Profiler: Show one timeline per process :^)

Instead of smashing together all the samples into a single timeline,
make one per process and put them all in a ScrollableContainerWidget.

This makes it much easier to see which processes were active and when.
No timeline is displayed for processes with zero samples in the profile.

Userland/DevTools/Profiler/ProfileTimelineWidget.cpp

@@ -8,14 +8,17 @@
 #include "Profile.h"
 #include <LibGUI/Painter.h>
 #include <LibGfx/Font.h>
+#include <LibGfx/Palette.h>
 
 namespace Profiler {
 
-ProfileTimelineWidget::ProfileTimelineWidget(Profile& profile)
+ProfileTimelineWidget::ProfileTimelineWidget(Profile& profile, Process const& process)
     : m_profile(profile)
+    , m_process(process)
 {
     set_fill_with_background_color(true);
-    set_fixed_height(80);
+    set_fixed_height(40);
+    set_fixed_width(m_profile.length_in_ms() / 10);
     m_hover_time = m_profile.first_timestamp();
 }
 
@@ -41,6 +44,12 @@ void ProfileTimelineWidget::paint_event(GUI::PaintEvent& event)
     float frame_height = (float)frame_inner_rect().height() / (float)m_profile.deepest_stack_depth();
 
     for (auto& event : m_profile.events()) {
+        if (event.pid != m_process.pid)
+            continue;
+
+        if (!m_process.valid_at(event.timestamp))
+            continue;
+
         u64 t = clamp_timestamp(event.timestamp) - start_of_trace;
         int x = (int)((float)t * column_width);
         int cw = max(1, (int)column_width);
@@ -66,6 +75,8 @@ void ProfileTimelineWidget::paint_event(GUI::PaintEvent& event)
     {
         StringBuilder timeline_desc_builder;
 
+        timeline_desc_builder.appendff("{} ({}), ", m_process.executable, m_process.pid);
+
         timeline_desc_builder.appendff("Time: {} ms", normalized_hover_time - start_of_trace);
         if (normalized_start_time != normalized_end_time) {
             auto start = normalized_start_time - start_of_trace;

Userland/DevTools/Profiler/ProfileTimelineWidget.h

@@ -10,6 +10,7 @@
 
 namespace Profiler {
 
+class Process;
 class Profile;
 
 class ProfileTimelineWidget final : public GUI::Frame {
@@ -23,11 +24,12 @@ private:
     virtual void mousemove_event(GUI::MouseEvent&) override;
     virtual void mouseup_event(GUI::MouseEvent&) override;
 
-    explicit ProfileTimelineWidget(Profile&);
+    explicit ProfileTimelineWidget(Profile&, Process const&);
 
     u64 timestamp_at_x(int x) const;
 
     Profile& m_profile;
+    Process const& m_process;
 
     bool m_selecting { false };
     u64 m_select_start_time { 0 };

Userland/DevTools/Profiler/main.cpp

@@ -24,6 +24,7 @@
 #include <LibGUI/MessageBox.h>
 #include <LibGUI/Model.h>
 #include <LibGUI/ProcessChooser.h>
+#include <LibGUI/ScrollableContainerWidget.h>
 #include <LibGUI/Splitter.h>
 #include <LibGUI/TabWidget.h>
 #include <LibGUI/TableView.h>
@@ -88,7 +89,24 @@ int main(int argc, char** argv)
     main_widget.set_fill_with_background_color(true);
     main_widget.set_layout<GUI::VerticalBoxLayout>();
 
-    main_widget.add<ProfileTimelineWidget>(*profile);
+    auto timelines_widget = GUI::Widget::construct();
+    timelines_widget->set_layout<GUI::VerticalBoxLayout>();
+    timelines_widget->set_shrink_to_fit(true);
+
+    for (auto& process : profile->processes()) {
+        size_t event_count = 0;
+        for (auto& event : profile->events()) {
+            if (event.pid == process.pid && process.valid_at(event.timestamp))
+                ++event_count;
+        }
+        if (!event_count)
+            continue;
+        timelines_widget->add<ProfileTimelineWidget>(*profile, process);
+    }
+
+    auto& scrollable_container = main_widget.add<GUI::ScrollableContainerWidget>();
+    scrollable_container.set_widget(timelines_widget.ptr());
+
     main_widget.add<ProcessPickerWidget>(*profile);
 
     auto& tab_widget = main_widget.add<GUI::TabWidget>();