Updated README.md with examples for ProgressBar usage

README.md

@@ -5,3 +5,123 @@
 <p align="center">
   <img src="img/demo.gif"/> 
 </p>
+
+## Progress bar
+
+To introduce a progress bar in your application, include `indica/progress_bar.hpp` and create a `ProgressBar` object. 
+
+```cpp
+#include <indica/progress_bar.hpp>
+
+int main() {
+  indica::ProgressBar bar;
+  return 0;
+}
+```
+
+Here's the general structure of a progress bar:
+
+```
+<prefix_text> <bar_start> <fill> <lead> <remaining> <bar_end>   <progress_percentage> <postfix_text>
+              ^^^^^^^^^^^^^^^^^^ Bar Width ^^^^^^^^^^^^^^^^^^   ^^^^^ Show/Hide ^^^^^
+```
+
+Each of these elements can be configured using the ProgressBar API:
+
+```cpp
+#include <indica/progress_bar.hpp>
+
+int main() {
+  indica::ProgressBar bar;
+  
+  // Configure the bar
+  bar.set_bar_width(50);
+  bar.start_bar_with("[");
+  bar.fill_bar_progress_with("=");
+  bar.lead_bar_progress_with(">");
+  bar.fill_bar_remainder_with(" ");
+  bar.end_bar_with("]");
+  bar.set_postfix_text("Getting started");
+  bar.set_foreground_color(indica::Color::GREEN); 
+
+  return 0;
+}
+```
+
+Now that the bar is configured, let's update the state of the bar. The amount of progress in ProgressBar is maintained as a float in range `[0, 100]`. When progress reaches 100, the progression is complete. 
+
+From application-level code, there are two ways in which you can update this progress:
+
+### Update progress using `tick()`
+
+You can update the progress bar using `bar.tick()` which increments progress by exactly `1%`.
+
+```cpp
+#include <indica/progress_bar.hpp>
+#include <thread>
+#include <chrono>
+
+int main() {
+  indica::ProgressBar bar;
+  
+  // Configure the bar
+  bar.set_bar_width(50);
+  bar.start_bar_with("[");
+  bar.fill_bar_progress_with("=");
+  bar.lead_bar_progress_with(">");
+  bar.fill_bar_remainder_with(" ");
+  bar.end_bar_with("]");
+  bar.set_postfix_text("Getting started");
+  bar.set_foreground_color(indica::Color::GREEN); 
+  
+  // Update bar state
+  while (true) {
+    bar.tick();
+    if (bar.is_completed())
+      break;
+    std::this_thread::sleep_for(std::chrono::milliseconds(100));
+  }
+
+  return 0;
+}
+```
+
+The above code will print a progress bar that goes from 0 to 100% at the rate of 1% every 100 ms.
+
+### Updating progress using `bar.set_progress(value)`
+
+If you'd rather control progress of the bar in discrete steps, consider using `bar.set_progress(value)`. Example:
+
+```cpp
+#include <indica/progress_bar.hpp>
+#include <thread>
+#include <chrono>
+
+int main() {
+  indica::ProgressBar bar;
+  
+  // Configure the bar
+  bar.set_bar_width(50);
+  bar.start_bar_with("[");
+  bar.fill_bar_progress_with("=");
+  bar.lead_bar_progress_with(">");
+  bar.fill_bar_remainder_with(" ");
+  bar.end_bar_with("]");
+  bar.set_postfix_text("Getting started");
+  bar.set_foreground_color(indica::Color::GREEN); 
+  
+  // Update bar state
+  size_t i = 0;
+  while (i < 101) {
+    bar.set_progress(i);
+    std::this_thread::sleep_for(std::chrono::milliseconds(100));
+    i += 10;
+  }
+
+  return 0;
+}
+```
+
+The above code will print a progress bar that goes from 0 to 100% at the rate of 10% every 100 ms.
+
+For more examples, checkout the examples in the `samples/` directory.