graphics.h: Add initial version

openrtx/include/interfaces/graphics.h

@@ -0,0 +1,128 @@
+/***************************************************************************
+ *   Copyright (C) 2020 by Federico Amedeo Izzo IU2NUO,                    *
+ *                         Niccolò Izzo IU2KIN                             *
+ *                         Silvano Seva IU2KWO                             *
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 3 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ *   This program is distributed in the hope that it will be useful,       *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+ *   GNU General Public License for more details.                          *
+ *                                                                         *
+ *   You should have received a copy of the GNU General Public License     *
+ *   along with this program; if not, see <http://www.gnu.org/licenses/>   *
+ ***************************************************************************/
+
+#ifndef GRAPHICS_H
+#define GRAPHICS_H
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <display.h>
+
+/**
+ * Standard high-level graphic interface for all display types.
+ * This interface is based on the lower level interface display.h
+ * Many methods of graphics.h are basically calls to methods in display.h.
+ *
+ * On top of basic framebuffer and backlight control, graphics.h implements
+ * graphics primitives for drawing fonts and shapes
+ *
+ *********************** HOW TO MANAGE FRAMEBUFFER *****************************
+ *
+ * This driver allocates the framebuffer as a block of linearly addressed memory
+ * equivalent to an array of SCREEN_HEIGHT*SCREEN_WIDTH elements.
+ * With respect to it, screen is indexed in this way:
+ *
+ *   (0,0)
+ *     +-------> x
+ *     |
+ *     |    o (X,Y)
+ *     |
+ *     v
+ *     y
+ *
+ * then to set the value of the pixel having coordinates (X,Y), framebuffer has
+ * to be indexed in this way: buf[X + Y*SCREEN_WIDTH].
+ *
+ */
+
+/**
+ * This function calls the correspondent method of the low level interface display.h
+ * It initializes the display and sets the backlight to zero.
+ */
+void graphics_init();
+
+/**
+ * This function calls the correspondent method of the low level interface display.h
+ * It turns off backlight, shuts down backlight control and deallocates the framebuffer.
+ */
+void graphics_terminate();
+
+/**
+ * This function calls the correspondent method of the low level interface display.h
+ * Get screen width in pixels.
+ * @return screen width, in pixels.
+ */
+uint16_t graphics_screenWidth();
+
+/**
+ * This function calls the correspondent method of the low level interface display.h
+ * Get screen height in pixels.
+ * @return screen height, in pixels.
+ */
+uint16_t graphics_screenHeight();
+
+/**
+ * This function calls the correspondent method of the low level interface display.h
+ * Set screen backlight to a given level.
+ * @param level: backlight level, from 0 (backlight off) to 255 (backlight at
+ * full brightness).
+ */
+void graphics_setBacklightLevel(uint8_t level);
+
+/**
+ * This function calls the correspondent method of the low level interface display.h
+ * Copy a given section, between two given rows, of framebuffer content to the
+ * display.
+ * @param startRow: first row of the framebuffer section to be copied
+ * @param endRow: last row of the framebuffer section to be copied
+ */
+void graphics_renderRows(uint8_t startRow, uint8_t endRow);
+
+/**
+ * This function calls the correspondent method of the low level interface display.h
+ * Copy framebuffer content to the display internal buffer. To be called
+ * whenever there is need to update the display.
+ */
+void graphics_render();
+
+/**
+ * This function calls the correspondent method of the low level interface display.h
+ * Check if framebuffer is being copied to the screen or not, in which case it
+ * can be modified without problems.
+ * @return false if rendering is not in progress.
+ */
+bool graphics_renderingInProgress();
+
+/**
+ * This function calls the correspondent method of the low level interface display.h
+ * Get pointer to framebuffer. Being this a standard interface for all the
+ * low-level display drivers, this function returns a pointer to void: it's up
+ * to the caller performing the correct cast to one of the standard types used
+ * for color coding.
+ * Changes to the framebuffer will not be reflected on the display until
+ * graphics_render() or graphics_renderRows() are called.
+ *
+ * 
+ * WARNING: no bound check is performed! Do not call free() on the pointer
+ * returned, doing so will destroy the framebuffer!
+ * @return pointer to framebuffer.
+ */
+void *graphics_getFrameBuffer();
+
+#endif /* GRAPHICS_H */