Lv2: Improve LED widget's digit calculation

This improves the way digits are calculated for display in
`Lv2ViewProc`:

- More than 2 digits are now recognized
- Minus signs are now recognized
- Tests have been added

include/lmms_math.h

@@ -325,6 +325,32 @@ static inline T absMin( T a, T b )
 	return std::abs(a) < std::abs(b) ? a : b;
 }
 
+// @brief Calculate number of digits which LcdSpinBox would show for a given number
+// @note Once we upgrade to C++20, we could probably use std::formatted_size
+static inline int numDigitsAsInt(float f)
+{
+	// use rounding:
+	// LcdSpinBox sometimes uses roundf(), sometimes cast rounding
+	// we use rounding to be on the "safe side"
+	const float rounded = roundf(f);
+	int asInt = static_cast<int>(rounded);
+	int digits = 1; // always at least 1
+	if(asInt < 0)
+	{
+		++digits;
+		asInt = -asInt;
+	}
+	// "asInt" is positive from now
+	int32_t power = 1;
+	for(int32_t i = 1; i<10; ++i)
+	{
+		power *= 10;
+		if(static_cast<int32_t>(asInt) >= power) { ++digits; } // 2 digits for >=10, 3 for >=100
+		else { break; }
+	}
+	return digits;
+}
+
 
 } // namespace lmms
 

src/gui/Lv2ViewBase.cpp

@@ -39,6 +39,7 @@
 #include "GuiApplication.h"
 #include "embed.h"
 #include "gui_templates.h"
+#include "lmms_math.h"
 #include "Lv2ControlBase.h"
 #include "Lv2Manager.h"
 #include "Lv2Proc.h"
@@ -74,8 +75,10 @@ Lv2ViewProc::Lv2ViewProc(QWidget* parent, Lv2Proc* proc, int colNum) :
 					case PortVis::Integer:
 					{
 						sample_rate_t sr = Engine::audioEngine()->processingSampleRate();
-						m_control = new LcdControl((port.max(sr) <= 9.0f) ? 1 : 2,
-													m_parent);
+						auto pMin = port.min(sr);
+						auto pMax = port.max(sr);
+						int numDigits = std::max(numDigitsAsInt(pMin), numDigitsAsInt(pMax));
+						m_control = new LcdControl(numDigits, m_parent);
 						break;
 					}
 					case PortVis::Enumeration:

tests/CMakeLists.txt

@@ -21,6 +21,7 @@ ADD_EXECUTABLE(tests
 
 	src/core/ArrayVectorTest.cpp
 	src/core/AutomatableModelTest.cpp
+	src/core/MathTest.cpp
 	src/core/ProjectVersionTest.cpp
 	src/core/RelativePathsTest.cpp
 

tests/src/core/MathTest.cpp

@@ -0,0 +1,53 @@
+/*
+ * MathTest.cpp
+ *
+ * Copyright (c) 2023 Johannes Lorenz <jlsf2013$users.sourceforge.net, $=@>
+ *
+ * This file is part of LMMS - https://lmms.io
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program (see COPYING); if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301 USA.
+ *
+ */
+
+#include "QTestSuite.h"
+
+#include "lmms_math.h"
+
+#include <QDir>
+
+class MathTest : QTestSuite
+{
+	Q_OBJECT
+private slots:
+	void NumDigitsTest()
+	{
+		using namespace lmms;
+		QCOMPARE(numDigitsAsInt(1.f), 1);
+		QCOMPARE(numDigitsAsInt(9.9f), 2);
+		QCOMPARE(numDigitsAsInt(10.f), 2);
+		QCOMPARE(numDigitsAsInt(0.f), 1);
+		QCOMPARE(numDigitsAsInt(-100.f), 4);
+		QCOMPARE(numDigitsAsInt(-99.f), 3);
+		QCOMPARE(numDigitsAsInt(-0.4f), 1); // there is no "-0" for LED spinbox
+		QCOMPARE(numDigitsAsInt(-0.99f), 2);
+		QCOMPARE(numDigitsAsInt(1000000000), 10);
+		QCOMPARE(numDigitsAsInt(-1000000000), 11);
+		QCOMPARE(numDigitsAsInt(900000000), 9);
+		QCOMPARE(numDigitsAsInt(-900000000), 10);
+	}
+} MathTests;
+
+#include "MathTest.moc"