From b2db7d11ec8dfd9d8a8fa164a2479a83d8418ddc Mon Sep 17 00:00:00 2001
From: jaswantp <40538987+jaswantp@users.noreply.github.com>
Date: Mon, 24 Aug 2020 15:18:29 +0200
Subject: [PATCH] Recover from almost equal axis limits.

When state.Axis->Range.Size() == DBL_EPSILON, the 'speed' to DragFloat is about 1.0e-14 which makes it virtually impossible to recover from that state!
The fix proposes to detect and adjust the drag_speed accordingly.
---
 implot.cpp | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/implot.cpp b/implot.cpp
index 85e34e5..7beb903 100644
--- a/implot.cpp
+++ b/implot.cpp
@@ -1140,7 +1140,8 @@ inline void ShowAxisContextMenu(ImPlotAxisState& state) {
     bool grid     = ImHasFlag(state.Axis->Flags, ImPlotAxisFlags_GridLines);
     bool ticks    = ImHasFlag(state.Axis->Flags, ImPlotAxisFlags_TickMarks);
     bool labels   = ImHasFlag(state.Axis->Flags, ImPlotAxisFlags_TickLabels);
-
+    double drag_speed = (state.Axis->Range.Size() <= DBL_EPSILON) ? DBL_EPSILON * 1.0e+13 : 0.01 * state.Axis->Range.Size(); // recover from almost equal axis limits.
+    
     BeginDisabledControls(total_lock);
     if (ImGui::Checkbox("##LockMin", &state.LockMin))
         ImFlipFlag(state.Axis->Flags, ImPlotAxisFlags_LockMin);
@@ -1148,7 +1149,8 @@ inline void ShowAxisContextMenu(ImPlotAxisState& state) {
 
     ImGui::SameLine();
     BeginDisabledControls(state.LockMin);
-    DragFloat("Min", &state.Axis->Range.Min, 0.01f * (float)state.Axis->Range.Size(), -HUGE_VAL, state.Axis->Range.Max - DBL_EPSILON);
+    //DragFloat("Min", &state.Axis->Range.Min, 0.01f * (float)state.Axis->Range.Size(), -HUGE_VAL, state.Axis->Range.Max - DBL_EPSILON);
+    DragFloat("Min", &state.Axis->Range.Min, (float)drag_speed, -HUGE_VAL, state.Axis->Range.Max - DBL_EPSILON);
     EndDisabledControls(state.LockMin);
 
     BeginDisabledControls(total_lock);
@@ -1158,7 +1160,8 @@ inline void ShowAxisContextMenu(ImPlotAxisState& state) {
 
     ImGui::SameLine();
     BeginDisabledControls(state.LockMax);
-    DragFloat("Max", &state.Axis->Range.Max, 0.01f * (float)state.Axis->Range.Size(), state.Axis->Range.Min + DBL_EPSILON, HUGE_VAL);
+    //DragFloat("Max", &state.Axis->Range.Max, 0.01f * (float)state.Axis->Range.Size(), state.Axis->Range.Min + DBL_EPSILON, HUGE_VAL);
+    DragFloat("Max", &state.Axis->Range.Max, (float)drag_speed, state.Axis->Range.Min + DBL_EPSILON, HUGE_VAL);
     EndDisabledControls(state.LockMax);
 
     ImGui::Separator();