Re: Zooming into an image on the mouse position

Hi,

I'm currently maintaining an application in C++ using MFC (Visual Studio 10). It use LAnnotationWindow object to show and manipulate an image.

I would like to zoom in/out when the mouse wheel is used. I would like to zoom the entire bitmap but keep the point under the mouse cursor in its old position (to get the cursor's position and zoom centered on the cursor).

Is there a C++ example?

Thank You in advance :)

You can use ZoomToRect() and make the mouse coordinates as the rectangle center. And you can use the following post to convert from mouse coordinates to bitmap coordinates:
http://support.leadtools.com/CS/forums/5309/ShowPost.aspx

Hi,

Can you please provide a more specific example where you will calculate the new zoomed rect (parameter of ZoomToRect) based on the Zoom percent or the zoom factor.

Thank You

Here is what I done so far:

1. Get the mouse position from OnMouseMove since specifies the x- and y-coordinate of the cursor relative to the upper-left corner of the window.

2. call SetZoomFactor with the new calculated zoom factor
Question: do we need to call SetZoomFactor for what I need to do ?

3. do the following code base on your previous suggestion:
POINT pt, bitmapPoint;
CRect rcDst;

pt = zoomCenter (muse location from OnMouseMove) ;

this->GetRects(NULL, NULL, &rcDst, NULL);

bitmapPoint.x = (pt.x - rcDst.left);
bitmapPoint.y = (pt.y - rcDst.top);

bitmapPoint.x = (long)(bitmapPoint.x * 100 / GetZoomPercent());
bitmapPoint.y = (long)(bitmapPoint.y * 100 / GetZoomPercent());

Note that previous step 3 is done in OnMouseWheel

Hello,
I apologize for the delay. I was working on a project for you.
However, after investigating this more, I discovered that what you want can't be achieved because the image size has limited width and height and when zooming out eventually you will reach a point that the image is fitted or smaller than the viewer and the zoom point is no longer under the mouse pointer.

What !!!!

That why we implement a zoom limit. If user is zooming more or less than a zoom lomit then he cannot zoom anymore.

Technically what I'm trying to do is the same as SetToolType(TOOL_ZOOM_ON_MOUSECLICK);
which will zoom the image on the mouse position, but with the mouse wheel instead!!

Hello,
I apologize for the delay but we have created a project for you that zooms in and out based on the mouse pointer position and uploaded it to our forums.
You can download it from the following link:
http://support.leadtools.com/CS/forums/42771/ShowPost.aspx#42771

thank you