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Added dithering for 24 bit backdrops on 16 bit displays. FORMAT_DITHER should be specified to dither a bitmap when loading. Feel free to flame me if I got the RGB565SWAPPED thing wrong.

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@11180 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Michael Sevakis 2006-10-11 01:26:09 +00:00
parent 38168222ae
commit 76a6aaa278
3 changed files with 56 additions and 18 deletions
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3
apps/recorder/backdrop.c
View file

@ -36,7 +36,8 @@ bool load_backdrop(char* filename, fb_data* backdrop_buffer)
/* load the image */
bm.data=(char*)backdrop_buffer;
ret = read_bmp_file(filename, &bm, sizeof(main_backdrop), FORMAT_NATIVE);
ret = read_bmp_file(filename, &bm, sizeof(main_backdrop),
FORMAT_NATIVE | FORMAT_DITHER);
if ((ret > 0) && (bm.width == LCD_WIDTH) && (bm.height == LCD_HEIGHT))
{

70
apps/recorder/bmp.c
View file

@ -94,6 +94,39 @@ inline int getpix(int px, unsigned char *bmpbuf) {
return (bmpbuf[a] & (1 << b)) != 0;
}
#if LCD_DEPTH == 16
/* Cheapo 24 -> 16 bit dither */
#if LCD_PIXELFORMAT == RGB565SWAPPED
#define RGBSWAPPED(rgb) swap16(rgb)
#else
#define RGBSWAPPED(rgb) rgb
#endif
static unsigned short dither_24_to_16(struct rgb_quad rgb, int row, int col)
{
static const unsigned char dith[2][16] = {
{ /* 5 bit */
0,6,1,7,
4,2,5,3,
1,7,0,6,
5,3,4,2
},
{ /* 6 bit */
0,3,0,3,
2,1,2,1,
0,3,0,3,
2,1,2,1
}
};
const int elm = (row & 3) + ((col & 3) << 2);
short b = 31*((unsigned short)rgb.blue + dith[0][elm]) >> 8;
short g = 63*((unsigned short)rgb.green + dith[1][elm]) >> 8;
short r = 31*((unsigned short)rgb.red + dith[0][elm]) >> 8;
return RGBSWAPPED(b | (g << 5) | (r << 11));
}
#endif /* LCD_DEPTH == 16 */
/******************************************************************************
* read_bmp_file()
@ -115,21 +148,25 @@ int read_bmp_file(char* filename,
int depth;
int totalsize;
char *bitmap = bm->data;
unsigned char bmpbuf[LCD_WIDTH*sizeof(struct rgb_quad)]; /* Buffer for one line */
#if LCD_DEPTH == 1
format = FORMAT_MONO;
#else
bool transparent;
#if LCD_DEPTH != 1
bool transparent = false;
#if LCD_DEPTH == 16
/* Should adapt dithering to all native depths */
bool dither = false;
if(format & FORMAT_DITHER) {
dither = true;
format &= ~FORMAT_DITHER;
}
#endif
if(format & FORMAT_TRANSPARENT) {
transparent = true;
format &= ~FORMAT_TRANSPARENT;
}
#else
format = FORMAT_MONO;
#endif
fd = open(filename, O_RDONLY);
/* Exit if file opening failed */
@ -362,12 +399,11 @@ int read_bmp_file(char* filename,
#elif LCD_DEPTH == 16
} else {
/* 8-bit RGB24 palette -> RGB16 */
for (col = 0; col < width; col++) {
for (col = 0; col < width; col++, p++) {
struct rgb_quad rgb = palette[*p];
unsigned short rgb16 =
dest[width * (height - row - 1) + col] = dither ?
dither_24_to_16(rgb, row, col) :
LCD_RGBPACK(rgb.red, rgb.green, rgb.blue);
dest[width * (height - row - 1) + col] = rgb16;
p++;
}
}
#endif
@ -429,10 +465,10 @@ int read_bmp_file(char* filename,
#elif LCD_DEPTH == 16
} else {
/* RGB24 -> RGB16 */
for (col = 0; col < width; col++) {
unsigned short rgb = LCD_RGBPACK(p[2],p[1],p[0]);
dest[width * (height - row - 1) + col] = rgb;
p += 3;
for (col = 0; col < width; col++, p += 3) {
dest[width * (height - row - 1) + col] = dither ?
dither_24_to_16(*(struct rgb_quad *)p, row, col) :
LCD_RGBPACK(p[2], p[1], p[0]);
}
}
#endif

1
firmware/export/lcd.h
View file

@ -246,6 +246,7 @@ enum
};
#define FORMAT_TRANSPARENT 0x40000000
#define FORMAT_DITHER 0x20000000
#define TRANSPARENT_COLOR LCD_RGBPACK(255,0,255)