彻底改版2.0

third/qwtdemo/examples/scatterplot/mainwindow.cpp

@@ -0,0 +1,35 @@
+#include "mainwindow.h"
+#include "plot.h"
+#include <qmath.h>
+
+static double randomValue()
+{
+    // a number between [ 0.0, 1.0 ]
+    return ( qrand() % 100000 ) / 100000.0;
+}
+
+MainWindow::MainWindow()
+{
+    d_plot = new Plot( this );
+    d_plot->setTitle( "Scatter Plot" );
+    setCentralWidget( d_plot );
+
+    // a million points
+    setSamples( 100000 );
+}
+
+void MainWindow::setSamples( int numPoints )
+{
+    QPolygonF samples;
+
+    for ( int i = 0; i < numPoints; i++ )
+    {
+        const double x = randomValue() * 24.0 + 1.0;
+        const double y = ::log( 10.0 * ( x - 1.0 ) + 1.0 ) 
+            * ( randomValue() * 0.5 + 0.9 );
+
+        samples += QPointF( x, y );
+    }
+
+    d_plot->setSamples( samples );
+}