From 205cb02efafa2880f63378b5abea7eecbdd853b9 Mon Sep 17 00:00:00 2001
From: Joseph Lenox <lenox.joseph@gmail.com>
Date: Sat, 30 Mar 2019 13:02:54 -0500
Subject: [PATCH] Restrict speed setting to fixed-point output with 3 decimal
 places. Includes test.

Fixes #4769
---
 src/test/libslic3r/test_gcodewriter.cpp | 27 +++++++++++++++++++++++++
 xs/src/libslic3r/GCodeWriter.cpp        |  3 ++-
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/src/test/libslic3r/test_gcodewriter.cpp b/src/test/libslic3r/test_gcodewriter.cpp
index 5f770a6a4..d69e32acd 100644
--- a/src/test/libslic3r/test_gcodewriter.cpp
+++ b/src/test/libslic3r/test_gcodewriter.cpp
@@ -98,3 +98,30 @@ SCENARIO("lift() is not ignored after unlift() at normal values of Z") {
         }
     }
 }
+
+SCENARIO("set_speed emits values with fixed-point output.") {
+
+    GIVEN("GCodeWriter instance") {
+        GCodeWriter writer;
+        WHEN("set_speed is called to set speed to 1.09321e+06") {
+            THEN("Output string is G1 F1093210.000") {
+                REQUIRE_THAT(writer.set_speed(1.09321e+06), Catch::Equals("G1 F1093210.000\n"));
+            }
+        }
+        WHEN("set_speed is called to set speed to 1") {
+            THEN("Output string is G1 F1.000") {
+                REQUIRE_THAT(writer.set_speed(1.0), Catch::Equals("G1 F1.000\n"));
+            }
+        }
+        WHEN("set_speed is called to set speed to 203.200022") {
+            THEN("Output string is G1 F203.200") {
+                REQUIRE_THAT(writer.set_speed(203.200022), Catch::Equals("G1 F203.200\n"));
+            }
+        }
+        WHEN("set_speed is called to set speed to 203.200522") {
+            THEN("Output string is G1 F203.200") {
+                REQUIRE_THAT(writer.set_speed(203.200522), Catch::Equals("G1 F203.201\n"));
+            }
+        }
+    }
+}
diff --git a/xs/src/libslic3r/GCodeWriter.cpp b/xs/src/libslic3r/GCodeWriter.cpp
index 2bae7cbf9..8e666fadc 100644
--- a/xs/src/libslic3r/GCodeWriter.cpp
+++ b/xs/src/libslic3r/GCodeWriter.cpp
@@ -309,7 +309,8 @@ GCodeWriter::set_speed(double F, const std::string &comment,
                        const std::string &cooling_marker) const
 {
     std::ostringstream gcode;
-    gcode << "G1 F" << F;
+    gcode.precision(3);
+    gcode << "G1 F" << std::fixed << F;
     COMMENT(comment);
     gcode << cooling_marker;
     gcode << "\n";