pimoroni-pico/libraries/bitmap_fonts/bitmap_fonts.cpp

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#include "bitmap_fonts.hpp"
namespace bitmap {
int32_t measure_character(const font_t *font, const char c, const uint8_t scale, unicode_sorta::codepage_t codepage, bool fixed_width) {
if(c < 32 || c > 127 + 64) { // + 64 char remappings defined in unicode_sorta.hpp
return 0;
}
if(fixed_width) {
return font->max_width * scale;
}
uint8_t char_index = c;
if(char_index > 127) {
if(codepage == unicode_sorta::PAGE_195) {
char_index = unicode_sorta::char_base_195[c - 128];
} else {
char_index = unicode_sorta::char_base_194[c - 128 - 32];
}
}
char_index -= 32;
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return font->widths[char_index] * scale;
}
int32_t measure_text(const font_t *font, const std::string_view &t, const uint8_t scale, const uint8_t letter_spacing, bool fixed_width) {
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int32_t text_width = 0;
unicode_sorta::codepage_t codepage = unicode_sorta::PAGE_195;
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for(auto c : t) {
if(c == unicode_sorta::PAGE_194_START) {
codepage = unicode_sorta::PAGE_194;
continue;
} else if (c == unicode_sorta::PAGE_195_START) {
continue;
}
text_width += measure_character(font, c, scale, codepage, fixed_width);
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text_width += letter_spacing * scale;
codepage = unicode_sorta::PAGE_195; // Reset back to default
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}
return text_width;
}
void character(const font_t *font, rect_func rectangle, const char c, const int32_t x, const int32_t y, const uint8_t scale, int32_t rotation, unicode_sorta::codepage_t codepage) {
if(c < 32 || c > 127 + 64) { // + 64 char remappings defined in unicode_sorta.hpp
return;
}
uint8_t char_index = c;
unicode_sorta::accents char_accent = unicode_sorta::ACCENT_NONE;
// Remap any chars that fall outside of the 7-bit ASCII range
// using our unicode fudge lookup table.
if(char_index > 127) {
if(codepage == unicode_sorta::PAGE_195) {
char_index = unicode_sorta::char_base_195[c - 128];
char_accent = unicode_sorta::char_accent[c - 128];
} else {
char_index = unicode_sorta::char_base_194[c - 128 - 32];
char_accent = unicode_sorta::ACCENT_NONE;
}
}
// We don't map font data for the first 32 non-printable ASCII chars
char_index -= 32;
// If our font is taller than 8 pixels it must be two bytes per column
bool two_bytes_per_column = font->height > 8;
// Figure out how many bytes we need to skip per char to find our data in the array
uint8_t bytes_per_char = two_bytes_per_column ? font->max_width * 2 : font->max_width;
// Get a pointer to the start of the data for this character
const uint8_t *d = &font->data[char_index * bytes_per_char];
// Accents can be up to 8 pixels tall on both 8bit and 16bit fonts
// Each accent's data is font->max_width bytes + 2 offset bytes long
const uint8_t *a = &font->data[(base_chars + extra_chars) * bytes_per_char + char_accent * (font->max_width + 2)];
// Effectively shift off the first two bytes of accent data-
// these are the lower and uppercase accent offsets
const uint8_t offset_lower = *a++;
const uint8_t offset_upper = *a++;
// Pick which offset we should use based on the case of the char
// This is only valid for A-Z a-z.
// Note this magic number is relative to the start of printable ASCII chars.
uint8_t accent_offset = char_index < 65 ? offset_upper : offset_lower;
// Offset our y position to account for our column canvas being 32 pixels
// this gives us 8 "pixels" of headroom above the letters for diacritic marks
int font_offset = (8 * scale);
// Iterate through each horizontal column of font (and accent) data
for(uint8_t cx = 0; cx < font->widths[char_index]; cx++) {
// Our maximum bitmap font height will be 16 pixels
// give ourselves a 32 pixel high canvas in which to plot the char and accent.
// We shift the char down 8 pixels to make room for an accent above.
uint32_t data = *d << 8;
int32_t o_x = cx * scale;
// For fonts that are taller than 8 pixels (up to 16) they need two bytes
if(two_bytes_per_column) {
d++;
data <<= 8; // Move down the first byte
data |= *d << 8; // Add the second byte
}
// If the char has an accent, merge it into the column data at its offset
if(char_accent != unicode_sorta::ACCENT_NONE) {
data |= *a << accent_offset;
}
// Draw the 32 pixel column
for(uint8_t cy = 0; cy < 32; cy++) {
if((1U << cy) & data) {
int32_t o_y = cy * scale;
int32_t px = 0;
int32_t py = 0;
switch (rotation) {
case 0:
px = x + o_x;
py = y - font_offset + o_y;
break;
case 90:
px = x + font_offset - o_y;
py = y + o_x;
break;
case 180:
px = x - o_x;
py = y + font_offset - o_y;
break;
case 270:
px = x - font_offset + o_y;
py = y - o_x;
break;
}
rectangle(px, py, scale, scale);
}
}
// Move to the next columns of char and accent data
d++;
a++;
}
}
void text(const font_t *font, rect_func rectangle, const std::string_view &t, const int32_t x, const int32_t y, const int32_t wrap, const uint8_t scale, const uint8_t letter_spacing, bool fixed_width, int32_t rotation) {
uint32_t char_offset = 0;
uint32_t line_offset = 0; // line (if wrapping) offset
unicode_sorta::codepage_t codepage = unicode_sorta::PAGE_195;
int32_t space_width = measure_character(font, ' ', scale, codepage, fixed_width);
space_width += letter_spacing * scale;
size_t i = 0;
while(i < t.length()) {
// find length of current word
size_t next_space = t.find(' ', i + 1);
if(next_space == std::string::npos) {
next_space = t.length();
}
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size_t next_linebreak = t.find('\n', i + 1);
if(next_linebreak == std::string::npos) {
next_linebreak = t.length();
}
size_t next_break = std::min(next_space, next_linebreak);
uint16_t word_width = 0;
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for(size_t j = i; j < next_break; j++) {
if (t[j] == unicode_sorta::PAGE_194_START) {
codepage = unicode_sorta::PAGE_194;
continue;
} else if (t[j] == unicode_sorta::PAGE_195_START) {
continue;
}
word_width += measure_character(font, t[j], scale, codepage, fixed_width);
word_width += letter_spacing * scale;
codepage = unicode_sorta::PAGE_195;
}
// if this word would exceed the wrap limit then
// move to the next line
if(char_offset != 0 && char_offset + word_width > (uint32_t)wrap) {
char_offset = 0;
line_offset += (font->height + 1) * scale;
}
// draw word
for(size_t j = i; j < std::min(next_break + 1, t.length()); j++) {
if (t[j] == unicode_sorta::PAGE_194_START) {
codepage = unicode_sorta::PAGE_194;
continue;
} else if (t[j] == unicode_sorta::PAGE_195_START) {
continue;
}
if (t[j] == '\n') { // Linebreak
line_offset += (font->height + 1) * scale;
char_offset = 0;
} else if (t[j] == ' ') { // Space
char_offset += space_width;
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} else {
switch(rotation) {
case 0:
character(font, rectangle, t[j], x + char_offset, y + line_offset, scale, rotation, codepage);
break;
case 90:
character(font, rectangle, t[j], x - line_offset, y + char_offset, scale, rotation, codepage);
break;
case 180:
character(font, rectangle, t[j], x - char_offset, y - line_offset, scale, rotation, codepage);
break;
case 270:
character(font, rectangle, t[j], x + line_offset, y - char_offset, scale, rotation, codepage);
break;
}
char_offset += measure_character(font, t[j], scale, codepage, fixed_width);
char_offset += letter_spacing * scale;
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}
codepage = unicode_sorta::PAGE_195;
}
// move character offset
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i = next_break += 1;
}
}
}