數碼相框 在LCD上顯示多行文字(6)
數碼相框 在LCD上顯示多行文字(6)
目的:
1、從左邊起顯示幾行文字
2、居中顯示幾行文字
在LCD上顯示下列兩行文字:
我是程式設計師gif
Hello World
分析:
1、從左邊起顯示幾行文字
(1)先描畫字型
(2)然後算出邊框
定義兩個標誌變數:line_box_ymax和line_box_ymin
通過FT_Glyph_Get_CBox()測量字形圖象,獲取一行文字的yMax,Min最大值,最小值。
顯示第一行時:
pen.x = 0*64; //單位是64分之一畫素
顯示第2~n行時:
pen.y = (var.yres - 24) * 64; //fb_var.yres:LCD總高度,原點為(0, 24)
2、居中顯示幾行文字
(1)先算出邊框(知道起點,長、寬)
(2)再確定座標並描畫
程式碼中的一些變數解釋:
bbox:是每個字型檔案在x和y方向最大值和最小值的結構體
face:字型檔案
pen:原點和位置
從左顯示多行24X24文字
內容如下:
定義:某一行的BBox的y最小值line_box_ymin和最大值line_box_ymax
通過函式FT_Glyph_Get_CBox()測量字型圖象,從glyph得到BBox,BBox含有每個文字的xMin,xMax,yMin,yMax,獲取一行文字的yMax,Min最大值和最小值。
從左起顯示幾行文字程式碼如下:
#include <sys/mman.h> #include <sys/types.h> #include <sys/stat.h> #include <unistd.h> #include <linux/fb.h> #include <fcntl.h> #include <stdio.h> #include <string.h> #include <math.h> #include <wchar.h> #include <ft2build.h> #include FT_FREETYPE_H #include FT_GLYPH_H int fd_fb; struct fb_var_screeninfo var; /* Current var */ struct fb_fix_screeninfo fix; /* Current fix */ int screen_size; unsigned char *fbmem; unsigned int line_width; unsigned int pixel_width; /* color : 0x00RRGGBB */ void lcd_put_pixel(int x, int y, unsigned int color) { unsigned char *pen_8 = fbmem+y*line_width+x*pixel_width; unsigned short *pen_16; unsigned int *pen_32; unsigned int red, green, blue; pen_16 = (unsigned short *)pen_8; pen_32 = (unsigned int *)pen_8; switch (var.bits_per_pixel) { case 8: { *pen_8 = color; break; } case 16: { /* 565 */ red = (color >> 16) & 0xff; green = (color >> 8) & 0xff; blue = (color >> 0) & 0xff; color = ((red >> 3) << 11) | ((green >> 2) << 5) | (blue >> 3); *pen_16 = color; break; } case 32: { *pen_32 = color; break; } default: { printf("can't surport %dbpp\n", var.bits_per_pixel); break; } } } /* Replace this function with something useful. */ void draw_bitmap( FT_Bitmap* bitmap, FT_Int x, FT_Int y) { FT_Int i, j, p, q; FT_Int x_max = x + bitmap->width; FT_Int y_max = y + bitmap->rows; //printf("x = %d, y = %d\n", x, y); for ( i = x, p = 0; i < x_max; i++, p++ ) { for ( j = y, q = 0; j < y_max; j++, q++ ) { if ( i < 0 || j < 0 || i >= var.xres || j >= var.yres )//點陣圖超過這個範圍就不顯示 continue; //image[j][i] |= bitmap->buffer[q * bitmap->width + p]; //輸出函式,因為buffer是一個位元組,而lcd_put_pixel()是0x00RRGGBB,所以打印出來的是藍色字型 lcd_put_pixel(i, j, bitmap->buffer[q * bitmap->width + p]);//引數:x座標,y座標,顏色值 } } } int main(int argc, char **argv) { wchar_t *wstr1 = L"我是程式設計師gif"; wchar_t *wstr2 = L"Hello World"; FT_Library library; FT_Face face; int error; FT_Vector pen; /* untransformed origin */ FT_GlyphSlot slot; int i; //方框 FT_BBox bbox; FT_Glyph glyph; //某一行的BBox的y最小值和最大值 int line_box_ymin = 10000; int line_box_ymax = 0; if (argc != 2)//打印出用法 { printf("Usage : %s <font_file>\n", argv[0]); return -1; } fd_fb = open("/dev/fb0", O_RDWR);//開啟LCD if (fd_fb < 0) { printf("can't open /dev/fb0\n"); return -1; } if (ioctl(fd_fb, FBIOGET_VSCREENINFO, &var)) { printf("can't get var\n"); return -1; } if (ioctl(fd_fb, FBIOGET_FSCREENINFO, &fix)) { printf("can't get fix\n"); return -1; } //記錄LCD的引數 line_width = var.xres * var.bits_per_pixel / 8; pixel_width = var.bits_per_pixel / 8; screen_size = var.xres * var.yres * var.bits_per_pixel / 8; fbmem = (unsigned char *)mmap(NULL , screen_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd_fb, 0);//記憶體對映 if (fbmem == (unsigned char *)-1) { printf("can't mmap\n"); return -1; } /* 清屏: 全部設為黑色 */ memset(fbmem, 0, screen_size); /* 顯示向量字型,把show_font和example2兩個合在一起 */ error = FT_Init_FreeType( &library ); /* 初始化freetype庫 */ /* error handling omitted */ //裝載字型檔案 error = FT_New_Face( library, argv[1], 0, &face ); /* 開啟一個字型檔案 */ /* error handling omitted */ //每得到一個face,都會有一個slot插槽,插槽就是裝載一個字型裡面的資料 //每載入一個文字,插槽slot就會變換一下,裡面的資料時最新的 slot = face->glyph; //設定字型的大小24X24 FT_Set_Pixel_Sizes(face, 24, 0); /* 確定座標: A中\向量字型\ * lcd_x = 0 * lcd_y = 24 * 轉換為笛卡爾座標系: * x = lcd_x = 0 * y = var.yres - lcd_y = var.yres/2 - 24 */ //pen就是向量字型的位置 //第一個字元的原點“我” pen.x = 0 * 64;//單位是64分之一畫素 pen.y = (var.yres - 24) * 64; for (i = 0; i < wcslen(wstr1); i++) { /* 設定轉換方法 */ FT_Set_Transform( face, 0, &pen );//設定轉換矩陣matrix,轉換引數,0表示不旋轉 /* load glyph image into the slot (erase previous one) */ //FT_LOAD_RENDER引數會把glyph向量檔案轉換為點陣圖 //根據chinese_str(字元unicode碼),在字型檔案face得到glyph,載入到slot(face->glyph)裡面 error = FT_Load_Char( face, wstr1[i], FT_LOAD_RENDER ); if (error) { printf("FT_Load_Char error\n"); return -1; } error = FT_Get_Glyph( face->glyph, &glyph ); if (error) { printf("FT_Get_Glyph error!\n"); return -1; } //從glyph得到BBox,BBox含有每個文字的xMin,xMax,yMin,yMax FT_Glyph_Get_CBox(glyph, FT_GLYPH_BBOX_TRUNCATE, &bbox ); if (line_box_ymin > bbox.yMin) line_box_ymin = bbox.yMin; if (line_box_ymax < bbox.yMax) line_box_ymax = bbox.yMax; /* now, draw to our target surface (convert position) */ //描繪出來,slot就是face裡面的glyph draw_bitmap( &slot->bitmap, slot->bitmap_left,//bitmap_left這是笛卡爾座標系 var.yres - slot->bitmap_top );//slot->bitmap_top是笛卡爾座標系 /* increment pen position */ //增加筆的位置 pen.x += slot->advance.x; //pen.y += slot->advance.y; } /* 確定座標: A中\向量字型\ * lcd_x = 0 * lcd_y = line_box_ymax - line_box_ymin + 24 * 轉換為笛卡爾座標系: * x = lcd_x = 0 * y = var.yres - lcd_y = var.yres - (line_box_ymax - line_box_ymin + 24) */ //pen就是向量字型的位置 //第一個字元的原點“我” pen.x = 0 * 64;//單位是64分之一畫素 pen.y = (var.yres - (line_box_ymax - line_box_ymin + 24)) * 64; for (i = 0; i < wcslen(wstr2); i++) { /* 設定轉換方法 */ FT_Set_Transform( face, 0, &pen );//設定轉換矩陣matrix,轉換引數,0表示不旋轉 /* load glyph image into the slot (erase previous one) */ //FT_LOAD_RENDER引數會把glyph向量檔案轉換為點陣圖 //根據chinese_str(字元unicode碼),在字型檔案face得到glyph,載入到slot(face->glyph)裡面 error = FT_Load_Char( face, wstr2[i], FT_LOAD_RENDER ); if (error) { printf("FT_Load_Char error\n"); return -1; } error = FT_Get_Glyph( face->glyph, &glyph ); if (error) { printf("FT_Get_Glyph error!\n"); return -1; } //從glyph得到BBox,BBox含有每個文字的xMin,xMax,yMin,yMax FT_Glyph_Get_CBox(glyph, FT_GLYPH_BBOX_TRUNCATE, &bbox ); if (line_box_ymin > bbox.yMin) line_box_ymin = bbox.yMin; if (line_box_ymax < bbox.yMax) line_box_ymax = bbox.yMax; /* now, draw to our target surface (convert position) */ //描繪出來,slot就是face裡面的glyph draw_bitmap( &slot->bitmap, slot->bitmap_left,//bitmap_left這是笛卡爾座標系 var.yres - slot->bitmap_top );//slot->bitmap_top是笛卡爾座標系 /* increment pen position */ //增加筆的位置 pen.x += slot->advance.x; //pen.y += slot->advance.y; } return 0; }
居中顯示
內容如下:
參考第11頁:https://wenku.baidu.com/view/060a0b44f12d2af90342e63a.html?from=search
(1)首先定義一個用來儲存一行文字的字形圖象陣列
(2)首先以座標(0,0)為基值,獲取每個文字的字形影象和座標值,存到glyphs[]裡
(3)通過glyphs[]存的一行字形圖象,計算出邊界框
(4)通過邊界框,找到居中顯示的座標資訊
(5)通過座標資訊,將glyphs[]存的一行字形影象顯示出來
居中顯示文字程式碼如下:
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <linux/fb.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <math.h>
#include <wchar.h>
#include <ft2build.h>
#include FT_FREETYPE_H
#include FT_GLYPH_H
typedef struct TGlyph_
{
FT_UInt index; /* glyph index */
FT_Vector pos; /* glyph origin on the baseline */
FT_Glyph image; /* glyph image *///真正的glyph
} TGlyph, *PGlyph;
#define MAX_GLYPHS 100
int fd_fb;
struct fb_var_screeninfo var; /* Current var */
struct fb_fix_screeninfo fix; /* Current fix */
int screen_size;
unsigned char *fbmem;
unsigned int line_width;
unsigned int pixel_width;
/* color : 0x00RRGGBB */
void lcd_put_pixel(int x, int y, unsigned int color)
{
unsigned char *pen_8 = fbmem+y*line_width+x*pixel_width;
unsigned short *pen_16;
unsigned int *pen_32;
unsigned int red, green, blue;
pen_16 = (unsigned short *)pen_8;
pen_32 = (unsigned int *)pen_8;
switch (var.bits_per_pixel)
{
case 8:
{
*pen_8 = color;
break;
}
case 16:
{
/* 565 */
red = (color >> 16) & 0xff;
green = (color >> 8) & 0xff;
blue = (color >> 0) & 0xff;
color = ((red >> 3) << 11) | ((green >> 2) << 5) | (blue >> 3);
*pen_16 = color;
break;
}
case 32:
{
*pen_32 = color;
break;
}
default:
{
printf("can't surport %dbpp\n", var.bits_per_pixel);
break;
}
}
}
/* Replace this function with something useful. */
void
draw_bitmap( FT_Bitmap* bitmap,
FT_Int x,
FT_Int y)
{
FT_Int i, j, p, q;
FT_Int x_max = x + bitmap->width;
FT_Int y_max = y + bitmap->rows;
//printf("x = %d, y = %d\n", x, y);
for ( i = x, p = 0; i < x_max; i++, p++ )
{
for ( j = y, q = 0; j < y_max; j++, q++ )
{
if ( i < 0 || j < 0 ||
i >= var.xres || j >= var.yres )//點陣圖超過這個範圍就不顯示
continue;
//image[j][i] |= bitmap->buffer[q * bitmap->width + p];
//輸出函式,因為buffer是一個位元組,而lcd_put_pixel()是0x00RRGGBB,所以打印出來的是藍色字型
lcd_put_pixel(i, j, bitmap->buffer[q * bitmap->width + p]);//引數:x座標,y座標,顏色值
}
}
}
//從寬字元獲得glyphs
int Get_Glyphs_Frm_Wstr(FT_Face face, wchar_t *wstr, TGlyph glyphs[])
{
int n;
PGlyph glyph = glyphs;
int pen_x = 0;
int pen_y = 0;
int error;
FT_GlyphSlot slot = face->glyph;//插槽
//把wstr每個字元取出來
for (n = 0; n < wcslen(wstr); n++)
{
//根據字串wstr的unicode碼wstr[n]獲得glyph的索引
glyph->index = FT_Get_Char_Index( face, wstr[n] );
/* store current pen position */
glyph->pos.x = pen_x;
glyph->pos.y = pen_y;
//從字型檔案face的glyph加載出來
//load時是把glyph放入face->glyph插槽
error = FT_Load_Glyph( face, glyph->index, FT_LOAD_DEFAULT );
if ( error )
continue;
//把glyph拷貝出來,防止覆蓋
error = FT_Get_Glyph( face->glyph, &glyph->image );
if ( error )
continue;
/* translate the glyph image now */
//這使得glyph->image裡含有位置資訊
FT_Glyph_Transform( glyph->image, 0, &glyph->pos );
//下一個原點的位置
pen_x += slot->advance.x;//單位是1/64point
/* increment number of glyphs */
//指向下一個儲存的位置
glyph++;
}
/* count number of glyphs loaded */
//返回glyph的個數
return (glyph - glyphs);
}
//計算長度和寬度,計算glyphs
void compute_string_bbox(TGlyph glyphs[], FT_UInt num_glyphs, FT_BBox *abbox)
{
//含有x和y方向最小值,最大值
FT_BBox bbox;
int n;
bbox.xMin = bbox.yMin = 32000;
bbox.xMax = bbox.yMax = -32000;
//取出每一個字的BBox,一一比較,確定值
for ( n = 0; n < num_glyphs; n++ )
{
FT_BBox glyph_bbox;
//FT_CLYPH_BBOX_TRUNCATE以畫素為單位取出來
FT_Glyph_Get_CBox(glyphs[n].image, FT_GLYPH_BBOX_TRUNCATE, &glyph_bbox );
//更新資料
if (glyph_bbox.xMin < bbox.xMin)
bbox.xMin = glyph_bbox.xMin;
if (glyph_bbox.yMin < bbox.yMin)
bbox.yMin = glyph_bbox.yMin;
if (glyph_bbox.xMax > bbox.xMax)
bbox.xMax = glyph_bbox.xMax;
if (glyph_bbox.yMax > bbox.yMax)
bbox.yMax = glyph_bbox.yMax;
}
*abbox = bbox;
}
//描繪
void Draw_Glyphs(TGlyph glyphs[], FT_UInt num_glyphs, FT_Vector pen)
{
int n;
int error;
for (n = 0; n < num_glyphs; n++)
{
//pen是新舊位置的偏移值,因為原本是在笛卡爾座標系的原點,現在要移動到中間
FT_Glyph_Transform(glyphs[n].image, 0, &pen);
/* convert glyph image to bitmap (destroy the glyph copy!) */
//轉換為點陣圖
error = FT_Glyph_To_Bitmap(&glyphs[n].image, FT_RENDER_MODE_NORMAL,
0, /* no additional translation */
1 ); /* destroy copy in "image" */
if ( !error )
{
//獲得點陣圖
FT_BitmapGlyph bit = (FT_BitmapGlyph)glyphs[n].image;
//描繪出來
draw_bitmap(&bit->bitmap, bit->left, var.yres - bit->top);
//釋放空間
FT_Done_Glyph(glyphs[n].image);
}
}
}
int main(int argc, char **argv)
{
wchar_t *wstr1 = L"我是程式設計師gif";
wchar_t *wstr2 = L"Hello World";
FT_Library library;
FT_Face face;//字型
int error;
FT_Vector pen; /* untransformed origin */
FT_GlyphSlot slot;
int i;
//方框
FT_BBox bbox;
//某一行的BBox的y最小值和最大值
int line_box_ymin = 10000;
int line_box_ymax = 0;
//中間顯示時的寬度和高度
int line_box_width;
int line_box_height;
TGlyph glyphs[MAX_GLYPHS]; /* glyphs table */
FT_UInt num_glyphs; //glyphs陣列存有多少文字
if (argc != 2)//打印出用法
{
printf("Usage : %s <font_file>\n", argv[0]);
return -1;
}
fd_fb = open("/dev/fb0", O_RDWR);//開啟LCD
if (fd_fb < 0)
{
printf("can't open /dev/fb0\n");
return -1;
}
if (ioctl(fd_fb, FBIOGET_VSCREENINFO, &var))
{
printf("can't get var\n");
return -1;
}
if (ioctl(fd_fb, FBIOGET_FSCREENINFO, &fix))
{
printf("can't get fix\n");
return -1;
}
//記錄LCD的引數
line_width = var.xres * var.bits_per_pixel / 8;
pixel_width = var.bits_per_pixel / 8;
screen_size = var.xres * var.yres * var.bits_per_pixel / 8;
fbmem = (unsigned char *)mmap(NULL , screen_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd_fb, 0);//記憶體對映
if (fbmem == (unsigned char *)-1)
{
printf("can't mmap\n");
return -1;
}
/* 清屏: 全部設為黑色 */
memset(fbmem, 0, screen_size);
/* 顯示向量字型,把show_font和example2兩個合在一起 */
error = FT_Init_FreeType( &library ); /* 初始化freetype庫 */
/* error handling omitted */
//裝載字型檔案
error = FT_New_Face( library, argv[1], 0, &face ); /* 開啟一個字型檔案 */
/* error handling omitted */
//每得到一個face,都會有一個slot插槽,插槽就是裝載一個字型裡面的資料
//每載入一個文字,插槽slot就會變換一下,裡面的資料時最新的
slot = face->glyph;
//設定字型的大小24X24
FT_Set_Pixel_Sizes(face, 24, 0);
/* 第一行字元wstr1 */
//從Wstr裡面獲得glyphs,face是字型檔案,
num_glyphs = Get_Glyphs_Frm_Wstr(face, wstr1, glyphs);
compute_string_bbox(glyphs, num_glyphs, &bbox);
line_box_width = bbox.xMax - bbox.xMin;
line_box_height = bbox.yMax - bbox.yMin;
//確定座標系
pen.x = (var.xres - line_box_width)/2 * 64;
pen.y = (var.yres - line_box_height)/2 * 64;
//描繪
Draw_Glyphs(glyphs, num_glyphs, pen);
/* 第二行字wstr2 */
//把wstr2從字型檔案face 加載出來到glyphs
num_glyphs = Get_Glyphs_Frm_Wstr(face, wstr2, glyphs);
//計算大小
compute_string_bbox(glyphs, num_glyphs, &bbox);
line_box_width = bbox.xMax - bbox.xMin;
line_box_height = bbox.yMax - bbox.yMin;
//確定座標系
pen.x = (var.xres - line_box_width)/2 * 64;
pen.y = pen.y - 24 * 64;//減24相當於往下移動24
//描繪
Draw_Glyphs(glyphs, num_glyphs, pen);
return 0;
}
效果圖: