ch21_12.htm

by Randal L. Schwartz and Tom Phoenix ISBN 0-596-00132-0 Third Edition, published July 2001. (See

Assigns the tag to the item below the specified item in the display
list
</p>
</dd>


<dt><i> <tt class="literal">closest</tt></i></dt>
<dd>
Assigns the tag to the item closest to the specified x,y coordinate</p>
</dd>


<dt><i> <tt class="literal">enclosed</tt></i></dt>
<dd>
Assigns the tag to all items that are completely enclosed within the
specified bounding box
</p>
</dd>


<dt><i> <tt class="literal">overlapping</tt></i></dt>
<dd>
Assigns the tag to all items that are even partially inside the
specified bounding box
</p>
</dd>


<dt><i> <tt class="literal">withtag</tt></i></dt>
<dd>
Assigns the tag to all items with the specified tag</p>
</dd>

</dl>
</dd>


<dt><b><tt class="literal">bind</tt></b></dt>
<dd>
<a name="INDEX-3012" />Binds a callback to an item. (To bind a
callback to the Canvas widget itself, you must specify Tk::bind.)
</p>
</dd>


<dt><b><tt class="literal">bbox</tt></b></dt>
<dd>
<a name="INDEX-3013" />Returns the bounding box of an item.
For example, to get the bounding box for all items in the canvas:
</p>


<blockquote><pre class="code">$canvas-&gt;bbox("all");</pre></blockquote>
</dd>


<dt><b><tt class="literal">itemconfigure</tt></b></dt>
<dd>
<a name="INDEX-3014" />Configures one of the items within the
canvas. Works just like the <tt class="literal">configure</tt> method for
widgets, but the first argument is the tag name or ID for the canvas
item.
</p>
</dd>


<dt><b><tt class="literal">itemcget</tt></b></dt>
<dd>
<a name="INDEX-3015" />Gets configuration information for one
of the items within the canvas. Works just like the
<tt class="literal">cget</tt> method for widgets, but the first argument is
the tag name or ID for the canvas item.
</p>
</dd>


<dt><b><tt class="literal">move</tt></b></dt>
<dd>
<a name="INDEX-3016" />Moves an item on the canvas by adding
the specified x and y distances to it:
</p>

<blockquote><pre class="code">$canvas-&gt;move("circle1", 100, 100);</pre></blockquote>
</dd>


<dt><b><tt class="literal">coords</tt></b></dt>
<dd>
<a name="INDEX-3017" />Gets the current x,y coordinates for an
item, or moves an item to an explicit x,y coordinate.
</p>
</dd>


<dt><b><tt class="literal">lower</tt></b></dt>
<dd>
<a name="INDEX-3018" />Sets the priority for the item in the
display list to be lower than the item identified by the specified
tag or ID.
</p>
</dd>


<dt><b><tt class="literal">raise</tt></b></dt>
<dd>
<a name="INDEX-3019" />Sets the priority for the item in the
display list to be higher than the item identified by the specified
tag or ID.
</p>
</dd>


<dt><b><tt class="literal">delete</tt></b></dt>
<dd>
<a name="INDEX-3020" />Removes an item from the canvas. You
can specify as many tags or IDs in the argument list as you want.
</p>
</dd>


<dt><b><tt class="literal">find</tt></b></dt>
<dd>
<a name="INDEX-3021" />Finds the specified items. The first
argument can be any of:
</p>
<dl>

<dt><i> <tt class="literal">above</tt></i></dt>
<dd>
Finds the item above the specified item in the display list</p>
</dd>


<dt><i> <tt class="literal">all</tt></i></dt>
<dd>
Finds all items in the canvas</p>
</dd>


<dt><i> <tt class="literal">below</tt></i></dt>
<dd>
Finds the item below the specified item in the display list</p>
</dd>


<dt><i> <tt class="literal">closest</tt></i></dt>
<dd>
Finds the item closest to the specified x,y coordinate</p>
</dd>


<dt><i> <tt class="literal">enclosed</tt></i></dt>
<dd>
Finds all items that are completely enclosed within the specified
bounding box
</p>
</dd>


<dt><i> <tt class="literal">overlapping</tt></i></dt>
<dd>
Finds all items that are even partially inside the specified bounding
box
</p>
</dd>


<dt><i> <tt class="literal">withtag</tt></i></dt>
<dd>
Finds all items with the specified tag</p>
</dd>

</dl>
</dd>


<dt><b><tt class="literal">gettags</tt></b></dt>
<dd>
<a name="INDEX-3022" />Retrieves a list of all tags associated
with an item.
</p>
</dd>


<dt><b><tt class="literal">type</tt></b></dt>
<dd>
<a name="INDEX-3023" />Determines the type of the specified
item.
</p>
</dd>


<dt><b><tt class="literal">focus</tt></b></dt>
<dd>
<a name="INDEX-3024" />Assigns the keyboard focus to the
specified item.
</p>
</dd>


<dt><b><tt class="literal">postscript</tt></b></dt>
<dd>
<a name="INDEX-3025" />Renders the canvas as PostScript.
Options are:
</p>
<dl>

<dt><i> <tt class="literal">-colormap =&gt; \@</tt><em class="replaceable"><tt>colorcommand</tt></em></i></dt>
<dd>
Specifies a PostScript command for setting color values.</p>
</dd>


<dt><i> <tt class="literal">-colormode =&gt;</tt> <em class="replaceable"><tt>mode</tt></em></i></dt>
<dd>
Sets the mode to <tt class="literal">color</tt> (full color),
<tt class="literal">gray</tt> (grayscale), or <tt class="literal">mono</tt>
(black and white).
</p>
</dd>


<dt><i> <tt class="literal">-file =&gt;</tt> <em class="replaceable"><tt>filename</tt></em></i></dt>
<dd>
The name of the file to store the PostScript output.</p>
</dd>


<dt><i> <tt class="literal">-fontmap =&gt; \@</tt><em class="replaceable"><tt>fontspec</tt></em></i></dt>
<dd>
Specifies a font name and point size.</p>
</dd>


<dt><i> <tt class="literal">-height =&gt;</tt> <em class="replaceable"><tt>size</tt></em></i></dt>
<dd>
The height of the area to print.</p>
</dd>


<dt><i> <tt class="literal">-pageanchor =&gt;</tt> <em class="replaceable"><tt>position</tt></em></i></dt>
<dd>
The anchor position of the page. Values are <tt class="literal">center</tt>
(default), <tt class="literal">n</tt>, <tt class="literal">e</tt>,
<tt class="literal">s</tt>, and <tt class="literal">w</tt>.
</p>
</dd>


<dt><i> <tt class="literal">-pageheight =&gt;</tt> <em class="replaceable"><tt>height</tt></em></i></dt>
<dd>
The height of the printed page.</p>
</dd>


<dt><i> <tt class="literal">-pagewidth =&gt;</tt> <em class="replaceable"><tt>width</tt></em></i></dt>
<dd>
The width of the printed page.</p>
</dd>


<dt><i> <tt class="literal">-pagex =&gt;</tt> <em class="replaceable"><tt>x</tt></em></i></dt>
<dd>
The x positioning point.</p>
</dd>


<dt><i> <tt class="literal">-pagey =&gt;</tt> <em class="replaceable"><tt>y</tt></em></i></dt>
<dd>
The y positioning point.</p>
</dd>


<dt><i> <tt class="literal">-rotate =&gt;</tt> <em class="replaceable"><tt>boolean</tt></em></i></dt>
<dd>
Whether to rotate to landscape orientation. Default is
<tt class="literal">0</tt>. 
</p>
</dd>


<dt><i> <tt class="literal">-width =&gt;</tt> <em class="replaceable"><tt>size</tt></em></i></dt>
<dd>
The width of the area to print.</p>
</dd>


<dt><i> <tt class="literal">-x =&gt;</tt> <em class="replaceable"><tt>x</tt></em></i></dt>
<dd>
The left edge of the canvas.</p>
</dd>


<dt><i> <tt class="literal">-y =&gt;</tt> <em class="replaceable"><tt>y</tt></em></i></dt>
<dd>
The top edge of the canvas.</p>
</dd>

</dl>
</dd>


<dt><b><tt class="literal">scale</tt></b></dt>
<dd>
<a name="INDEX-3026" />Changes the scaling of the canvas or
any individual items. For example, to scale the entire canvas to half
its dimensions:
</p>


<blockquote><pre class="code">$canvas-&gt;scale("all", 0, 0, .5, .5);</pre></blockquote>
</dd>


<dt><b><tt class="literal">xview</tt></b></dt>
<dd>
<a name="INDEX-3027" />Manipulates the canvas area in view.
With no arguments, returns a list of two numbers between 0 and 1,
defining the portion of the canvas that is currently hidden on the
left and right sides, respectively. With arguments, the function of
<tt class="literal">xview</tt> changes:
</p>
<dl>

<dt><i> <tt class="literal">moveto</tt></i></dt>
<dd>
Moves the specified fraction of the text to the left of the visible
portion.
</p>
</dd>


<dt><i> <tt class="literal">scroll</tt></i></dt>
<dd>
Scrolls the canvas left or right by the specified number of units or
pages. Used primarily as a callback to a scrollbar; pressing on an
arrow would move by units (characters), and pressing on the trough
would move by pages. The number is either <tt class="literal">1</tt> or
<tt class="literal">-1</tt>, to move forwards or backwards, respectively.
</p>
</dd>

</dl>
</dd>


<dt><b><tt class="literal">yview</tt></b></dt>
<dd>
<a name="INDEX-3028" />Manipulates the canvas in view. With no
arguments, returns a list of two numbers between 0 and 1, defining
that portion of the canvas that is currently hidden on the top and
bottom, respectively. With arguments, its function changes:
</p>
<dl>

<dt><i> <tt class="literal">moveto</tt></i></dt>
<dd>
Moves the specified fraction of the canvas area to the top of the
visible portion.
</p>
</dd>


<dt><i> <tt class="literal">scroll</tt></i></dt>
<dd>
Scrolls the canvas up or down by the specified number of units or
pages. Used primarily as a callback to a scrollbar; pressing on an
arrow would move by units (lines), and pressing on the trough would
move by pages. The number is either <tt class="literal">1</tt> or
<tt class="literal">-1</tt>, to move forwards or backwards,
respectively.<a name="INDEX-3029" /><a name="INDEX-3030" /><a name="INDEX-3031" /> 
</p>
</dd>

</dl>
</dd>

</dl>

</div>


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