ProcessManager: Rename it to SystemMonitor

This is a more appropriate name now that it does a lot
more than just manage processes ^)

Applications/SystemMonitor/GraphWidget.cpp

@@ -0,0 +1,52 @@
+#include "GraphWidget.h"
+#include <LibGUI/GPainter.h>
+
+GraphWidget::GraphWidget(GWidget* parent)
+    : GFrame(parent)
+{
+    set_frame_thickness(2);
+    set_frame_shape(FrameShape::Container);
+    set_frame_shadow(FrameShadow::Sunken);
+}
+
+GraphWidget::~GraphWidget()
+{
+}
+
+void GraphWidget::add_value(int value)
+{
+    m_values.enqueue(value);
+    update();
+}
+
+void GraphWidget::paint_event(GPaintEvent& event)
+{
+    GFrame::paint_event(event);
+    GPainter painter(*this);
+    painter.add_clip_rect(event.rect());
+    painter.add_clip_rect(frame_inner_rect());
+    painter.fill_rect(event.rect(), Color::Black);
+
+    auto inner_rect = frame_inner_rect();
+    float scale = (float)inner_rect.height() / (float)m_max;
+
+    Point prev_point;
+    for (int i = 0; i < m_values.size(); ++i) {
+        int x = inner_rect.right() - (i * 2) + 1;
+        if (x < 0)
+            break;
+        float scaled_value = (float)m_values.at(m_values.size() - i - 1) * scale;
+        Point point = { x, inner_rect.bottom() - (int)scaled_value };
+        if (i != 0)
+            painter.draw_line(prev_point, point, m_graph_color);
+        prev_point = point;
+    }
+
+    if (!m_values.is_empty() && text_formatter) {
+        Rect text_rect = inner_rect.shrunken(8, 8);
+        text_rect.set_height(font().glyph_height());
+        auto text = text_formatter(m_values.last(), m_max);
+        painter.draw_text(text_rect.translated(1, 1), text.characters(), TextAlignment::CenterRight, Color::Black);
+        painter.draw_text(text_rect, text.characters(), TextAlignment::CenterRight, m_text_color);
+    }
+}