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<h1>The mouseGrabber example</h1>
<center>
<img src="../images/mouseGrabber.jpg" width="300" height="200" alt="mouseGrabber"/>
</center>
<p>
Illustration of the <code>MouseGrabber</code> class.
</p>
<p>
A <code>MouseGrabber</code> is an abstract class which defines objects that are sensitive to the mouse.
When activated, they grab the mouse events. Possible applications are interactive 2D or 3D GUI,
object auto-selection, auto drop-down menu and much more.
</p>
<p>
In this example, MouseGrabbers are defined and associated with Camera keyFrame paths
or position. Clicking a MouseGrabber will play (resp. restore) the Camera path (resp. position).
</p>
<h2>mouseGrabber.h</h2>
<pre>
<span class="dir">#include <QGLViewer/qglviewer.h>
</span>
<span class="key">class </span>CameraPathPlayer : <span class="key">public </span>qglviewer::MouseGrabber
{
<span class="key">public</span>:
CameraPathPlayer(<span class="typ">int </span>nb) : pathNb(nb) {};
<span class="typ">void </span>checkIfGrabsMouse(<span class="typ">int </span>x, <span class="typ">int </span>y, <span class="typ">const </span>qglviewer::Camera* <span class="typ">const </span>camera);
<span class="typ">int </span>yPos() { <span class="key">return </span><span class="num">25</span>*pathNb + <span class="num">25</span>; };
<span class="key">protected</span>:
<span class="typ">void </span>mousePressEvent(QMouseEvent* <span class="typ">const</span>, qglviewer::Camera* <span class="typ">const </span>camera) { camera->playKeyFramePath(pathNb); };
<span class="key">private</span>:
<span class="typ">int </span>pathNb;
};
<span class="key">class </span>Viewer : <span class="key">public </span>QGLViewer
{
<span class="key">protected </span>:
<span class="key">virtual </span><span class="typ">void </span>init();
<span class="key">virtual </span><span class="typ">void </span>draw();
<span class="key">virtual </span>QString helpString() <span class="typ">const</span>;
<span class="typ">void </span>displayPlayers();
<span class="typ">void </span>updatePlayers();
<span class="key">private</span>:
CameraPathPlayer** player_;
};</pre>
<h2>mouseGrabber.cpp</h2>
<pre>
<span class="dir">#include </span><span class="dstr">"mouseGrabber.h"</span><span class="dir">
</span>
<span class="key">using namespace </span>qglviewer;
<span class="key">using namespace </span>std;
<span class="typ">void </span>CameraPathPlayer::checkIfGrabsMouse(<span class="typ">int </span>x, <span class="typ">int </span>y, <span class="typ">const </span>Camera* <span class="typ">const</span>)
{
<span class="com">// Rectangular activation array - May have to be tune depending on your default font size
</span> setGrabsMouse((x < <span class="num">80</span>) && (y<yPos()) && ((yPos()-y) < <span class="num">16</span>));
}
<span class="typ">void </span>Viewer::displayPlayers()
{
<span class="key">for </span>(<span class="typ">int </span>i=<span class="num">0</span>; i<camera()->nbPaths(); ++i)
{
CameraPathPlayer* cpp = player_[i];
<span class="key">if </span>(cpp)
{
QString s;
<span class="key">if </span>(cpp->grabsMouse())
{
glColor3f(<span class="num">1</span>,<span class="num">1</span>,<span class="num">1</span>);
<span class="key">if </span>(camera()->keyFrameInterpolator(i)->numberOfKeyFrames() > <span class="num">1</span>)
s = <span class="str">"Play path F"</span> + QString::number(i+<span class="num">1</span>);
<span class="key">else
</span>s = <span class="str">"Restore pos F"</span> + QString::number(i+<span class="num">1</span>);
}
<span class="key">else
</span>{
glColor3f(<span class="num">0.6</span>, <span class="num">0.6</span>, <span class="num">0.6</span>);
<span class="key">if </span>(camera()->keyFrameInterpolator(i)->numberOfKeyFrames() > <span class="num">1</span>)
s = <span class="str">"Path F"</span> + QString::number(i+<span class="num">1</span>);
<span class="key">else
</span>s = <span class="str">"Pos F"</span> + QString::number(i+<span class="num">1</span>);
}
glDisable(GL_LIGHTING);
drawText(<span class="num">10</span>, cpp->yPos()<span class="num">-3</span>, s);
}
}
}
<span class="typ">void </span>Viewer::updatePlayers()
{
<span class="key">for </span>(<span class="typ">int </span>i=<span class="num">0</span>; i<camera()->nbPaths(); ++i)
{
<span class="com">// Check if CameraPathPlayer is still valid
</span> <span class="key">if </span>((player_[i]) && (!camera()->keyFrameInterpolator(i)))
{
<span class="key">delete </span>player_[i];
player_[i] = NULL;
}
<span class="com">// Or add it if needed
</span> <span class="key">if </span>((camera()->keyFrameInterpolator(i)) && (!player_[i]))
player_[i] = <span class="key">new </span>CameraPathPlayer(i);
}
}
<span class="typ">void </span>Viewer::init()
{
<span class="com">// Absolutely needed for MouseGrabber
</span> setMouseTracking(<span class="key">true</span>);
<span class="com">// In order to make the manipulatedFrame displacements clearer
</span> setDrawAxis();
<span class="com">// Initialize the CameraPathPlayer MouseGrabber array
</span> player_ = <span class="key">new </span>CameraPathPlayer*[camera()->nbPaths()];
<span class="key">for </span>(<span class="typ">int </span>i=<span class="num">0</span>; i<camera()->nbPaths(); ++i)
player_[i] = NULL;
setManipulatedFrame(<span class="key">new </span>ManipulatedFrame());
restoreFromFile();
help();
}
<span class="typ">void </span>Viewer::draw()
{
glMultMatrixd(manipulatedFrame()->matrix());
<span class="com">// Visual feedback for the manipulatedFrame grab.
</span> <span class="key">if </span>(manipulatedFrame()->grabsMouse())
drawAxis(<span class="num">0.9</span>);
<span class="key">else
</span>drawAxis(<span class="num">0.7</span>);
<span class="com">// Draw a spiral
</span> <span class="typ">const float </span>nbSteps = <span class="num">500.0</span>;
glBegin(GL_QUAD_STRIP);
<span class="key">for </span>(<span class="typ">float </span>i=<span class="num">0</span>; i<nbSteps; ++i)
{
<span class="typ">float </span>ratio = i/nbSteps;
<span class="typ">float </span>angle = <span class="num">21.0</span>*ratio;
<span class="typ">float </span>c = cos(angle);
<span class="typ">float </span>s = sin(angle);
<span class="typ">float </span>r1 = <span class="num">1.0 </span>- <span class="num">0.8</span>*ratio;
<span class="typ">float </span>r2 = <span class="num">0.8 </span>- <span class="num">0.8</span>*ratio;
<span class="typ">float </span>alt = ratio <span class="num">- 0.5</span>;
<span class="typ">const float </span>nor = .<span class="num">5</span>;
<span class="typ">const float </span>up = sqrt(<span class="num">1.0</span>-nor*nor);
glColor3f(<span class="num">1</span>-ratio, .<span class="num">2 </span>, ratio);
glNormal3f(nor*c, up, nor*s);
glVertex3f(r1*c, alt, r1*s);
glVertex3f(r2*c, alt+<span class="num">0.05</span>, r2*s);
}
glEnd();
updatePlayers();
displayPlayers();
}
QString Viewer::helpString() <span class="typ">const
</span>{
QString text(<span class="str">"<h2>M o u s e G r a b b e r </h2>"</span>);
text += <span class="str">"This example illustrates the use of <i>MouseGrabber</i>, which is an abstract "</span>;
text += <span class="str">"class for objects that react (usually when the mouse hovers over them).<br><br>"</span>;
text += <span class="str">"Define new camera paths (or positions) using <b>Alt</b>+[<b>F1</b>-<b>F12</b>]. "</span>;
text += <span class="str">"New <i>MouseGrabbers</i> are created and displayed in the left corner. "</span>;
text += <span class="str">"Note how they react to the mouse, and click them to play the associated path.<br><br>"</span>;
text += <span class="str">"<i>ManipulatedFrame</i>, such as the one which defines the spiral position, are "</span>;
text += <span class="str">"also <i>MouseGrabbers</i>. When the mouse is close to the axis origin, the <i>ManipulatedFrame</i> "</span>;
text += <span class="str">"will react to mouse click, as if the <b>Control</b> key was pressed. This is very convenient "</span>;
text += <span class="str">"to intuitively move scene objects (such as lights) without any key or GUI interaction.<br><br>"</span>;
text += <span class="str">"Note that <i>setMouseTracking()</i> must be enabled to enable <i>MouseGrabbers</i>."</span>;
<span class="key">return </span>text;
}</pre>
<h2>main.cpp</h2>
<pre>
<span class="dir">#include </span><span class="dstr">"mouseGrabber.h"</span><span class="dir">
</span><span class="dir">#include <qapplication.h>
</span>
<span class="typ">int </span>main(<span class="typ">int </span>argc, <span class="typ">char</span>** argv)
{
<span class="com">// Read command lines arguments.
</span> QApplication application(argc,argv);
<span class="com">// Instantiate the viewer, show it on screen.
</span> Viewer viewer;
viewer.show();
<span class="com">// Set the viewer as the application main widget.
</span> application.setMainWidget(&viewer);
<span class="com">// Run main loop.
</span> <span class="key">return </span>application.exec();
}</pre>
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<i>Last modified on Thursday, February 5, 2004.</i>
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