter, leave, click};

                            };
                        
                            Defines the event type for format listener.
                    
                C++11

                            enum class command{ enter, leave, click
                            };
                        
                            Ditto.
                    
                Members

                            label()
                        
                            The construction.
                    
                            label(window wd, bool visible)
                        
                            Creates a label.
                    
                            label(window wd, const nana::string& title, bool visible = true)
                        
                            Ditto.
                    
                            label(window wd, const nana::char_t* title, bool visible = true) 
                        
                            Ditto.
                    
                            label(window wd, const rectangle& r = rectangle(), bool visible = true)
                        
                            Ditto.
                    
                            void format(bool enter_format_mode)
                        
                            Switchs the format mode of the widget.
                    
                            void transparent(bool)
                        
                            Switchs the label widget to the transparent background mode.
                    
                            bool transparent() const
                        
                            True if the label is transparent background mode.
                    
                            nana::size measure(unsigned limited) const
                        
                            Return the size of the text. If the limited is not zero, it returns the size that the text changes lines when a line of text beyonds the width specified by limited
                    
                C++03

                            void add_format_listener(const nana::functor<void(command::t, const nana::string&)> & ) 
                        
                            Adds the format listener.
                    
                            void text_align(nana::align::t, nana::align_v::t = nana::align_v::top)
                        
                            Set the text alignment.
                    
                C++11

                            void add_format_listener(const std::function<void(command, const nana::string&)>&)
                        
                            Ditto.
                    
                            void add_format_listener(std::function<void(command, const nana::string&)> && )
                        
                            Ditto.
                    
                            void text_align(nana::align, nana::align_v = nana::align_v::top)
                        
                            Set the text alignment.
                    
                File

                nana/gui/widgets/label.hpp

                Notes

                1. It is not good efficient that the background mode of the label is transparent.

                2. If the caption of a lable contains a character '\n', the label will hide the
                character and display the text string after '\n' in a new line.

                3. The format mode accepts the definition for displaying mutile-style text. For
                example.

                label.format(true);

                    label.caption(STR("Hello, <bold=true>This is a bold text</>"));

                    label.caption(STR("Hello, <bold=true color=0xff0000>This
                        is a bold red text</>"));

                    label.caption(STR("Hello <bold=true color=0xff0000
                        font=\"Consolas\">This is a bold red Consolas text</>"));

                    label.caption(STR("Hello, <bold=true color=0xff0000
                        font=\"Consolas\" url=\"http://nanapro.sourceforge.net\">This is a bold red Consolas
                        text</>"));

                    Arrow cursor becomes a hand when the cursor moves over the red text. Meanwhile, it is open a web browser to open the URL by clicking the red text.[NOTE: the url only works under Windows]

                using namespace nana::gui;

                //void listener(label::command cmd, const nana::string& s) //C++11

                void listener(label::command::t cmd, const nana::string& s)

                {

    if(label::command::click == cmd)

    {

        msgbox mb(STR("target clicked"));

        mb<<STR("the target \"")<<s<<"\" is clicked";

        mb();

    }

                }

                int main()

                {

    form fm;

    label lab(fm, nana::rectangle(0, 0, 100, 40));

    lab.format(true);

    lab.add_format_listener(listener);

    lab.caption(STR("Click <color=0xFF target=\"target id\">here</>"));

    fm.show();

    exec();

                }

                4, Some reserved words: red, green, blue, white, black. It can simplify the format text and increas it readable.

                lab.caption(STR("Click <color=0xFF target=\"target id\">here</>"));

                vs

                lab.caption(STR("Click <blue target=\"target id\">here</>"));

                5, Image is supported for format mode.

                lab.caption(STR("<image=\"file.bmp\"><bold red size=20>Nana C++ Library</>"));

                As you see, the image tag has not a close-tag </>

                Defaultly, the image is displayed with its orignal size. With specifying a size, we can get a proper size by which the image is displayed.

                label.caption(STR("<image=\"file.bmp\" size=(150,150)><bold red size=20>Nana C++ Library</>"));

                size=(150,150) means that it stretchs the image to the specified size.

                In many situations, we want to display the image as it is if it is greater than/less than a specified size. There are two reserved words can achieve it.

                max_limited: stretchs the image to the specified size with preserving aspect ratio when its one of edge beyonds the specified size.

                min_limited: stretchs the image to the specified size with preserving aspect ratio when its one of edge is less than the specified size.

                label.caption(STR("<image=\"file.bmp\" size=(150,150) max_limited><bold red size=20>Nana C++ Library</>"));

                6, Alignments for format mode.

                Defaulty, the alignment is baseline-aligned. The library provides 
                4 kinds of alignment which are: top, center, bottom and baseline. They are useful tools when display texts with different size in a line.

                label.caption(STR("<size=12 top>top</><size=14 center>center<size=16 bottom>bottom</><size=30>baseline</><size=10>small font by baseline</>"));

                See also

                None.

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