I have to make an app with 2d drawing for Windows RT. I don't know how can achieve that. Drawing with xaml is not a option, because I have to draw it at run time, and the content of graphic will varies. I am looking for something like android's View and it's onDraw() method, Is that possible?
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I want to build a simple Xamarin app that can draw shapes with editing handles. I can then drag and drop the handles to edit the shapes. This can be done with Syncfusion image editor controls but the shapes I wanted are not available.
Can anybody give me some clue about what should I do? Or point me to an open-source project?
Shape examples
SkiaSharp is a 2D graphics system for .NET and C# powered by the open-source Skia graphics engine that is used extensively in Google products. You can use SkiaSharp in your Xamarin.Forms applications to draw 2D vector graphics, bitmaps, and text.
You can refer to the tutorials in the following link:https://learn.microsoft.com/en-us/xamarin/xamarin-forms/user-interface/graphics/skiasharp/basics/
Is there a way to get OpenGL context from native code? Lets say, I need to draw something from my obj-c code. Anything, some object, complex bezier curve etc. I know that I need enterprise account. So I'm asking just about the OpenGL context. How it will look like and how to do it?
Corona Enterprise has APIs that allow you to interact with the Corona "Environment" from the native code. But I don't think it is possible to add something inside the Corona OpenGL (i.e, possible may even be, but Corona doesn't make that easy for you).
Usually when you draw or add something from the native code, like an image, you add that image to overlay view that is above the Corona OpenGL view. (In fact, that is why when using Corona Pro, all native objects always appear above of your corona elements)
Something like dragging and dropping an image
Is there a basic sample that I can use for that purpose?
You can use OnManipulationStarter, OnManipulationDelta and OnManipulationCompleted events with TranslateTransform on some object to move it below your finger.
Also, advanced stuff will be MultiTouch Behavior for Windows Phone 7
This is basically a scoping question, where would I look for the facility to render window contents to 3d surfaces and manipulate them? I mean can I have a program like a shell that composites live windows in 3d like the Vista DWM's 3d Task Switcher and can translate UI interactions back into 2d interactions for each window?
I've seen mention of DWM extensions here and there on the web but can't find any resources as to how that would work. Also there are guides to implementing DWM Thumbnails by relating two windows' HWNDs but that doesn't allow me to do arbitrary transforms on the window and is display only (you can't click on stuff in the thumbnail.)
Any ideas?
There is no interface for manipulating the DWM's 3D visuals. They are internal to the DWM.
Through experience I have found that the native windows forms/components don’t like to be changed. I know using Delphi or Visual Studio you are given native windows components to populate a form or window with and then you attach code on events that these components may do (onClick for example).
However, how do all of these programs like Word or google’s Chrome browser alter the standard windows’ window? I thought it was somehow protected?
Chrome seems to have tabs actually on the window’s frame?
I know you can also get toolkits like Swing and QT that have their own controls/components to populate a form. How do these work? (How does the operating system/computer know what a non-native button should act like? For example; Chrome's back and forward buttons, they're not native components?).
I can understand how OpenGL/DirectX window would work because you’re telling the computer exactly what to draw with polygons/quads.
I hope this question is clear!
Windows does not protect GUI elements. Windows and controls can be subclassed to handle various drawing operations in a custom way. For example, windows may override and reimplement the handling of the WM_NCPAINT message to draw a custom titlebar and frame:
http://msdn.microsoft.com/en-us/library/dd145212(VS.85).aspx
Some Windows controls have an "owner-draw" mode. If you use this, you get to draw the control (or at least vital parts of the control), while Windows takes care of responding to user input in the standard way.
Swing ant QT draw their own widgets at a low level using basic primitives, but they also have theme engines which can mimic the native controls.
Qt moved to native controls a while back. As for how swing does it, it gets a basic window from the OS. Then much like Opengl\Directx it does all of the drawing with in that window. As for where to position things that is what the layout managers do. Each manager has a layout style horizontal, vertical, grid, components it has to draw and a section of window it is expected to fill. From there it does some pretty easy math to allocate its space to its controls.
There's no magic: non native controls are simply drawn on a blank window. Or, instead of being drawn they may be represented as one of several bitmaps based on state (ie: a button may be represented as a .png for the normal state, another .png for the pressed state, etc)