Added graphic primitives

Makefile

@@ -5,8 +5,8 @@ ISPPORT ?= /dev/kaboard
 VERSION = 0.1
 
 HEADERS = include/spi.h include/st7735.h include/st7735initcmds.h
-HEADERS += images/logo_bw.h images/logo.h
-SRC = main.c spi.c st7735.c
+HEADERS += images/logo_bw.h images/logo.h include/st7735_gfx.h
+SRC = main.c spi.c st7735.c st7735_gfx.c
 TARGET = st7735_test
 OBJDIR = bin
 

include/st7735.h

@@ -93,7 +93,7 @@ void st7735_init(void);
 
 void st7735_set_orientation(enum ST7735_ORIENTATION orientation);
 
-void st7735_draw_pixel(uint8_t x, uint8_t y, uint16_t color);
+void st7735_draw_pixel(int16_t x, int16_t y, uint16_t color);
 void st7735_fill_rect(uint8_t x, uint8_t y, uint8_t w, uint8_t h, uint16_t color);
 
 static inline void st7735_draw_fast_vline(uint8_t x, uint8_t y, uint8_t h, uint16_t color) {

include/st7735_gfx.h

@@ -0,0 +1,10 @@
+#ifndef _ST7735_GFX_H_
+#define _ST7735_GFX_H_
+
+#include<stdint.h>
+
+void st7735_draw_line(uint8_t x0, uint8_t y0, uint8_t x1, uint8_t y1, uint16_t color);
+void st7735_draw_rect(uint8_t x, uint8_t y, uint8_t w, uint8_t h,  uint16_t color);
+void st7735_draw_circle(uint8_t x0, uint8_t y0, uint8_t r, uint16_t color);
+
+#endif

main.c

@@ -3,6 +3,7 @@
 
 #include "spi.h"
 #include "st7735.h"
+#include "st7735_gfx.h"
 
 #include "logo.h"
 #include "logo_bw.h"
@@ -18,5 +19,30 @@ int main(void) {
 
     st7735_draw_bitmap(10, 10, &logo);
 
+
+    for(uint8_t x = 8; x <= 160; x += 8) {
+        st7735_draw_line(0, 0, x, 128, ST7735_COLOR_GREEN);
+    }
+
+    for(uint8_t y = 8; y <= 128; y += 8) {
+        st7735_draw_line(0, 0, 160, y, ST7735_COLOR_GREEN);
+    }
+
+    for(uint8_t r = 8; r <= 80; r += 8) {
+        st7735_draw_circle(80, 64, r, ST7735_COLOR_RED);
+    }
+
+    for(uint8_t r = 8; r <= 160; r += 8) {
+        st7735_draw_circle(0, 0, r, ST7735_COLOR_BLUE);
+    }
+
+    uint8_t h = 16;
+    uint8_t w = 20;
+    for(uint8_t i = 0; i < 8; i++) {
+        st7735_draw_rect(80 - w / 2, 64 - h / 2, w, h, ST7735_COLOR_YELLOW);
+        h += 16;
+        w += 20;
+    }
+
     while(1);
 }

st7735.c

@@ -243,7 +243,7 @@ void st7735_set_addr_win(uint8_t x0, uint8_t y0, uint8_t x1, uint8_t y1) {
 	st7735_write_cmd(ST7735_RAMWR); // write to RAM
 }
 
-void st7735_draw_pixel(uint8_t x, uint8_t y, uint16_t color) {
+void st7735_draw_pixel(int16_t x, int16_t y, uint16_t color) {
 	if(x < 0 || x >= st7735_width || y < 0 || y >= st7735_height){
 		return;
 	}

st7735_gfx.c

@@ -0,0 +1,103 @@
+#include "st7735_gfx.h"
+
+#include<stdlib.h>
+
+#include "st7735.h"
+
+#define _swap_uint8_t(a, b) { uint8_t t = a; a = b; b = t; }
+
+void st7735_draw_line(uint8_t x0, uint8_t y0, uint8_t x1, uint8_t y1, uint16_t color) {
+	uint8_t steep_dir = abs(y1 - y0) > abs(x1 - x0);
+	if (steep_dir) {
+		_swap_uint8_t(x0, y0);
+		_swap_uint8_t(x1, y1);
+	}
+
+	if (x0 > x1) {
+		_swap_uint8_t(x0, x1);
+		_swap_uint8_t(y0, y1);
+	}
+
+  	int16_t dx, dy;
+  	dx = x1 - x0;
+  	dy = abs(y1 - y0);
+
+	int16_t err = dx / 2;
+	int16_t y_step;
+
+	if (y0 < y1) {
+		y_step = 1;
+	} else {
+		y_step = -1;
+	}
+
+	uint8_t seg = x0;
+	uint8_t cur_x;
+	for(cur_x = x0; cur_x <= x1; cur_x++) {
+		err -= dy;
+		if (err < 0) {
+			if (steep_dir) {
+				st7735_draw_fast_vline(y0, seg, cur_x - seg + 1, color);
+			} else {
+				st7735_draw_fast_hline(seg, y0, cur_x - seg +1, color);
+			}
+			y0 += y_step;
+			err += dx;
+			seg = cur_x + 1;
+		}
+	}
+
+	// x0 incremented
+	if (steep_dir) {
+		st7735_draw_fast_vline(y0, seg, cur_x - seg, color);
+	} else {
+		st7735_draw_fast_hline(seg, y0, cur_x - seg, color);
+	}
+}
+
+
+void st7735_draw_rect(uint8_t x, uint8_t y, uint8_t w, uint8_t h, uint16_t color) {
+	if(w < 1 || h < 1) {
+			return;
+	}
+
+	st7735_draw_fast_hline(x, y, w, color);
+	st7735_draw_fast_hline(x, y + h - 1, w, color);
+	st7735_draw_fast_vline(x, y, h, color);
+	st7735_draw_fast_vline(x + w - 1, y, h, color);
+}
+
+
+void st7735_draw_circle(uint8_t x0, uint8_t y0, uint8_t r, uint16_t color) {
+	int16_t f = 1 - r;
+	int16_t ddF_x = 1;
+	int16_t ddF_y = -2 * r;
+	int16_t x = 0;
+	int16_t y = r;
+
+	st7735_draw_pixel(x0, y0 + r, color);
+	st7735_draw_pixel(x0, y0 - r, color);
+	st7735_draw_pixel(x0 + r, y0, color);
+	st7735_draw_pixel(x0 - r, y0, color);
+
+	while (x<y) {
+		if (f >= 0) {
+			y--;
+			ddF_y += 2;
+			f += ddF_y;
+		}
+
+		x++;
+		ddF_x += 2;
+		f += ddF_x;
+
+		st7735_draw_pixel(x0 + x, y0 + y, color);
+		st7735_draw_pixel(x0 - x, y0 + y, color);
+		st7735_draw_pixel(x0 + x, y0 - y, color);
+		st7735_draw_pixel(x0 - x, y0 - y, color);
+		st7735_draw_pixel(x0 + y, y0 + x, color);
+		st7735_draw_pixel(x0 - y, y0 + x, color);
+		st7735_draw_pixel(x0 + y, y0 - x, color);
+		st7735_draw_pixel(x0 - y, y0 - x, color);
+	}
+}