Ahhh, PROGMEM, pointers, pointers to pointers, addresses of pointers... My head boggles.
I have a data array for the font in question
const uint8_t dejaVuSans9ptBitmaps[] =
{
/* @0 ' ' (5 pixels wide) */
0x00, /* */
0x00, /* */
...
to which I have added PROGMEM
const uint8_t dejaVuSans9ptBitmaps[] PROGMEM =
This is referenced in another structure like so;
const FONT_INFO dejaVuSans9ptFontInfo = {
13,
' ',
'~',
dejaVuSans9ptDescriptors,
dejaVuSans9ptBitmaps,
};
The structure is defined as;
typedef struct {
const uint8_t height;
const uint8_t startChar;
const uint8_t endChar;
const FONT_CHAR_INFO* charInfo;
const uint8_t* data;
} FONT_INFO;
Am I correct in assuming this needs to change to;
typedef struct {
const uint8_t height;
const uint8_t startChar;
const uint8_t endChar;
const FONT_CHAR_INFO* charInfo;
const PGM_P data;
} FONT_INFO;
When I do so, it complains that
warning: pointer targets in initialization differ in signedness
For this particular line in the FONT_INFO variable;
const FONT_INFO dejaVuSans9ptFontInfo = {
13,
' ',
'~',
dejaVuSans9ptDescriptors,
--> dejaVuSans9ptBitmaps, <--
};
It is then drawn using the function;
void drawString(uint16_t x, uint16_t y, uint16_t color, const FONT_INFO *fontInfo, char *str) {
...
drawCharBitmap(currentX, y, color, &fontInfo->data[charOffset], charWidth, fontInfo->height);
...
Which finally draws the glyph;
void drawCharBitmap(const uint16_t xPixel, const uint16_t yPixel, uint16_t color, const uint8_t *glyph, uint8_t cols, uint8_t rows) {
...
if (glyph[indexIntoGlyph] & (0X80)) drawPixel(currentX, currentY, color);
...
I am in over my head :/ Can anyone give me some direction? I have spent hours trying to use PGM_P, and pgm_read_byte etc to no avail - I always get garbage on the screen.
Save me!