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text.cpp
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text.cpp
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/*
-------------------------------------------------------------------------------
File: text,cpp
Author: Tim Crockford ([email protected])
Version: 0.1
-------------------------------------------------------------------------------
Refer to header file for detailed descriptions of this class.
*/
#ifndef __text_cpp__
#define __text_cpp__
#include "text.h"
textEngine::textEngine(u8 font_array[],
u16 palette_array[],
u8 font_size,
u8 size_array[])
{
this->initialize(font_array, palette_array, font_size, size_array, false);
}
textEngine::textEngine(u8 font_array[],
u16 palette_array[],
u8 font_size,
u8 fixed_size)
{
// Create a temporary array which becomes the 'size' array for the font
u8p size_array = new u8[GLYPHS];
// Copy fixed_size into each element of the size array.
for ( u8 x = 0; x < GLYPHS; x++ ) { size_array[x] = fixed_size; }
// Call the other constructor will the new size array as a parameter.
this->initialize(font_array, palette_array, font_size, size_array, true);
}
textEngine::~textEngine()
{
// Delete the widths array if it is necessary
if ( this->dynamic )
{
delete [] this->widths;
}
this->widths = NULL;
// Delete the offsets array (this was dynamic, so it _will_ need to be
// deleted.)
delete [] this->offsets;
this->offsets = NULL;
}
void textEngine::initialize(u8 font_array[],
u16 palette_array[],
u8 font_size,
u8 size_array[],
bool setDynamic)
{
// Sets a pointer to the font array so the print routine can use it.
this->font = font_array;
// Load the font palette into memory.
this->loadPalette(palette_array);
// Store the height on the font.
this->height = font_size;
// Store the font widths array, and generate the offsets array.
this->widths = size_array;
this->offsets = new u16[GLYPHS];
this->calcOffsets();
// Set the 'dynamic' boolean variable
this->dynamic = setDynamic;
// Set the charBaseBlock and screenBaseBlock variables
this->charBaseBlock = (u16vp) 0x600C000;
this->screenBaseBlock = (u16vp) 0x600B800;
// Set up the map
this->setupMap();
// Enable BG0 in the display register
*REG_DISPCNT |= 0x0100;
// Set up the BG0 register
*REG_BG0CNT = 0x170C;
}
void textEngine::calcOffsets()
{
// Set the initial offset to zero
this->offsets[0] = 0;
// Create the offset table by adding the width of the current character and
// the current running total of the total offset value and storing in the
// next offset.
for ( u16 loop = 0; loop < (GLYPHS - 1); loop++ )
{
this->offsets[loop + 1] = this->offsets[loop] + this->widths[loop];
}
}
void textEngine::loadPalette(u16 palette[])
{
// Copy only the first 16 entries, the rest are irrelavent as only 16 color
// palettes will be used. Should be plenty, even with anti-aliasing.
for ( u8 loop = 0; loop < 16; loop++ )
{
BGPaletteMem[loop] = palette[loop];
}
}
u16 textEngine::length(char* text)
{
// Define a temporary variable to store the total
u16 total = 0;
// Add the widths of the characters in text
for ( u16 n = 0; n < strlen(text); n++ )
{
// Determines the ascii value of the character and subtracts the value
// of the space character (since that is our first character).
total += this->widths[text[n] - ' '];
}
// Return the total
return (total);
}
void textEngine::print(char* text, u8 x, u8 y)
{
// Okay, first step is to declare some variables used by this function.
// I mean, text doesn't just appear after all. I'll try and describe each
// variable as I declare it.
// The shift_offset variable contains the current offset value within the
// current word. In 16 color mode, we're writing 4 pixels at a time, so
// this will keep track of what nibble of the word we're currently in.
u16 shift_offset;
// The mem_offset variable keeps track of what the address of the current
// memory block is. Basically it is the upper left value of the tile we're
// currently dealing with. The next_block boolean variable is also used to
// determine the next value of this variable. It detemines the value to get
// to the next column of tiles.
u16 mem_offset;
bool next_block;
// The row_offset variable keeps track of the current row in the tile. That
// a clear enough explaination? No? Well, look at the code, it should
// hopefully make things clearer.
u16 row_offset;
u16 row_offset_init;
// These are just some other variables used for counters, looping,
// the usual, etc.
u16 n, a, b;
u16 glyph_width = offsets[GLYPHS - 1] + widths[GLYPHS - 1];
// Okay, here's where the code starts. Firstly we determine the initial
// values based on the x,y parameters those pesky users gave us.
// Determine the initial row offset in memory for the text
row_offset_init = (y << 1);
// Now determine the initial memory offset. Sorry, but this uses a modulo
// function :( Any recommendations are heartily accepted.
n = x % 8;
mem_offset = (x - n) * 40;
if ( n > 3 )
{
shift_offset = n - 4;
next_block = true;
}
else
{
shift_offset = n;
next_block = false;
}
// Okay, the main block of code begins here. This will copy the text across
// to the display as needed.
for ( n = 0; n < strlen(text); n++ )
{
// Get the offset and width of the character to print
u16 offset = offsets[text[n] - ' '];
u16 width = widths[text[n] - ' '];
// This loop prints the character column by column
for ( a = 0; a < width; a++ )
{
// Reset the row position for each column
row_offset = row_offset_init;
// This loop prints the column, pixel by pixel. It looks up the
// font array to get the pixel at that point. (The shift offset
// value is used to move the pixel into the correct position in
// the word, as we're dealing with 4 pixels per word.)
for ( b = 0; b < height; b++ )
{
charBaseBlock[mem_offset + row_offset] |=
font[b * glyph_width + a + offset] << (shift_offset << 2);
row_offset += 2;
}
// Increase the shift offset, and move onto the next word if the
// current one is finished. If the current tile is done, then the
// next column of tiles is selected.
shift_offset++;
if ( shift_offset == 4 )
{
shift_offset = 0;
if ( next_block )
{
mem_offset += 320;
mem_offset--;
// This section will allow text to wrap on the screen if it
// exceeds the width of the display.
if ( mem_offset == 9600 )
{
mem_offset = 0;
row_offset_init += ((height << 1) + 4);
}
}
else
{
mem_offset++;
}
next_block = ! next_block;
}
}
}
}
// This function simply clears the screen.
void textEngine::clear()
{
for ( u16 x = 0; x < 16384; x++ )
{
charBaseBlock[x] = 0;
}
}
// This function will set up the map for BG0. This doesn't change, as the text
// is blitted onto the tile memory. Tile 0xFF is kept blank, as it will be the
// transparent background.
void textEngine::setupMap()
{
for ( u16 x = 0; x < 32; x++ )
{
for ( u16 y = 0; y < 32; y++ )
{
if ( (x < 30) && (y < 20) )
{
screenBaseBlock[y * 32 + x] = y + x * 20;
}
else
{
screenBaseBlock[y * 32 + x] = 0xFF;
}
}
}
}
#endif