From 7da6ed69f3458db6af85c3215f4e06676bcf2a4f Mon Sep 17 00:00:00 2001
From: epezent <epezent@rice.edu>
Date: Wed, 19 Aug 2020 23:50:12 -0500
Subject: [PATCH] add FitNextPlotAxes

---
 implot.cpp        | 32 ++++++++++++++++++++++++--------
 implot.h          |  2 ++
 implot_demo.cpp   |  5 +++++
 implot_internal.h |  4 ++++
 4 files changed, 35 insertions(+), 8 deletions(-)

diff --git a/implot.cpp b/implot.cpp
index 3ed29b6..5ea473f 100644
--- a/implot.cpp
+++ b/implot.cpp
@@ -227,7 +227,8 @@ void Reset(ImPlotContext* ctx) {
         ctx->YTicks[i].shrink(0);
         ctx->YTickLabels[i].Buf.shrink(0);
     }
-    // reset extents
+    // reset extents/fit
+    ctx->FitThisFrame = false;
     ctx->FitX = false;
     ctx->ExtentsX.Min = HUGE_VAL;
     ctx->ExtentsX.Max = -HUGE_VAL;
@@ -971,19 +972,25 @@ bool BeginPlot(const char* title, const char* x_label, const char* y_label, cons
         plot.QueryRect = ImRect(0,0,0,0);
     }
 
-    // DOUBLE CLICK -----------------------------------------------------------
+    // FIT -----------------------------------------------------------
 
-    if ( IO.MouseDoubleClicked[gp.InputMap.FitButton] && gp.Hov_Frame && (plot.XAxis.HoveredTot || any_hov_y_axis_region) && !hov_legend && !hov_query) {
+    // fit from double click
+    if ( IO.MouseDoubleClicked[gp.InputMap.FitButton] && gp.Hov_Frame && (plot.XAxis.HoveredTot || any_hov_y_axis_region) && !hov_legend && !hov_query ) {
         gp.FitThisFrame = true;
         gp.FitX = plot.XAxis.HoveredTot;
         for (int i = 0; i < IMPLOT_Y_AXES; i++) 
             gp.FitY[i] = plot.YAxis[i].HoveredTot;        
     }
-    else {
-        gp.FitThisFrame = false;
-        gp.FitX = false;
-        for (int i = 0; i < IMPLOT_Y_AXES; i++) 
-            gp.FitY[i] = false;        
+    // fit from FitNextPlotAxes
+    if (gp.NextPlotData.FitX) {
+        gp.FitThisFrame = true;
+        gp.FitX         = true;
+    }
+    for (int i = 0; i < IMPLOT_Y_AXES; ++i) {
+        if (gp.NextPlotData.FitY[i]) {
+            gp.FitThisFrame = true;
+            gp.FitY[i]      = true;
+        }
     }
 
     // FOCUS ------------------------------------------------------------------
@@ -1554,6 +1561,15 @@ void SetNextPlotLimitsY(double y_min, double y_max, ImGuiCond cond, int y_axis)
     gp.NextPlotData.Y[y_axis].Max = y_max;
 }
 
+void FitNextPlotAxes(bool x, bool y, bool y2, bool y3) {
+    ImPlotContext& gp = *GImPlot;
+    IM_ASSERT_USER_ERROR(gp.CurrentPlot == NULL, "FitNextPlotAxes() needs to be called before BeginPlot()!");
+    gp.NextPlotData.FitX = x;
+    gp.NextPlotData.FitY[0] = y;
+    gp.NextPlotData.FitY[1] = y2;
+    gp.NextPlotData.FitY[2] = y3;
+}
+
 void SetNextPlotTicksX(const double* values, int n_ticks, const char** labels, bool show_default) {
     ImPlotContext& gp = *GImPlot;
     IM_ASSERT_USER_ERROR(gp.CurrentPlot == NULL, "SetNextPlotTicksX() needs to be called before BeginPlot()!");
diff --git a/implot.h b/implot.h
index 971f79e..9f2025d 100644
--- a/implot.h
+++ b/implot.h
@@ -382,6 +382,8 @@ void SetNextPlotLimits(double x_min, double x_max, double y_min, double y_max, I
 void SetNextPlotLimitsX(double x_min, double x_max, ImGuiCond cond = ImGuiCond_Once);
 // Set the Y axis range limits of the next plot. Call right before BeginPlot(). If ImGuiCond_Always is used, the Y axis limits will be locked.
 void SetNextPlotLimitsY(double y_min, double y_max, ImGuiCond cond = ImGuiCond_Once, int y_axis = 0);
+// Fits the next plot axes if they are unlocked.
+void FitNextPlotAxes(bool x = true, bool y = true, bool y2 = true, bool y3 = true);
 
 // Set the X axis ticks and optionally the labels for the next plot.
 void SetNextPlotTicksX(const double* values, int n_ticks, const char** labels = NULL, bool show_default = false);
diff --git a/implot_demo.cpp b/implot_demo.cpp
index 2735747..7e5339d 100644
--- a/implot_demo.cpp
+++ b/implot_demo.cpp
@@ -600,6 +600,11 @@ void ShowDemoWindow(bool* p_open) {
         ImGui::ColorEdit4("##Col2", &y2_col.x, ImGuiColorEditFlags_NoInputs);
         ImGui::SameLine();
         ImGui::ColorEdit4("##Col3", &y3_col.x, ImGuiColorEditFlags_NoInputs);
+        // you can fit axes programatically 
+        ImGui::SameLine(); if (ImGui::Button("Fit X"))  ImPlot::FitNextPlotAxes(true, false, false, false);
+        ImGui::SameLine(); if (ImGui::Button("Fit Y"))  ImPlot::FitNextPlotAxes(false, true, false, false);
+        ImGui::SameLine(); if (ImGui::Button("Fit Y2")) ImPlot::FitNextPlotAxes(false, false, true, false);
+        ImGui::SameLine(); if (ImGui::Button("Fit Y3")) ImPlot::FitNextPlotAxes(false, false, false, true);
         for (int i = 0; i < 1001; ++i) {
             xs[i]  = (i*0.1f);
             ys1[i] = Sin(xs[i]) * 3 + 1;
diff --git a/implot_internal.h b/implot_internal.h
index 2baaf6b..1fd8cd1 100644
--- a/implot_internal.h
+++ b/implot_internal.h
@@ -299,13 +299,17 @@ struct ImPlotNextPlotData
     bool        HasYRange[IMPLOT_Y_AXES];
     bool        ShowDefaultTicksX;
     bool        ShowDefaultTicksY[IMPLOT_Y_AXES];
+    bool        FitX;
+    bool        FitY[IMPLOT_Y_AXES];
 
     ImPlotNextPlotData() {
         HasXRange         = false;
         ShowDefaultTicksX = true;
+        FitX              = false;
         for (int i = 0; i < IMPLOT_Y_AXES; ++i) {
             HasYRange[i]         = false;
             ShowDefaultTicksY[i] = true;
+            FitY[i]              = false;
         }
     }
 };