From 5274baaf008948fa1726b2aaee2059d3fff06692 Mon Sep 17 00:00:00 2001
From: Giovanni Mascellani <giovanni@mascellani.eu>
Date: Wed, 13 Nov 2024 16:38:19 +0100
Subject: [PATCH] Support panning with the mouse wheel.

The movement scheme is based on common browsers, like Firefox
and Chromium, assumed to be a good approximation of what users
find intuitive.
---
 src/gpuvis.cpp       |  4 +++-
 src/gpuvis_graph.cpp | 21 +++++++++++++++++++--
 2 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/src/gpuvis.cpp b/src/gpuvis.cpp
index 68ce7048..e9838d25 100644
--- a/src/gpuvis.cpp
+++ b/src/gpuvis.cpp
@@ -1383,7 +1383,9 @@ void MainApp::render()
             {
                 { "Ctrl+click drag", "Graph: Select area" },
                 { "Shift+click drag", "Graph: Zoom selected area" },
-                { "Mousewheel", "Graph: Zoom in / out" },
+                { "Mousewheel", "Graph: Pan up / down" },
+                { "Shift+mousewheel", "Graph: Pan left / right" },
+                { "Ctrl+mousewheel", "Graph: Zoom in / out" },
                 { "Alt down", "Graph: Hide labels" },
             };
             int graph_entry_count = 0;
diff --git a/src/gpuvis_graph.cpp b/src/gpuvis_graph.cpp
index 3b64bd64..4477f3e0 100644
--- a/src/gpuvis_graph.cpp
+++ b/src/gpuvis_graph.cpp
@@ -4714,9 +4714,26 @@ void TraceWin::graph_handle_mouse_over( graph_info_t &gi )
     }
     else if ( io.MouseWheel )
     {
-        bool zoomin = ( io.MouseWheel > 0.0f );
+        // wheel: move vertically
+        // shift + wheel: move horizontally
+        // alt + wheel: zoom
+        uint32_t mask = ( io.KeyCtrl << 0 ) | ( io.KeyAlt << 1 ) | ( io.KeyShift << 2 );
+
+        if ( mask == ( 1 << 0 ) )
+        {
+            bool zoomin = ( io.MouseWheel > 0.0f );
 
-        graph_zoom( mouse_ts, gi.ts0, zoomin );
+            graph_zoom( mouse_ts, gi.ts0, zoomin );
+        }
+        else if ( mask == ( 1 << 2 ))
+        {
+            m_graph.start_ts += (int64_t)(io.MouseWheel * m_graph.length_ts / 10);
+            m_graph.recalc_timebufs = true;
+        }
+        else if ( mask == 0 )
+        {
+            m_graph.start_y += io.MouseWheel * ImGui::GetTextLineHeightWithSpacing() * 4;
+        }
     }
 }