jp: zoom improvements

(cherry picked from commit f804d3468e05820f11e3580d6aa797bc958c7b82)

openpilot/tools/jotpluggler/app.h

@@ -663,6 +663,11 @@ struct UndoStack {
   }
 };
 
+struct PlotView {
+  ImGuiID plot_id = 0;
+  PlotRange range;
+};
+
 struct UiState {
   bool open_open_route = false;
   bool open_stream = false;
@@ -734,6 +739,12 @@ struct UiState {
   bool init_data_selected = false;
   std::string init_data_search;
   UndoStack undo;
+  std::vector<PlotView> plot_view_history;
+  std::optional<PlotView> restore_plot_view;
+  ImGuiID last_plot_view_id = 0;
+  double last_plot_view_change = -1.0;
+  bool last_plot_view_wheel = false;
+  double last_plot_pan_click = -1.0;
 };
 
 // app.cc public API

openpilot/tools/jotpluggler/plot.cc

@@ -1,6 +1,7 @@
 #include "tools/jotpluggler/internal.h"
 
 #include "implot.h"
+#include "implot_internal.h"
 #include "imgui_internal.h"
 
 #include <cmath>
@@ -801,7 +802,13 @@ void draw_plot(const AppSession &session, Pane *pane, UiState *state) {
     plot_flags |= ImPlotFlags_NoLegend;
   }
 
-  const ImPlotAxisFlags x_axis_flags = ImPlotAxisFlags_NoMenus | ImPlotAxisFlags_NoHighlight;
+  ImPlotAxisFlags x_axis_flags = ImPlotAxisFlags_NoMenus | ImPlotAxisFlags_NoHighlight;
+  const ImGuiIO &input = ImGui::GetIO();
+  const bool at_zoom_limit = state->x_view_max - state->x_view_min <= MIN_HORIZONTAL_ZOOM_SECONDS + 1.0e-6;
+  if (at_zoom_limit && (input.MouseWheel > 0.0f || input.MouseReleased[ImGuiMouseButton_Left])) {
+    // Further zoom-in must not move the time window; panning and zoom-out remain available.
+    x_axis_flags |= ImPlotAxisFlags_LockMin | ImPlotAxisFlags_LockMax;
+  }
   ImPlotAxisFlags y_axis_flags = ImPlotAxisFlags_NoMenus | ImPlotAxisFlags_NoHighlight;
   if (state_block_mode) {
     y_axis_flags |= ImPlotAxisFlags_NoDecorations;
@@ -817,6 +824,8 @@ void draw_plot(const AppSession &session, Pane *pane, UiState *state) {
   if (ImPlot::BeginPlot("##plot", plot_size, plot_flags)) {
     ImPlot::SetupAxes(nullptr, nullptr, x_axis_flags, y_axis_flags);
     ImPlot::SetupAxisFormat(ImAxis_X1, "%.1f");
+    // ImPlot updates pan endpoints separately; a minimum span would distort the pan.
+    ImPlot::SetupAxisZoomConstraints(ImAxis_X1, input.MouseDown[ImGuiMouseButton_Right] ? 0.0 : MIN_HORIZONTAL_ZOOM_SECONDS, INFINITY);
     if (state_block_mode) {
       ImPlot::SetupAxisLimits(ImAxis_Y1, 0.0, 1.0, ImPlotCond_Always);
     } else if (pane_value_format.valid) {
@@ -841,6 +850,28 @@ void draw_plot(const AppSession &session, Pane *pane, UiState *state) {
       ImPlot::SetupLegend(ImPlotLocation_NorthEast);
     }
 
+    ImPlotPlot *plot = ImPlot::GetCurrentPlot();
+    const PlotRange previous_view = {.left = previous_x_min, .right = previous_x_max,
+                                     .bottom = plot->Axes[ImAxis_Y1].Range.Min, .top = plot->Axes[ImAxis_Y1].Range.Max};
+    const bool was_selecting = plot->Selecting;
+    const bool restoring_view = state->restore_plot_view && state->restore_plot_view->plot_id == plot->ID;
+    if (restoring_view) {
+      ImPlot::SetupAxisLimits(ImAxis_Y1, state->restore_plot_view->range.bottom, state->restore_plot_view->range.top, ImPlotCond_Always);
+      state->restore_plot_view.reset();
+    }
+    const ImGuiIO &io = ImGui::GetIO();
+    const ImVec2 drag(io.MousePos.x - plot->SelectStart.x, io.MousePos.y - plot->SelectStart.y);
+    const bool zoom_ready = ImGui::GetTime() - io.MouseClickedTime[ImGuiMouseButton_Left] >= 0.09
+                         && (std::abs(drag.x) > 12.0f || std::abs(drag.y) > 12.0f);
+    // Cancel before ImPlot processes release; hide the box until both thresholds are met.
+    if (io.MouseReleased[ImGuiMouseButton_Left] && !zoom_ready) {
+      plot->Selecting = false;
+    }
+    ImPlot::SetupFinish();
+    if (!zoom_ready) {
+      plot->Selected = false;
+    }
+
     if (state_block_mode) {
       draw_state_blocks_pane(prepared_curves, state);
     } else {
@@ -873,6 +904,28 @@ void draw_plot(const AppSession &session, Pane *pane, UiState *state) {
       state->tracker_time = std::clamp(ImPlot::GetPlotMousePos().x, state->route_x_min, state->route_x_max);
       state->has_tracker_time = true;
     }
+    const ImPlotRect view = ImPlot::GetPlotLimits();
+    const bool changed = std::abs(view.X.Min - previous_view.left) > 1.0e-6
+                      || std::abs(view.X.Max - previous_view.right) > 1.0e-6
+                      || std::abs(view.Y.Min - previous_view.bottom) > 1.0e-6
+                      || std::abs(view.Y.Max - previous_view.top) > 1.0e-6;
+    const bool wheel = io.MouseWheel != 0.0f;
+    const bool pan = ImGui::IsMouseDown(ImGuiMouseButton_Right);
+    if (changed && (ImPlot::IsPlotHovered() || was_selecting || plot->Held) && (wheel || pan || io.MouseReleased[ImGuiMouseButton_Left])
+        && !restoring_view && !state->suppress_range_side_effects && !plot->JustCreated) {
+      // Keep continuous pans and wheel bursts as one view-history entry.
+      const bool continuing = state->last_plot_view_id == plot->ID
+                           && ((pan && state->last_plot_pan_click == io.MouseClickedTime[ImGuiMouseButton_Right])
+                               || (wheel && state->last_plot_view_wheel && ImGui::GetTime() - state->last_plot_view_change < 0.3));
+      if (!continuing) {
+        if (state->plot_view_history.size() == 50) state->plot_view_history.erase(state->plot_view_history.begin());
+        state->plot_view_history.push_back({plot->ID, previous_view});
+      }
+      state->last_plot_view_id = plot->ID;
+      state->last_plot_view_change = ImGui::GetTime();
+      state->last_plot_view_wheel = wheel;
+      state->last_plot_pan_click = io.MouseClickedTime[ImGuiMouseButton_Right];
+    }
     ImPlot::EndPlot();
   }
   app_pop_mono_font();

openpilot/tools/jotpluggler/render.cc

@@ -68,6 +68,18 @@ void render_layout(AppSession *session, UiState *state, bool show_camera_feed) {
   if (!ImGui::GetIO().WantTextInput && ImGui::IsKeyPressed(ImGuiKey_Space, false)) {
     state->playback_playing = !state->playback_playing;
   }
+  // GLFW/ImGui mouse button 4 is the conventional mouse Back button.
+  if (ImGui::IsMouseClicked(3) && !state->plot_view_history.empty()) {
+    const PlotView view = state->plot_view_history.back();
+    state->plot_view_history.pop_back();
+    state->x_view_min = view.range.left;
+    state->x_view_max = view.range.right;
+    state->restore_plot_view = view;
+    state->follow_latest = false;
+    state->playback_playing = false;
+    state->suppress_range_side_effects = true;
+    state->last_plot_view_id = 0;
+  }
   advance_playback(state, *session);
   CameraFeedView *sidebar_camera = session->pane_camera_feeds[static_cast<size_t>(sidebar_preview_camera_view(*session))].get();
   if (show_camera_feed && sidebar_camera != nullptr && state->has_tracker_time) {

openpilot/tools/jotpluggler/session.cc

@@ -31,6 +31,9 @@ void apply_route_data(AppSession *session, UiState *state, RouteData route_data)
   } else if (session->route_name.empty() && session->data_mode == SessionDataMode::Route) {
     session->route_id = {};
   }
+  state->plot_view_history.clear();
+  state->last_plot_view_id = 0;
+  state->restore_plot_view.reset();
   session->route_data = std::move(route_data);
   rebuild_route_index(session);
   rebuild_browser_nodes(session, state);