littlevgl_image_dsc_buffer.c

#define USE_SDL 1

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "lvgl/lvgl.h"
#include <pango/pangocairo.h>

#if USE_SDL
#include <SDL2/SDL.h>
#include "lv_drivers/display/monitor.h"
#else
#include "lv_drivers/display/fbdev.h"
#endif

static char * label_text = "Billy Bob 你会说英语吗";
static char * label_text2 = "不用谢 かわいい!";

static void hal_init(void);
void disp_init(void);
void build_container(lv_obj_t * parent);

int main (int argc, char ** argv)
{
    lv_init();
    hal_init();
    disp_init();

    while (1) {
        lv_tick_inc(5);
        lv_task_handler();
        usleep(5 * 1000);
    }
}

static void hal_init(void)
{
    #if USE_SDL
        monitor_init();
    #else
        fbdev_init();
    #endif

    lv_disp_drv_t disp_drv;
    lv_disp_drv_init(&disp_drv);

    #if USE_SDL
        disp_drv.disp_flush = monitor_flush;
        disp_drv.disp_fill = monitor_fill;
        disp_drv.disp_map = monitor_map;
    #else
        disp_drv.disp_flush = fbdev_flush;
        disp_drv.disp_fill = fbdev_fill;
        disp_drv.disp_map = fbdev_map;
    #endif

    lv_disp_drv_register(&disp_drv);
}

void disp_init(void)
{
    lv_obj_t *scr = lv_obj_create(NULL, NULL);
    lv_scr_load(scr);

    build_container(scr);
    build_container2(scr);
}

cairo_t*
create_layout_context ()
{
    cairo_surface_t *temp_surface;
    cairo_t *context;

    temp_surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, 0, 0);
    context = cairo_create (temp_surface);
    cairo_surface_destroy (temp_surface);

    return context;
}

cairo_t*
create_cairo_context (int width,
                      int height,
                      int channels,
                      cairo_surface_t** surf,
                      unsigned char** buffer)
{
    *buffer = calloc (channels * width * height, sizeof (unsigned char));
    *surf = cairo_image_surface_create_for_data (*buffer,
                                                 CAIRO_FORMAT_ARGB32,
                                                 width,
                                                 height,
                                                 channels * width);
    return cairo_create (*surf);
}

void build_container(lv_obj_t *parent)
{
    lv_obj_t *main_container = lv_obj_create(parent, NULL);
    lv_obj_set_size(main_container, 200, 100);

    cairo_t *layout_context;
    cairo_t *render_context;
    cairo_surface_t *surface;
    PangoFontDescription *desc;
    PangoLayout *layout;
    unsigned int *text_width = 200;
    unsigned int *text_height = 100;
    char * sd;

    layout_context = create_layout_context ();

    layout = pango_cairo_create_layout (layout_context);
    pango_layout_set_text (layout, label_text, -1);

    desc = pango_font_description_from_string("Noto Sans");
    render_context = create_cairo_context(text_width, text_height, 4, &surface, &sd);

    cairo_set_source_rgba (render_context, 0.333, 0.588, 0.847, 1);
    cairo_paint(render_context);

    cairo_set_source_rgba (render_context, 0.0, 0.0, 1.0, 1);
    pango_cairo_show_layout(render_context, layout);

    static lv_img_dsc_t thing;
    thing.header.w = text_width;
    thing.header.h = text_height;
    thing.header.cf = LV_IMG_CF_TRUE_COLOR;
    thing.header.always_zero = 0;
    thing.data_size = sizeof(sd);
    thing.data = sd;

    lv_obj_t *img = lv_img_create(main_container, NULL);
    lv_img_set_src(img, &thing);

    // /* Clean up */
    free(sd);
    g_object_unref (layout);
    cairo_destroy (layout_context);
    cairo_destroy (render_context);
    cairo_surface_destroy (surface);
}

void build_container2(lv_obj_t *parent)
{
    lv_obj_t *main_container = lv_obj_create(parent, NULL);
    lv_obj_set_size(main_container, 200, 100);

    cairo_t *layout_context;
    cairo_t *render_context;
    cairo_surface_t *surface;
    PangoFontDescription *desc;
    PangoLayout *layout;
    unsigned int *text_width = 200;
    unsigned int *text_height = 100;
    char * sd;

    layout_context = create_layout_context ();

    layout = pango_cairo_create_layout (layout_context);
    pango_layout_set_text (layout, label_text2, -1);

    desc = pango_font_description_from_string("Noto Sans");
    render_context = create_cairo_context(text_width, text_height, 4, &surface, &sd);

    cairo_set_source_rgba (render_context, 0.333, 0.588, 0.847, 1);
    cairo_paint(render_context);

    cairo_set_source_rgba (render_context, 0.0, 0.0, 1.0, 1);
    pango_cairo_show_layout(render_context, layout);

    static lv_img_dsc_t thing;
    thing.header.w = text_width;
    thing.header.h = text_height;
    thing.header.cf = LV_IMG_CF_TRUE_COLOR;
    thing.header.always_zero = 0;
    thing.data_size = sizeof(sd);
    thing.data = sd;

    lv_obj_t *img = lv_img_create(main_container, NULL);
    lv_img_set_src(img, &thing);
    lv_obj_align(main_container, parent, LV_ALIGN_IN_BOTTOM_MID, 0, 0);

    // /* Clean up */
    free(sd);
    g_object_unref (layout);
    cairo_destroy (layout_context);
    cairo_destroy (render_context);
    cairo_surface_destroy (surface);
}