1 files changed, 228 insertions, 0 deletions

diff --git a/libraries/evas/src/examples/evas-buffer-simple.c b/libraries/evas/src/examples/evas-buffer-simple.c
new file mode 100644
index 0000000..6676ef1
--- /dev/null
+++ b/libraries/evas/src/examples/evas-buffer-simple.c
@@ -0,0 +1,228 @@
+/**
+ * Simple Evas example using the Buffer engine.
+ *
+ * You must have Evas compiled with the buffer engine, and have the
+ * evas-software-buffer pkg-config files installed.
+ *
+ * Compile with:
+ *
+ * @verbatim
+ * gcc -o evas-buffer-simple evas-buffer-simple.c `pkg-config --libs --cflags evas evas-software-buffer`
+ * @endverbatim
+ *
+ */
+#include <Evas.h>
+#include <Evas_Engine_Buffer.h>
+#include <stdio.h>
+#include <errno.h>
+
+#define WIDTH (320)
+#define HEIGHT (240)
+
+/*
+ * create_canvas(), destroy_canvas() and draw_scene() are support functions.
+ *
+ * They are only required to use raw Evas, but for real world usage,
+ * it is recommended to use ecore and its ecore-evas submodule, that
+ * provide convenience canvas creators, integration with main loop and
+ * automatic render of updates (draw_scene()) when system goes back to
+ * main loop.
+ */
+static Evas *create_canvas(int width, int height);
+static void destroy_canvas(Evas *canvas);
+static void draw_scene(Evas *canvas);
+
+// support function to save scene as PPM image
+static void save_scene(Evas *canvas, const char *dest);
+
+int main(void)
+{
+   Evas *canvas;
+   Evas_Object *bg, *r1, *r2, *r3;
+
+   evas_init();
+
+   // create your canvas
+   // NOTE: consider using ecore_evas_buffer_new() instead!
+   canvas = create_canvas(WIDTH, HEIGHT);
+   if (!canvas)
+     return -1;
+
+   bg = evas_object_rectangle_add(canvas);
+   evas_object_color_set(bg, 255, 255, 255, 255); // white bg
+   evas_object_move(bg, 0, 0);                    // at origin
+   evas_object_resize(bg, WIDTH, HEIGHT);         // covers full canvas
+   evas_object_show(bg);
+
+   puts("initial scene, with just background:");
+   draw_scene(canvas);
+
+   r1 = evas_object_rectangle_add(canvas);
+   evas_object_color_set(r1, 255, 0, 0, 255); // 100% opaque red
+   evas_object_move(r1, 10, 10);
+   evas_object_resize(r1, 100, 100);
+   evas_object_show(r1);
+
+   // pay attention to transparency! Evas color values are pre-multiplied by
+   // alpha, so 50% opaque green is:
+   // non-premul: r=0, g=255, b=0    a=128 (50% alpha)
+   // premul:
+   //         r_premul = r * a / 255 =      0 * 128 / 255 =      0
+   //         g_premul = g * a / 255 =    255 * 128 / 255 =    128
+   //         b_premul = b * a / 255 =      0 * 128 / 255 =      0
+   //
+   // this 50% green is over a red background, so it will show in the
+   // final output as yellow (green + red = yellow)
+   r2 = evas_object_rectangle_add(canvas);
+   evas_object_color_set(r2, 0, 128, 0, 128); // 50% opaque green
+   evas_object_move(r2, 10, 10);
+   evas_object_resize(r2, 50, 50);
+   evas_object_show(r2);
+
+   r3 = evas_object_rectangle_add(canvas);
+   evas_object_color_set(r3, 0, 128, 0, 255); // 100% opaque dark green
+   evas_object_move(r3, 60, 60);
+   evas_object_resize(r3, 50, 50);
+   evas_object_show(r3);
+
+   puts("final scene (note updates):");
+   draw_scene(canvas);
+   save_scene(canvas, "/tmp/evas-buffer-simple-render.ppm");
+
+   // NOTE: use ecore_evas_buffer_new() and here ecore_evas_free()
+   destroy_canvas(canvas);
+
+   evas_shutdown();
+
+   return 0;
+}
+
+static Evas *create_canvas(int width, int height)
+{
+   Evas *canvas;
+   Evas_Engine_Info_Buffer *einfo;
+   int method;
+   void *pixels;
+
+   method = evas_render_method_lookup("buffer");
+   if (method <= 0)
+     {
+        fputs("ERROR: evas was not compiled with 'buffer' engine!\n", stderr);
+        return NULL;
+     }
+
+   canvas = evas_new();
+   if (!canvas)
+     {
+        fputs("ERROR: could not instantiate new evas canvas.\n", stderr);
+        return NULL;
+     }
+
+   evas_output_method_set(canvas, method);
+   evas_output_size_set(canvas, width, height);
+   evas_output_viewport_set(canvas, 0, 0, width, height);
+
+   einfo = (Evas_Engine_Info_Buffer *)evas_engine_info_get(canvas);
+   if (!einfo)
+     {
+        fputs("ERROR: could not get evas engine info!\n", stderr);
+        evas_free(canvas);
+        return NULL;
+     }
+
+   // ARGB32 is sizeof(int), that is 4 bytes, per pixel
+   pixels = malloc(width * height * sizeof(int));
+   if (!pixels)
+     {
+        fputs("ERROR: could not allocate canvas pixels!\n", stderr);
+        evas_free(canvas);
+        return NULL;
+     }
+
+   einfo->info.depth_type = EVAS_ENGINE_BUFFER_DEPTH_ARGB32;
+   einfo->info.dest_buffer = pixels;
+   einfo->info.dest_buffer_row_bytes = width * sizeof(int);
+   einfo->info.use_color_key = 0;
+   einfo->info.alpha_threshold = 0;
+   einfo->info.func.new_update_region = NULL;
+   einfo->info.func.free_update_region = NULL;
+   evas_engine_info_set(canvas, (Evas_Engine_Info *)einfo);
+
+   return canvas;
+}
+
+static void destroy_canvas(Evas *canvas)
+{
+   Evas_Engine_Info_Buffer *einfo;
+
+   einfo = (Evas_Engine_Info_Buffer *)evas_engine_info_get(canvas);
+   if (!einfo)
+     {
+        fputs("ERROR: could not get evas engine info!\n", stderr);
+        evas_free(canvas);
+        return;
+     }
+
+   free(einfo->info.dest_buffer);
+   evas_free(canvas);
+}
+
+static void draw_scene(Evas *canvas)
+{
+   Eina_List *updates, *n;
+   Eina_Rectangle *update;
+
+   // render and get the updated rectangles:
+   updates = evas_render_updates(canvas);
+
+   // informative only here, just print the updated areas:
+   EINA_LIST_FOREACH(updates, n, update)
+     printf("UPDATED REGION: pos: %3d, %3d    size: %3dx%3d\n",
+            update->x, update->y, update->w, update->h);
+
+   // free list of updates
+   evas_render_updates_free(updates);
+}
+
+static void save_scene(Evas *canvas, const char *dest)
+{
+   Evas_Engine_Info_Buffer *einfo;
+   const unsigned int *pixels, *pixels_end;
+   int width, height;
+   FILE *f;
+
+   einfo = (Evas_Engine_Info_Buffer *)evas_engine_info_get(canvas);
+   if (!einfo)
+     {
+        fputs("ERROR: could not get evas engine info!\n", stderr);
+        return;
+     }
+   evas_output_size_get(canvas, &width, &height);
+
+   f = fopen(dest, "wb+");
+   if (!f)
+     {
+        fprintf(stderr, "ERROR: could not open for writing '%s': %s\n",
+                dest, strerror(errno));
+        return;
+     }
+
+   pixels = einfo->info.dest_buffer;
+   pixels_end = pixels + (width * height);
+
+   // PPM P6 format is dead simple to write:
+   fprintf(f, "P6\n%d %d\n255\n",  width, height);
+   for (; pixels < pixels_end; pixels++)
+     {
+        int r, g, b;
+
+        r = ((*pixels) & 0xff0000) >> 16;
+        g = ((*pixels) & 0x00ff00) >> 8;
+        b = (*pixels) & 0x0000ff;
+
+        fprintf(f, "%c%c%c", r, g, b);
+     }
+
+   fclose(f);
+   printf("saved scene as '%s'\n", dest);
+}