Initial commit
This commit is contained in:
rxi
+326
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#include <stdio.h>
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#include <assert.h>
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#include <math.h>
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#include "lib/stb/stb_truetype.h"
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#include "xalloc.h"
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#include "renderer.h"
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#define MAX_GLYPHSET 256
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struct RenImage {
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RenColor *pixels;
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int width, height;
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};
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typedef struct {
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RenImage *image;
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stbtt_bakedchar glyphs[256];
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} GlyphSet;
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struct RenFont {
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void *data;
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stbtt_fontinfo stbfont;
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GlyphSet *sets[MAX_GLYPHSET];
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float size;
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int height;
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};
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static SDL_Window *window;
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static struct { int left, top, right, bottom; } clip;
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static const char* utf8_to_codepoint(const char *p, unsigned *dst) {
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unsigned res, n;
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switch (*p & 0xf0) {
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case 0xf0 : res = *p & 0x07; n = 3; break;
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case 0xe0 : res = *p & 0x0f; n = 2; break;
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case 0xd0 :
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case 0xc0 : res = *p & 0x1f; n = 1; break;
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default : res = *p; n = 0; break;
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}
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while (n--) {
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res = (res << 6) | (*(++p) & 0x3f);
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}
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*dst = res;
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return p + 1;
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}
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void ren_init(SDL_Window *win) {
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assert(win);
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window = win;
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SDL_Surface *surf = SDL_GetWindowSurface(window);
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ren_set_clip_rect( (RenRect) { 0, 0, surf->w, surf->h } );
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}
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void ren_update_rects(RenRect *rects, int count) {
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SDL_UpdateWindowSurfaceRects(window, (SDL_Rect*) rects, count);
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}
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void ren_set_clip_rect(RenRect rect) {
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clip.left = rect.x;
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clip.top = rect.y;
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clip.right = rect.x + rect.width;
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clip.bottom = rect.y + rect.height;
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}
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void ren_get_size(int *x, int *y) {
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SDL_Surface *surf = SDL_GetWindowSurface(window);
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*x = surf->w;
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*y = surf->h;
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}
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RenImage* ren_new_image(int width, int height) {
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assert(width > 0 && height > 0);
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RenImage *image = xmalloc(sizeof(RenImage) + width * height * sizeof(RenColor));
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image->pixels = (void*) (image + 1);
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image->width = width;
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image->height = height;
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return image;
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}
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void ren_free_image(RenImage *image) {
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xfree(image);
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}
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static GlyphSet* load_glyphset(RenFont *font, int idx) {
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GlyphSet *set = xcalloc(1, sizeof(GlyphSet));
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/* init image */
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int width = 128;
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int height = 128;
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retry:
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set->image = ren_new_image(width, height);
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/* load glyphs */
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float s =
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stbtt_ScaleForMappingEmToPixels(&font->stbfont, 1) /
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stbtt_ScaleForPixelHeight(&font->stbfont, 1);
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int res = stbtt_BakeFontBitmap(
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font->data, 0, font->size * s, (void*) set->image->pixels,
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width, height, idx * 256, 256, set->glyphs);
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/* retry with a larger image buffer if the buffer wasn't large enough */
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if (res < 0) {
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width *= 2;
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height *= 2;
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ren_free_image(set->image);
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goto retry;
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}
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/* adjust glyph yoffsets and xadvance */
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int ascent, descent, linegap;
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stbtt_GetFontVMetrics(&font->stbfont, &ascent, &descent, &linegap);
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float scale = stbtt_ScaleForMappingEmToPixels(&font->stbfont, font->size);
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int scaled_ascent = ascent * scale + 0.5;
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for (int i = 0; i < 256; i++) {
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set->glyphs[i].yoff += scaled_ascent;
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set->glyphs[i].xadvance = floor(set->glyphs[i].xadvance);
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}
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/* convert 8bit data to 32bit */
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for (int i = width * height - 1; i >= 0; i--) {
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uint8_t n = *((uint8_t*) set->image->pixels + i);
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set->image->pixels[i] = (RenColor) { .r = 255, .g = 255, .b = 255, .a = n };
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}
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return set;
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}
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static GlyphSet* get_glyphset(RenFont *font, int codepoint) {
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int idx = (codepoint >> 8) % MAX_GLYPHSET;
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if (!font->sets[idx]) {
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font->sets[idx] = load_glyphset(font, idx);
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}
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return font->sets[idx];
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}
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RenFont* ren_load_font(const char *filename, float size) {
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RenFont *font = NULL;
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FILE *fp = NULL;
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/* init font */
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font = xcalloc(1, sizeof(RenFont));
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font->size = size;
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/* load font into buffer */
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fp = fopen(filename, "rb");
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if (!fp) { return NULL; }
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/* get size */
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fseek(fp, 0, SEEK_END); int buf_size = ftell(fp); fseek(fp, 0, SEEK_SET);
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/* load */
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font->data = xmalloc(buf_size);
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int _ = fread(font->data, 1, buf_size, fp); (void) _;
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fclose(fp);
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fp = NULL;
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/* init stbfont */
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int ok = stbtt_InitFont(&font->stbfont, font->data, 0);
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if (!ok) { goto fail; }
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/* get height and scale */
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int ascent, descent, linegap;
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stbtt_GetFontVMetrics(&font->stbfont, &ascent, &descent, &linegap);
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float scale = stbtt_ScaleForMappingEmToPixels(&font->stbfont, size);
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font->height = (ascent - descent + linegap) * scale + 0.5;
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return font;
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fail:
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if (fp) { fclose(fp); }
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if (font) { xfree(font->data); }
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xfree(font);
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return NULL;
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}
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void ren_free_font(RenFont *font) {
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for (int i = 0; i < MAX_GLYPHSET; i++) {
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GlyphSet *set = font->sets[i];
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if (set) {
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ren_free_image(set->image);
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xfree(set);
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}
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}
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xfree(font->data);
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xfree(font);
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}
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void ren_set_font_tab_width(RenFont *font, int n) {
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GlyphSet *set = get_glyphset(font, '\t');
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set->glyphs['\t'].xadvance = n;
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}
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int ren_get_font_width(RenFont *font, const char *text) {
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int x = 0;
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const char *p = text;
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unsigned codepoint;
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while (*p) {
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p = utf8_to_codepoint(p, &codepoint);
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GlyphSet *set = get_glyphset(font, codepoint);
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stbtt_bakedchar *g = &set->glyphs[codepoint & 0xff];
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x += g->xadvance;
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}
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return x;
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}
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int ren_get_font_height(RenFont *font) {
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return font->height;
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}
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static inline RenColor blend_pixel(RenColor dst, RenColor src) {
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int ia = 0xff - src.a;
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dst.r = ((src.r * src.a) + (dst.r * ia)) >> 8;
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dst.g = ((src.g * src.a) + (dst.g * ia)) >> 8;
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dst.b = ((src.b * src.a) + (dst.b * ia)) >> 8;
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return dst;
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}
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static inline RenColor blend_pixel2(RenColor dst, RenColor src, RenColor color) {
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src.a = (src.a * color.a) >> 8;
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int ia = 0xff - src.a;
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dst.r = ((src.r * color.r * src.a) >> 16) + ((dst.r * ia) >> 8);
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dst.g = ((src.g * color.g * src.a) >> 16) + ((dst.g * ia) >> 8);
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dst.b = ((src.b * color.b * src.a) >> 16) + ((dst.b * ia) >> 8);
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return dst;
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}
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#define rect_draw_loop(expr) \
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for (int j = y1; j < y2; j++) { \
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for (int i = x1; i < x2; i++) { \
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*d = expr; \
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d++; \
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} \
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d += dr; \
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}
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void ren_draw_rect(RenRect rect, RenColor color) {
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if (color.a == 0) { return; }
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int x1 = rect.x < clip.left ? clip.left : rect.x;
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int y1 = rect.y < clip.top ? clip.top : rect.y;
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int x2 = rect.x + rect.width;
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int y2 = rect.y + rect.height;
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x2 = x2 > clip.right ? clip.right : x2;
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y2 = y2 > clip.bottom ? clip.bottom : y2;
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SDL_Surface *surf = SDL_GetWindowSurface(window);
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RenColor *d = (RenColor*) surf->pixels;
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d += x1 + y1 * surf->w;
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int dr = surf->w - (x2 - x1);
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if (color.a == 0xff) {
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rect_draw_loop(color);
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} else {
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rect_draw_loop(blend_pixel(*d, color));
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}
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}
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void ren_draw_image(RenImage *image, RenRect *sub, int x, int y, RenColor color) {
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if (color.a == 0) { return; }
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/* clip */
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int n;
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if ((n = clip.left - x) > 0) { sub->width -= n; sub->x += n; x += n; }
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if ((n = clip.top - y) > 0) { sub->height -= n; sub->y += n; y += n; }
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if ((n = x + sub->width - clip.right ) > 0) { sub->width -= n; }
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if ((n = y + sub->height - clip.bottom) > 0) { sub->height -= n; }
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if (sub->width <= 0 || sub->height <= 0) {
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return;
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}
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/* draw */
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SDL_Surface *surf = SDL_GetWindowSurface(window);
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RenColor *s = image->pixels;
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RenColor *d = (RenColor*) surf->pixels;
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s += sub->x + sub->y * image->width;
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d += x + y * surf->w;
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int sr = image->width - sub->width;
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int dr = surf->w - sub->width;
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for (int j = 0; j < sub->height; j++) {
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for (int i = 0; i < sub->width; i++) {
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*d = blend_pixel2(*d, *s, color);
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d++;
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s++;
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}
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d += dr;
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s += sr;
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}
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}
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int ren_draw_text(RenFont *font, const char *text, int x, int y, RenColor color) {
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RenRect rect;
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const char *p = text;
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unsigned codepoint;
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while (*p) {
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p = utf8_to_codepoint(p, &codepoint);
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GlyphSet *set = get_glyphset(font, codepoint);
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stbtt_bakedchar *g = &set->glyphs[codepoint & 0xff];
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rect.x = g->x0;
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rect.y = g->y0;
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rect.width = g->x1 - g->x0;
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rect.height = g->y1 - g->y0;
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ren_draw_image(set->image, &rect, x + g->xoff, y + g->yoff, color);
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x += g->xadvance;
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}
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return x;
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}
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