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<header>
  <copyright>
    <year>2020</year>
    <holder>Ericsson AB. All Rights Reserved.</holder></copyright>
  <legalnotice>
      Licensed under the Apache License, Version 2.0 (the "License");
      you may not use this file except in compliance with the License.
      You may obtain a copy of the License at

          http://www.apache.org/licenses/LICENSE-2.0

      Unless required by applicable law or agreed to in writing, software
      distributed under the License is distributed on an "AS IS" BASIS,
      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
      See the License for the specific language governing permissions and
      limitations under the License.

  </legalnotice>
  <title>wxMemoryDC</title>
</header>
<module>wxMemoryDC</module>
<modulesummary>Functions for wxMemoryDC class</modulesummary>
<description><p>A memory device context provides a means to draw graphics onto a bitmap. When drawing in to a mono-bitmap, using <c>wxWHITE</c>, <c>wxWHITE_PEN</c> and <c>wxWHITE_BRUSH</c> will draw the background colour (i.e. 0) whereas all other colours will draw the foreground colour (i.e. 1).
      </p><p>A bitmap must be selected into the new memory DC before it may be used for anything. Typical usage is as follows:
      </p><p>Note that the memory DC must be deleted (or the bitmap selected out of it) before a bitmap can be reselected into another memory DC.
      </p><p>And, before performing any other operations on the bitmap data, the bitmap must be selected out of the memory DC:
      </p><p>This happens automatically when <seeerl marker="wxMemoryDC"><c>wxMemoryDC</c></seeerl> object goes out of scope.
      </p><p>See: <seeerl marker="wxBitmap"><c>wxBitmap</c></seeerl>, <seeerl marker="wxDC"><c>wxDC</c></seeerl>
      </p>
  <p>This class is derived (and can use functions) from: 
    <seeerl marker="wxDC"><c>wxDC</c></seeerl></p>
  
  <p>wxWidgets docs: <url href="https://docs.wxwidgets.org/3.1/classwx_memory_d_c.html">wxMemoryDC</url></p>
  </description>
<datatypes><datatype><name name="wxMemoryDC"/></datatype></datatypes>

<funcs>
  <func>
    <name name="new" arity="0" clause_i="1" since=""/>
    <fsummary>Constructs a new memory device context. </fsummary>
    <desc><p>Constructs a new memory device context. 
      </p><p>Use the <seemfa marker="wxDC#isOk/1"><c>wxDC:isOk/1</c></seemfa> member to test whether the constructor was successful in creating a usable device context. Don't forget to select a bitmap into the DC before drawing on it. 
      </p></desc>
  </func>
  
  <func>
    <name name="new" arity="1" clause_i="1" since=""/>
    <fsummary>Constructs a new memory device context having the same characteristics as the given existing device context. </fsummary>
    <desc><p>Constructs a new memory device context having the same characteristics as the given existing device context. 
      </p><p>This constructor creates a memory device context <c>compatible</c> with <c>dc</c> in wxMSW, the argument is ignored in the other ports. If <c>dc</c> is NULL, a device context compatible with the screen is created, just as with the default constructor. 
      </p></desc>
  </func>
  
  <func>
    <name name="selectObject" arity="2" clause_i="1" since=""/>
    <fsummary>Works exactly like <c>selectObjectAsSource/2</c> but this is the function you should use when you select a bitmap because you want to modify it, e.g. </fsummary>
    <desc><p>Works exactly like <seemfa marker="#selectObjectAsSource/2"><c>selectObjectAsSource/2</c></seemfa> but this is the function you should use when you select a bitmap because you want to modify it, e.g. 
      </p><p>drawing on this DC.
      </p><p>Using <seemfa marker="#selectObjectAsSource/2"><c>selectObjectAsSource/2</c></seemfa> when modifying the bitmap may incur some problems related to <seeerl marker="wxBitmap"><c>wxBitmap</c></seeerl> being a reference counted object (see overview_refcount).
      </p><p>Before using the updated bitmap data, make sure to select it out of context first either by selecting ?wxNullBitmap into the device context or destroying the device context entirely.
      </p><p>If the bitmap is already selected in this device context, nothing is done. If it is selected in another context, the function asserts and drawing on the bitmap won't work correctly.
      </p><p>See: <seemfa marker="wxDC#drawBitmap/4"><c>wxDC:drawBitmap/4</c></seemfa>
      </p></desc>
  </func>
  
  <func>
    <name name="selectObjectAsSource" arity="2" clause_i="1" since=""/>
    <fsummary>Selects the given bitmap into the device context, to use as the memory bitmap. </fsummary>
    <desc><p>Selects the given bitmap into the device context, to use as the memory bitmap. 
      </p><p>Selecting the bitmap into a memory DC allows you to draw into the DC (and therefore the bitmap) and also to use <seemfa marker="wxDC#blit/6"><c>wxDC:blit/6</c></seemfa> to copy the bitmap to a window. For this purpose, you may find <seemfa marker="wxDC#drawIcon/3"><c>wxDC:drawIcon/3</c></seemfa> easier to use instead.
      </p><p>If the argument is ?wxNullBitmap (or some other uninitialised <seeerl marker="wxBitmap"><c>wxBitmap</c></seeerl>) the current bitmap is selected out of the device context, and the original bitmap restored, allowing the current bitmap to be destroyed safely. 
      </p></desc>
  </func>
  
  <func>
    <name name="destroy" arity="1" clause_i="1" since=""/>
    <fsummary>Destructor</fsummary>
    <desc><p>Destroys the object.</p></desc>
  </func>
  </funcs>
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