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来自「GUI Programming with Python」· HTM 代码 · 共 755 行 · 第 1/2 页

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>A gentle warning</P
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>A dire warning</P
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>About your application</P
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>About Qt</P
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><H2
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>QTabDialog</A
></H2
><P
>One of the best ways to organize a
        multitude of options is to group them together and show the
        user only the pertinent set, hiding the rest between tabs.
        Usability studies have shown that a moderate number of tabs,
        presented in a single row showing all available tabs at one
        time, promotes the greatest usability. Twenty tabs in three
        rows confuse the user; one scrolling row of twenty tabs
        irritates the user. I have once used tabs within tabs myself,
        but it's not something I'd recommend.
        </P
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><DIV
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><H2
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>QWizard</A
></H2
><P
>Complex, infrequent actions are
        eminently suited to the wizard approach. A wizard is a set of
        pages that guide the user through a certain path. The user
        need not visit all pages, and there might be more than one
        possible path. Avoid using wizards where tab pages might be
        more suited (when there are many options but no clear
        progression through the steps of a complex action).
        </P
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><DIV
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><H2
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>QFileDialog</A
></H2
><P
>The first of the Qt standard dialogs is the
        <TT
CLASS="CLASSNAME"
>QFileDialog</TT
>. The file dialog can be
        extended with custom icons, toolbuttons and extra widgets.
        In its default format it is
        extremely easy to use: just call one of the predefined class
        methods that return the name of a directory or file, such as
        <TT
CLASS="FUNCTION"
>getOpenFileName()</TT
> or
        <TT
CLASS="FUNCTION"
>getOpenFileNames()</TT
>.
        </P
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></A
><P
><B
>Example 10-15. fragment from dialogs.py - opening a file dialog
          </B
></P
><PRE
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>...
    def slotFile(self):
        filename=QFileDialog.getOpenFileName("", "*.py", self, "FileDialog")
...
        </PRE
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>The Qt File dialog</P
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><H2
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>QFontDialog</A
></H2
><P
>A useful dialog,
        <TT
CLASS="CLASSNAME"
>QFontDialog</TT
> lets the user select a font
        by giving parameters for font name, style, size, effects and
        script &#8212; this last parameter being the encoding of the
        font, such as Unicode. Just as with
        <TT
CLASS="CLASSNAME"
>QFileDialog</TT
>,
        <TT
CLASS="CLASSNAME"
>QFontDialog</TT
> provides a set of class
        methods that return the selected value, in this case a tuple
        containing a <TT
CLASS="CLASSNAME"
>QFont</TT
> object and a boolean
        value that indicates whether OK or Cancel was pressed..
        </P
><P
>Of course, with Qt3, you no longer set
        the desired encoding, but rather the script - Greek, Tamil, or
        whatever you want.</P
><DIV
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></A
><P
><B
>Example 10-16. fragment from dialogs.py - opening a font dialog
          </B
></P
><PRE
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>...
    def slotFont(self):
        (font, ok) = QFontDialog.getFont(self, "FontDialog")
...
          </PRE
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><DIV
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>The Qt font dialog</P
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></P
></DIV
></DIV
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><H2
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>QColorDialog</A
></H2
><P
><TT
CLASS="CLASSNAME"
>QColorDialog</TT
>
        provides a standard dialog for color selection. An interesting
        addition to this class is that you ask it to store a set of
        custom colors. This set will be kept during the lifetime of
        the application, and you can store those colors in a
        configuration file and restore them when the app is restarted.
        You can ask the color dialog either for a
        <TT
CLASS="CLASSNAME"
>QColor</TT
> object, or for a set of RGB
        values, encapsulated in a <TT
CLASS="CLASSNAME"
>QRgb</TT
> object.
        In contrast with <TT
CLASS="CLASSNAME"
>QFileDialog</TT
>, which is
        extensible, or <TT
CLASS="CLASSNAME"
>QFontDialog</TT
>, which
        really suffices, <TT
CLASS="CLASSNAME"
>QColorDialog</TT
> provides
        just barely enough for simple color selection, but won't do
        for more complex graphics applications (with which you might
        want to implement something that works with HSV values, or
        with a color wheel).
        </P
><DIV
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></A
><P
><B
>Example 10-17. fragment from dialogs.py - opening a color dialog
          </B
></P
><PRE
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>...
    def slotColor(self):
        color=QColorDialog.getColor(QColor("linen"), self, "ColorDialog")
...
          </PRE
></DIV
><DIV
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><P
><DIV
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><P
>The Qt Color dialog</P
></DIV
></P
></DIV
></DIV
><DIV
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><H2
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>QInputDialog</A
></H2
><P
>You can use
        <TT
CLASS="CLASSNAME"
>QInputDialog</TT
> to ask the user for a
        simple, single value. This value can be of the following type:
        text, integer, double, or an item from a listbox. Frankly,
        I've never had a need for these. The open remote location
        dialog in browsers like Opera or Netscape are a common
        example.
        </P
></DIV
><DIV
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><H2
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>QProgressDialog</A
></H2
><P
>The
        <TT
CLASS="CLASSNAME"
>QProgressDialog</TT
> is a useful little
        dialog that can be used to inform the user that a certain
        action will be taking a lot of time. If the operation of the
        dialog is meant to block the whole application, use a modal
        <TT
CLASS="CLASSNAME"
>QprogressDialog</TT
>. If the operation won't
        block the entire application, then it's possible to use a
        modeless <TT
CLASS="CLASSNAME"
>QProgressDialog</TT
>, but it may be
        more effective to use a <TT
CLASS="CLASSNAME"
>QProgressBar</TT
> in
        the statusbar of the application.
        <TT
CLASS="CLASSNAME"
>QProgressDialog</TT
> is based on the
        <TT
CLASS="CLASSNAME"
>QSemiModal</TT
> class.
      </P
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