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<div class="section" id="module-pygame.mask">
<span id="pygame-mask"></span><dl class="definition module">
<dt class="title module">
<tt class="docutils literal"><span class="pre">pygame.mask</span></tt></dt>
<dd><div class="line-block">
<div class="line"><span class="summaryline">pygame module for image masks.</span></div>
</div>
<table border="1" class="toc docutils">
<colgroup>
<col width="35%" />
<col width="1%" />
<col width="64%" />
</colgroup>
<tbody valign="top">
<tr><td><a class="toc reference external" href="mask.html#pygame.mask.from_surface">pygame.mask.from_surface</a></td>
<td></td>
<td>Returns a Mask from the given surface.</td>
</tr>
<tr><td><a class="toc reference external" href="mask.html#pygame.mask.from_threshold">pygame.mask.from_threshold</a></td>
<td></td>
<td>Creates a mask by thresholding Surfaces</td>
</tr>
<tr><td><a class="toc reference external" href="mask.html#pygame.mask.Mask">pygame.mask.Mask</a></td>
<td></td>
<td>pygame object for representing 2d bitmasks</td>
</tr>
</tbody>
</table>
<p>Useful for fast pixel perfect collision detection. A Mask uses 1bit per pixel
to store which parts collide.</p>
<p>New in pygame 1.8.</p>
<dl class="definition function">
<dt class="title" id="pygame.mask.from_surface">
<tt class="descclassname">pygame.mask.</tt><tt class="descname">from_surface</tt><big>(</big><big>)</big><a class="headerlink" href="#pygame.mask.from_surface" title="Permalink to this definition"></a></dt>
<dd><div class="line-block">
<div class="line"><span class="summaryline">Returns a Mask from the given surface.</span></div>
<div class="line"><span class="signature">from_surface(Surface, threshold = 127) -&gt; Mask</span></div>
</div>
<p>Makes the transparent parts of the Surface not set, and the opaque parts
set.</p>
<p>The alpha of each pixel is checked to see if it is greater than the given
threshold.</p>
<p>If the Surface is color keyed, then threshold is not used.</p>
</dd></dl>

<dl class="definition function">
<dt class="title" id="pygame.mask.from_threshold">
<tt class="descclassname">pygame.mask.</tt><tt class="descname">from_threshold</tt><big>(</big><big>)</big><a class="headerlink" href="#pygame.mask.from_threshold" title="Permalink to this definition"></a></dt>
<dd><div class="line-block">
<div class="line"><span class="summaryline">Creates a mask by thresholding Surfaces</span></div>
<div class="line"><span class="signature">from_threshold(Surface, color, threshold = (0,0,0,255), othersurface = None, palette_colors = 1) -&gt; Mask</span></div>
</div>
<p>This is a more featureful method of getting a Mask from a Surface. If
supplied with only one Surface, all pixels within the threshold of the
supplied color are set in the Mask. If given the optional othersurface, all
pixels in Surface that are within the threshold of the corresponding pixel
in othersurface are set in the Mask.</p>
</dd></dl>

<dl class="definition class">
<dt class="title" id="pygame.mask.Mask">
<em class="property">class </em><tt class="descclassname">pygame.mask.</tt><tt class="descname">Mask</tt><a class="headerlink" href="#pygame.mask.Mask" title="Permalink to this definition"></a></dt>
<dd><div class="line-block">
<div class="line"><span class="summaryline">pygame object for representing 2d bitmasks</span></div>
<div class="line"><span class="signature">Mask((width, height)) -&gt; Mask</span></div>
</div>
<table border="1" class="toc docutils">
<colgroup>
<col width="24%" />
<col width="1%" />
<col width="75%" />
</colgroup>
<tbody valign="top">
<tr><td><a class="toc reference external" href="mask.html#pygame.mask.Mask.get_size">pygame.mask.Mask.get_size</a></td>
<td></td>
<td>Returns the size of the mask.</td>
</tr>
<tr><td><a class="toc reference external" href="mask.html#pygame.mask.Mask.get_at">pygame.mask.Mask.get_at</a></td>
<td></td>
<td>Returns nonzero if the bit at (x,y) is set.</td>
</tr>
<tr><td><a class="toc reference external" href="mask.html#pygame.mask.Mask.set_at">pygame.mask.Mask.set_at</a></td>
<td></td>
<td>Sets the position in the mask given by x and y.</td>
</tr>
<tr><td><a class="toc reference external" href="mask.html#pygame.mask.Mask.overlap">pygame.mask.Mask.overlap</a></td>
<td></td>
<td>Returns the point of intersection if the masks overlap with the given offset - or None if it does not overlap.</td>
</tr>
<tr><td><a class="toc reference external" href="mask.html#pygame.mask.Mask.overlap_area">pygame.mask.Mask.overlap_area</a></td>
<td></td>
<td>Returns the number of overlapping &#8216;pixels&#8217;.</td>
</tr>
<tr><td><a class="toc reference external" href="mask.html#pygame.mask.Mask.overlap_mask">pygame.mask.Mask.overlap_mask</a></td>
<td></td>
<td>Returns a mask of the overlapping pixels</td>
</tr>
<tr><td><a class="toc reference external" href="mask.html#pygame.mask.Mask.fill">pygame.mask.Mask.fill</a></td>
<td></td>
<td>Sets all bits to 1</td>
</tr>
<tr><td><a class="toc reference external" href="mask.html#pygame.mask.Mask.clear">pygame.mask.Mask.clear</a></td>
<td></td>
<td>Sets all bits to 0</td>
</tr>
<tr><td><a class="toc reference external" href="mask.html#pygame.mask.Mask.invert">pygame.mask.Mask.invert</a></td>
<td></td>
<td>Flips the bits in a Mask</td>
</tr>
<tr><td><a class="toc reference external" href="mask.html#pygame.mask.Mask.scale">pygame.mask.Mask.scale</a></td>
<td></td>
<td>Resizes a mask</td>
</tr>
<tr><td><a class="toc reference external" href="mask.html#pygame.mask.Mask.draw">pygame.mask.Mask.draw</a></td>
<td></td>
<td>Draws a mask onto another</td>
</tr>
<tr><td><a class="toc reference external" href="mask.html#pygame.mask.Mask.erase">pygame.mask.Mask.erase</a></td>
<td></td>
<td>Erases a mask from another</td>
</tr>
<tr><td><a class="toc reference external" href="mask.html#pygame.mask.Mask.count">pygame.mask.Mask.count</a></td>
<td></td>
<td>Returns the number of set pixels</td>
</tr>
<tr><td><a class="toc reference external" href="mask.html#pygame.mask.Mask.centroid">pygame.mask.Mask.centroid</a></td>
<td></td>
<td>Returns the centroid of the pixels in a Mask</td>
</tr>
<tr><td><a class="toc reference external" href="mask.html#pygame.mask.Mask.angle">pygame.mask.Mask.angle</a></td>
<td></td>
<td>Returns the orientation of the pixels</td>
</tr>
<tr><td><a class="toc reference external" href="mask.html#pygame.mask.Mask.outline">pygame.mask.Mask.outline</a></td>
<td></td>
<td>list of points outlining an object</td>
</tr>
<tr><td><a class="toc reference external" href="mask.html#pygame.mask.Mask.convolve">pygame.mask.Mask.convolve</a></td>
<td></td>
<td>Return the convolution of self with another mask.</td>
</tr>
<tr><td><a class="toc reference external" href="mask.html#pygame.mask.Mask.connected_component">pygame.mask.Mask.connected_component</a></td>
<td></td>
<td>Returns a mask of a connected region of pixels.</td>
</tr>
<tr><td><a class="toc reference external" href="mask.html#pygame.mask.Mask.connected_components">pygame.mask.Mask.connected_components</a></td>
<td></td>
<td>Returns a list of masks of connected regions of pixels.</td>
</tr>
<tr><td><a class="toc reference external" href="mask.html#pygame.mask.Mask.get_bounding_rects">pygame.mask.Mask.get_bounding_rects</a></td>
<td></td>
<td>Returns a list of bounding rects of regions of set pixels.</td>
</tr>
</tbody>
</table>
<dl class="definition method">
<dt class="title" id="pygame.mask.Mask.get_size">
<tt class="descname">get_size</tt><big>(</big><big>)</big><a class="headerlink" href="#pygame.mask.Mask.get_size" title="Permalink to this definition"></a></dt>
<dd><div class="line-block">
<div class="line"><span class="summaryline">Returns the size of the mask.</span></div>
<div class="line"><span class="signature">get_size() -&gt; width,height</span></div>
</div>
</dd></dl>

<dl class="definition method">
<dt class="title" id="pygame.mask.Mask.get_at">
<tt class="descname">get_at</tt><big>(</big><big>)</big><a class="headerlink" href="#pygame.mask.Mask.get_at" title="Permalink to this definition"></a></dt>
<dd><div class="line-block">
<div class="line"><span class="summaryline">Returns nonzero if the bit at (x,y) is set.</span></div>
<div class="line"><span class="signature">get_at((x,y)) -&gt; int</span></div>
</div>
<p>Coordinates start at (0,0) is top left - just like Surfaces.</p>
</dd></dl>

<dl class="definition method">
<dt class="title" id="pygame.mask.Mask.set_at">
<tt class="descname">set_at</tt><big>(</big><big>)</big><a class="headerlink" href="#pygame.mask.Mask.set_at" title="Permalink to this definition"></a></dt>
<dd><div class="line-block">
<div class="line"><span class="summaryline">Sets the position in the mask given by x and y.</span></div>
<div class="line"><span class="signature">set_at((x,y),value) -&gt; None</span></div>
</div>
</dd></dl>

<dl class="definition method">
<dt class="title" id="pygame.mask.Mask.overlap">
<tt class="descname">overlap</tt><big>(</big><big>)</big><a class="headerlink" href="#pygame.mask.Mask.overlap" title="Permalink to this definition"></a></dt>
<dd><div class="line-block">
<div class="line"><span class="summaryline">Returns the point of intersection if the masks overlap with the given offset - or None if it does not overlap.</span></div>
<div class="line"><span class="signature">overlap(othermask, offset) -&gt; x,y</span></div>
</div>
<p>The overlap tests uses the following offsets (which may be negative):</p>
<div class="highlight-python"><pre>+----+----------..
|A   | yoffset
|  +-+----------..
+--|B
|xoffset
|  |
:  :</pre>
</div>
</dd></dl>

<dl class="definition method">
<dt class="title" id="pygame.mask.Mask.overlap_area">
<tt class="descname">overlap_area</tt><big>(</big><big>)</big><a class="headerlink" href="#pygame.mask.Mask.overlap_area" title="Permalink to this definition"></a></dt>
<dd><div class="line-block">
<div class="line"><span class="summaryline">Returns the number of overlapping &#8216;pixels&#8217;.</span></div>
<div class="line"><span class="signature">overlap_area(othermask, offset) -&gt; numpixels</span></div>
</div>
<p>You can see how many pixels overlap with the other mask given. This can
be used to see in which direction things collide, or to see how much the
two masks collide. An approximate collision normal can be found by
calculating the gradient of the overlap area through the finite
difference.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">dx</span> <span class="o">=</span> <span class="n">Mask</span><span class="o">.</span><span class="n">overlap_area</span><span class="p">(</span><span class="n">othermask</span><span class="p">,(</span><span class="n">x</span><span class="o">+</span><span class="mi">1</span><span class="p">,</span><span class="n">y</span><span class="p">))</span> <span class="o">-</span> <span class="n">Mask</span><span class="o">.</span><span class="n">overlap_area</span><span class="p">(</span><span class="n">othermask</span><span class="p">,(</span><span class="n">x</span><span class="o">-</span><span class="mi">1</span><span class="p">,</span><span class="n">y</span><span class="p">))</span>
<span class="n">dy</span> <span class="o">=</span> <span class="n">Mask</span><span class="o">.</span><span class="n">overlap_area</span><span class="p">(</span><span class="n">othermask</span><span class="p">,(</span><span class="n">x</span><span class="p">,</span><span class="n">y</span><span class="o">+</span><span class="mi">1</span><span class="p">))</span> <span class="o">-</span> <span class="n">Mask</span><span class="o">.</span><span class="n">overlap_area</span><span class="p">(</span><span class="n">othermask</span><span class="p">,(</span><span class="n">x</span><span class="p">,</span><span class="n">y</span><span class="o">-</span><span class="mi">1</span><span class="p">))</span>
</pre></div>
</div>
</dd></dl>

<dl class="definition method">
<dt class="title" id="pygame.mask.Mask.overlap_mask">
<tt class="descname">overlap_mask</tt><big>(</big><big>)</big><a class="headerlink" href="#pygame.mask.Mask.overlap_mask" title="Permalink to this definition"></a></dt>
<dd><div class="line-block">
<div class="line"><span class="summaryline">Returns a mask of the overlapping pixels</span></div>
<div class="line"><span class="signature">overlap_mask(othermask, offset) -&gt; Mask</span></div>
</div>
<p>Returns a Mask the size of the original Mask containing only the
overlapping pixels between Mask and othermask.</p>
</dd></dl>

<dl class="definition method">
<dt class="title" id="pygame.mask.Mask.fill">
<tt class="descname">fill</tt><big>(</big><big>)</big><a class="headerlink" href="#pygame.mask.Mask.fill" title="Permalink to this definition"></a></dt>
<dd><div class="line-block">
<div class="line"><span class="summaryline">Sets all bits to 1</span></div>
<div class="line"><span class="signature">fill() -&gt; None</span></div>
</div>
<p>Sets all bits in a Mask to 1.</p>
</dd></dl>

<dl class="definition method">
<dt class="title" id="pygame.mask.Mask.clear">
<tt class="descname">clear</tt><big>(</big><big>)</big><a class="headerlink" href="#pygame.mask.Mask.clear" title="Permalink to this definition"></a></dt>
<dd><div class="line-block">
<div class="line"><span class="summaryline">Sets all bits to 0</span></div>
<div class="line"><span class="signature">clear() -&gt; None</span></div>
</div>
<p>Sets all bits in a Mask to 0.</p>
</dd></dl>

<dl class="definition method">
<dt class="title" id="pygame.mask.Mask.invert">
<tt class="descname">invert</tt><big>(</big><big>)</big><a class="headerlink" href="#pygame.mask.Mask.invert" title="Permalink to this definition"></a></dt>
<dd><div class="line-block">
<div class="line"><span class="summaryline">Flips the bits in a Mask</span></div>
<div class="line"><span class="signature">invert() -&gt; None</span></div>
</div>
<p>Flips all of the bits in a Mask, so that the set pixels turn to unset
pixels and the unset pixels turn to set pixels.</p>
</dd></dl>

<dl class="definition method">
<dt class="title" id="pygame.mask.Mask.scale">
<tt class="descname">scale</tt><big>(</big><big>)</big><a class="headerlink" href="#pygame.mask.Mask.scale" title="Permalink to this definition"></a></dt>
<dd><div class="line-block">
<div class="line"><span class="summaryline">Resizes a mask</span></div>
<div class="line"><span class="signature">scale((x, y)) -&gt; Mask</span></div>
</div>
<p>Returns a new Mask of the Mask scaled to the requested size.</p>
</dd></dl>

<dl class="definition method">
<dt class="title" id="pygame.mask.Mask.draw">
<tt class="descname">draw</tt><big>(</big><big>)</big><a class="headerlink" href="#pygame.mask.Mask.draw" title="Permalink to this definition"></a></dt>
<dd><div class="line-block">
<div class="line"><span class="summaryline">Draws a mask onto another</span></div>
<div class="line"><span class="signature">draw(othermask, offset) -&gt; None</span></div>
</div>
<p>Performs a bitwise <tt class="docutils literal"><span class="pre">OR</span></tt>, drawing othermask onto Mask.</p>
</dd></dl>

<dl class="definition method">
<dt class="title" id="pygame.mask.Mask.erase">
<tt class="descname">erase</tt><big>(</big><big>)</big><a class="headerlink" href="#pygame.mask.Mask.erase" title="Permalink to this definition"></a></dt>
<dd><div class="line-block">
<div class="line"><span class="summaryline">Erases a mask from another</span></div>
<div class="line"><span class="signature">erase(othermask, offset) -&gt; None</span></div>
</div>
<p>Erases all pixels set in othermask from Mask.</p>
</dd></dl>

<dl class="definition method">
<dt class="title" id="pygame.mask.Mask.count">
<tt class="descname">count</tt><big>(</big><big>)</big><a class="headerlink" href="#pygame.mask.Mask.count" title="Permalink to this definition"></a></dt>
<dd><div class="line-block">
<div class="line"><span class="summaryline">Returns the number of set pixels</span></div>
<div class="line"><span class="signature">count() -&gt; pixels</span></div>
</div>
<p>Returns the number of set pixels in the Mask.</p>
</dd></dl>

<dl class="definition method">
<dt class="title" id="pygame.mask.Mask.centroid">
<tt class="descname">centroid</tt><big>(</big><big>)</big><a class="headerlink" href="#pygame.mask.Mask.centroid" title="Permalink to this definition"></a></dt>
<dd><div class="line-block">
<div class="line"><span class="summaryline">Returns the centroid of the pixels in a Mask</span></div>
<div class="line"><span class="signature">centroid() -&gt; (x, y)</span></div>
</div>
<p>Finds the centroid, the center of pixel mass, of a Mask. Returns a
coordinate tuple for the centroid of the Mask. In the event the Mask is
empty, it will return (0,0).</p>
</dd></dl>

<dl class="definition method">
<dt class="title" id="pygame.mask.Mask.angle">
<tt class="descname">angle</tt><big>(</big><big>)</big><a class="headerlink" href="#pygame.mask.Mask.angle" title="Permalink to this definition"></a></dt>
<dd><div class="line-block">
<div class="line"><span class="summaryline">Returns the orientation of the pixels</span></div>
<div class="line"><span class="signature">angle() -&gt; theta</span></div>
</div>
<p>Finds the approximate orientation of the pixels in the image from -90 to
90 degrees. This works best if performed on one connected component of
pixels. It will return 0.0 on an empty Mask.</p>
</dd></dl>

<dl class="definition method">
<dt class="title" id="pygame.mask.Mask.outline">
<tt class="descname">outline</tt><big>(</big><big>)</big><a class="headerlink" href="#pygame.mask.Mask.outline" title="Permalink to this definition"></a></dt>
<dd><div class="line-block">
<div class="line"><span class="summaryline">list of points outlining an object</span></div>
<div class="line"><span class="signature">outline(every = 1) -&gt; [(x,y), (x,y) ...]</span></div>
</div>
<p>Returns a list of points of the outline of the first object it comes
across in a Mask. For this to be useful, there should probably only be
one connected component of pixels in the Mask. The every option allows
you to skip pixels in the outline. For example, setting it to 10 would
return a list of every 10th pixel in the outline.</p>
</dd></dl>

<dl class="definition method">
<dt class="title" id="pygame.mask.Mask.convolve">
<tt class="descname">convolve</tt><big>(</big><big>)</big><a class="headerlink" href="#pygame.mask.Mask.convolve" title="Permalink to this definition"></a></dt>
<dd><div class="line-block">
<div class="line"><span class="summaryline">Return the convolution of self with another mask.</span></div>
<div class="line"><span class="signature">convolve(othermask, outputmask = None, offset = (0,0)) -&gt; Mask</span></div>
</div>
<p>Returns a mask with the (i-offset[0],j-offset[1]) bit set if shifting
othermask so that it&#8217;s lower right corner pixel is at (i,j) would cause
it to overlap with self.</p>
<p>If an outputmask is specified, the output is drawn onto outputmask and
outputmask is returned. Otherwise a mask of size <tt class="docutils literal"><span class="pre">self.get_size()</span></tt> +
<tt class="docutils literal"><span class="pre">othermask.get_size()</span></tt> - (1,1) is created.</p>
</dd></dl>

<dl class="definition method">
<dt class="title" id="pygame.mask.Mask.connected_component">
<tt class="descname">connected_component</tt><big>(</big><big>)</big><a class="headerlink" href="#pygame.mask.Mask.connected_component" title="Permalink to this definition"></a></dt>
<dd><div class="line-block">
<div class="line"><span class="summaryline">Returns a mask of a connected region of pixels.</span></div>
<div class="line"><span class="signature">connected_component((x,y) = None) -&gt; Mask</span></div>
</div>
<p>This uses the <tt class="docutils literal"><span class="pre">SAUF</span></tt> algorithm to find a connected component in the
Mask. It checks 8 point connectivity. By default, it will return the
largest connected component in the image. Optionally, a coordinate pair
of a pixel can be specified, and the connected component containing it
will be returned. In the event the pixel at that location is not set, the
returned Mask will be empty. The Mask returned is the same size as the
original Mask.</p>
</dd></dl>

<dl class="definition method">
<dt class="title" id="pygame.mask.Mask.connected_components">
<tt class="descname">connected_components</tt><big>(</big><big>)</big><a class="headerlink" href="#pygame.mask.Mask.connected_components" title="Permalink to this definition"></a></dt>
<dd><div class="line-block">
<div class="line"><span class="summaryline">Returns a list of masks of connected regions of pixels.</span></div>
<div class="line"><span class="signature">connected_components(min = 0) -&gt; [Masks]</span></div>
</div>
<p>Returns a list of masks of connected regions of pixels. An optional
minimum number of pixels per connected region can be specified to filter
out noise.</p>
</dd></dl>

<dl class="definition method">
<dt class="title" id="pygame.mask.Mask.get_bounding_rects">
<tt class="descname">get_bounding_rects</tt><big>(</big><big>)</big><a class="headerlink" href="#pygame.mask.Mask.get_bounding_rects" title="Permalink to this definition"></a></dt>
<dd><div class="line-block">
<div class="line"><span class="summaryline">Returns a list of bounding rects of regions of set pixels.</span></div>
<div class="line"><span class="signature">get_bounding_rects() -&gt; Rects</span></div>
</div>
<p>This gets a bounding rect of connected regions of set pixels. A bounding
rect is one for which each of the connected pixels is inside the rect.</p>
</dd></dl>

</dd></dl>

</dd></dl>

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