【读书笔记-《30天自制操作系统》-10】Day11

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本篇内容继续围绕显示展开。首先对鼠标显示做了些优化，鼠标箭头在到达画面边缘时能够实现部分隐藏；接下来制作了窗口，实现了窗口显示；最后还在窗口的基础上实现了计数器，显示计数的变化并消除闪烁的问题。

1. 画面边缘隐藏部分鼠标

首先优化一下鼠标显示，在鼠标箭头移动到画面边缘时，隐藏部分鼠标箭头。主程序中原代码如下：

	if (mx > binfo->scrnx - 16) {mx = binfo->scrnx - 16;}if (my > binfo->scrny - 16) {my = binfo->scrny - 16;}

修改为如下代码：

	if (mx > binfo->scrnx - 1) {mx = binfo->scrnx - 1;}if (my > binfo->scrny - 1) {my = binfo->scrny - 1;}

原理也比较简单，显示效果如下：

可以看出鼠标箭头实现了在画面边缘的部分隐藏，但移出画面之外的部分又产生了其他异常。这里是与图层的刷新有关，只要对于画面之外的部分不进行刷新，就不会产生上面的问题了。修改sheet_refreshsub函数如下：

void sheet_refreshsub(struct SHTCTL *ctl, int vx0, int vy0, int vx1, int vy1)
{int h, bx, by, vx, vy, bx0, by0, bx1, by1;unsigned char *buf, c, *vram = ctl->vram;struct SHEET *sht;for (h = 0; h <= ctl->top; h++) {sht = ctl->sheets[h];buf = sht->buf;bx0 = vx0 - sht->vx0;by0 = vy0 - sht->vy0;bx1 = vx1 - sht->vx0;by1 = vy1 - sht->vy0;/* 如果超出了范围则进行修正 */if (bx0 < 0) { bx0 = 0; }if (by0 < 0) { by0 = 0; }if (bx1 > sht->bxsize) { bx1 = sht->bxsize; }if (by1 > sht->bysize) { by1 = sht->bysize; }for (by = by0; by < by1; by++) {vy = sht->vy0 + by;for (bx = bx0; bx < bx1; bx++) {vx = sht->vx0 + bx;c = buf[by * sht->bxsize + bx];if (c != sht->col_inv) {vram[vy * ctl->xsize + vx] = c;}}}}return;
}

这样修改之后，鼠标在画面边缘的显示就正常多了

2. 窗口显示

在进入下一步 制作窗口之前，先进行一个小优化。

之前图层控制的数据结构SHTCTL *ctl，在每次进行图层相关的操作时，都需要将ctl指针作为参数传入进去。为了简化，将这一指针加入图层信息描述的结构体中，这样每次操作图层时从图层信息结构体中获取该指针即可，不需要再作为参数单独传入了。

struct SHEET {unsigned char *buf;int bxsize, bysize, vx0, vy0, col_inv, height, flags;struct SHTCTL *ctl; /* 此处增加图层控制指针 */
};

在初始化函数shtctl_init中，需要给此指针赋值：

struct SHTCTL *shtctl_init(struct MEMMAN *memman, unsigned char *vram, int xsize, int ysize)
{struct SHTCTL *ctl;int i;ctl = (struct SHTCTL *) memman_alloc_4k(memman, sizeof (struct SHTCTL));if (ctl == 0) {goto err;}ctl->vram = vram;ctl->xsize = xsize;ctl->ysize = ysize;ctl->top = -1;for (i = 0; i < MAX_SHEETS; i++) {ctl->sheets0[i].flags = 0; ctl->sheets0[i].ctl = ctl; }
err:return ctl;
}

之前所有涉及到ctl指针的部分也都要一并修改。

接下来就可以制作窗口了。其实制作窗口也是准备一个图层，并在上面绘制图案，这里作者写了一个函数make_window8

void make_window8(unsigned char *buf, int xsize, int ysize, char *title)
{static char closebtn[14][16] = {"OOOOOOOOOOOOOOO@","OQQQQQQQQQQQQQ$@","OQQQQQQQQQQQQQ$@","OQQQ@@QQQQ@@QQ$@","OQQQQ@@QQ@@QQQ$@","OQQQQQ@@@@QQQQ$@","OQQQQQQ@@QQQQQ$@","OQQQQQ@@@@QQQQ$@","OQQQQ@@QQ@@QQQ$@","OQQQ@@QQQQ@@QQ$@","OQQQQQQQQQQQQQ$@","OQQQQQQQQQQQQQ$@","O$$$$$$$$$$$$$$@","@@@@@@@@@@@@@@@@"};int x, y;char c;boxfill8(buf, xsize, COL8_C6C6C6, 0,         0,         xsize - 1, 0        );boxfill8(buf, xsize, COL8_FFFFFF, 1,         1,         xsize - 2, 1        );boxfill8(buf, xsize, COL8_C6C6C6, 0,         0,         0,         ysize - 1);boxfill8(buf, xsize, COL8_FFFFFF, 1,         1,         1,         ysize - 2);boxfill8(buf, xsize, COL8_848484, xsize - 2, 1,         xsize - 2, ysize - 2);boxfill8(buf, xsize, COL8_000000, xsize - 1, 0,         xsize - 1, ysize - 1);boxfill8(buf, xsize, COL8_C6C6C6, 2,         2,         xsize - 3, ysize - 3);boxfill8(buf, xsize, COL8_000084, 3,         3,         xsize - 4, 20       );boxfill8(buf, xsize, COL8_848484, 1,         ysize - 2, xsize - 2, ysize - 2);boxfill8(buf, xsize, COL8_000000, 0,         ysize - 1, xsize - 1, ysize - 1);putfonts8_asc(buf, xsize, 24, 4, COL8_FFFFFF, title);for (y = 0; y < 14; y++) {for (x = 0; x < 16; x++) {c = closebtn[y][x];if (c == '@') {c = COL8_000000;} else if (c == '$') {c = COL8_848484;} else if (c == 'Q') {c = COL8_C6C6C6;} else {c = COL8_FFFFFF;}buf[(5 + y) * xsize + (xsize - 21 + x)] = c;}}return;
}

虽然程序代码看起来不少，其实与之前描绘鼠标的原理一样，只是在适当的位置描绘出图案。这样在主函数中也需要增加一些内容：

/* 新增了窗口的图层管理指针与buf*/struct SHEET *sht_back, *sht_mouse, *sht_win;unsigned char *buf_back, buf_mouse[256], *buf_win;/* 为窗口分配图层和内存*/sht_win   = sheet_alloc(shtctl);buf_win   = (unsigned char *) memman_alloc_4k(memman, 160 * 68);sheet_setbuf(sht_win, buf_win, 160, 68, -1);init_screen8(buf_back, binfo->scrnx, binfo->scrny);init_mouse_cursor8(buf_mouse, 99);make_window8(buf_win, 160, 68, "window");putfonts8_asc(buf_win, 160, 24, 28, COL8_000000, "Welcome to");putfonts8_asc(buf_win, 160, 24, 44, COL8_000000, "  Haribote-OS!");sheet_slide(sht_win, 80, 72);sheet_updown(sht_back,  0);sheet_updown(sht_win,   1);sheet_updown(sht_mouse, 2);

从程序中可以看出，将窗口图层的高度设置为1，处于背景图层与鼠标图层之间，这样鼠标就可以位于窗口图层之上。运行之后的显示结果如下
窗口的显示完成了，下面更进一步，由CPU进行计数，并将数字在窗口中显示出来：

void HariMain(void)
{struct BOOTINFO *binfo = (struct BOOTINFO *) ADR_BOOTINFO;char s[40], keybuf[32], mousebuf[128];int mx, my, i;unsigned int memtotal, count = 0;struct MOUSE_DEC mdec;struct MEMMAN *memman = (struct MEMMAN *) MEMMAN_ADDR;struct SHTCTL *shtctl;struct SHEET *sht_back, *sht_mouse, *sht_win;unsigned char *buf_back, buf_mouse[256], *buf_win;init_gdtidt();init_pic();io_sti();fifo8_init(&keyfifo, 32, keybuf);fifo8_init(&mousefifo, 128, mousebuf);io_out8(PIC0_IMR, 0xf9); io_out8(PIC1_IMR, 0xef); init_keyboard();enable_mouse(&mdec);memtotal = memtest(0x00400000, 0xbfffffff);memman_init(memman);memman_free(memman, 0x00001000, 0x0009e000); /* 0x00001000 - 0x0009efff */memman_free(memman, 0x00400000, memtotal - 0x00400000);init_palette();shtctl = shtctl_init(memman, binfo->vram, binfo->scrnx, binfo->scrny);sht_back  = sheet_alloc(shtctl);sht_mouse = sheet_alloc(shtctl);sht_win   = sheet_alloc(shtctl);buf_back  = (unsigned char *) memman_alloc_4k(memman, binfo->scrnx * binfo->scrny);buf_win   = (unsigned char *) memman_alloc_4k(memman, 160 * 52);sheet_setbuf(sht_back, buf_back, binfo->scrnx, binfo->scrny, -1); sheet_setbuf(sht_mouse, buf_mouse, 16, 16, 99);sheet_setbuf(sht_win, buf_win, 160, 52, -1); init_screen8(buf_back, binfo->scrnx, binfo->scrny);init_mouse_cursor8(buf_mouse, 99);make_window8(buf_win, 160, 52, "counter");/* 增加计数器 */sheet_slide(sht_back, 0, 0);mx = (binfo->scrnx - 16) / 2; my = (binfo->scrny - 28 - 16) / 2;sheet_slide(sht_mouse, mx, my);sheet_slide(sht_win, 80, 72);sheet_updown(sht_back,  0);sheet_updown(sht_win,   1);sheet_updown(sht_mouse, 2);sprintf(s, "(%3d, %3d)", mx, my);putfonts8_asc(buf_back, binfo->scrnx, 0, 0, COL8_FFFFFF, s);sprintf(s, "memory %dMB   free : %dKB",memtotal / (1024 * 1024), memman_total(memman) / 1024);putfonts8_asc(buf_back, binfo->scrnx, 0, 32, COL8_FFFFFF, s);sheet_refresh(sht_back, 0, 0, binfo->scrnx, 48);for (;;) {count++; /* 计数 */sprintf(s, "%010d", count);boxfill8(buf_win, 160, COL8_C6C6C6, 40, 28, 119, 43);putfonts8_asc(buf_win, 160, 40, 28, COL8_000000, s);sheet_refresh(sht_win, 40, 28, 120, 44);io_cli();if (fifo8_status(&keyfifo) + fifo8_status(&mousefifo) == 0) {io_sti();} else {if (fifo8_status(&keyfifo) != 0) {i = fifo8_get(&keyfifo);io_sti();sprintf(s, "%02X", i);boxfill8(buf_back, binfo->scrnx, COL8_008484,  0, 16, 15, 31);putfonts8_asc(buf_back, binfo->scrnx, 0, 16, COL8_FFFFFF, s);sheet_refresh(sht_back, 0, 16, 16, 32);} else if (fifo8_status(&mousefifo) != 0) {i = fifo8_get(&mousefifo);io_sti();if (mouse_decode(&mdec, i) != 0) {sprintf(s, "[lcr %4d %4d]", mdec.x, mdec.y);if ((mdec.btn & 0x01) != 0) {s[1] = 'L';}if ((mdec.btn & 0x02) != 0) {s[3] = 'R';}if ((mdec.btn & 0x04) != 0) {s[2] = 'C';}boxfill8(buf_back, binfo->scrnx, COL8_008484, 32, 16, 32 + 15 * 8 - 1, 31);putfonts8_asc(buf_back, binfo->scrnx, 32, 16, COL8_FFFFFF, s);sheet_refresh(sht_back, 32, 16, 32 + 15 * 8, 32);mx += mdec.x;my += mdec.y;if (mx < 0) {mx = 0;}if (my < 0) {my = 0;}if (mx > binfo->scrnx - 1) {mx = binfo->scrnx - 1;}if (my > binfo->scrny - 1) {my = binfo->scrny - 1;}sprintf(s, "(%3d, %3d)", mx, my);boxfill8(buf_back, binfo->scrnx, COL8_008484, 0, 0, 79, 15); putfonts8_asc(buf_back, binfo->scrnx, 0, 0, COL8_FFFFFF, s); sheet_refresh(sht_back, 0, 0, 80, 16);sheet_slide(sht_mouse, mx, my);}}}}
}

显示的结果就是窗口中的数字在不断增加。但是数字显示的地方闪烁很严重，能看到背景色在一闪一闪。这是因为在刷新图层的时候，总是先刷新背景图层，再刷新窗口图层，因为数字的更新，刷新一直在进行，就会导致背景色一直在闪烁。

解决这一问题的方法很简单，如果只有窗口变化，其实不用刷新背景图层。因此refresh只对对象图层及其上面的图层进行刷新就可以了。实际修改时，sheet_refresh函数只刷新指定的图层及其上面的图层；而sheet_slide函数中，图层的移动有时会导致下面的图层露出，因此需要从最下面的图层开始刷新，而对于移动后的位置，也只需要刷新目标图层与上面的图层即可。

进行这些修改之后，计数器的数字显示闪烁问题解决了，但将鼠标放在计数器上面，又会发现鼠标的闪烁问题。这里需要另外的解决方法了。

struct SHTCTL {unsigned char *vram, *map;int xsize, ysize, top;struct SHEET *sheets[MAX_SHEETS];struct SHEET sheets0[MAX_SHEETS];
};struct SHTCTL *shtctl_init(struct MEMMAN *memman, unsigned char *vram, int xsize, int ysize)
{struct SHTCTL *ctl;int i;ctl = (struct SHTCTL *) memman_alloc_4k(memman, sizeof (struct SHTCTL));if (ctl == 0) {goto err;}ctl->map = (unsigned char *) memman_alloc_4k(memman, xsize * ysize);if (ctl->map == 0) {memman_free_4k(memman, (int) ctl, sizeof (struct SHTCTL));goto err;}ctl->vram = vram;ctl->xsize = xsize;ctl->ysize = ysize;ctl->top = -1; for (i = 0; i < MAX_SHEETS; i++) {ctl->sheets0[i].flags = 0;ctl->sheets0[i].ctl = ctl;}
err:return ctl;
}

这里开辟了一块与VRAM同样大小的内存，命名为map，用来表示画面上的点是哪个图层的像素，如图所示：

多个图层重叠的情况下，根据这个map进行刷新，就可以清楚地确定图层互相之间的覆盖关系了。

使用map首先要向map中写入图层的号码

void sheet_refreshmap(struct SHTCTL *ctl, int vx0, int vy0, int vx1, int vy1, int h0)
{int h, bx, by, vx, vy, bx0, by0, bx1, by1;unsigned char *buf, sid, *map = ctl->map;struct SHEET *sht;if (vx0 < 0) { vx0 = 0; }if (vy0 < 0) { vy0 = 0; }if (vx1 > ctl->xsize) { vx1 = ctl->xsize; }if (vy1 > ctl->ysize) { vy1 = ctl->ysize; }for (h = h0; h <= ctl->top; h++) {sht = ctl->sheets[h];sid = sht - ctl->sheets0; /* 将进行了减法计算的地址作为图层号码使用*/buf = sht->buf;bx0 = vx0 - sht->vx0;by0 = vy0 - sht->vy0;bx1 = vx1 - sht->vx0;by1 = vy1 - sht->vy0;if (bx0 < 0) { bx0 = 0; }if (by0 < 0) { by0 = 0; }if (bx1 > sht->bxsize) { bx1 = sht->bxsize; }if (by1 > sht->bysize) { by1 = sht->bysize; }for (by = by0; by < by1; by++) {vy = sht->vy0 + by;for (bx = bx0; bx < bx1; bx++) {vx = sht->vx0 + bx;if (buf[by * sht->bxsize + bx] != sht->col_inv) {map[vy * ctl->xsize + vx] = sid;}}}}return;
}

这个函数的原理其实与refreshsub函数基本一样，只不过后者是写入色号，而这里是把图层号码sid写入到map。

同样改写了sheet_refreshsub函数，使其可以使用map:

void sheet_refreshsub(struct SHTCTL *ctl, int vx0, int vy0, int vx1, int vy1, int h0, int h1)
{int h, bx, by, vx, vy, bx0, by0, bx1, by1;unsigned char *buf, *vram = ctl->vram, *map = ctl->map, sid;struct SHEET *sht;if (vx0 < 0) { vx0 = 0; }if (vy0 < 0) { vy0 = 0; }if (vx1 > ctl->xsize) { vx1 = ctl->xsize; }if (vy1 > ctl->ysize) { vy1 = ctl->ysize; }for (h = h0; h <= h1; h++) {sht = ctl->sheets[h];buf = sht->buf;sid = sht - ctl->sheets0;bx0 = vx0 - sht->vx0;by0 = vy0 - sht->vy0;bx1 = vx1 - sht->vx0;by1 = vy1 - sht->vy0;if (bx0 < 0) { bx0 = 0; }if (by0 < 0) { by0 = 0; }if (bx1 > sht->bxsize) { bx1 = sht->bxsize; }if (by1 > sht->bysize) { by1 = sht->bysize; }for (by = by0; by < by1; by++) {vy = sht->vy0 + by;for (bx = bx0; bx < bx1; bx++) {vx = sht->vx0 + bx;if (map[vy * ctl->xsize + vx] == sid) {vram[vy * ctl->xsize + vx] = buf[by * sht->bxsize + bx];}}}}return;
}

根据map中记录的图层编号，分别进行刷新。由于参照map进行刷新，不需要再从下到上刷新每一个图层，因此这个函数增加了传参h1，用于和h0一起指定刷新图层的范围。

对于sheet_slide做如下修改：

void sheet_slide(struct SHEET *sht, int vx0, int vy0)
{struct SHTCTL *ctl = sht->ctl;int old_vx0 = sht->vx0, old_vy0 = sht->vy0;sht->vx0 = vx0;sht->vy0 = vy0;if (sht->height >= 0) { sheet_refreshmap(ctl, old_vx0, old_vy0, old_vx0 + sht->bxsize, old_vy0 + sht->bysize, 0);sheet_refreshmap(ctl, vx0, vy0, vx0 + sht->bxsize, vy0 + sht->bysize, sht->height);sheet_refreshsub(ctl, old_vx0, old_vy0, old_vx0 + sht->bxsize, old_vy0 + sht->bysize, 0, sht->height - 1);sheet_refreshsub(ctl, vx0, vy0, vx0 + sht->bxsize, vy0 + sht->bysize, sht->height, sht->height);}return;
}

在sheet_slide函数中，首先重写map，分别对应移动前后的图层。然后调用sheet_refrehsub函数。对于原位置，需要对上层图层移动后的下层图层重新绘制；而在新位置，只需要绘制移动过去的图层即可。

简单理解，其实就是通过map把叠加后的显示结果存储起来，最终绘制的时候只需要绘制一张画面，而不是从下向上描绘多个图层来最终实现叠加效果，这样避免了从下而上的刷新，就消除了闪烁。相比原来实现叠加的方法也更进了一步。

本篇内容其实修改增加的代码不多，主要还是在前文的基础上进行，但是方法概念需要好好理解。显示问题暂告一段落，下一篇开始定时器的相关内容，敬请期待。

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