[.. upper level ..]

Video functions

Functions for graphical output to the game-window.

• Structures and Enumerations


• Images
• Creating images
• VG3_image_create()
  
  Create a new empty image.
• VG3_image_text()
  
  Create a new image containing text.
• VG3_image_clone()
  
  Clone an image as a new image (copy), also useful for saving as file.
• VG3_image_clone_reference()
  
  Clone an image as a reference, that is no new image, but returns the original image.
• VG3_image_load()
  
  Load an image from disk, must be a BMP-File.
• Querying images
• VG3_image_getsize()
  
  Get size of an image.
• Copying images
• VG3_image_copy()
  
  Copy an image onto the window or another image.
• Unloading images
• VG3_image_unload()
  
  Unload an image resp. decrement it's references incremented by VG3_image_clone_reference().


• Fonts
  Fonts are defined in special fontfiles, like the standard fontfile 8x8.font located below share/.
• VG3_font_highdouble()
  
  Set or remove default double-zooming of fonts when using VGAG3_VGAVERSION_HIGH.
• VG3_fontsize()
  
  Get fontsize and padding of a font.
• VG3_fontchar_from_name()
  
  Return a character-number from 0 to 255 of a symbol-fontfile via a defined name in the fontfile.


• Simple drawing onto images or the window
• VG3_draw_clear()
  
  Clear an image or the window.
• VG3_draw_point()
  
  Draw a pixel onto an image or the window.
• VG3_draw_line()
  
  Draw a line onto an image or the window.
• VG3_draw_rect()
  
  Draw a rectangle onto an image or the window.
• VG3_draw_text()
  
  Draw a text onto an image or the window.
  (see also Complexer handling with text and input)
• VG3_draw_colorchange()
  
  Replace pixels of one color with another.
• VG3_draw_colorize()
  
  Colorize an image.


• Miscellaneous
• VG3_replace_colormap()
  
  Replace the colormap (for a window with 256 colors (VGAG3_VGAVERSION_LOW)).
  This affects only images created/loaded after this function call.
• VG3_image_attr_sum()
  
  Get the sum of two image-attribute structures.
  Image-attributes can be passed to some image-functions to act with a modified image, e.g. zooming or brightness.

Example

  /* create an image with a text
   * draw this image onto the window waiting for pressing space-key
   */

  struct vg3_window *wstruct;
  int winw, winh;

  /* open window */
  wstruct = VG3_window_new(argv[0], VGAG3_VGAVERSION_LOW, VGAG3_WINSCALE_BESTSCALE);
  if (wstruct == NULL) { fprintf(stderr, "%s\n", VG3_error()); exit(1); }

  /* get the size of the window */
  VG3_window_getsize(wstruct, &winw, &winh);

  /* draw text to an image and copy it onto the window */
  { const int do_i_want_a_corrected_rectangle = 0;  /* set this to 0 or 1 */
    struct vg3_image *imgptr;
    struct vg3_text stxt;
    struct vg3_rect rect;
    int imgw, imgh;

    /* +++ create an image and print a text to it +++ */

    /* create an empty image with width+height 150x80 pixels */
    imgw = 150;
    imgh = 80;
    imgptr = VG3_image_create(wstruct, imgw, imgh);
    if (imgptr == NULL) { fprintf(stderr, "%s\n", VG3_error()); goto byebye; }

    /* draw a rectangle to the borders of the image */
    rect.x = 0;
    rect.w = imgw;
    rect.y = 0;
    rect.h = imgh;
    VG3_draw_rect(wstruct, imgptr, &rect, 0, VGAG3_COLOR_RED);

    /* prepare the text structure,
     * we want to display "Press space to exit"
     * with the shipped fontfile "10x17.font"
     */
    VGAG3_TEXT_ATTRIBUTES_SET(&stxt, "10x17.font", '\n', 0, "Press space to exit");

    /* set the destination rectangle,
     * we want to have a border of minimal 10 pixels on each side
     */
    rect.x = 10;
    rect.w = imgw - 20;
    rect.y = 10;
    rect.h = imgh - 20;

    /* now we could do a dry-run drawing to get the corrected destination rectangle */
    if (do_i_want_a_corrected_rectangle) {
      rect = VG3_draw_text(wstruct, imgptr, &rect, ' ', &stxt, VGAG3_COLOR_RED, VGAG3_COLOR_BLUE, 1);
    }

    /* draw the text to the image */
    VG3_draw_text(wstruct, imgptr, &rect, ' ', &stxt, VGAG3_COLOR_RED, VGAG3_COLOR_BLUE, 0);


    /* +++ copy the image onto the window and wait for pressing space-key +++ */

    /* copy the image right aligned and vertically centered to the window */
    VG3_image_copy(wstruct, NULL, imgptr, winw - (imgw / 2), winh / 2, NULL, 0);

    /* update window contents and wait for pressing space-key */
    VG3_discard_input(wstruct);
    for (;;) {
      if (VG3_inputevent_update(wstruct) > 0) { break; }
      if (VG3_key_ispressed(wstruct, VGAG3_KEY_SPACE, VGAG3_IS_NEW_PRESSED)) { break; }
      VG3_window_update(wstruct, 0, 0);
      VG3_wait_time(50);
    }
    VG3_discard_input(wstruct);

    /* free the image */
    VG3_image_unload(wstruct, imgptr);
  }

  /* if an error occurred after creating the window, close it before exiting */
  byebye:
  /* close window */
  VG3_window_free(wstruct);