sec-gdkcursor.html

gtk 开发手册和参考文档。 包括gtk glib gdk等

</pre>
                </td>
              </tr>
            </table>
            <p>
              <code><code class="FUNCDEF">gint <tt class=
              "FUNCTION">gdk_pointer_grab</tt></code>(GdkWindow*
              <tt class="PARAMETER"><i>window</i></tt>, gint <tt
              class="PARAMETER"><i>owner_events</i></tt>,
              GdkWindow* <tt class="PARAMETER"><i>
              confine_to</i></tt>, GdkCursor* <tt class=
              "PARAMETER"><i>cursor</i></tt>, guint32 <tt class= 
              "PARAMETER"><i>time</i></tt>);</code>
            </p>
            <p>
              <code><code class="FUNCDEF">void <tt class=
              "FUNCTION">gdk_pointer_ungrab</tt></code>(guint32 <tt
              class="PARAMETER"><i>time</i></tt>);</code>
            </p>
            <p>
              <code><code class="FUNCDEF">gint <tt class=
              "FUNCTION">
              gdk_pointer_is_grabbed</tt></code>(void);</code>
            </p>
          </div>
          <p>
            <b>Figure 8. Grabbing the Pointer</b>
          </p>
        </div>
      </div>
      <div class="SECT2">
        <h2 class="SECT2">
          <a name="Z130">Changing the Cursor</a>
        </h2>
        <p>
          You can change the cursor shape at any time; cursor
          shapes are set on a window-by-window basis with <tt
          class="FUNCTION">gdk_window_set_cursor()</tt> (<a href= 
          "sec-gdkcursor.html#FL-CURSOR">Figure 9</a>). By default,
          windows use their parent's cursor; you can restore the
          default cursor by setting a window's cursor to <span
          class="STRUCTNAME">NULL</span>.
        </p>
        <p>
          Two ways are provided to create a cursor. The simplest
          way is to choose a cursor from the cursor font that comes
          with X. The cursor font contains cursors instead of
          characters; you can view it with the command <tt class= 
          "APPLICATION">xfd -fn cursor</tt>. You can also browse
          the available cursors using the <tt class="APPLICATION">
          testgtk</tt> program that comes with GTK+. Each cursor
          shape has a constant defined in <tt class="FILENAME">
          gdk/gdkcursors.h</tt>. <tt class="FUNCTION">
          gdk_cursor_new()</tt> accepts one of these constants as
          its only argument:
        </p>
        <table border="0" bgcolor="#E0E0E0" width="100%">
          <tr>
            <td>
<pre class="PROGRAMLISTING">
&#13;  GdkCursor* cursor;
  cursor = gdk_cursor_new(GDK_CLOCK);
  gdk_window_set_cursor(window, cursor);
  gdk_cursor_destroy(cursor);&#13;
</pre>
            </td>
          </tr>
        </table>
        <p>
          Notice that you can destroy the cursor as soon as you
          attach it to a window; <span class="STRUCTNAME">
          GdkCursor</span> is a client-side handle for a
          server-side resource, and X will keep the server-side
          resource around as long as it's in use.
        </p>
        <p>
          If none of the cursors in the cursor font are
          appropriate, you can create a custom cursor from a
          bitmap. Two bitmaps, actually: the <span class=
          "STRUCTNAME">source</span> pixmap, and the <span class= 
          "STRUCTNAME">mask</span>. Since these are bitmaps, every
          pixel is either on or off (0 or 1). If a pixel is 0 in
          the mask, that pixel will be transparent. If a pixel is 1
          in both pixmaps, it will be displayed in the <span class= 
          "STRUCTNAME">fg</span> (foreground) color passed to <tt
          class="FUNCTION">gdk_cursor_new_from_pixmap()</tt>. If a
          pixel is 1 in the mask but 0 in the <span class= 
          "STRUCTNAME">source</span> pixmap, it will be displayed
          in the <span class="STRUCTNAME">bg</span> (background)
          color. The <span class="STRUCTNAME">source</span> and
          <span class="STRUCTNAME">mask</span> pixmaps must be the
          same size, and they must have a depth of one.
        </p>
        <p>
          The foreground and background colors should be
          contrasting, so the cursor will be visible against any
          background. Most cursors are drawn in the foreground
          color and outlined in the background color. (To see this,
          move an X cursor over a dark background; you will notice
          a white outline around its edges.) To achieve this, <span
          class="STRUCTNAME">mask</span> should be slightly larger
          than <span class="STRUCTNAME">source</span>, but the same
          shape.
        </p>
        <p>
          The final two arguments to <tt class="FUNCTION">
          gdk_cursor_new_from_pixmap()</tt> are the coordinates of
          the cursor's <i class="FIRSTTERM">hot spot</i>. This is
          the point drawn at the mouse pointer's location---the tip
          of an arrow cursor, or the center of a crosshair cursor.
          <tt class="FUNCTION">gdk_cursor_new_from_pixmap()</tt>
          will fail if the hot spot is not within the bitmap.
        </p>
        <div class="FIGURE">
          <a name="FL-CURSOR"></a>
          <div class="FUNCSYNOPSIS">
            <a name="FL-CURSOR.SYNOPSIS"></a>
            <table border="0" bgcolor="#E0E0E0" width="100%">
              <tr>
                <td>
<pre class="FUNCSYNOPSISINFO">
#include &lt;gdk/gdk.h&gt;
</pre>
                </td>
              </tr>
            </table>
            <p>
              <code><code class="FUNCDEF">GdkCursor* <tt class= 
              "FUNCTION">gdk_cursor_new</tt></code>(GdkCursorType
              <tt class="PARAMETER"><i>
              cursor_type</i></tt>);</code>
            </p>
            <p>
              <code><code class="FUNCDEF">GdkCursor* <tt class= 
              "FUNCTION">
              gdk_cursor_new_from_pixmap</tt></code>(GdkPixmap* <tt
              class="PARAMETER"><i>source</i></tt>, GdkPixmap* <tt
              class="PARAMETER"><i>mask</i></tt>, GdkColor* <tt
              class="PARAMETER"><i>fg</i></tt>, GdkColor* <tt
              class="PARAMETER"><i>bg</i></tt>, gint <tt class= 
              "PARAMETER"><i>x</i></tt>, gint <tt class=
              "PARAMETER"><i>y</i></tt>);</code>
            </p>
            <p>
              <code><code class="FUNCDEF">void <tt class=
              "FUNCTION">gdk_cursor_destroy</tt></code>(GdkCursor*
              <tt class="PARAMETER"><i>cursor</i></tt>);</code>
            </p>
            <p>
              <code><code class="FUNCDEF">void <tt class=
              "FUNCTION">
              gdk_window_set_cursor</tt></code>(GdkWindow* <tt
              class="PARAMETER"><i>window</i></tt>, GdkCursor* <tt
              class="PARAMETER"><i>cursor</i></tt>);</code>
            </p>
          </div>
          <p>
            <b>Figure 9. <span class="STRUCTNAME">
            GdkCursor</span></b>
          </p>
        </div>
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