I've been banging my head about this seemingly easy task and I could really use some help.
I have a wide Image loaded in the gui (using the designer..) and I want to be able to draw only a portion of it, a rectangle.
I need to be able to change this rectangle position over the large image, in order to draw a different part of the larger image at will. In this process the rect must maintain its size.
Using the Ui::MainWindow object I'm able to access the label holding the image and a solution that involves using this option is preferred (in order to keep up with the rest of the code I've already written )
Any solution will be much appreciated :)
Thanks,
Itamar
I would definitely (for ease of use) just place an empty label as placeholder in Designer.
Then implement the paintEvent for this label (delegate it to your own method). You'll have also have to look into QPainter, QPixMap, etc... Should be doable based on these hints and the documentation.
If you want more, I suggest you provide a small code snippet to work upon.
If you want to do this more or less purely through designer, you could put a QScrollArea where you want the portion of the image to appear. If you set the scroll area's scrollbar policy to be never shown, you can then manually change what part is visible via the scroll area widget. However, this would probably be more complex that creating a derived widget and reimplementing the paint function.
Related
I have been working on using Drag and Drop with JavaFX, and one thing I notice is that items are given lowered opacity compared to their actual images, as well as the larger the image the made "Faded/transparent" the image gets. I am working on am application that can drag fairly large items which end up almost invisible when dragging, which defeats the purpose of using a DragView Image in the first place, and makes this unusable for larger items (the way I'm using the DragView I want the images to be a certain size compared to the scene in which I'm dragging onto).
My application essentially has 2 Windows (Stages) where the data is in one Stage and I get the item from a list and drag it onto the scene. The DragView image is a representation of the object going onto the scene, so when I drop the DragView Image, it gets dropped exactly into place on the scene, so the DragView is important to my overall application.
Just a NOTE: There is also backing data in my transfer in order to recreate the box, as well as additional data that gets transferred with the Drag and Drop.
I tried looking at the FX DragView Internal code but didn't find anything that sets the Opacity or anything like that, so one of my assumptions of "it's built into the OS" is something I keep thinking about, as lowered opacity is something I remember being built in, and when trying it it does happen, but very very slight, and not as bad as what I'm experiencing (Also possible that since the icons are much smaller they don't run into the "larger image opacity issue."
I am running Windows 7 64-Bit for those who are wondering.
My question is, is it possible to change the opacity settings of the Drag and Drop ImageView either via JavaFX or possibly Native with using something along the lines of JNI?
I don't have any example code at the moment, but can add if someone is interested, but I'm sure for those who know about Drag and Drop ImageViews should already know about the opacity.
Thank you all.
I'm trying to build a game that uses a concept from the known game "The Sims". Right now I'm building the AI for a 3d Character, and I need the player to be able to tell where the character should go or do. I want to know the best ways to create a pop up menu with animations, kind of to show some choices, so that when the player clicks over the 3d Character he can pick wherever he wants to do. I know this must be using UI elements under a Canvas that's placed over the player. However I can not have 2 Canvas in a Scene and I don't know how to fix them to the character so that it moves with him. Thanks in advance.
Here you can see what I mean, this is the Sims Game
You have two main approaches here:
1) Use a world space UI.
2) Use a screen space UI and position it in real time using a worldspace to screen space transformation.
Both of these topics will expand substantially when you approach them, so it's not possible to give any more specifics from here.
Having played the Sims a bit before though, I would suggest you use a world space UI system if you're chasing the same style as them.
You can have as many canvases as you want. To control levels of canvases (which one is on top) you use "Order in Layer" parameter in "Canvas" component of your chosen Canvas. The lower the number is the higher interactivity and visibility your canvas has.
You can create one canvas ant parent it to you character. AS the canvas will be smaller your should play with these parameters to get the resolution you want (don't over do it):
To make canvas always facing the camera you should give Canvas a new script, with a command:
canvas.transform.LookAt(camera.transform);
To control canvas' visibility you may use this code line:
canvas.enabled = bool;
Where bool is false when you want to hide it and bool is true when you want to show it.
In the "Sims" the visibility comes with animation which you may do also, but I would leave it after I did all the functionality.
I have built so far an application that allows the user to drag and drop images onto a NSImageView. However, I want to be able to move these images by simply clicking on any image and hold down the mouse button to move it's location.
How can I manipulate NSImageView to translate/scale after setting the images down? Is that possible? I've read about the NSAffineTransform, but it seems like that is moving the images before creating the image itself. I already have the images on the canvas, and simply want to click and hold the image and move it with my mouse. Please help anyone!
There are two sides to this.
NSImage is the model object, which you might want to display in different ways, save to disk/archive, etc. If you want to actually change the model (scaling, rotating, etc.), implying a permanent change, then you are going to probably want to look at NSAffineTransform, Quartz drawing, etc.
But you probably didn't mean that. Instead you probably are interested in NSImageView, which is a view object, displaying the contents of the NSImage model object using whatever display attributes are desired. If you only want to change how an image is displayed, not what the actual bytes in the image are, then you are going to manipulate the NSImageView at run-time. You can use NSAffineTransform here as well, but it's somewhat uncommon (and usually unnecessary).
The key thing to note that is the NSImageView inherits from NSView, so you have all its power at your disposal. Take a look at certain methods, such as:
-setFrameSize: - useful for changing the view size, and thus the image display scale
-setFrameOrigin: - useful for changing the view position, and thus the apparent image position
Note again that these have nothing to do with images per se, and apply to all Cocoa views. You may want to take a look at a book like Cocoa Programming for Mac OS X to get you past the basics. (You can then do more interesting things, like rotation, animation, etc.)
I have an NSMutableArray of jpg images and I want to be able to touch and, moving my finger from right to left, move through the array of images in order. I've been reading about UIScrollView, but I'm not sure if this accomplishes what I am looking for. It seems to me that UIScrollView is more used for viewing an object that is too large to be displayed entirely on the screen and you need to be able to move to see every part of the object. I need to move to an entirely new image, the next image in my array. What is the best way to go about this?
You certainly can use a UIScrollView for what you want. A scroll view can be used, as you noted, to scroll an area that is too large for the screen. However, you can also use it to scroll through "pages". This is really the best way to do what you want, short of rolling your won scroll view.
There is a property of UIScrollView, called pagingEnabled, which you'll want to set to YES. I suggest that you give it a try. Also, have a look at the UIScrollView documentation and the Scroll View programming guide. It will tell you all that you need to know about UIScrollViews. Also, remember that for proper memory management, you'll want to only load three images at any given time. See this answer that I wrote for more information on that, and on UIScrollViews in general.
A coworker is encountering an error when he tries to run a VB6 app we're working on. The error is, "480: Can't create AutoRedraw image". Microsoft's documentation says this is because "There isn't enough available memory for the AutoRedraw property to be set to True. Set the AutoRedraw property to False and perform your own redraw in the Paint event procedure or make the PictureBox control or Form object smaller..."
Making the PictureBox smaller isn't an option. I'd be glad to "...perform my own redraw in the Paint event procedure...", but I'm not sure how to go about it. Can someone show me the way?
Without details this will be a simplistic answer. In general most beginning VB6 programmers use AutoRedraw=True draw in responds to some input. Fill out some data, click draw, and it appears in the picture box.
The click event in the Draw Button is linked do your drawing code. The first step is move the call to the drawing code to the paint event of the picture. The second step is to replace all calls to the drawing code with MyPictureBox.Refresh. Refresh forces the paint event of that picture box to fire.
The main problem you will have to be concerned with is that the paint event is going to be fired everytime the form needs refreshed. Like if a window covering it is moved. This means that any speed issue in your drawing code will be exposed. AutoRedraw=True takes what you drew and puts in a hidden bitmap that the PictureBox uses to display what you drew.
The Paint event will execute each step of your drawing process so you have to make sure you are as fast as possible. Depending on how dynamic your application is the worse slowdown issues will become. If you are displaying a static image then the problem isn't as bad.
Making the PictureBox smaller isn't an option. I'd be glad to "...perform my own redraw in the Paint event procedure...", but I'm not sure how to go about it. Can someone show me the way?
That is easy. You just implement the _Paint()-Event of your Form or PictureBox and draw.
Because you are asking, i think i should clarify what the AutoRedraw-Propeprty does. If it is set to true, you can "just draw your image" any way you want. In multiple steps. Whatever. If it needs to be redrawn, for example, because another windows was on top it, it will be magically done. The down site is, that is slow, for the drawing part.
If AutoRedraw is false, no magic will happen. The Paint()-Event will be fired and you are responsible to draw your image again. This will be much faster, if your window is not "invalidated" (e.g. "covered") often. Or you are doing a lot of drawing.
Or you are running out of memory for the "magic space" ;-)
If you don't mind rewriting your graphics code to use the GDI API - this could be a fairly big task - I found this thread from 2006 in the VB6 discussion group, where Mike Sutton said in answer to a similar problem:
VB's back-buffer implementation uses a
Device Dependant Bitmap (DDB) to store
the image data, which is quite limited
in how large it can be made. On older
OS' this used to be ~16mb uncompressed
data size, on later OS this has been
expanded but is still quite
restrictive.
A workaround for this is to use a
Device Independent Bitmap (DIB) and
manage the GDI resources yourself,
have a look at the DIB article on my
site for an example of how to work
with them.
I haven't tried it myself.
There's usually a drop-down box of events for your control in the forms code window. You need to pick the paint event:
Private Sub object_Paint()
and fill in your your code for drawing on the PictureBox.