Tools

Make sure the following tools are installed:

• Visual Studio 2017+
  • Microsoft.VisualStudio.Workload.NativeDesktop workload is needed for Desktop C++ development
• CMake
  • Command cmake should be in %PATH%
  • Verify if cmake --version shows version

If in doubt, run python3 verify_or_install_tools.py (requires Python 3.7+).

Build

git clone https://github.com/sundaramramaswamy/inker

cd inker

cmake -B build

cmake --build build

This should build ink.exe under //build/Debug.

Open Visual Studio with

start build\Inker.sln

In the Solution Explorer, right-click ink project and click Set as Startup Project.

Code

Add new sources (.h/.cpp) to src/ and list them in //CMakeLists.txt along with other sources. Build in Visual Studio. It should pick up the changes you made in the CMake script.

Workshop Mini-project

Controller/Adapter

The idea is to implement an inking application using MVA Pattern (an extension of MVC). Refer and use the interfaces in eventing.h and view.h; implement a Controller class which extends/inherits from WindowEventHandler -- an interface containing methods like OnMousePressed, OnKeyReleased, OnPaint, etc.

Model

Build an ink document (model) using the OnMousePressed, OnMouseDragged and OnMouseReleased functions. One way to structure your document

Document
  Collection of Stroke

Stroke
  Collection of Points

Point
  A pair of floats (Vector2)

When the user clicks, drags and releases the mouse, you'd get a bunch of points which form one stroke. A document is a collection of such strokes.

View

During the OnPaint(View*) you'd refer to your document (model) and for every stroke do a bunch of View::DrawLine calls. This would render the document on to the view.

Files

The default state of the project comes with a TestController class (//src/test_controller.h) that simply logs the events it receives and paints Hello, world. You've to implement your own InkController for the above work. Make sure in main.cpp you set your InkController as the window's event handler. Other than main.cpp, eventing.h and view.h you can pretty much ignore all the other files in the project.

Extensions

Stroke Erase

When the user clicks a stroke with Ctrl held down, you can hit-test all the strokes in the document and check if the click was atop a stroke. If yes, you'd remove that stroke from your document. In the next OnPaint call this change would automatically be picked up and you don't have to do anything extra to see the stroke go away.

Multi-Colour Strokes

You can make the document fancy by having strokes of different colours. It’s up to you define how to switch the pen colour. One way would be to assign colours to keyboard keys 1 (Black), 2 (Red), 3 (Blue), etc. and switch the colour when the user presses a corresponding key. You’d store every stroke with a colour in your model. During render, you’d draw the stroke with DrawLines passing the stroke’s colour as Color (which is a collection of four unsigned chars).

C++ Material

• Spirit of C++
• C++ Language and Standard Library Reference
  • Keep this open when you’re writing C++ code
• C++ Function Parameter Choices -- Cheatsheet
  • Useful to know what parameter type to take in functions
• C++ ISO FAQ
  • Very useful when you’ve doubts