Integrate Fast and Efficient String Formatting Library (#244)

This PR introduces a trimmed-down version of the
[mpaland/printf](https://github.com/mpaland/printf) library to handle
string formatting on embedded systems. The integration of this library
significantly enhances the performance and efficiency of string
formatting operations.

Key changes include:

- Addition of the `mpaland/printf` library to the project.
- Refactoring string formatting in menu items to use a more efficient
and flexible approach.

These changes ensure that our string formatting operations are optimized
for embedded systems, leading to faster and more efficient code
execution.

---

### Checklist

#### General Requirements

- [x] I have kept this PR in draft until all the required tasks are
completed.
- [x] I have reviewed the [contributing guidelines](/CONTRIBUTING.md)
for this project.
- [x] I have tagged this PR with `breaking-change` if it introduces a
breaking change.
- [x] I have checked that this PR does not introduce any breaking
changes unless explicitly stated.
- [x] I have checked that changes generate no new warnings.
- [x] I have performed a self-review of my own code
- [x] I have built and tested **ALL** the examples to ensure that I
haven't broken anything.

#### Refactor/Enhancement

- [x] **This PR is a code refactor.**
- [x] I have tagged this PR with `enhancement`.
- [x] I have made changes to the code that improve
readability/performance/maintainability.
- [x] I have added documentation for the changes if necessary.
- [x] I have [generated](/docs/README.md) and reviewed the documentation
locally if necessary.

docs/source/overview/items/range.rst

@@ -31,7 +31,7 @@ An integer range item can be created using the following syntax:
 
 When the ``Brightness`` menu item is selected, the user can adjust the brightness level within the range of 0 to 100.
 
-You can also optionally specify a unit string to be displayed next to the value:
+You can also optionally specify formatting for the value by providing a format string argument:
 
 .. code-block:: cpp
 
@@ -40,10 +40,10 @@ You can also optionally specify a unit string to be displayed next to the value:
         // Callback function to handle value change
         // value is the selected value within the range
         // Do something with the selected value
-    }, (const char*) "dB"),
+    }, "%02ddB"), // Print the value with two digits and the unit string "dB" e.g. "50dB", "05dB"
     // ... More menu items
 
-When the ``Volume`` menu item is selected, the user can adjust the volume level within the range of 0 to 100, with the unit string **"dB"** displayed next to the value.
+When the ``Volume`` menu item is selected, the user can adjust the volume level within the range of 0 to 100, and the value will be displayed with the format string ``"%02ddB"``.
 
 .. image:: images/item-int-range.gif
     :width: 400px
@@ -63,15 +63,12 @@ A float range item can be created using the following syntax:
         // Callback function to handle value change
         // value is the selected value within the range
         // Do something with the selected value
-    }, (const char*) " km", 0.5f),
+    }, "%.02f km", 0.5f), // Print the value with two decimal places and the unit string "km" e.g. "5.00 km", "5.50 km"
     // ... More menu items
 
 - The last argument is the step size of the range (the increment or decrement value when changing the value).
-  This argument also determines the number of decimal places to display.
-  For example, a step size of ``0.5`` will display values with one decimal place,
-  while a step size of ``0.01`` will display values with two decimal places.
 
-When the ``Dist`` menu item is selected, the user can adjust the pressure within the range of 0.0 to 100.0, with the unit string **"km"** displayed next to the value.
+When the ``Dist`` menu item is selected, the user can adjust the distance within the range of 0.0 to 100.0
 
 .. image:: images/item-float-range.png
     :width: 400px

examples/IntFloatValues/IntFloatValues.ino

@@ -17,8 +17,8 @@ void callbackFloat(float value);
 // clang-format off
 MENU_SCREEN(mainScreen, mainItems,
     ITEM_BASIC("Con"),
-    ITEM_INT_RANGE("Dist", 100, 200, 100, callbackInt, (const char*) "m"),
-    ITEM_FLOAT_RANGE("Curr", -1.0f, 1.0f, -1.0f, callbackFloat, (const char*) "mA", 0.01f),
+    ITEM_INT_RANGE("Dist", 100, 200, 100, callbackInt, "%02dm"),
+    ITEM_FLOAT_RANGE("Curr", -1.0f, 1.0f, -1.0f, callbackFloat, "%.2fmA", 0.01f),
     ITEM_BASIC("Blink SOS"),
     ITEM_BASIC("Blink random"));
 // clang-format on

examples/SimpleRotary/SimpleRotary.ino

@@ -23,7 +23,7 @@ MENU_SCREEN(mainScreen, mainItems,
     ITEM_BASIC("Connect to WiFi"),
     ITEM_STRING_LIST("Color", colors, 8, colorsCallback),
     ITEM_BASIC("Blink SOS"),
-    ITEM_INT_RANGE("Dist", 0, 50, 0, callback, (const char*) "m"),
+    ITEM_INT_RANGE("Dist", 0, 50, 0, callback, "%dm"),
     ITEM_TOGGLE("Backlight", toggleBacklight),
     ITEM_BASIC("Blink random"));
 // clang-format on

src/ItemFloatRange.h

@@ -2,79 +2,30 @@
 #define ItemFloatRange_H
 
 #include "ItemRangeBase.h"
+#include <utils/printf.h>
 
 /**
  * @brief Item that allows user to input float information within a range.
  * The value can be incremented or decremented by a specified step.
  */
 class ItemFloatRange : public ItemRangeBase<float> {
-  private:
-    uint8_t decimalPlaces = 1;
-
   public:
     ItemFloatRange(
         const char* text,
         const float min,
         const float max,
         float startingValue,
         fptrFloat callback,
-        const char* unit = NULL,
+        const char* format = "%.2f",
         float step = 0.1f,
         bool commitOnChange = false)
-        : ItemRangeBase(text, min, max, startingValue, callback, unit, step, commitOnChange) {
-        decimalPlaces = calculateDecimalPlaces(step);
-    }
+        : ItemRangeBase(text, min, max, startingValue, callback, format, step, commitOnChange) {}
 
     char* getDisplayValue() override {
         static char buffer[10];
-        dtostrf(currentValue, calculateWidth(currentValue, decimalPlaces), decimalPlaces, buffer);
-        if (unit == NULL) {
-            return buffer;
-        }
-        concat(buffer, unit, buffer);
+        snprintf(buffer, sizeof(buffer), format, currentValue);
         return buffer;
     }
-
-    /**
-     * @brief Calculates the width of a floating-point number when displayed with a specified number of decimal places.
-     *
-     * This function computes the width of the string representation of a floating-point number, including the decimal point
-     * and the specified number of decimal places.
-     *
-     * @param currentValue The floating-point number whose width is to be calculated.
-     * @param decimalPlaces The number of decimal places to include in the width calculation.
-     * @return The width of the floating-point number when displayed as a string.
-     */
-    static inline uint8_t calculateWidth(float currentValue, uint8_t decimalPlaces) {
-        int intPart = static_cast<int>(currentValue);
-        int intPartWidth = (intPart == 0) ? 1 : static_cast<int>(log10(abs(intPart))) + 1;
-        return intPartWidth + 1 + decimalPlaces;  // +1 for the decimal point
-    }
-
-    /**
-     * @brief Calculates the number of decimal places in a given floating-point step value.
-     *
-     * This function converts the floating-point step value to a string representation,
-     * then determines the number of decimal places by counting the digits after the
-     * decimal point. Trailing zeros are not counted as decimal places.
-     *
-     * @param step The floating-point step value to analyze.
-     * @return The number of decimal places in the step value.
-     */
-    static uint8_t calculateDecimalPlaces(float step) {
-        char buffer[10];
-        dtostrf(step, 5, 5, buffer);
-
-        char* decimalPos = strchr(buffer, '.');
-        if (decimalPos == NULL) return 0;
-
-        uint8_t numDecimalPlaces = strlen(decimalPos + 1);
-        while (numDecimalPlaces > 0 && buffer[strlen(buffer) - 1] == '0') {
-            buffer[strlen(buffer) - 1] = '\0';
-            numDecimalPlaces--;
-        }
-        return numDecimalPlaces;
-    }
 };
 
 #define ITEM_FLOAT_RANGE(...) (new ItemFloatRange(__VA_ARGS__))

src/ItemInput.h

@@ -61,22 +61,6 @@ class ItemInput : public MenuItem {
      * First parameter will be a `value` string.
      */
     fptrStr callback;
-    /**
-     * @brief The number of visible characters.
-     *
-     * ```
-     *          visible area
-     *        ┌───────────────┐
-     * X X X X│X X X X █ X X X│X X
-     *        ├───────────────┤
-     *        │<── viewSize ─>│
-     * ```
-     *
-     * Effectively const, but initialized lately when renderer is injected.
-     */
-    inline uint8_t getViewSize(MenuRenderer* renderer) const {
-        return renderer->getEffectiveCols() - strlen(text) - 1 + renderer->viewShift;
-    };
 
   public:
     /**

src/ItemIntRange.h

@@ -15,18 +15,14 @@ class ItemIntRange : public ItemRangeBase<int> {
         const int max,
         int startingValue,
         fptrInt callback,
-        const char* unit = NULL,
+        const char* format = "%d",
         int step = 1,
         bool commitOnChange = false)
-        : ItemRangeBase(text, min, max, startingValue, callback, unit, step, commitOnChange) {}
+        : ItemRangeBase(text, min, max, startingValue, callback, format, step, commitOnChange) {}
 
     char* getDisplayValue() override {
         static char buffer[10];
-        itoa(currentValue, buffer, 10);
-        if (unit == NULL) {
-            return buffer;
-        }
-        concat(buffer, unit, buffer);
+        sprintf(buffer, format, currentValue);
         return buffer;
     }
 };

src/ItemRangeBase.h

@@ -9,12 +9,13 @@ template <typename T>
 /**
  * @brief Item that allows user to select a value from a range.
  *        It can be used to display all sorts of values that can be incremented or decremented.
- *        You can additionally pass a unit to be displayed after the value. e.g. "%", "°C", "°F" etc.
+ *        You can additionally pass format string to format the value.
+ *        e.g. you can use `%.2f` to display float with 2 decimal places.
  *
  * ```
- * ┌──────────────────────────────────┐
- * │ > T E X T : V A L U E U N I T    │
- * └──────────────────────────────────┘
+ * ┌────────────────────────────────────────┐
+ * │ > T E X T : F O R M A T E D V A L U E  │
+ * └────────────────────────────────────────┘
  * ```
  *
  * Additionally to `text` this item has float `currentValue`.
@@ -26,7 +27,7 @@ class ItemRangeBase : public MenuItem {
     const T maxValue;
     T currentValue;
     void (*callback)(T);
-    const char* unit;
+    const char* format;
     const T step;
     bool commitOnChange;
 
@@ -39,7 +40,7 @@ class ItemRangeBase : public MenuItem {
      * @param max The maximum value.
      * @param startingValue The current value.
      * @param callback A pointer to the callback function to execute when this menu item is selected.
-     * @param unit The unit e.g. "%", "°C", "°F".
+     * @param format The format string to format the value.
      * @param step The step value for increment/decrement.
      * @param commitOnChange If true, the callback will be called every time the value changes.
      */
@@ -49,10 +50,10 @@ class ItemRangeBase : public MenuItem {
         const T max,
         T startingValue,
         void (*callback)(T),
-        const char* unit = NULL,
+        const char* format = "%s",
         T step = 1,
         bool commitOnChange = false)
-        : MenuItem(text), minValue(min), maxValue(max), currentValue(startingValue), callback(callback), unit(unit), step(step), commitOnChange(commitOnChange) {}
+        : MenuItem(text), minValue(min), maxValue(max), currentValue(startingValue), callback(callback), format(format), step(step), commitOnChange(commitOnChange) {}
 
     /**
      * @brief Increments the value.

src/MenuItem.h

@@ -72,6 +72,22 @@ class MenuItem {
     ~MenuItem() noexcept = default;
 
   protected:
+    /**
+     * @brief The number of available columns for the potential value of the item.
+     *
+     * ```
+     *          visible area
+     *        ┌───────────────┐
+     * X X X X│X X X X █ X X X│X X
+     *        ├───────────────┤
+     *        │<── viewSize ─>│
+     * ```
+     *
+     * Effectively const, but initialized lately when renderer is injected.
+     */
+    inline uint8_t getViewSize(MenuRenderer* renderer) const {
+        return renderer->getEffectiveCols() - strlen(text) - 1 + renderer->viewShift;
+    };
     /**
      * @brief Process a command decoded in 1 byte.
      * It can be a printable character or a control command like `ENTER` or `LEFT`.