gpath-bezier

Drawing complex paths requires a lot of manual work on Pebble. You can do this efficiently and quickly using a Pebble-optimized GPath algorithm and Bezier curves.

This library introduces the GPathBuilder API that allows you to programmatically contruct GPath objects by specifying start and end points for a curve. The builder than adds intermetiary points to make the curve as smooth as is practical.

Code Example

You can draw the path shown above using only the GPathBuilder code below:

// Create GPathBuilder object
GPathBuilder *builder = gpath_builder_create(MAX_POINTS);

// Move to the starting point of the GPath
gpath_builder_move_to_point(builder, GPoint(0, -60));
// Create curve
gpath_builder_curve_to_point(builder, GPoint(60, 0), GPoint(35, -60), GPoint(60, -35));
// Create straight line
gpath_builder_line_to_point(builder, GPoint(-60, 0));
// Create another curve
gpath_builder_curve_to_point(builder, GPoint(0, 60), GPoint(-60, 35), GPoint(-35, 60));
// Create another straight line
gpath_builder_line_to_point(builder, GPoint(0, -60));

// Create GPath object out of our GPathBuilder object
s_path = gpath_builder_create_path(builder);
// Destroy GPathBuilder object
gpath_builder_destroy(builder);

// Get window bounds
GRect bounds = layer_get_bounds(window_get_root_layer(window));
// Move newly created GPath to the center of the screen
gpath_move_to(s_path, GPoint((int16_t)(bounds.size.w/2), (int16_t)(bounds.size.h/2)));

More Information

You can learn more about Bezier curves by reading the Pebble Developers blog post Bezier Curves and GPaths on Pebble.