Pixel readback

Read pixels, flood fill, grab and stamp images, take screenshots.

For the full list see "UI development". Each call below comes with a one-line usage note and an example; signatures come from Lib/c/vml_ui.h (the authoritative source).

ui_2d_flood_fill(int x, int y, int color, int border)

Flood fills from (x,y), stopping at the border color (four-connected). Returns the number of rectangles written; 0 means nothing was filled (that happens when the seed point itself sits on the border color - very common with old programs that "click on the line", and not an error).

ui_2d_flood_fill(50, 50, 0xFF00FF00, 0xFFFF0000);   /* fill green inside a red frame */

ui_2d_get_image(int x, int y, int w, int h)

Saves a region of the picture and returns a handle (at least 1), or 0 on failure. An old program's malloc(imagesize(...)) still works fine - we just do not use that memory.

int img = ui_2d_get_image(0, 0, 32, 32);   /* grab a 32x32 region */

ui_2d_get_pixel(int x, int y)

Reads the color of one pixel (0xRRGGBB; -1 if out of range). Note: the scene is retained-mode, so every call makes the host rasterize on the spot - do not put it in a tight loop.

int c = ui_2d_get_pixel(100, 100);
if (c == 0xFFFFFF) { /* it is white there */ }

ui_2d_put_image(int x, int y, int handle, int mode)

Stamps the handle's region at (x,y). mode: 0 = COPY, stamp directly / 1 = XOR (XOR has to read the destination pixel first, so it is slower).

ui_2d_put_image(200, 100, img, 0);    /* stamp it there */
ui_2d_put_image(200, 100, img, 1);    /* XOR once more = erase it (the old way of animating sprites) */

ui_scr_screenshot(char* path)

Saves the current window as a PNG (the path is relative to the workspace; with no path it picks a name automatically under shot/). Returns 1 on success.

ui_scr_screenshot("shot/win.png");