Shrinking Images rather than Stretching - wpf

I am having a little trouble in WPF - I am fully aware of the image stretch function and how to use it, and have that working fine. What I am trying to do however, is only apply the stretch if the image is too large (essentially to make it a shrink), and retain the original size if the image would fit into the view. The stretch method currently performs the shrinking perfectly, but will expand smaller images to fill the view which is not what I am after.
Is there a simple way of doing this?

you have to use the StretchDirection property in conjunction with the Stretch Property:
image.StretchDirection = StretchDirection.DownOnly;

Related

Scale all screen elements with window vb.net wpf

First time working on a GUI project.. and first time doing work on Windows so apologies in advance if this is a really noob question.
I'm taking baby steps into windows programming starting with vb.net WPF. Working in Visual Studio Express 2012.
I'm trying to work out how I can scale all the elements in a window with the window itself.
So for example, I'd create a window, say 1280x720, and place some images in the window. Say one at the top and one in the corner. (this is a basic media based application)
When I resize that window, I want the entire window to scale with it, so image 1 & 2 will get larger if the window gets larger, however this has to happen proportionally so that if I make the window a lot bigger in one direction one image can't overlap the other. Imagine the window is an image and I'm trying to resize it. (The overlap thing is the closest I've gotten to getting this working in my current attempts).
The layout in produciton will be more complex, comprising of mediaelements (video), images, text etc and all must scale accordingly.
This isn't something the user interacts with and so there are no form elements etc, and so I don't need form fields etc to stay the same size throughout scaling. I just need everything to scale like I'm scaling a picture. If for example I displayed this 1280x720 (16:9) layout on a 1920x1080 screen, maximised it should look identical only larger.
Hoping someone can point me in the right direction with this.
What I've tried so far- the few articles I did find on google relating to this (I may well be searching the wrong things) lead me to put all the elements in a viewbox, this lead to the overlap I mentioned earlier.
Ideas ?
I think you could use ViewBox container. The basic idea is as follows: ViewBox scales its content just as if it was an image scaled. This seems to be the closest result to what you've described in your question. Just put a Grid with absolutely-sized columns and rows into the ViewBox and set its Stretch to be Uniform:
<Viewbox Stretch="Uniform">
<Grid>
<..>Your controls, MediaElements, etc
<Grid>
</Viewbox>
You could also combine it (or entirely replace) with (e.g.) Grid Container : it gives you an ability to specify cell width and size usign star-syntax which is similair to html's percent syntax.
Another way is to use the DockPanel.
All-in-all there are plenty ways to achieve something similair and the way to go largely depends on the nuances of your particulair requirements.
Have a look at This tutorial to see a good overview of WPF containers and how to use them.

Issues with rendering a large tiled map in WPF

What is the best way to manage a very large amount of images (10,000+) in WPF? This is for a 2d tile map editor similar to this : http://www.mapeditor.org/ .
At the moment i have a canvas with all tiles as an image and a list box which contains the different images to choose from. Each tile is added to the canvas as children and then stored in a list for later access. You paint into the canvas by setting the Source property of a tile to the one selected in the listbox. It works well with around 50x50 tile maps but anything above that causes loading delays, in general slow application.
Any suggestions on this? Would QT maybe be more suited instead of wpf?
Thanks in advance
Check out Implementing virtualized panel series of articles.
Virtualized panels are efficient, because:
Only the displayed elements (and a few extra around the borders to enable smooth scrolling) are in the memory (and rendered).
Elements are reused, instead of being repeatedly created and discarded - an old cell is simply filled with new content (supplied with new DataContext) and used in new location.
You might also try to use WPF's DataGrid for this, it supports virtualization out of the box and is essentially what are you trying to do.
WPF is certainly able to do this, if implemented properly (if you can do that in JavaScript, you can certainly do it in WPF as well).

Sizing WPF windows automatically

When designing WPF dialog windows in the XAML designer (that are not manually resizeable by the user), the windows automatically resize to fit their content, and everything is fine. But when I run my app, the windows become huge and there's a lot of empty space.
I know this is a "feature" of WPF that can be "fixed" by setting the SizeToContent tag, but another issue arises when I do this: If the window contains a textbox, for instance, and the user enters data that overflows the visible area, the window will stretch to accommodate it. This happens with listboxes, treeviews, you name it.
All I want is for Visual Studio to figure out the ideal window size that it shows me at design time, then set the window to be that size at runtime, and don't change the size after that. It seems like this should be an easy thing to do.
Edit: Figured out part of the problem: I have controls set up in a grid, and the column's width is set to "Auto" which is why everything is resizing.
Use View Box
The ViewBox is a very useful control in WPF. If does nothing more than scale to fit the content to the available size. It does not resize the content, but it transforms it. This means that also all text sizes and line widths were scaled. Its about the same behavior as if you set the Stretch property on an Image or Path to Uniform.
Although it can be used to fit any type of control, it's often used for 2D graphics, or to fit a scalable part of a user interface into an screen area.
<Viewbox>
<Enter your code/>
</Viewbox>
Try setting the window's height and width to Auto. Also, remove the SizeToContent attribute. This should fix it.
I do not think that this is this is something which is commonly requested so it's probably not easy to do, one method i can think of would be starting with automatic SizeToContent and handling the Loaded event and setting:
Height = ActualHeight;
Width = ActualWidth;
SizeToContent = System.Windows.SizeToContent.Manual;

Scale usercontrol in wpf ? vertical and horizontal scrollbars

I implemented a usercontrol, but i have a problem with rescaling the window. I know when i make the window smaller, everything scales, and every textbox and label becomes also smaller. But this is not what i want, i just want that when i make the screen smaller, everything stays the same size, and that scrollbars appear ( vertical and horizontal ). How do i do that?
Thanks
Assumption
The behaviour you describe, is not mandatory the default layout-behaviour of WPF. It depends on the layout-controls you use. I assume, you're using a Grid with setting it's columns and rows to the Start (*)-GridLengths. This would have more or less such an effect as you describe (without scaling). Or maybe you are using a ViewBox, this control scales the whole content based on the available layout size.
Solution
I guess that wrapping your whole content into a ScrollViewer will probably do what you desire. If not, I suggest that you post some XAML-code to show us how you have built your content.
<ScrollViewer>
<YourContent>
</YourContent>
</ScrollViewer>
Update
If you really scale your window (applying a ScaleTransformation) and you want your UserControl to be the only control within that does not scale, you have to scale your UserControl in the opposite direction as you have done it with your window. Apply a ScaleTransformation and set the scale values to 1/scale. Or try to use the ViewBox to blow up the content of your UserControl, but this will not be very exact.

Is there a way to automagically make a canvas scroll on overflow in WPF?

Been checking the web and this site, but couldn't come up with any descent results.
Is there a way to make a canvas in WPF show scrollbars on overflow ? Been trying the scrollviewer, but can't get it to work :(
Thanks in advance..
The problem you're running into is that Canvas, unlike many WPF panels and containers, does not size to contents. That means if you add an element which goes outside the canvas boundaries it will not update it's size. Hence embedding a Canvas in a ScrollViewer will do no good unless you manually update the size of the Canvas.
It sounds like what you want is a Canvas which supports size to contents. This blog entry has exactly that control.
http://themechanicalbride.blogspot.com/2008/11/auto-sizing-canvas-for-silverlight-and.html
I took a different approach and abandoned the Canvas for Grid. The Canvas is more performant but for my purposes at least I haven't noticed a difference. The grid can mimic the behavior of canvas by doing the following.
Create a single row,single column grid.
Set the HorizontalAlignment to Left
Set the VerticalAlignment to Top
Use Margin "x,y,0,0" to set the position.
Bam..works just like canvas and it works great in a Scrollviewer.

Resources