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2025-10-14 02:17:36 +08:00 · 2019-03-31 23:55:47 -07:00
parent e6029ed384
commit 0838ad15c7
1 changed files with 153 additions and 0 deletions
--- a/experiments/cairo/cairo2.cpp
+++ b/experiments/cairo/cairo2.cpp
@@ -0,0 +1,153 @@
+
+#include <cairo.h>
+
+#include <SDL.h>
+
+int main() {
+    double ang = 0,angv = (M_PI * 2) / 360,angstep = (M_PI * 2) / 4;
+
+    if (SDL_Init(SDL_INIT_VIDEO) != 0)
+        return 1;
+
+    SDL_Window *window = SDL_CreateWindow("Cairo",SDL_WINDOWPOS_UNDEFINED,SDL_WINDOWPOS_UNDEFINED,320,240,SDL_WINDOW_SHOWN);
+    if (window == NULL)
+        return 1;
+
+    SDL_Surface *surface = SDL_GetWindowSurface(window);
+    if (surface == NULL)
+        return 1;
+
+    cairo_format_t csurffmt = CAIRO_FORMAT_INVALID;
+    if (surface->format->BytesPerPixel == 4) {
+        csurffmt = CAIRO_FORMAT_ARGB32;
+    }
+    else if (surface->format->BytesPerPixel == 3) {
+        csurffmt = CAIRO_FORMAT_RGB24;
+    }
+    else if (surface->format->BytesPerPixel == 2) {
+        csurffmt = CAIRO_FORMAT_RGB16_565;
+    }
+    else {
+        return 1;
+    }
+
+    cairo_surface_t* csurf = cairo_image_surface_create(csurffmt, 320, 240);
+    if (csurf == NULL)
+        return 1;
+
+    cairo_t* cactx = cairo_create(csurf);
+    if (cactx == NULL)
+        return 1;
+
+    bool run = true;
+    while (run) {
+        SDL_Event ev;
+
+        while (SDL_PollEvent(&ev)) {
+            switch (ev.type) {
+                case SDL_WINDOWEVENT:
+                    switch (ev.window.event) {
+                        case SDL_WINDOWEVENT_CLOSE:
+                            run = false;
+                            break;
+                    }
+                    break;
+                case SDL_KEYDOWN:
+                    switch (ev.key.keysym.sym) {
+                        case SDLK_ESCAPE:
+                            run = false;
+                            break;
+                    }
+                    break;
+            }
+        }
+
+        // clear
+        cairo_reset_clip(cactx);
+        cairo_set_source_rgb(cactx,0.25,0.25,0.25);
+        cairo_paint(cactx);
+
+        // draw
+        cairo_set_line_width(cactx,8.0);
+
+        {
+            unsigned int step=0;
+
+            for (double a=0;a < (M_PI * 2);a += angstep,step++) {
+                double x = 160.0 + cos(a+ang)*100.0 + 20;
+                double y = 120.0 + sin(a+ang)*100.0 + 20;
+
+                if (step == 0)
+                    cairo_move_to(cactx,x,y);
+                else
+                    cairo_line_to(cactx,x,y);
+            }
+
+            cairo_close_path(cactx);
+            ang += angv;
+        }
+
+        cairo_set_source_rgba(cactx,0,0,0,0.5);
+        cairo_fill(cactx);
+
+        {
+            unsigned int step=0;
+
+            for (double a=0;a < (M_PI * 2);a += angstep,step++) {
+                double x = 160.0 + cos(a+ang)*100.0;
+                double y = 120.0 + sin(a+ang)*100.0;
+
+                if (step == 0)
+                    cairo_move_to(cactx,x,y);
+                else
+                    cairo_line_to(cactx,x,y);
+            }
+
+            cairo_close_path(cactx);
+            ang += angv;
+        }
+
+        cairo_set_source_rgb(cactx,1.0,1.0,1.0);
+        cairo_fill_preserve(cactx);
+
+        cairo_set_source_rgb(cactx,0.0,0.0,1.0);
+        cairo_stroke(cactx);
+
+        // copy Cairo output to display
+        cairo_surface_flush(csurf);
+        {
+            unsigned char *cbuf = cairo_image_surface_get_data(csurf);
+            int width = cairo_image_surface_get_width(csurf);
+            int height = cairo_image_surface_get_height(csurf);
+            int stride = cairo_image_surface_get_stride(csurf);
+
+            SDL_LockSurface(surface);
+
+            if (cbuf != NULL && surface->pixels != NULL) {
+                if (width > surface->w) width = surface->w;
+                if (height > surface->h) height = surface->h;
+
+                for (int y=0;y < height;y++) {
+                    unsigned char *d = (unsigned char*)(surface->pixels) + (surface->pitch * y);
+                    unsigned char *s = (unsigned char*)(cbuf) + (stride * y);
+                    memcpy(d,s,width*surface->format->BytesPerPixel);
+                }
+            }
+
+            SDL_UnlockSurface(surface);
+            SDL_UpdateWindowSurface(window);
+        }
+
+        SDL_Delay(1000 / 30);
+    }
+
+    cairo_surface_flush(csurf);
+    cairo_destroy(cactx);
+    cairo_surface_destroy(csurf);
+
+    // do not free surface, owned by dinwo
+    SDL_DestroyWindow(window);
+    SDL_Quit();
+    return 0;
+}
+