A display test for BMP file (includes 24bit RGB and 32bit RGBA) using LVGL Canvas function

pros_lvgl_canvas_image_test.cpp

#include "main.h"

void drawBmp(lv_obj_t* canvas, const char* filename){
    printf("Start: %d\n",pros::millis());

    FILE* f = fopen(filename, "rb");
    unsigned char info[54];
    fread(info, sizeof(unsigned char), 54, f); // read the 54-byte header

    // extract image height and width from header
    int width = *(int*)&info[18];
    int height = *(int*)&info[22];

    int pixelbit = info[28] / 8;
    int linebyte = width * pixelbit;
    int offset = linebyte % 4;
    if (offset != 0)
        offset = 4 - offset;

    bool isBottom = false;
    if (height > 0) // read from bottom
        isBottom = true;

    printf("%d %d %d\n",offset,linebyte,pixelbit);

    int size = pixelbit * width * height;
    unsigned char* data = new unsigned char[size]; // allocate 3 bytes per pixel
    fread(data, sizeof(unsigned char), size, f); // read the rest of the data at once
    fclose(f);
    //lv_color_t pbuf[width][height] = {0};
    printf("Finish read: %d\n",pros::millis());
    int ing_w = 0;
    int ing_h = 0;
    for(int i = 0; i < size; i += 3) {
        //BGR color mode 
        //i+2 = red, i+1 = green, i = blue
        int x = ing_w;
        int y = isBottom ? (height - ing_h - 1) : ing_h;
        lv_color_t c = LV_COLOR_MAKE(data[i+2],data[i+1],data[i]);
        
        ing_w += 1;
        if(ing_w >= width){
            ing_w = 0;
            ing_h += 1;
        }

        lv_canvas_set_px(canvas,x,y,c);//Maybe change
    }
    
    printf("Finish draw: %d\n",pros::millis());
}


void draw32BitBmp(lv_obj_t* canvas, const char* filename){
    printf("Start: %d\n",pros::millis());

    FILE* f = fopen(filename, "rb");
    unsigned char info[54];
    fread(info, sizeof(unsigned char), 54, f); // read the 54-byte header

    // extract image height and width from header
    int width = *(int*)&info[18];
    int height = *(int*)&info[22];

    int pixelbit = info[28] / 8;
    int linebyte = width * pixelbit;
    int offset = linebyte % 4;
    if (offset != 0)
        offset = 4 - offset;

    bool isBottom = false;
    if (height > 0) // read from bottom
        isBottom = true;

    printf("%d %d %d\n",offset,linebyte,pixelbit);

    int size = pixelbit * width * height;
    unsigned char* data = new unsigned char[size]; // allocate 3 bytes per pixel
    fread(data, sizeof(unsigned char), size, f); // read the rest of the data at once
    fclose(f);
    //lv_color_t pbuf[width][height] = {0};
    printf("Finish read: %d\n",pros::millis());
    int ing_w = 0;
    int ing_h = 0;
    for(int i = 0; i < size; i += pixelbit) {
        //BGR color mode 
        //i+2 = red, i+1 = green, i = blue
        int x = ing_w;
        int y = isBottom ? (height - ing_h - 1) : ing_h;

        int a = pixelbit == 4 ? data[i+3] : 255;
        int r = data[i+2];
        int g = data[i+1];
        int b = data[i];
        
        float a_float = a / 2.55 / 100;
        float a_m_float = 1 - a_float;

        lv_color_t bg_c = lv_canvas_get_px(canvas, x, y);
        bg_c.red   = bg_c.red   * a_m_float + r * a_float;
        bg_c.green = bg_c.green * a_m_float + g * a_float;
        bg_c.blue  = bg_c.blue  * a_m_float + b * a_float;
        
        ing_w += 1;
        if(ing_w >= width){
            ing_w = 0;
            ing_h += 1;
        }

        lv_canvas_set_px(canvas,x,y,bg_c);//Maybe change
    }
    
    printf("Finish draw: %d\n",pros::millis());
}


void initialize() {
    pros::delay(100);
    
    printf("Dummy init");
    
    lv_obj_t * jcd_dummy = lv_canvas_create(lv_scr_act(), NULL);
    lv_obj_set_size(jcd_dummy, 480, 240);
    
    printf("Canvas init");

    static lv_color_t cbuf[sizeof(lv_color_t) * 480 * 240];
    uint32_t i;
    for(i = 0; i < sizeof(cbuf) / sizeof(cbuf[0]); i++) {
        cbuf[i] = LV_COLOR_HEX3(0xacf);
    }

    /*Create the canvas object*/
    lv_obj_t * canvas = lv_canvas_create(jcd_dummy, NULL);

    /*Assign the buffer to the canvas*/
    lv_canvas_set_buffer(canvas, cbuf, 480, 240, LV_IMG_CF_TRUE_COLOR);

    printf("Draw test");
    
    //drawBmp(canvas,"/usd/pros-icon.bmp");
    draw32BitBmp(canvas,"/usd/pros-icon-rgba.bmp");
}

void disabled() {}

void competition_initialize() {}