Re: Qt graphics zooming

[Ben Abbott]

> On Mar 3, 2015, at 2:43 PM, Ben Abbott <address@hidden> wrote:
> 
>> On Mar 3, 2015, at 2:05 PM, John W. Eaton <address@hidden> wrote:
>> 
>> On 03/03/2015 02:01 PM, Ben Abbott wrote:
>>>> On Mar 3, 2015, at 1:55 PM, John W. Eaton <address@hidden> wrote:
>>>> 
>>>> On 03/03/2015 01:28 PM, Rik wrote:
>>>> 
>>>>> This works well when using single mouse clicks.  I would add the same
>>>>> code to the canvasWheelEvent so that mouse wheel zoom is also based on
>>>>> the current location.
>>>>> 
>>>>> -- Canvas.cc:795 --
>>>>> // FIXME: should we zoom about point for 2D plots?
>>>>> 
>>>>> ap.zoom (mode, factor);
>>>>> -- End Code --
>>>>> 
>>>>> It looks like that may have been intended.
>>>> 
>>>> I'm not sure that's how Matlab works.  Maybe someone else can verify?
>>>> 
>>>> I don't really care one way or the other, but if we diverge from what 
>>>> Matlab does, I expect we'll get a bug report about it...
>>>> 
>>>> jwe
>>> 
>>> I happy to try on Matlab, but I'm not following what needs to be done.
>>> 
>>> To illustrate where I'm lost .... If the mouse clicking the a zoom button 
>>> why would the zoom be based upon the location of the mouse?
>>> 
>>> If a hot key is being used to zoom, I don't think Matlab supports that.
>> 
>> If you create a plot, then select the zoom mode from the toolbar, then click 
>> in the plot window, does the zooming happen around the location of the 
>> click, or does it happen around the center of the plot axes?
> 
> It zoom in on where the was located when clicked. I typically click-n-drag 
> and Matlab zooms in on the contents of the rectangle.
> 
>> Similarly, if you are in zoom mode and zoom with the mouse wheel, does it 
>> zoom around the location of the cursor, or does it zoom around the center of 
>> the plot axes?
> 
> Matlab zoom relative to the center of the plot axes. For zoom-in mode, Matlab 
> will not zoom-out beyond the original xlim(), ylim(). For zoom-out mode, 
> Matlab will not zoom-in beyond the original limits either.
> 
> Ben

jeezzz ... that's embarrassing ;-)

It zooms in on where the mouse was located when clicked. I typically 
click-n-drag and Matlab zooms in on the contents of the rectangle.

> Similarly, if you are in zoom mode and zoom with the mouse wheel, does it 
> zoom around the location of the cursor, or does it zoom around the center of 
> the plot axes?

I'd never tried this before. Matlab zooms relative to the center of the plot 
axes. For zoom-in mode, Matlab will not zoom-out beyond the original xlim(), 
ylim(). For zoom-out mode, Matlab will not zoom-in beyond the original limits 
either.

Ben