106 lines
4.6 KiB
HTML
106 lines
4.6 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
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<html><head><meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type"><title>View class</title>
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<meta name="GENERATOR" content="Mozilla/3.01Gold (X11; I; SunOS 5.6 sun4u) [Netscape]"></head>
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<body>
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<h1>class <tt>View(<a href="Container.html">Container</a>,</tt> <tt><a href="ViewBase.html">ViewBase</a>, <a href="Printable.html">Printable</a>)</tt></h1>
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<p>Class View is a general-purpose component
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for displaying 2D graphics and handling mouse and keyboard input. It
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also provides special support
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for being an observer of one or more <a href="Model.html">Models</a>.<br>
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</p>
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<p>This page documents properties and methods concerned with drawing. See
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<a href="ViewBase.html">ViewBase</a> for information about input handling
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and model observation.<br>
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</p><h2>Abstract methods</h2>
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<blockquote> <dl>
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<dt><tt>draw(</tt><i>canvas, update_rect</i><tt>)</tt></dt>
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<dd>Called when some or all of the view needs to be drawn. The <i>canvas
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</i>parameter is an object of class <a href="Canvas.html">Canvas</a>
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upon which the drawing should be done. The <span style="font-style: italic;">update_rect</span> is the rectangle in the view's coordinate system that needs drawing.<br>
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<br>
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You can use the update_rect to improve efficiency by only drawing parts
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of the view that lie within it, although this is optional. Drawing will
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be clipped to the update_rect in any case.<br><br>The <span style="font-family: monospace;">printing</span>
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property of the canvas can be used to determine whether to draw
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features, such as selection highlighting, that should only appear on
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the screen and not on a printed page.<br>
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<br>
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<span style="font-style: italic;">Note:</span> The canvas is only valid for the duration
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of this call and should not be retained beyond it. To draw into the view
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at other times, use the <tt>with_canvas</tt> method.</dd>
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<dd><br>
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</dd>
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<dt><tt>resized((</tt><i>dw</i><tt>,</tt> <i>dh</i><tt>))</tt></dt>
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<dd>Called whenever the size of the view changes as a result of the user
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resizing the containing window.</dd>
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<dd><br>
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</dd>
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<dt><tt>container_resized((</tt><i>dw</i><tt>,</tt> <i>dh</i><tt>))</tt></dt>
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<dd>Called whenever the view's container changes size as a result of the
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user resizing the containing window. The default implementation of this
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method adjusts the position and size of this component according to the
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settings of its resizing attributes.</dd>
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</dl>
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</blockquote>
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<dl>
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<h2>Methods</h2>
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</dl>
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<blockquote> <dl>
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<dt><tt>viewed_rect()</tt></dt>
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<dd>Returns the viewed rectangle, i.e. the rectangle in local coordinates
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that is currently visible in the view.<br>
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</dd>
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<dd><br>
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</dd>
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<dt><tt>invalidate()</tt></dt>
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<dd>Marks the whole viewed rectangle as needing to be redrawn.</dd>
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<dd> </dd>
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<dt><tt>invalidate_rect(</tt><i>rect</i><tt>)</tt></dt>
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<dd>Mark the given rectangle, in local coordinates, as needing to be
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redrawn.</dd>
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</dl>
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<dl>
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<dt><tt>update()</tt></dt>
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<dd>Causes invalidated areas to be redrawn immediately, without waiting
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for a return to the event loop.<br>
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</dd>
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<dd><br>
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</dd>
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<dt><tt>with_canvas(</tt><i>function</i>)</dt>
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<dd>The function should be a callable object expecting one parameter.
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The function is called with a <a href="Canvas.html">Canvas</a> instance
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for drawing in the view. The canvas is only valid for the duration of the
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call and should not be retained beyond it.</dd>
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<dd> </dd><dt><tt>local_to_global(</tt><i>p</i><tt>)</tt></dt>
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<dd>Transforms the given point from the view's local coordinate system
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to screen coordinates.</dd>
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<dd><br>
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</dd>
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<dt><tt>global_to_local(</tt><i>p</i><tt>)</tt></dt>
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<dd>Transforms the given point from screen coordinates to the view's local
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coordinate system.</dd>
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<dd><br>
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</dd>
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<dt><tt>local_to_container(</tt><i>p</i><tt>)</tt></dt>
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<dd>Transforms the given point from the view's local coordinate system
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to its container's local coordinate system.</dd>
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<dd><br>
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</dd>
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<dt><tt>container_to_local(</tt><i>p</i><tt>)</tt></dt>
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<dd>Transforms the given point from the view's container's local coordinate
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system to the view's local coordinate system.</dd>
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<dd><br>
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</dd></dl>
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</blockquote>
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<dl>
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---<br>
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<br>
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</dl>
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<br>
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<br>
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<br>
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<br>
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<br>
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<br>
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</body></html> |