Scooter

I’m assuming you know the correct commands of A5 so I’ll paraphrase what I would do. Keep in mind I’m a novice with A5 so some of the others might give a more concise way of doing this.
I’m also assuming you already have the smaller image drawn as a default size.

int pos_x = 0;
int pos_y = 0;
bool Img_Size = false; // default smaller size

//With in the program while loop

// I would record mouse position.
if(event.type == ALLEGRO_EVENT_MOUSE_AXES)
{
pos_y = event.mouse.y;
pos_x = event.mouse.x;
} // end mouse axis

// Then I would react when button pressed.

if(event.type == ALLEGRO_EVENT_MOUSE_BUTTON_DOWN){ // The pos_X & Y are coordinates from a program I’m writing. You would use yours of course.

if(pos_x >= 180 && pos_y >= 240){ // Confirming I’m within the upper left hand corner of the “Large Image” section of the yellow rectangle.
if(pos_x <= 290 && pos_y<= 280){ // And that I’m within lower right hand corner of the “Large Image” section of the yellow rectangle.
Img_Size = true;
}}// end location if

if (pos_x >= 440 && pos_y >= 240){ // Confirming I’m within the upper left hand corner of the “Small Image” section of the yellow rectangle.
if(pos_x <= 560 && pos_y<= 280){ // And that I’m within lower right hand corner of the “Smaller Image” section of the yellow rectangle.
Img_Size = false;
}}// end location if
}// end button down

// Then draw specific image based on Img_Size

if( Img_Size == true)
al_draw_bitmap(lrg_bmp, x, y, 0);

if( Img_Size == false)
al_draw_bitmap(small_bmp, x, y, 0);

Let me know if I’ve misunderstood your question. Good Luck.

Scooter,

I enjoy programming as well. I usually decide to program something just to see if I can do it. Most of my programming is never seen by anyone but me.

In any case, sounds like you are asking about real time scaling. And that is well above my abilities. Like you, I'm not sure Allegro has that capability. Maybe one of the site experts might chime in.

Good luck and keep me updated on how it turns out.

BTW I found these doing a quick check...
al_draw_scaled_bitmap
&
https://www.youtube.com/watch?v=vkWivB3aCAo Rotating, Scaling and Tinting BMP in Allegro 5

Thanks AceBlkwell:
That is exactly the function I am using.
Here is the code that does the trick:

pos_x = ev.mouse.x; // get mouse x position
pos_y = ev.mouse.y; // get mouse y position
// al_set_mouse_xy(display, pos_x, pos_y);
image_height = al_get_bitmap_height(image);
image_width = al_get_bitmap_width(image);
al_clear_to_color(al_map_rgb(0,0,0));
draw_work_area();

scale_factor = working_screen_height / image_height;
dist = pos_x - 1030; // 1030 is the distance to left edge of rectangle
scale_factor = scale_factor * (dist / 125);
al_draw_scaled_bitmap(image,
0, 0, image_width, image_height,
(screen_width - (scale_factor * image_width)) / 2.0, // x position
((working_screen_height - scale_factor * image_height) / 2.0), // y position
image_width * scale_factor, image_height * scale_factor, 0);
al_flip_display();

I am going to redo some of the code to see if I can figure this out.
I will keep you posted!

AceBlkwell:

Sorry, could not work it out.
Can move the mouse when in the rectangle
and mouse coordinates will change like they
should but image does not change.
Probably screwed up events. Don't even
know if it is possible using Allegro.
Have a great day!

It's perfectly possible with Allegro5!!

Attached is an example program (tested on Windows), and the source code: