Graphic Library

Graphic Library provides functions for drawing to a display driver.

To use this library

Header: #include "gl.h"

memake: MikroSDK.GraphicLibrary

The library is responsible for common drawing tasks and uses gl_driver_t structure to interface with underlying display driver. The library supports drawing common graphical primitives, images and texts. The library has modular architecture, so it can work with any driver which implements gl_driver_t interface, including some click board drivers.

Initialization

Before using any of the drawing functions, a driver must be initialized and set, as shown below:

#include "gl.h"
#include "board.h"
#include "tft8.h"

static gl_driver_t driver;
static tft8_cfg_t tft_cfg;

  void main ()
  {
     // initialize driver 
     TFT8_MAP_PINOUTS_16BIT(tft_cfg);
     tft_cfg.board = &TFT_BOARD_7_CAPACITIVE;
     tft8_init(&tft_cfg, &driver);

     gl_set_driver(&driver); // Set driver before drawing

     // Drawing is now available...
  }

driver instance is specific to a display driver and it must be initialized before using any drawing functions. Component library usually provides an initialization function for the driver instance. For more detailed explanation for how to properly initialize a component's driver, refer to its documentation.

Drawing

Drawing to a display is done by setting GL state for pen, brush, font, etc. and calling draw functions. The following example shows how to clear a display with black color, set pen to white color 3px wide, and draw a center aligned rectangle.

// Assume driver is already set

gl_clear(GL_BLACK);  // Clear screen.

gl_set_pen(&gl, GL_WHITE, 3);  // Set pen.

uint16_t center_x = gl_get_screen_width(&gl) / 2 - 50;
uint16_t center_y = gl_get_screen_height(&gl) / 2 - 50;
gl_draw_rect(center_x, center_y, 100, 100);

Coordinate system

The library uses cartesian coordinate system in plane, and each point represents one pixel on display. The origin is placed in top-left corner of a display. The x value increases to the right and the y value increases downwards.

Reference