lite-xl/src/rencache.c

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C
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#include <stddef.h>
#include <stdint.h>
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#include <stdio.h>
#include <stdbool.h>
#include <string.h>
#ifdef _MSC_VER
#ifndef alignof
#define alignof _Alignof
#endif
/* max_align_t is a compiler defined type, but
** MSVC doesn't provide it, so we'll have to improvise */
typedef long double max_align_t;
#else
#include <stdalign.h>
#endif
#include <lauxlib.h>
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#include "rencache.h"
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/* a cache over the software renderer -- all drawing operations are stored as
** commands when issued. At the end of the frame we write the commands to a grid
** of hash values, take the cells that have changed since the previous frame,
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** merge them into dirty rectangles and redraw only those regions */
#define CELLS_X 80
#define CELLS_Y 50
#define CELL_SIZE 96
#define CMD_BUF_RESIZE_RATE 1.2
#define CMD_BUF_INIT_SIZE (1024 * 512)
#define COMMAND_BARE_SIZE offsetof(Command, text)
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enum { SET_CLIP, DRAW_TEXT, DRAW_RECT };
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typedef struct {
int8_t type;
int8_t tab_size;
int32_t size;
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RenRect rect;
RenColor color;
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RenFont *fonts[FONT_FALLBACK_MAX];
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float text_x;
size_t len;
char text[];
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} Command;
static unsigned cells_buf1[CELLS_X * CELLS_Y];
static unsigned cells_buf2[CELLS_X * CELLS_Y];
static unsigned *cells_prev = cells_buf1;
static unsigned *cells = cells_buf2;
static RenRect rect_buf[CELLS_X * CELLS_Y / 2];
size_t command_buf_size = 0;
uint8_t *command_buf = NULL;
static bool resize_issue;
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static int command_buf_idx;
static RenRect screen_rect;
static RenRect last_clip_rect;
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static bool show_debug;
static inline int rencache_min(int a, int b) { return a < b ? a : b; }
static inline int rencache_max(int a, int b) { return a > b ? a : b; }
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/* 32bit fnv-1a hash */
#define HASH_INITIAL 2166136261
static void hash(unsigned *h, const void *data, int size) {
const unsigned char *p = data;
while (size--) {
*h = (*h ^ *p++) * 16777619;
}
}
static inline int cell_idx(int x, int y) {
return x + y * CELLS_X;
}
static inline bool rects_overlap(RenRect a, RenRect b) {
return b.x + b.width >= a.x && b.x <= a.x + a.width
&& b.y + b.height >= a.y && b.y <= a.y + a.height;
}
static RenRect intersect_rects(RenRect a, RenRect b) {
int x1 = rencache_max(a.x, b.x);
int y1 = rencache_max(a.y, b.y);
int x2 = rencache_min(a.x + a.width, b.x + b.width);
int y2 = rencache_min(a.y + a.height, b.y + b.height);
return (RenRect) { x1, y1, rencache_max(0, x2 - x1), rencache_max(0, y2 - y1) };
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}
static RenRect merge_rects(RenRect a, RenRect b) {
int x1 = rencache_min(a.x, b.x);
int y1 = rencache_min(a.y, b.y);
int x2 = rencache_max(a.x + a.width, b.x + b.width);
int y2 = rencache_max(a.y + a.height, b.y + b.height);
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return (RenRect) { x1, y1, x2 - x1, y2 - y1 };
}
static bool expand_command_buffer() {
size_t new_size = command_buf_size * CMD_BUF_RESIZE_RATE;
if (new_size == 0) {
new_size = CMD_BUF_INIT_SIZE;
}
uint8_t *new_command_buf = realloc(command_buf, new_size);
if (!new_command_buf) {
return false;
}
command_buf_size = new_size;
command_buf = new_command_buf;
return true;
}
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static Command* push_command(int type, int size) {
if (resize_issue) {
// Don't push new commands as we had problems resizing the command buffer.
// Let's wait for the next frame.
return NULL;
}
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size_t alignment = alignof(max_align_t) - 1;
size = (size + alignment) & ~alignment;
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int n = command_buf_idx + size;
while (n > command_buf_size) {
if (!expand_command_buffer()) {
fprintf(stderr, "Warning: (" __FILE__ "): unable to resize command buffer (%ld)\n",
(size_t)(command_buf_size * CMD_BUF_RESIZE_RATE));
resize_issue = true;
return NULL;
}
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}
Command *cmd = (Command*) (command_buf + command_buf_idx);
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command_buf_idx = n;
memset(cmd, 0, size);
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cmd->type = type;
cmd->size = size;
return cmd;
}
static bool next_command(Command **prev) {
if (*prev == NULL) {
*prev = (Command*) command_buf;
} else {
*prev = (Command*) (((char*) *prev) + (*prev)->size);
}
return *prev != ((Command*) (command_buf + command_buf_idx));
}
void rencache_show_debug(bool enable) {
show_debug = enable;
}
void rencache_set_clip_rect(RenRect rect) {
Command *cmd = push_command(SET_CLIP, COMMAND_BARE_SIZE);
if (cmd) {
cmd->rect = intersect_rects(rect, screen_rect);
last_clip_rect = cmd->rect;
}
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}
void rencache_draw_rect(RenRect rect, RenColor color) {
if (rect.width == 0 || rect.height == 0 || !rects_overlap(last_clip_rect, rect)) {
return;
}
Command *cmd = push_command(DRAW_RECT, COMMAND_BARE_SIZE);
if (cmd) {
cmd->rect = rect;
cmd->color = color;
}
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}
float rencache_draw_text(RenFont **fonts, const char *text, size_t len, float x, int y, RenColor color)
{
float width = ren_font_group_get_width(fonts, text, len);
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RenRect rect = { x, y, (int)width, ren_font_group_get_height(fonts) };
if (rects_overlap(last_clip_rect, rect)) {
int sz = len + 1;
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Command *cmd = push_command(DRAW_TEXT, COMMAND_BARE_SIZE + sz);
if (cmd) {
memcpy(cmd->text, text, sz);
cmd->color = color;
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memcpy(cmd->fonts, fonts, sizeof(RenFont*)*FONT_FALLBACK_MAX);
cmd->rect = rect;
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cmd->text_x = x;
cmd->len = len;
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cmd->tab_size = ren_font_group_get_tab_size(fonts);
}
}
return x + width;
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}
void rencache_invalidate(void) {
memset(cells_prev, 0xff, sizeof(cells_buf1));
}
void rencache_begin_frame() {
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/* reset all cells if the screen width/height has changed */
int w, h;
resize_issue = false;
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ren_get_size(&w, &h);
if (screen_rect.width != w || h != screen_rect.height) {
screen_rect.width = w;
screen_rect.height = h;
rencache_invalidate();
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}
last_clip_rect = screen_rect;
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}
static void update_overlapping_cells(RenRect r, unsigned h) {
int x1 = r.x / CELL_SIZE;
int y1 = r.y / CELL_SIZE;
int x2 = (r.x + r.width) / CELL_SIZE;
int y2 = (r.y + r.height) / CELL_SIZE;
for (int y = y1; y <= y2; y++) {
for (int x = x1; x <= x2; x++) {
int idx = cell_idx(x, y);
hash(&cells[idx], &h, sizeof(h));
}
}
}
static void push_rect(RenRect r, int *count) {
/* try to merge with existing rectangle */
for (int i = *count - 1; i >= 0; i--) {
RenRect *rp = &rect_buf[i];
if (rects_overlap(*rp, r)) {
*rp = merge_rects(*rp, r);
return;
}
}
/* couldn't merge with previous rectangle: push */
rect_buf[(*count)++] = r;
}
void rencache_end_frame() {
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/* update cells from commands */
Command *cmd = NULL;
RenRect cr = screen_rect;
while (next_command(&cmd)) {
if (cmd->type == SET_CLIP) { cr = cmd->rect; }
RenRect r = intersect_rects(cmd->rect, cr);
if (r.width == 0 || r.height == 0) { continue; }
unsigned h = HASH_INITIAL;
hash(&h, cmd, cmd->size);
update_overlapping_cells(r, h);
}
/* push rects for all cells changed from last frame, reset cells */
int rect_count = 0;
int max_x = screen_rect.width / CELL_SIZE + 1;
int max_y = screen_rect.height / CELL_SIZE + 1;
for (int y = 0; y < max_y; y++) {
for (int x = 0; x < max_x; x++) {
/* compare previous and current cell for change */
int idx = cell_idx(x, y);
if (cells[idx] != cells_prev[idx]) {
push_rect((RenRect) { x, y, 1, 1 }, &rect_count);
}
cells_prev[idx] = HASH_INITIAL;
}
}
/* expand rects from cells to pixels */
for (int i = 0; i < rect_count; i++) {
RenRect *r = &rect_buf[i];
r->x *= CELL_SIZE;
r->y *= CELL_SIZE;
r->width *= CELL_SIZE;
r->height *= CELL_SIZE;
*r = intersect_rects(*r, screen_rect);
}
/* redraw updated regions */
for (int i = 0; i < rect_count; i++) {
/* draw */
RenRect r = rect_buf[i];
ren_set_clip_rect(r);
cmd = NULL;
while (next_command(&cmd)) {
switch (cmd->type) {
case SET_CLIP:
ren_set_clip_rect(intersect_rects(cmd->rect, r));
break;
case DRAW_RECT:
ren_draw_rect(cmd->rect, cmd->color);
break;
case DRAW_TEXT:
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ren_font_group_set_tab_size(cmd->fonts, cmd->tab_size);
ren_draw_text(cmd->fonts, cmd->text, cmd->len, cmd->text_x, cmd->rect.y, cmd->color);
break;
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}
}
if (show_debug) {
RenColor color = { rand(), rand(), rand(), 50 };
ren_draw_rect(r, color);
}
}
/* update dirty rects */
if (rect_count > 0) {
ren_update_rects(rect_buf, rect_count);
}
/* swap cell buffer and reset */
unsigned *tmp = cells;
cells = cells_prev;
cells_prev = tmp;
command_buf_idx = 0;
}