pixel_mode.c

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#include <banjo/log.h>
#include <banjo/main.h>
#include <banjo/pixel.h>
 
void display_value(bj_pixel_mode mode, uint8_t red, uint8_t green, uint8_t blue) {
    // bj_get_pixel_value() converts 8-bit RGB components (0-255) into a packed
    // integer value according to the specified pixel format. The packing order
    // and bit depth vary by format.
    const uint32_t val = bj_get_pixel_value(mode, red, green, blue);
 
    // Convert the packed value to binary string for visualization of bit layout.
    char binarystr[33] = {0};
    for(size_t b = 0 ; b < 32 ; ++b) {
        binarystr[31-b] = '0' + ((val >> b) & 0x01);
    }
 
    bj_info("R:%d, G:%d, B:%d -[0x%08x]--> %ld\t0x%08x\t0b%s",
        red, green, blue, mode, 0, val, binarystr
    );
}
 
int main(int argc, char* argv[]) {
    (void)argc;
    (void)argv;
 
    // RGB565: 16-bit format with 5 bits red, 6 bits green, 5 bits blue.
    // Uses less memory (2 bytes per pixel) but lower colour precision.
    // Green gets 6 bits because human eyes are most sensitive to green.
    display_value(BJ_PIXEL_MODE_RGB565, 255, 0, 0);
    display_value(BJ_PIXEL_MODE_RGB565, 0, 255, 0);
    display_value(BJ_PIXEL_MODE_RGB565, 0, 0, 255);
 
    // XRGB1555: 16-bit format with 1 unused bit, then 5 bits each for RGB.
    // Also 2 bytes per pixel but with equal precision across all channels.
    display_value(BJ_PIXEL_MODE_XRGB1555, 255, 0, 0);
    display_value(BJ_PIXEL_MODE_XRGB1555, 0, 255, 0);
    display_value(BJ_PIXEL_MODE_XRGB1555, 0, 0, 255);
 
    // XRGB8888: 32-bit format with 8 bits per channel (full precision).
    // Uses 4 bytes per pixel but retains all 8 bits of input colour data.
    // The 'X' byte is unused padding for alignment.
    display_value(BJ_PIXEL_MODE_XRGB8888, 255, 0, 0);
    display_value(BJ_PIXEL_MODE_XRGB8888, 0, 255, 0);
    display_value(BJ_PIXEL_MODE_XRGB8888, 0, 0, 255);
 
    return 0;
}