From 2fa69a20a17f44fc099032d34e9c32e51b0f48f4 Mon Sep 17 00:00:00 2001 From: Drath Vader Date: Sat, 27 Jun 2026 20:03:48 +0200 Subject: [PATCH] yeahhhh --- CMakeLists.txt | 4 +++ README.md | 7 ++++ gfx.c | 92 ++++++++++++++++++++++++++++++++++++++++++++++++++ gfx.h | 43 +++++++++++++++++++++++ 4 files changed, 146 insertions(+) create mode 100644 CMakeLists.txt create mode 100644 README.md create mode 100644 gfx.c create mode 100644 gfx.h diff --git a/CMakeLists.txt b/CMakeLists.txt new file mode 100644 index 0000000..ea26dab --- /dev/null +++ b/CMakeLists.txt @@ -0,0 +1,4 @@ +idf_component_register( + SRCS "gfx.c" + INCLUDE_DIRS "." +) diff --git a/README.md b/README.md new file mode 100644 index 0000000..d98642b --- /dev/null +++ b/README.md @@ -0,0 +1,7 @@ +# Simple graphics library + +Will draw Adafruit GFX compatible fonts, lines, squares, and it will also fill a square. It can draw or clear any of these. That's it, graphics as God intended. + +Made for ST7920 with my own driver library, but it should be pretty universal, it just needs draw and clear functions taking x,y coords of a pixel + some user context. + +Idk why I added a readme, it's pretty self documenting. Maybe i'll break this into it's own git repo and add it as submodule, along with the disp driver. \ No newline at end of file diff --git a/gfx.c b/gfx.c new file mode 100644 index 0000000..2b5a471 --- /dev/null +++ b/gfx.c @@ -0,0 +1,92 @@ +#include "gfx.h" + +#include + +void gfx_draw_char(const gfx_canvas_t *canvas, const GFXfont *f, const bool inverted, const int16_t x, const int16_t y, const char c) { + void (*draw_cb)(void* ctx, uint8_t x, uint8_t y) = inverted ? canvas->clear_pixel_callback : canvas->draw_pixel_callback; + if (c < f->first || c > f->last) return; + + const GFXglyph *g = &f->glyph[c - f->first]; + const uint8_t *bm = f->bitmap + g->bitmapOffset; + + uint16_t bit = 0; // current bit index into bitmap bytes + + for (uint8_t row = 0; row < g->height; row++) + for (uint8_t col = 0; col < g->width; col++, bit++) + if (bm[bit / 8] & (0x80 >> (bit & 7))) + draw_cb(canvas->ctx, x + g->xOffset + col, y + g->yOffset + row); +} + +int16_t gfx_string_width(const GFXfont *f, const char *s) { + int16_t w = 0; + while (*s) { + const char c = *s++; + if (c >= f->first && c <= f->last) + w += f->glyph[c - f->first].xAdvance; + } + return w; +} + +/* returns x position of the end of the string */ +int16_t gfx_draw_string(const gfx_canvas_t *canvas, const GFXfont *f, int16_t x, const int16_t y, const char *s, const bool inverted) { + while (*s) { + gfx_draw_char(canvas, f, inverted, x, y, *s); + const char c = *s++; + if (c >= f->first && c <= f->last) + x += f->glyph[c - f->first].xAdvance; + } + return x; +} + +int16_t gfx_draw_string_centered(const gfx_canvas_t *canvas, const GFXfont *f, const int16_t centerpoint, const int16_t y, const char *s, const bool inverted) { + const uint8_t x = centerpoint - gfx_string_width(f, s) / 2; + return gfx_draw_string(canvas, f, x, y, s, inverted); +} + +/* only draws top->bottom and left->right */ +void gfx_draw_line(const gfx_canvas_t *canvas, const uint8_t start_x, const uint8_t start_y, const uint8_t end_x, const uint8_t end_y, const bool inverted) { + void (*draw_cb)(void* ctx, uint8_t x, uint8_t y) = inverted ? canvas->clear_pixel_callback : canvas->draw_pixel_callback; + const uint8_t dx = end_x - start_x; + const uint8_t dy = end_y - start_y; + + // if it's a straight line just draw it + if (dx == 0) { + for (uint8_t y = start_y; y < end_y; y++) + draw_cb(canvas->ctx, start_x, y); + return; + } + + if (dy == 0) { + for (uint8_t x = start_x; x < end_x; x++) + draw_cb(canvas->ctx, x, start_y); + return; + } + + // if not, do bresenham's line algo + int16_t D = 2*dy - dx; + uint8_t y = start_y; + + for (uint8_t x = start_x; x <= end_x; x++) { + draw_cb(canvas->ctx, x, y); + if (D > 0) { + y++; + D += (2 * (dy - dx)); + } else { + D += 2*dy; + } + } +} + +void gfx_draw_box(const gfx_canvas_t *canvas, const uint8_t pos_x, const uint8_t pos_y, const uint8_t size_x, const uint8_t size_y, const bool inverted) { + gfx_draw_line(canvas, pos_x, pos_y, pos_x + size_x - 1, pos_y, inverted); + gfx_draw_line(canvas, pos_x + size_x - 1, pos_y, pos_x + size_x - 1, pos_y + size_y - 1, inverted); + gfx_draw_line(canvas, pos_x, pos_y + size_y - 1, pos_x + size_x, pos_y + size_y - 1, inverted); + gfx_draw_line(canvas, pos_x, pos_y, pos_x, pos_y + size_y, inverted); +} + +void gfx_fill_box(const gfx_canvas_t *canvas, const uint8_t pos_x, const uint8_t pos_y, const uint8_t size_x, const uint8_t size_y, const bool inverted) { + void (*draw_cb)(void* ctx, uint8_t x, uint8_t y) = inverted ? canvas->clear_pixel_callback : canvas->draw_pixel_callback; + for (uint8_t x = pos_x; x < pos_x + size_x; x++) + for (uint8_t y = pos_y; y < pos_y + size_y; y++) + draw_cb(canvas->ctx, x, y); +} \ No newline at end of file diff --git a/gfx.h b/gfx.h new file mode 100644 index 0000000..2d63f9c --- /dev/null +++ b/gfx.h @@ -0,0 +1,43 @@ +#pragma once +#include +#include + +// compatibility for adafruit fonts +#ifndef PROGMEM +#define PROGMEM +#endif + +typedef struct { + uint16_t bitmapOffset; + uint8_t width, height; + uint8_t xAdvance; + int8_t xOffset, yOffset; +} GFXglyph; + +typedef struct { + const uint8_t *bitmap; + const GFXglyph *glyph; + uint8_t first, last; + uint8_t yAdvance; +} GFXfont; + +/** + * @brief Canvas struct for the gfx library + * Functions take the context and x,y coordinates of a pixel + * + * @param ctx any context that the draw/clear functions might need, ie display device + * @param draw_pixel_callback function that gets called to draw a pixel + * @param clear_pixel_callback function that gets called to clear a pixel + */ +typedef struct { + void (*draw_pixel_callback)(void *ctx, uint8_t x, uint8_t y); + void (*clear_pixel_callback)(void *ctx, uint8_t x, uint8_t y); + void *ctx; +} gfx_canvas_t; + +int16_t gfx_string_width(const GFXfont *f, const char *s); +int16_t gfx_draw_string(const gfx_canvas_t *canvas, const GFXfont* f, int16_t x, int16_t y, const char *s, bool inverted); +int16_t gfx_draw_string_centered(const gfx_canvas_t *canvas, const GFXfont *f, int16_t centerpoint, int16_t y, const char *s, bool inverted); +void gfx_draw_line(const gfx_canvas_t *canvas, uint8_t start_x, uint8_t start_y, uint8_t end_x, uint8_t end_y, bool inverted); +void gfx_draw_box(const gfx_canvas_t *canvas, uint8_t pos_x, uint8_t pos_y, uint8_t size_x, uint8_t size_y, bool inverted); +void gfx_fill_box(const gfx_canvas_t *canvas, uint8_t pos_x, uint8_t pos_y, uint8_t size_x, uint8_t size_y, bool inverted);